The Mars Exploration Rover 'Spirit' safely lands on the Red Planet

The Mars Exploration Rover Spirit lands on the Red Planet on January 3, 2004. 21 days later, its twin, Opportunity, also arrived safely. In one of the longest and most successful missions in NASA history, Spirit would survey Martian geography for the next seven years, while Opportunity remained active until June of 2018.

The rovers' primary mission was expected to last 90 sols, the term used for Martian days. In March, scientists announced that they had made a momentous discovery: a survey of Martian rocks strongly suggested that water had once flowed there, and analysis of Opportunity's landing site indicated that it had once been the bed of a salty sea. Later in 2004, Opportunity also discovered the first meteorite to be found on Mars.

The rovers continued to explore Mars for several years, with Spirit becoming a "stationary research platform" after getting stuck in sand. Spirit eventually fell out of contact with NASA, which declared its mission over in 2011. Opportunity, however, continued exploring. In 2014, it broke the record for longest distance driven by an off-Earth wheeled vehicle, and the next year NASA celebrated as Opportunity finished a "marathon," having traversed over 26.2 miles. In February 2019, NASA announced the end of the MER mission after Opportunity ceased responding to their communications. The rover had broken several other records, including the highest elevation reached on Mars, and sent back 224,642 images. Having far surpassed its original goals and contributed greatly to human understanding of Mars and its potential to host life, the MER mission had a major impact on mankind's knowledge of our solar system.

READ MORE: The Amazing Handmade Tech That Powered Apollo 11’s Moon Voyage

Perseverance Has Landed! Mars Rover Begins a New Era of Exploration

Humanity&rsquos on-again, off-again exploration of Mars has lived through its latest make-or-break moment, and scientists around the world are breathing sighs of relief.

Shortly after 3:44 P.M. Eastern time today, a visitor from Earth fell from a clear, cold Martian sky into a 3.5-billion-year old, 50-kilometer-wide bowl of rock, dust and volcanic ash called Jezero Crater that once held a large lake. Seven minutes earlier, it had touched the top of the planet&rsquos atmosphere at nearly 20,000 kilometers per hour, bleeding off most of its speed through friction, protected from the resulting fireball by a heat shield. A supersonic parachute the size of a Little League baseball field unfurled to slow it further, followed by a final computer-piloted descent on a robotic jetpack called a sky crane, which used a detachable tether to gently lower the visitor to rest upon the crater floor. Far overhead, orbital spacecraft monitored its progress, awaiting the first signals confirming its successful landing, which, beamed Earthward at the speed of light, would arrive at our planet some 11 minutes later.

At long last, NASA&rsquos Mars Perseverance Rover has arrived. Conceived a decade ago and distilled from the dreams of generations of scientists, the car-sized, nuclear-fueled rover launched in July 2020, months into a world-transforming pandemic, traveling nearly a half billion kilometers in seven months and surviving a high-tension seven-minute planetfall from space to reach Jezero Crater&mdashwhere its real hard work will now begin.

Perseverance (or even just &ldquoPercy,&rdquo for short) is meant to trundle across the terrain for at least a Martian year (two Earth years), following an ambitious to-do list. Explore the environment with rock-vaporizing lasers and ground-penetrating radar, and snap high-resolution panoramas, 3-D stereograms and microscopic close-ups with a suite of sophisticated cameras? Check. Listen to Martian soundscapes, and create weather reports with onboard sensors? Check. Test a device for manufacturing oxygen from the suffocatingly thin air, and launch Ingenuity, a first-of-its-kind four-bladed Marscopter on sorties through those alien skies? Check.

According to Matt Wallace, the project&rsquos deputy project manager at NASA&rsquos Jet Propulsion Laboratory (JPL) and a veteran of all previous Mars rover missions, those latter two tasks and Perseverance&rsquos overall complexity make it &ldquothe first one I think of as a human precursor mission.&rdquo Scaled up, its oxygen-producing experiment, MOXIE, could provide breathable air and rocket fuel for future astronauts, who could also use more advanced Marscopters to scout out their surroundings.

But, truth be told, all of that is secondary or supplemental to Perseverance&rsquos true reason for being, which is to determine if life ever existed on Mars&mdashand if it ever will.

Mars Exploration Rovers Update: Spirit Perseveres, Opportunity Arrives at Victoria Crater

The Mars Exploration Rovers are reaching new milestones and gaining newfound energy as winter slowly begins to pass on the Red Planet. Once again, Opportunity commanded the spotlight as it pulled up to the rim of the massive Victoria crater this week and began returning images that may redefine the word spellbinding. Twin sister, Spirit, meanwhile, is resigned to stay in its northward-tilted position for another month looking at the same scenery in order to collect the maximum energy supply for its solar panels.

"We're all pretty focused now on Victoria -- looking at these new NavCam [navigation camera] images and salivating over the PanCam (panorma camera) images, and wondering what we'll see next," said Bruce Banerdt, MER project scientist in an interview with The Planetary Society.

Ohhh -- Victoria
Opportunity reached the rim of Victoria rater in Mars' Meridiani Planum region with a 26-meter (85-foot) drive on Sol 951 (Sept. 26, 2006). "This is a geologist's dream come true," said Steve Squyres of Cornell University, principal investigator for the twin MER rovers. The far wall in this image is approximately 800 meters (one-half mile) from the rover.Credit: NASA / JPL-Caltech / MSSS / OSU

After finishing work on a trench it dug midway across the Victoria Annulus in August, Opportunity essentially spent September on the road to Victoria. The rover did stop briefly at Emma Dean, one in a small cluster of craters on the road to Victoria's rim, but then in short order continued its journey to the grand dame of craters.

Victoria was but a pipedream for Opportunity when the twin robot field geologist landed in January 2004. Within the last couple of days, however, the once impossible dream came true and the rover is currently just a few meters from the rim. It is finally -- after a 21-month journey across the flat plains of Meridiani -- there.

Of course, chuckled Steve Sqyures, the lead rover scientist, of Cornell University, "[a]t the risk of sounding like President Clinton, it depends on what your definition of 'there' is? By which I mean," he continued with a more serious tone, "at what point do you decide you've arrived at the rim? We're not going drive right to the rim on our very attempt and hang 2 wheels over the edge. We're going to get to a safe standoff distance from which we can see enough of the crater to make good decisions," he told The Planetary Society earlier this week. Opportunity has arrived at that safe position.

Measuring some 800 meters (about half a mile) in diameter, Victoria offers the science team untold scientific riches, giving them a glimpse not only into the subsurface, but into Mars' geological history. The initial images from Opportunity's first overlook of Victoria crater show rugged walls with layers of exposed rock and a floor blanketed with dunes. "This is a geologist's dream come true," said Squyres. "Those layers of rock, if we can get to them, will tell us new stories about the environmental conditions long ago. We especially want to learn whether the wet era that we found recorded in the rocks closer to the landing site extended farther back in time. The way to find that out is to go deeper, and Victoria may let us do that."

Spirit, meanwhile, has made some impressive achievements. It spent the month of September at Gusev Crater completing the fill-in images for the McMurdo pan, which is the largest panorama taken on the mission, garnering the rover yet another respectable 'first.'

In addition, it methodically continued its routine analyses of the elemental composition of dust on its magnets and in the atmosphere, and collecting data for the sky and ground surveys that it has been taking all winter from its position at Low Ridge in the Columbia Hills area. By the time the Martian winter is over, this rover will have collected more data about this one spot on Mars than has ever been collected about one locale before, a wealth of data that should better inform both planetary and atmospheric scientists.

The best news for Spirit is that its electrical power increased slightly mid-month, as the Sun began to ascend higher in the sky. With the "superior conjunction" -- a 2-week period when Mars orbits out of sight behind the Sun -- coming up -- the rover will stay in place for at least another month. After conjunction ends on October 29, the rover will finally move, making a clockwise turn to the right to put the instrument deployment device (IDD) within range of some new targets, including a little trench carved by the rover's dragging right front wheel as it pulled in backwards to Low Ridge. While Spirit will be keeping a mellow work profile during the next four weeks or so, focusing on the atmospheric observations that are part of its winter campaign, the action on the other side of the planet, at Meridiani Planum, is certain to keep the rovers in the news.

Overall, Spirit and Opportunity remain healthy. "The rovers are both doing great," reported Squyres. Although each rover has experienced an operational hiccup here and there, overall September proved smooth sailing in terms of their field work. Once again, there has been virtually no change in the performance of either rover's suite of instruments this month, "even the mini-thermal emission spectrometer (mini-TES) on Opportunity, which we've seriously abused," Squyres noted.

One of the big activities for both Spirit and Opportunity in September was booting up with their new flight software, Version R9.2. As it turned out, both rovers successfully woke up in their new software despite some dramatic scrambling by rover handlers to command both MERs to switch to new flight software during a bit of a traffic jam at the Red Planet. The X-band frequency for communicating directly with Earth -- the team's high-speed connection so to speak -- was in use by the Mars Reconnaissance Orbiter which was undergoing critical events for that mission. Engineers seamlessly switched to the back-up plan of using the UHF-band frequency to relay commands indirectly to the rovers via the Mars Odyssey orbiter. Time was of the essence, though, if they were going to begin running and testing the new software before the solar conjunction begins on October 18 making radio communication intermittent at best for a couple of weeks. Everything was going fine. But then -- there was another little wrinkle.

"We were booting the R9.2 software and a network failure occurred here on the ground at JPL, right in the middle of doing all this," said Banerdt. They were able to get the commands up to the spacecraft "through some of relatively heroic work on the part of the ground team here," he said. "We have a back-up command station in another building that's off the main flight network but is connected straight to the Deep Space Network (DSN). Someone finally found a floppy drive that they could use on the machine and walked it across the street to put it on. They regenerated the commands there and sent them up. While they got all the commands up, they couldn't get all the downlinks down. These are all the things that can typically happen, but you hope they don't all happen at once." But in the case, they did.

The MER team lost a couple of days re-doing some of the commanding to make sure the software -- which will give the twins enhanced capabilities -- was working okay. For the most part, the concern was mostly about Opportunity. "Spirit was actually on 2-day sequences, on restricted sols, so it wasn't as affected as Opportunity, which we had planned to command every day," Banerdt explained. "When all this happened, we had to take a day out just to do mobility tests on Opportunity to make sure the R9.2 software worked on Mars the same as we tested it on the ground here."

Since Spirit hasn't moved, it has yet to complete its mobility checks, and most likely won't until it starts to move again. "However, the flight software is identical on both vehicles, so if it works on one it'll work on the other," rationalized Squyres. And, added Banerdt, "[s]o far the software has been working perfectly and we haven't had any unexpected behavior on Mars at all."

In fact, things are going so well with the rovers that the MER team won approval this month for an additional year of funded exploration, a decision NASA made based on recommendations from an outside panel of scientists. [The space agency is also adding two more years of operations for Mars Global Surveyor, which has been orbiting the Red Planet since 1997, and the Mars Odyssey orbiter, in oribt since 2001. The mission extensions officially begin October 1, 2006.]

Spirit from Gusev Crater

At the end of August, Spirit experienced an unexpected software reset during the evening overpass of the Mars Odyssey orbiter on Sol 944 (August 29, 2006) while it was receiving its last command sequences for the month. As a result of the reset, the rover went into automode and did not attempt to execute the master sequence of activities for that day. Apparently, its central processing unit was overworked with several tasks running in parallel at the time.

Low Ridge Haven
Spirit acquired the images in this mosaic of its winter home with the navigation camera on Sol 807 (April 11, 2006). Approaching from the east are the rover's tracks, including a shallow trench created by the dragging front wheel, whichthe rover will investigate incoming weeks. On the horizon, in the center of the panorama, is McCool Hill.Credit: NASA / JPL-Caltech

As September rolled around, Spirit was back in the saddle, continuing to acquire fill-in images for the McMurdo panorama, and conducting its daily observations of the atmosphere and the sky and ground with the panorama camera (PanCam) and the mini-thermal emission spectrometer (mini-TES).

While the electrical power from the rover's solar array held steady for much of the first half of the month at around 280 watt-hours per sol, the rover kept its 1-hour-a-day work schedule. Like it always has, the rover made the most of it, managing to pack in some work on the soil target, Halley Brunt, with the Mössbauer spectrometer during the first week of the month in addition to its almost daily atmospheric observations and sky and ground surveys with the PanCam and mini-TES.

Despite the tedium of the work, the atmospheric monitoring and sky and ground observations are important endeavors because the Martian atmosphere is much more fickle and complex than Earth's. "The Martian atmosphere is a constantly changing thing -- it changes from day to day and with the season and it changes from year to year. There can be inter-annual differences where one year can be different than the year previous," explained Squyres. "So one of the things we do routinely with both rovers is atmospheric monitoring sequences. The sky and ground observations are standard atmospheric monitoring. We try to run the same sequence each day and we try to run it at roughly the same time of day each day so that we get a nice quantitative baseline that provides a continuous record of atmospheric conditions at both of the rover sites."

One of the main ways Spirit has managed to make such efficient use of its time is by multi-tasking. On Sol 957 (September 11, 2006), the once again demonstrated its enviable capacity by acquiring data on the rock target known as Vostok with the mini-TES while transmitting data to the Odyssey orbiter as it passed overhead. In the days that followed, the rover collected another part of the 15-part image mosaic of its own deck with the PanCam, spent about 5 hours acquiring data on the elemental composition of dust on its filter magnets using the alpha particle X-ray spectrometer (APXS), and took PanCam pictures of the soil target consisting of bright material in the rover’s tracks, known as Tyrone.

As the days passed, the Sun began to rise higher in the sky and Spirit began to experience an upward trend in electrical power, to 287 watt-hours during that second full week in September. The rover increased its workload accordingly, conducting 10 hours of analysis on the elemental composition of dust on its magnets using the APXS, in addition to finishing taking the pictures of its deck for the McMurdo pan, and conducting its daily atmospheric research.

On Sol 960 (September 14, 2006), Spirit mixed things up a bit by taking a morning measurement of sky brightness in the west with the PanCam (known as a PanCam skyspot) and a horizon survey, as well as searching for clouds using the navigation camera (NavCam), and taking pictures of the El Dorado dune field with the PanCam, and the ripples with the rear hazard avoidance camera (HazCam). The rover filled that weekend acquiring data from a target dubbed Macquarie and from from the calibration target with the mini-TES, again searching for clouds with the NavCam, acquiring the last segment of the 15-part panoramic mosaic of its own deck, and conducting a 4-hour and 35-minute APXS analysis of the filter magnets. In addition, Spirit acquired sky images with the PanCam and validated measurements of complete darkness by the camera.

Fragment of Spirit's McMurdo panorama
Since it's been parked at its winter quarters, Spirit has been working on capturing the largest panorama ever -- a 360-degree view of the surroundings through all 13 filters at very high resolution. This fragment of the McMurdo panorama consists of 16 individual frames captured during Sols 856 to 869 (May 31 to June 11, 2006). Although the view is through the rover's red, green, and blue filters, it is not correctly calibrated, making the sky appear blue and enhancing color variations in the rocks and soils.Credit: NASA / JPL / Cornell / Midnight Mars Browser

Last week, Spirit got off to a roaring start on Sol 963 (September 18, 2006), acquiring images of its tracks with the navigation camera, taking microscopic imager (MI) pictures of the filter and capture magnets, and placing the APXS on the capture magnet. It also took some pictures of its work volume with its HazCam, monitored dust on the PanCam mast assembly, surveyed the horizon with the PanCam, and searched for morning clouds with the navigation camera. But on the following sol, Spirit got an unexpected break.

Rover handlers originally planned to have the rover boot into the new flight software by sending a command over the X-band uplink, but the X-band became suddenly unavailable when it was needed by the Mars Reconnaissance Orbiter (MRO), so Spirit essentially stopped – and then sat, awaiting instructions from Earth. The team sent the reboot command via the UHF-band antenna on the Odyssey orbiter later the same day. And at 11 a.m. local solar time on Sol 965 (September 20, 2006), Spirit woke up for the first time running the new flight software, known as version R9.2.

During the next 2 sols the science activities were light as Spirit ran a series of engineering sequences to establish operating parameters for data products and imaging, and operating parameters for driving and operating the rover's IDD. By Sol 968 (September 23, 2006), Spirit had returned to relatively normal science operations without moving the IDD, as team members awaited confirmation that the rover had established the correct operating parameters for the arm. The rover was able, however, to complete 5 hours of analysis of dust on the rover's capture magnet using the APXS.

Since then, the rover has experienced another power bump. "The power is starting to creep up a little bit at the Spirit site," Squyres confirmed. "The last numbers I saw were a shade above 290 watt hours." [100 watt hours is the energy it takes to power a 100 watt bulb for 1 hour. 500 watt hours is considered good for the rovers, with 850-900 being optimum.]

"The atmospheric dust – which did rise there around the beginning of September -- has gone down a little bit over the last week or two, and it's been dropping since then," expounded Banerdt. "So our energy is finally showing a steady upward trend now."

Spirit has turned its attentions almost entirely to atmospheric studies now, measuring surface reflectivity with the PanCam, measuring atmospheric dust, and completing its morning scans of the sky and ground with the mini-TES, following it with similar observations in the afternoon. The rover is also regularly measuring sky brightness to check for changes over time in the PanCam.

Although the plan has been to have Spirit make a turn to the right once its power rose above 300 watt hours, even if the power rises to an acceptable level in the next week or so, the coming solar conjunction is putting that maneuver on hold. "We're going to turn after conjunction. We don't want to do it before," said Squyres.

Actually, all activities will be pre-commanded and kept to a minimum. The reason is that when Mars goes behind the Sun, the radio signals must then try to pierce through the edge of the Sun to make contact with the spacecraft on the other side. When contact is made, the signal is usually corrupted, so there will be a Command Moratorium in place for the rovers. "We will be attempting downlinks from the spacecraft to Earth pretty regularly, but for safety's sake, we can't depend on being able to use that data," said Banerdt. "Experience shows us we can use a lot of that data. The handlers are very conservative about their link margins in terms of solar activity and the losses through the Sun's corona and things like that, but usually that conservative works in your favor because you get back more than you expect."

Even though Spirit seems to only have "more of the same' in coming days and weeks, its methodical observations of the atmosphere, and surveys of the sky and ground surveys are building a rich bounty of data that will reveal more about this area of Mars than any other single locale characterized by a Martian lander.

Meanwhile, the Spirit team has plenty to keep it busy. The McMurdo pan is complete -- at long last -- and it's a monster of an image. "They finished the last fill-in images so it is complete," confirmed Banerdt. "It hasn't been completely processed, but we've got all the data in hand now to complete the picture."

The main horizon panorama, of course, was released previously, but now the McMurdo pan includes the deck portion of Spirit to the file of thousands of image squares. "We're working on the processing of that now," said Banerdt.

If the McMurdo pan were printed as a life-size picture in its entirety, and you stood in the middle of a 360-degree image, it would seem as if you were standing in Low Ridge yourself. "It's going to take a pretty big piece of paper to put the whole thing on and -- I can't imagine that -- but I'm confident these guys will rev up their memory machines and crank something out soon. I bring the pan up in PhotoShop now and cruise around and look, then choose something to zoom on and then just keep hitting Command plus, Command plus, Comman plus. You can keep going until you're looking at the sand grains. It's amazing."

Opportunity from Meridiani Planum

Opportunity was still tending to its arthritic IDD as August gave way to September, but all indications were that the inadvertent stall at the end of last month was nothing catastrophic, just the same old intermittent annoyance the rover has been experiencing for a while now.

On the verge of Victoria
Once it was more like a distant dream, now it is the ultimate bonus to an already marvelous Martian mission. Opportunity is on the brink of the expansive Victoria crater, a depression that makes those craters it passed on the Meridiani highway look like dimples. At about 800 meters (nearly half-a-mile) in diameter, Victoria is 5 times larger than Endurance crater. Opportunity took this image with its navigation camera. It is labeled to highlight the crater features. Credit: NASA / JPL-Caltech

On Sol 926 (September 1, 2006) the rover took some MI pictures and used the Mössbauer spectrometer on the scuff it dug in the Victoria Annulus, making up for the time it lost when the IDD froze. In the sols that followed, the rover the used the MI to look at targets in the scuff dubbed Powell and Powell's Brother, then used the APXS on Powell's Brother.

Luck has never seemed to stray far from Opportunity since the day it bounced to a landing inside Eagle crater, and it turned up again on Sol 929 (September 4, 2006), after the rover bumped back, took some pictures with the PanCam, then drove forward toward the small crater referred to as Emma Dean. At the end of that drive, the robot field geologist took some post-drive images showing that it had nearly roved for another "hole-in-one," although this one would probably not have been so fortuitous as the one it made on landing in January 2004. Instead, this "almost" was perfect -- the rover drove 100.31 meters (329 feet) to arrive just 5 meters (16 feet) short of the small crater.

During the rest of that first full week in September, Opportunity took several high-resolution images at different angles with its HazCams, then made a short bump to an ejecta rock and spent the remainder of the week conducting untargeted remote sensing of its general surroundings.

Engineers on the ground, meanwhile, worked on determining from images the rover rook on Sol 931 (September 6, 2006), how much "bite" is left in its rock abrasion tool (RAT) or, in other words, estimating how many more grinds it might be able to get with the tool. Spirit's RAT bit ground down long ago and is no longer useable, although it is still able to brush selected targets.

Victoria crater
This image from the Mars Orbiter Camera (MOC) onboard Mars Global Surveyor clearly shows the "alcoves" of Victoria crater. Opportunity headed up to the rim via Duck Bay, the largest of the "alcoves" which is straight ahead and to the left of Beagle crater.
Credit: NASA / JPL-Caltech / MSSS / OSU

Although Opportunity only drove 1.45 meters (4.8 feet) between Sols 936 and 940 (September 11, 2006 to September 15, 2006), it packed in the atmospheric science during the second week of September. While Americans were remembering 9/11 on the 5th anniversary, Opportunity monitored the amount of dust on itself using the panoramic mast assembly, took daily PanCam taus to assess the clarity of the sky, and in the midst of it all made a short bump to an IDD rock target near Emma Dean called Cape Faraday. The rover then took a PanCam image of the IDD work area, and during the Odyssey pass, multi-tasked with the mini-TES looking at that instrument's calibration target.

In the sols that followed, Opportunity used its mornings for its atmospheric investigations, and then moved on to other tasks, including examining the mini-TES' calibration targets, using its NavCam to search for clouds, and the mini-TES to look at targets dubbed Thompson and Jones. The plan had been to grind into Cape Faraday, but the plan was aborted on Sol 939 (September 14, 2006). "We had another stall in the IDD shoulder motor," explained Banerdt. "We commanded the rover's IDD to move and it seemed to have some hesitation and then the software shut it down as it's designed to do. We went back later and did an exercise and it's just fine. It was like the stall that happened at the end of last month, and there's a hint of something funny going on, but it doesn't seem to be anything seriously at this point," he said. "There are a lot of things that are non-catastrophic that can cause these motors to have little hiccups in them, especially when they gone through thousands of actuations."

"The incident was totally consistent with things we've seen before," added Squyres. "We will see these stalls occasionally and the way we're operating the arm, we actually expect that. There are parameters we can set to try to overcome the bulkiness of the arm. You can set those parameters aggressively or conservatively. If you set them aggressively, faults will be uncommon but you may put the arm at risk. Set them conservatively you keep the arm safe, but faults may be a more common occurrence. We've chosen a fairly conservative set of values that give us good operation of the arm most of the time, and occasionally produces faults [stalls] -- but not so often that it's a big inconvenience and it doesn't put the arm at risk. I think we've found the happy medium. So we do expect to see stalls occasionally and so from time to time we get them, and we just move on."

Cape Faraday, as it turns out, wasn't worth the wear and tear on the RAT anyway. "It was just a very inconveniently placed little piece of outcrop that just wasn't a good RAT target and it turned out to be fairly standard outcrop, nothing special or unusual," said Squyres.

On Sol 940 (September 15, 2005), after finishing its prerequisite atmospheric studies, Opportunity checked out a new rock, named Beaman, with the mini-TES and during the Odyssey pass, the rover use the instrument to look at its own calibration target. During the next couple of sols, Opportunity used the PanCam to image the soil target dubbed Dellinbaugh within Emma Dean, and tested parameters for its IDD with its new flight software.

Victoria crater promontory
This is one of the raw images Opportunity took with its navigation camera (NavCam) and sent home on Sol 952 (Sept. 28, 2006).
Credit: NASA / JPL

Opportunity roved into last week with a 35-meter (115-foot) drive on Sol 943 (September 18, 2006). After the drive, the rover paused and took a mid-drive NavCam mosaic of another crater in the series of small craters where Emma Dean lies just outside Victoria, this one named Kitty Clyde's Sister. It then drove another 25 meters (82 feet) and took images with the HazCams, NavCam, and PanCam of its new location, in addition to making more mini-TES observations of the ground.

Sol 944 (September 19, 2006) was "Boot Day" for Opportunity, so that sol and a couple that followed were primarily dedicated to the rover booting into the new Version R9.2 flight software and testing the imaging and data-product parameters to make sure everything was functioning properly. The MER software engineers also devoted a sol to updating the mobility parameters for the new flight software. The rover managed, however, to fill out the week with some additional remote sensing science.

This week, at long last, 21 months of driving, Opportunity began the long-awaited rove up to the rim of Victoria. All told, the rover has driven more than 9.2 kilometers (5.7 miles) since landing and most of that was to get from Endurance crater to Victoria, across the seemingly endless, flat plain, pocked with smaller craters and strewn with sand ripples.

"We are pulling up to the rim of the crater in an alcove we've called Duck Bay," Squyres detailed. "If you look at the shape of this crater it's got these kinds of cut-outs in it -- those are the alcoves and they're separated by points that jut out into the crater and those are the promontories," he explained. "When we pull up to the rim at Duck Bay, there are 2 promontories – one to our right, Cabo Frio, one to left, Cape Verde. Our intention is to pull up to a place along the rim of Duck Bay that's good enough to get a good look at those 2 promontories. Once we've gotten that look, we will choose between the 2 and we will immediately turn back away from the rim and head toward the tip of that promontory. So I don't know how close we're going to get at Duck Bay -- it could be 3 meters or 5 meters or 10 meters back I don't know. But we're going to pull up close enough that we get a good look at CF and CV and pick one of those 2." The jaunt toward the promontory they choose could happen as soon as this weekend, said Squyres.

Victoria crater promontory
This raw PanCam is one of the images Opportunity sent down on Sol 952 (Sept. 28, 2006). Credit: NASA / JPL / Cornell University

If you think Victoria crater was named for Queen Victoria, you're not thinking enough like an explorer. "The Victoria was one of Magellan's ships -- the only 1 of Magellan's fleet of 5 ships that completed the full circumnavigation of the globe," explained Squyres. Ferdinand Magellan took an expedition around the world in the 16th-Century. "Magellan left Spain with 5 ships and 260 men," Squyres continued. "And 3 years later, 1 ship, the Victoria, with 18 survivors onboard, made it back to Spain. Victoria crater is named after that ship. This pre-dates Queen Victoria by quite a few years," he points out.

Following that suit, the MER team has chosen to name the main features around the rim -- the promontories and the alcoves -- after places that were visited by the Victoria by Magellan's expedition during it cruise around the world. "Cape Verde, Cabo Frio, and Duck Bay -- Baía dos Patos in Spanish -- were places that were visited by Magellan while he was still in the Atlantic," informed Squyres. Cape Verde is an archipelago off the west coast of Africa (located at 15.02N, 23.34W) comprised of 10 main islands and some 8 islets. "Cabo Frio and Duck Bay are both on the eastern shore of South America," he continued. "Actually, they called it Baía dos Patos because they thought they saw ducks there, but the ducks were actually penguins. Nobody had ever seen penguins before, so they didn't recognize them for what they were. But that's what they were seeing." Little did anyone realize at the beginning of the mission how much rover fans would learn about their own history through the rover jaunts across the Martian landscape.

During the last 2 days, Opportunity has moved closer to the rim and sent back some exciting new images. Late last night, Squyres posted his update on his website ( "The last couple of days have been among the most exciting of the entire mission," he wrote. "The only other events I can compare this to are the two landings and the arrival of Opportunity at Endurance crater."

The order of business now, he reported, is going to be to take "a very big Pancam panorama." That work will begin soon and once it's done, the team has decided to head for -- Cape Verde. That doesn't mean, he wrote, "that we're going to traverse clockwise around the crater. we won't make that decision for quite awhile yet. And it also doesn't mean we'll never go to Cabo Frio."

It does mean that as Opportunity begins its in-depth investigation of Victoria and travels further back in Mars' past than it has gone before, the MER mission will begin anew once again.

Driving Mars Exploration: How the Perseverance Rover Will Pave a Path into the Future

If all goes according to plan, the landing of the Mars 2020 Perseverance rover (“Percy”) tomorrow (February 18, 2021) will mark the start of NASA’s ninth surface mission on the Red Planet. Percy will touch down in Jezero crater on Mars, where she will set off exploring new and uncharted terrains in search of ancient signs of life. Nearly 60 years have passed since the first spacecraft were sent to Mars, and it’s inspiring (albeit sometimes unbelievable) to reflect on the progress that has been made since then. First, we sent spacecraft to fly-by, then to orbit, then to land, and finally to rove. As we’ve become more familiar with Mars over time, and as our technological capabilities have improved, our methods of and goals for exploration have evolved in turn. And with each new mission, humans have pushed the boundaries a little more—or in the case of Percy, a lot more. Here I highlight three new (and particularly challenging) aspects of the Mars 2020 mission that distinguish it from previous missions and that have the potential to significantly impact the future of Mars exploration.

​​This illustration depicts NASA's Perseverance rover operating on the surface of Mars. Perseverance will land at the Red Planet's Jezero Crater a little after 3:40 p.m. EST (12:40 p.m. PST) on Feb. 18, 2021.

Bringing Mars Back to Earth

One of the primary objectives of the Perseverance mission is to act as the first leg in a Mars Sample Return (MSR) campaign that is being planned jointly by NASA and the European Space Agency. The rover's role in this interplanetary relay race will be to collect scientifically compelling rock samples and to place these samples in designated locations on the surface. Eventually, another rover will be sent to Jezero crater to retrieve the samples that Percy stockpiled. This fetch rover will then transfer these samples into a Mars Ascent Vehicle (MAV) that will launch into orbit and rendezvous with an Earth return orbiter one last handoff between the spacecraft, and the samples will be on their way back to Earth. Pretty cool, huh?

But let’s be clear. MSR is complex—technologically and logistically. Sample collection alone relies on an incredibly intricate and multifaceted robotic system: first the rover arm is used to drill a rock and collect drilled material in a small sample tube the sample is then transferred into the rover’s body to undergo a series of inspections finally, the sample tube arrives at the sealing station, where it gets hermetically sealed for the trip back home. Every step of this process requires extreme precision, and Percy may perform this task more than thirty times during her mission. Of course, Percy isn't totally autonomous, so there will also be some very real challenges for us humans to make decisions regarding where to drive, which rocks to drill (and which not to drill), and where to stash samples so that they can be accessed by the fetch rover. These decisions will spark healthy debate amongst the team, no doubt, but I would expect no less given the gravity of the task at hand. The rover can only collect a finite number of samples, and how the team chooses to handle those samples will have an impact not only on the success of this mission but on the success of the MSR campaign as a whole. This distinguishes Perseverance from prior Mars missions and increases the stakes even more.

Mars Ascent Vehicle concept for Mars Sample Return.

Even if Perseverance flawlessly executes her portion of the MSR campaign, there will be a great deal more work required to get the samples back to Earth. It will take a lot of time and money, multiple missions, and new technologies that have never been used on Mars before. But the potential payoff is big. By enabling scientists to study these samples back on Earth where they have access to a much more diverse set of scientific instruments, MSR offers an opportunity for us to make significant progress in our understanding of Mars' geology and potential habitability, and it will also help us plan for future human missions to the Red Planet. Rock samples brought back to Earth from the Apollo missions are still being studied decades later, and Mars samples would be no different. With MSR, Percy will continue to provide science long after her own surface mission is complete. In this sense, Mars 2020 is more than just a mission, it’s the start of an ambitious new endeavor in planetary exploration and one that has the potential to change the way we study Mars for years to come.

Schematic of overall Mars Sample Return campaign strategy.

Learning to Fly on Mars

Percy isn’t traveling alone. The rover is bringing along a small helicopter, Ingenuity, which will conduct a set of test flights shortly after landing—the first powered flights ever attempted on another planet. But flying a helicopter in the thin Martian atmosphere is no trivial feat. Mars’ atmospheric density is roughly a hundred times lower than Earth’s, making it harder for the helicopter to achieve lift. Ingenuity has undergone many tests in preparation for flying on Mars, including in wind tunnels with a Mars-like atmosphere. Still, we’re never able to fully simulate Martian conditions here on Earth, especially since we can’t escape our own terrestrial gravitational field. And while the lower gravity on Mars should theoretically make it easier for a helicopter to lift off the surface, nature never quite works the way we expect it to. So, all eyes will be on Ingenuity during this exciting extraterrestrial experiment.

The first of its kind, Ingenuity is what’s known as a “technology demonstration.” The helicopter flights are technically a separate project from Perseverance if the helicopter doesn’t function as expected, it will have no impact on the overall success of the Mars 2020 mission. But if the flights are successful, they could introduce a novel way of exploring the Red Planet. In fact, the first Martian rover, Sojourner, was a technology demonstration on the Mars Pathfinder mission, and its success led to a new generation of roving vehicles on Mars. Sojourner was followed by the Mars Exploration Rovers Spirit and Opportunity, then Curiosity, and now Perseverance. So, if Ingenuity has similar success to Sojourner, it’s not far-fetched to think that more helicopters might make their way to Mars in the future.

Illustration depicts Mars Helicopter Ingenuity during a test flight on Mars. Ingenuity was taken to the Red Planet strapped to the belly of the Perseverance rover (seen in the background).

Ingenuity, a technology experiment, will be the first aircraft to attempt controlled flight on another planet. It will arrive on Mars on Feb. 18, 2021, attached to the belly of NASA's Mars 2020 Perseverance rover. Ingenuity is expected to attempt its first flight test in spring 2021.

NASA's Jet Propulsion Laboratory built and will manage operations of Perseverance and Ingenuity for the agency. Caltech in Pasadena, California, manages JPL for NASA.

There are many potential benefits provided by an aerial spacecraft. Not only can a helicopter cover more ground than a rover can, but it can also provide a different perspective of the Martian surface. Ingenuity has two cameras attached to it images taken during test flights will help engineers study flight dynamics and might even be used to help decide where Percy should drive. Helicopters are able to capture the surface from above but at a much higher resolution than can be accomplished from cameras in orbit. This vantage point is incredibly useful for scoping out potentially interesting places to explore on Mars—and on other bodies across our solar system (in fact, work is already underway on the Dragonfly mission, which will send a robotic rotorcraft to Saturn’s moon Titan later this decade!).

Looking Beyond Robotic Exploration

A human mission to Mars has long been considered one of NASA’s strategic exploration objectives. But to be honest, this goal has always felt pretty far off. Whereas prior robotic missions have provided information that will help get humans safely to Mars and back, supporting human exploration has never been an explicit goal of a Mars surface mission. Not until now, that is.

One of the four stated primary objectives of the Mars 2020 mission is to acquire data and test technologies that will help prepare for crewed missions to Mars. Several new experiments onboard the rover will directly address this objective. The Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE) instrument will attempt to turn Mars’ carbon dioxide atmosphere into oxygen that can be used for astronaut consumption and rocket propellent. In situ resource utilization will likely play a key role in any human surface mission, especially due to the large amount of propellent that will be needed to launch a crewed MAV off the Martian surface to return to Earth. Bringing a large reserve of propellent all the way from Earth is costly, so there is great interest in identifying Martian resources that could be utilized to produce fuel on the surface and decrease spacecraft payloads.

The Martian atmosphere is one potential propellent source and subsurface ice is another. The Radar Imager for Mars' Subsurface Experiment (RIMFAX) instrument on Perseverance is the first ground-penetrating radar ever sent to the surface of Mars. It uses radar sounding to “see” many meters below the surface. Radar instruments in orbit around Mars have revealed evidence of vast subsurface ice deposits in some parts of the planet. If this ice could be extracted from the subsurface it could be used to produce fuel in situ. An instrument like RIMFAX could aid in the identification of these ice deposits from the surface (although to be clear, we don’t anticipate such a discovery at Jezero crater).

Artist’s rendition of the Radar Imager for Mars' Subsurface Experiment (RIMFAX) studying the ground beneath the rover.

The rover is also bringing five samples of astronaut spacesuit material, which will be used as calibration targets for the Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals (SHERLOC) instrument. But these samples will also provide a way to study how well these materials hold up under Mars surface conditions. In particular, pervasive Martian dust and radiation at the surface pose significant challenges to human exploration, so it will be critical to design spacesuits that can provide protection and operate effectively in this harsh environment. As someone who would personally love to step foot on the Red Planet one day, I am particularly excited by this aspect of the mission. By acquiring data on Martian surface conditions and testing new innovative technologies, the Perseverance mission will help make human exploration of Mars a reality.

Spacesuit materials being sent on the Mars 2020 rover.

In many ways, the Perseverance mission represents the next evolutionary step in Mars exploration. We have been studying the surface of Mars with landers and rovers for a half-century, and honestly, we’ve become pretty good at it! It would be easy (well, easier—planetary missions are never easy) to continue down this path instead of pursuing new, riskier kinds of exploration. But to quote President John F. Kennedy, we don’t do these things “because they are easy, but because they are hard.” We do them because they challenge our collective capabilities and because the potential risks are well worth the reward of doing something for the first time in human history. Percy will attempt many firsts, and in doing so, she will help carve a new path for future robots and humans to follow, for as much as lies behind us, even more lies ahead.


The primary surface mission for Spirit was planned to last at least 90 sols. The mission received several extensions and lasted about 2,208 sols. On August 11, 2007, Spirit obtained the second longest operational duration on the surface of Mars for a lander or rover at 1282 Sols, one sol longer than the Viking 2 lander. Viking 2 was powered by a nuclear cell whereas Spirit is powered by solar arrays. Until Opportunity overtook it on May 19, 2010, the Mars probe with longest operational period was Viking 1 that lasted for 2245 Sols on the surface of Mars. On March 22, 2010, Spirit sent its last communication, thus falling just over a month short of surpassing Viking 1's operational record. An archive of weekly updates on the rover's status can be found at the Spirit Update Archive. [17]

Spirit's total odometry as of March 22, 2010 (sol 2210) is 7,730.50 meters (4.80 mi). [18]

The scientific objectives of the Mars Exploration Rover mission were to: [19]

  • Search for and characterize a variety of rocks and soils that hold clues to past water activity. In particular, samples sought will include those that have minerals deposited by water-related processes such as precipitation, evaporation, sedimentary cementation or hydrothermal activity.
  • Determine the distribution and composition of minerals, rocks, and soils surrounding the landing sites.
  • Determine what geologic processes have shaped the local terrain and influenced the chemistry. Such processes could include water or wind erosion, sedimentation, hydrothermal mechanisms, volcanism, and cratering.
  • Perform calibration and validation of surface observations made by Mars Reconnaissance Orbiter instruments. This will help determine the accuracy and effectiveness of various instruments that survey Martian geology from orbit.
  • Search for iron-containing minerals, identify and quantify relative amounts of specific mineral types that contain water or were formed in water, such as iron-bearing carbonates.
  • Characterize the mineralogy and textures of rocks and soils and determine the processes that created them.
  • Search for geological clues to the environmental conditions that existed when liquid water was present.
  • Assess whether those environments were conducive to life.

NASA sought evidence of life on Mars, beginning with the question of whether the Martian environment was ever suitable for life. Life forms known to science require water, so the history of water on Mars is a critical piece of knowledge. Although the Mars Exploration Rovers did not have the ability to detect life directly, they offered very important information on the habitability of the environment during the planet's history.

Spirit (and its twin, Opportunity) are six-wheeled, solar-powered robots standing 1.5 meters (4.9 ft) high, 2.3 meters (7.5 ft) wide and 1.6 meters (5.2 ft) long and weighing 180 kilograms (400 lb). Six wheels on a rocker-bogie system enable mobility over rough terrain. Each wheel has its own motor. The vehicle is steered at front and rear and is designed to operate safely at tilts of up to 30 degrees. Maximum speed is 5 centimeters per second (2.0 in/s) [21] 0.18 kilometers per hour (0.11 mph), although average speed is about 1 centimeter per second (0.39 in/s). Both Spirit and Opportunity have pieces of the fallen World Trade Center's metal on them that were "turned into shields to protect cables on the drilling mechanisms". [22] [23]

Solar arrays generate about 140 watts for up to four hours per Martian day (sol) while rechargeable lithium ion batteries store energy for use at night. Spirit's onboard computer uses a 20 MHz RAD6000 CPU with 128 MB of DRAM, 3 MB of EEPROM, and 256 MB of flash memory. The rover's operating temperature ranges from −40 to +40 °C (−40 to 104 °F) and radioisotope heater units provide a base level of heating, assisted by electrical heaters when necessary. A gold film and a layer of silica aerogel provide insulation.

Communications depends on an omnidirectional low-gain antenna communicating at a low data rate and a steerable high-gain antenna, both in direct contact with Earth. A low gain antenna is also used to relay data to spacecraft orbiting Mars.

Science payload Edit

The science instruments include:

    – examines the texture, color, mineralogy, and structure of the local terrain. – monochrome with a higher field of view but lower resolution, for navigation and driving. – identifies promising rocks and soils for closer examination, and determines the processes that formed them. , two B&W cameras with 120 degree field of view, that provide additional data about the rover's surroundings.

The rover arm holds the following instruments:

    (MB) MIMOS II – used for close-up investigations of the mineralogy of iron-bearing rocks and soils. (APXS) – close-up analysis of the abundances of elements that make up rocks and soils.
  • Magnets – for collecting magnetic dust particles.
  • Microscopic Imager (MI) – obtains close-up, high-resolution images of rocks and soils. (RAT) – exposes fresh material for examination by instruments on board.

2004 Edit

The Spirit Mars rover and lander arrived successfully on the surface of Mars on 04:35 Ground UTC on January 4, 2004. This was the start of its 90-sol mission, but solar cell cleaning events would mean it was the start of a much longer mission, lasting until 2010.

Landing site: Columbia Memorial Station Edit

After the airbag-protected landing craft settled onto the surface, the rover rolled out to take panoramic images. These give scientists the information they need to select promising geological targets and drive to those locations to perform on-site scientific investigations. The panoramic image below shows a slightly rolling surface, littered with small rocks, with hills on the horizon up to 3 kilometers (1.9 mi) away. [26] The MER team named the landing site "Columbia Memorial Station," in honor of the seven astronauts killed in the Space Shuttle Columbia disaster.

"Sleepy Hollow," a shallow depression in the Mars ground at the right side of the above picture, was targeted as an early destination when the rover drove off its lander platform. NASA scientists were very interested in this crater. It is 9 meters (30 ft) across and about 12 meters (39 ft) north of the lander.

First color image Edit

To the right is the first color image derived from images taken by the panoramic camera on the Mars Exploration Rover Spirit. It was the highest resolution image taken on the surface of another planet. According to the camera designer Jim Bell of Cornell University, the panoramic mosaic consists of four pancam images high by three wide. The picture shown originally had a full size of 4,000 by 3,000 pixels. However, a complete pancam panorama is even 8 times larger than that, and could be taken in stereo (i.e., two complete pictures, making the resolution twice as large again.) The colors are fairly accurate. (For a technical explanation, see colors outside the range of the human eye.)

The MER pancams are black-and-white instruments. Thirteen rotating filter wheels produce multiple images of the same scene at different wavelengths. Once received on Earth, these images can be combined to produce color images. [27]

Sol 17 flash memory management anomaly Edit

On January 21, 2004 (sol 17), Spirit abruptly ceased communicating with mission control. The next day the rover radioed a 7.8 bit/s beep, confirming that it had received a transmission from Earth but indicating that the craft believed it was in a fault mode. Commands would only be responded to intermittently. This was described as a very serious anomaly, but potentially recoverable if it were a software or memory corruption issue rather than a serious hardware failure. Spirit was commanded to transmit engineering data, and on January 23 sent several short low-bitrate messages before finally transmitting 73 megabits via X band to Mars Odyssey. The readings from the engineering data suggested that the rover was not staying in sleep mode. As such, it was wasting its battery energy and overheating – risk factors that could potentially destroy the rover if not fixed soon. On sol 20, the command team sent it the command SHUTDWN_DMT_TIL ("Shutdown Dammit Until") to try to cause it to suspend itself until a given time. It seemingly ignored the command.

The leading theory at the time was that the rover was stuck in a "reboot loop". The rover was programmed to reboot if there was a fault aboard. However, if there was a fault that occurred during reboot, it would continue to reboot forever. The fact that the problem persisted through reboot suggested that the error was not in RAM, but in either the flash memory, the EEPROM, or a hardware fault. The last case would likely doom the rover. Anticipating the potential for errors in the flash memory and EEPROM, the designers had made it so that the rover could be booted without ever touching the flash memory. The radio itself could decode a limited command set – enough to tell the rover to reboot without using flash. Without access to flash memory the reboot cycle was broken.

On January 24, 2004 (sol 19) the rover repair team announced that the problem was with Spirit's flash memory and the software that wrote to it. The flash hardware was believed to be working correctly but the file management module in the software was "not robust enough" for the operations the Spirit was engaged in when the problem occurred, indicating that the problem was caused by a software bug as opposed to faulty hardware. NASA engineers finally came to the conclusion that there were too many files on the file system, which was a relatively minor problem. Most of these files contained unneeded in-flight data. After realizing what the problem was, the engineers deleted some files, and eventually reformatted the entire flash memory system. On February 6 (sol 32), the rover was restored to its original working condition, and science activities resumed. [28]

First intentional grinding of a rock on Mars Edit

For the first intentional grinding of a rock on Mars, the Spirit team chose a rock called "Adirondack". To make the drive there, the rover turned 40 degrees in short arcs totaling 95 centimetres (37 in). It then turned in place to face the target rock and drove four short moves straightforward totaling 1.9 m (6 ft 3 in). Adirondack was chosen over another rock called "Sashimi", which was closer to the rover, as Adirondack's surface was smoother, making it more suitable for the Rock Abrasion Tool (aka "RAT"). [29]

Spirit made a small depression in the rock, 45.5 millimetres (1.79 in) in diameter and 2.65 millimetres (0.104 in) deep. Examination of the freshly exposed interior with the rover's microscopic imager and other instruments confirmed that the rock is volcanic basalt. [30]

Humphrey rock Edit

On March 5, 2004, NASA announced that Spirit had found hints of water history on Mars in a rock dubbed "Humphrey". Raymond Arvidson, the McDonnell University Professor and chair of Earth and Planetary Sciences at Washington University in St. Louis, reported during a NASA press conference: "If we found this rock on Earth, we would say it is a volcanic rock that had a little fluid moving through it." In contrast to the rocks found by the twin rover Opportunity, this one was formed from magma and then acquired bright material in small crevices, which look like crystallized minerals. If this interpretation holds true, the minerals were most likely dissolved in water, which was either carried inside the rock or interacted with it at a later stage, after it formed. [31]

Bonneville crater Edit

On sol 65 March 11, 2004, Spirit reached Bonneville crater after a 400-yard (370 m) journey. [ citation needed ] This crater is about 200 meters (220 yd) across with a floor about 10 meters (11 yd) below the surface. [32] JPL decided that it would be a bad idea to send the rover down into the crater, as they saw no targets of interest inside. Spirit drove along the southern rim and continued to the southwest towards the Columbia Hills.

Spirit reached Missoula crater on sol 105. The crater is roughly 100 yards (91 m) across and 20 yards (18 m) deep. Missoula crater was not considered a high priority target due to the older rocks it contained. The rover skirted the northern rim, and continued to the southeast. It then reached Lahontan crater on sol 118, and drove along the rim until sol 120. Lahontan is about 60 yards (55 m) across and about 10 yards (9.1 m) deep. A long, snaking sand dune stretches away from its southwestern side, and Spirit went around it, because loose sand dunes present an unknown risk to the ability of the rover wheels to get traction.

Columbia Hills Edit

Spirit drove from Bonneville crater in a direct line to the Columbia Hills. The route was only directly controlled by the engineers when the terrain was difficult to navigate otherwise, the rover drove in an autonomous mode. On sol 159, Spirit reached the first of many targets at the base of the Columbia Hills called West Spur. Hank's Hollow was studied for 23 sols. Within Hank's Hollow was the strange-looking rock dubbed "Pot of Gold". Analysing this rock was difficult for Spirit, because it lay in a slippery area. After a detailed analysis with the AXPS-and the Mößbauer instrument it was detected that it contains hematite. [33] This kind of rock can be built in connection with water.

As the produced energy from the solar panels was lowering due to the setting Sun and dust the Deep Sleep Mode was introduced. In this mode the rover was shut down completely during the night in order to save energy, even if the instruments would fail. [34] The route was selected so that the rover's panels were tilted as much as possible towards the winter sunlight.

From here, Spirit took a northerly path along the base of the hill towards the target Wooly Patch, which was studied from sol 192 to sol 199. By sol 203, Spirit had driven southward up the hill and arrived at the rock dubbed "Clovis". Clovis was ground and analyzed from sol 210 to sol 225. Following Clovis came the targets of Ebenezer (Sols 226–235), Tetl (sol 270), Uchben and Palinque (Sols 281–295), and Lutefisk (Sols 296–303). From Sols 239 to 262, Spirit powered down for solar conjunction, when communications with the Earth are blocked. Slowly, Spirit made its way around the summit of Husband Hill, and at sol 344 was ready to climb over the newly designated "Cumberland Ridge" and into "Larry's Lookout" and "Tennessee Valley". Spirit also did some communication tests with the ESA orbiter Mars Express though most of the communication was usually done with the NASA orbiters Mars Odyssey and Mars Global Surveyor.

2005 Edit

Driving up to Husband Hill Edit

Spirit had now been on Mars for one Earth year and was driving slowly uphill towards the top of Husband Hill. This was difficult because there were many rocky obstacles and sandy parts. This led frequently to slippage and the route could not be driven as planned. In February, Spirit's computer received a software update in order to drive more autonomously. [35] On sol 371, Spirit arrived at a rock named "Peace" near the top of Cumberland Ridge. Spirit ground Peace with the RAT on sol 373. By sol 390 (mid-February 2005), Spirit was advancing towards "Larry's Lookout", by driving up the hill in reverse. The scientists at this time were trying to conserve as much energy as possible for the climb.

Spirit also investigated some targets along the way, including the soil target, "Paso Robles", which contained the highest amount of salt found on the red planet. The soil also contained a high amount of phosphorus in its composition, however not nearly as high as another rock sampled by Spirit, "Wishstone". One of the scientists working with Spirit, Dr. Steve Squyres, said of the discovery, "We're still trying to work out what this means, but clearly, with this much salt around, water had a hand here". [36]

Spirit's traverse up Husband Hill

Spirit artificially added to image (taken by itself) of Larry's Lookout

Martian sunset by Spirit at Gusev crater, May 19, 2005.

Dust devils Edit

On March 9, 2005 (probably during the Martian night), the rover's solar panel efficiency jumped from the original

60% to 93%, followed on March 10, by the sighting of dust devils. NASA scientists speculate a dust devil must have swept the solar panels clean, possibly significantly extending the duration of the mission. This also marks the first time dust devils had been spotted by Spirit or Opportunity, and is easily one of the top highlights of the mission to date. Dust devils had previously only been photographed by the Pathfinder probe.

Mission members monitoring Spirit on Mars reported on March 12, 2005 (sol 421), that a lucky encounter with a dust devil had cleaned the robot's solar panels. Energy levels dramatically increased and daily science work was anticipated to be expanded. [37]

Husband Hill summit Edit

As of August Spirit was only 100 metres (330 ft) away from the top. Here it was found that Husband Hill has two summits, with one a little higher than the other. On August 21 (sol 582), [38] Spirit reached the real summit of Husband Hill. The rover was the first spacecraft to climb atop a mountain on another planet. The whole distance driven totaled 4971 meters. The summit itself was flat. Spirit took a 360 degree panorama in real color, which included the whole Gusev crater. At night the rover observed the moons Phobos and Deimos in order to determine their orbits better. [39] On sol 656 Spirit surveyed the Mars sky and the opacity of the atmosphere with its pancam to make a coordinated science campaign with the Hubble Space Telescope in Earth orbit. [40]

From the peak Spirit spotted a striking formation, which was dubbed "Home Plate". This was an interesting target, but Spirit would be driven later to the McCool Hill to tilt its solar panels towards the Sun in the coming winter. At the end of October the rover was driven downhill and to Home Plate. On the way down Spirit reached the rock formation named "Comanche" on sol 690. Scientists used data from all three spectrometers to find out that about one-fourth of the composition of Comanche is magnesium iron carbonate. That concentration is 10 times higher than for any previously identified carbonate in a Martian rock. Carbonates originate in wet, near-neutral conditions but dissolve in acid. The find at Comanche is the first unambiguous evidence from the Mars Exploration Mission rovers for a past Martian environment that may have been more favorable to life than the wet but acidic conditions indicated by the rovers' earlier finds. [41]

2006 Edit

Driving to McCool Hill Edit

In 2006 Spirit drove towards an area dubbed Home Plate, and reached it in February. For events in 2006 by NASA see NASA Spirit Archive 2006

Spirit's next stop was originally planned to be the north face of McCool Hill, where Spirit would receive adequate sunlight during the Martian winter. On March 16, 2006 JPL announced that Spirit's troublesome front wheel had stopped working altogether. Despite this, Spirit was still making progress toward McCool Hill because the control team programmed the rover to drive toward McCool Hill backwards, dragging its broken wheel. [42] In late March, Spirit encountered loose soil that was impeding its progress toward McCool Hill. A decision was made to terminate attempts to reach McCool Hill and instead park on a nearby ridge named Low Ridge Haven.

Spirit arrived at the north west corner of Home Plate, a raised and layered outcrop on sol 744 (February 2006) after an effort to maximize driving. Scientific observations were conducted with Spirit's robotic arm.

Low Ridge Haven Edit

Reaching the ridge on April 9, 2006 and parking on the ridge with an 11° incline to the north, Spirit spent the next eight months on the ridge, spending that time undertaking observations of changes in the surrounding area. [43] No drives were attempted because of the low energy levels the rover was experiencing during the Martian winter. The rover made its first drive, a short turn to position targets of interest within reach of the robotic arm, in early November 2006, following the shortest days of winter and solar conjunction when communications with Earth were severely limited.

While at Low Ridge, Spirit imaged two rocks of similar chemical nature to that of Opportunity's Heat Shield Rock, a meteorite on the surface of Mars. Named "Zhong Shan" for Sun Yat-sen and "Allan Hills" for the location in Antarctica where several Martian meteorites have been found, they stood out against the background rocks that were darker. Further spectrographic testing is being done to determine the exact composition of these rocks, which may turn out to also be meteorites.

2007 Edit

Software upgrade Edit

On January 4, 2007 (sol 1067), both rovers received new flight software to the onboard computers. The update was received just in time for the third anniversary of their landing. The new systems let the rovers decide whether or not to transmit an image, and whether or not to extend their arms to examine rocks, which would save much time for scientists as they would not have to sift through hundreds of images to find the one they want, or examine the surroundings to decide to extend the arms and examine the rocks. [44]

Silica Valley Edit

Spirit's dead wheel turned out to have a silver lining. As it was traveling in March 2007, pulling the dead wheel behind, the wheel scraped off the upper layer of the Martian soil, uncovering a patch of ground that scientists say shows evidence of a past environment that would have been perfect for microbial life. It is similar to areas on Earth where water or steam from hot springs came into contact with volcanic rocks. On Earth, these are locations that tend to teem with bacteria, said rover chief scientist Steve Squyres. "We're really excited about this," he told a meeting of the American Geophysical Union (AGU). The area is extremely rich in silica–the main ingredient of window glass. The researchers have now concluded that the bright material must have been produced in one of two ways. One: hot-spring deposits produced when water dissolved silica at one location and then carried it to another (i.e. a geyser). Two: acidic steam rising through cracks in rocks stripped them of their mineral components, leaving silica behind. "The important thing is that whether it is one hypothesis or the other, the implications for the former habitability of Mars are pretty much the same," Squyres explained to BBC News. Hot water provides an environment in which microbes can thrive and the precipitation of that silica entombs and preserves them. Squyres added, "You can go to hot springs and you can go to fumaroles and at either place on Earth it is teeming with life – microbial life." [45] [46]

Global dust storm and Home Plate Edit

During 2007, Spirit spent several months near the base of the Home Plate plateau. On sol 1306 Spirit climbed onto the eastern edge of the plateau. In September and October it examined rocks and soils at several locations on the southern half of the plateau. On November 6, Spirit had reached the western edge of Home Plate, and started taking pictures for a panoramic overview of the western valley, with Grissom Hill and Husband Hill visible. The panorama image was published on NASA's website on January 3, 2008 to little attention, until January 23, when an independent website published a magnified detail of the image that showed a rock feature a few centimeters high resembling a humanoid figure seen from the side with its right arm partially raised. [47] [48]

Towards the end of June 2007, a series of dust storms began clouding the Martian atmosphere with dust. The storms intensified and by July 20, both Spirit and Opportunity were facing the real possibility of system failure due to lack of energy. NASA released a statement to the press that said (in part) "We're rooting for our rovers to survive these storms, but they were never designed for conditions this intense". [49] The key problem caused by the dust storms was a dramatic reduction in solar energy caused by there being so much dust in the atmosphere that it was blocking 99 percent of direct sunlight to Opportunity, and slightly more to Spirit.

Normally the solar arrays on the rovers are able to generate up to 700 watt-hours (2,500 kJ) of energy per Martian day. After the storms, the amount of energy generated was greatly reduced to 128 watt-hours (460 kJ). If the rovers generate less than 150 watt-hours (540 kJ) per day they must start draining their batteries to run survival heaters. If the batteries run dry, key electrical elements are likely to fail due to the intense cold. Both rovers were put into the lowest-power setting in order to wait out the storms. In early August the storms began to clear slightly, allowing the rovers to successfully charge their batteries. They were kept in hibernation in order to wait out the remainder of the storm. [50]

2008 Edit

Hibernating Edit

The main concern was the energy level for Spirit. To increase the amount of light hitting the solar panels, the rover was parked in the northern part of Home Plate on as steep a slope as possible. It was expected that the level of dust cover on the solar panels would increase by 70 percent and that a slope of 30 degrees would be necessary to survive the winter. In February, a tilt of 29.9 degrees was achieved. Extra energy was available at times, and a high definition panorama named Bonestell was produced. At other times when there was only enough solar energy to recharge the batteries, communication with Earth was minimized and all unnecessary instruments were switched off. At winter solstice the energy production declined to 235 watt hours per sol. [51]

Winter dust storm Edit

On November 10, 2008, a large dust storm further reduced the output of the solar panels to 89 watt-hours (320 kJ) per day—a critically low level. [52] NASA officials were hopeful that Spirit would survive the storm, and that the energy level would rise once the storm had passed and the skies started clearing. They attempted to conserve energy by shutting down systems for extended periods of time, including the heaters. On November 13, 2008 the rover awoke and communicated with mission control as scheduled. [53]

From November 14, 2008 to November 20, 2008 (sols 1728 to 1734), Spirit averaged 169 watt-hours (610 kJ) per day. The heaters for the thermal emission spectrometer, which used about 27 watt-hours (97 kJ) per day, were disabled on November 11, 2008. Tests on the thermal emission spectrometer indicate that it was undamaged, and the heaters would be enabled with sufficient energy. [54] The solar conjunction, where the Sun is between Earth and Mars, started on November 29, 2008 and communication with the rovers was not possible until December 13, 2008. [55]

2009 Edit

Increased energy Edit

On February 6, 2009, a beneficial wind blew off some of the dust accumulated on the panels. This led to an increase in energy output to 240 watt-hours (860 kJ) per day. NASA officials stated that this increase in energy was to be used predominantly for driving. [56]

On April 18, 2009 (sol 1879) and April 28, 2009 (sol 1889) energy output of the solar arrays were increased by cleaning events. [57] [58] The energy output of Spirit's solar arrays climbed from 223 watt-hours (800 kJ) per day on March 31, 2009 to 372 watt-hours (1,340 kJ) per day on April 29, 2009. [58]

Sand trap Edit

On May 1, 2009 (sol 1892), the rover became stuck in soft sand, the machine resting upon a cache of iron(III) sulfate (jarosite) hidden under a veneer of normal-looking soil. Iron sulfate has very little cohesion, making it difficult for the rover's wheels to gain traction. [59] [60]

JPL team members simulated the situation by means of a rover mock-up and computer models in an attempt to get the rover back on track. To reproduce the same soil mechanical conditions on Earth as those prevailing on Mars under low gravity and under very weak atmospheric pressure, tests with a lighter version of a mock-up of Spirit were conducted at JPL in a special sandbox to attempt to simulate the cohesion behavior of poorly consolidated soils under low gravity. [61] [62] Preliminary extrication drives began on November 17, 2009. [17]

On December 17, 2009 (sol 2116), the right-front wheel suddenly began to operate normally for the first three out of four rotations attempts. It was unknown what effect it would have on freeing the rover if the wheel became fully operational again. The right rear wheel had also stalled on November 28 (sol 2097) and remained inoperable for the remainder of the mission. This left the rover with only four fully operational wheels. [63] If the team could not gain movement and adjust the tilt of the solar panels, or gain a beneficial wind to clean the panels, the rover would only be able to sustain operations until May 2010. [64]

2010 Edit

Mars winter at Troy Edit

On January 26, 2010 (sol 2155), after several months attempting to free the rover, NASA decided to redefine the mobile robot mission by calling it a stationary research platform. Efforts were directed in preparing a more suitable orientation of the platform in relation to the Sun in an attempt to allow a more efficient recharge of the platform's batteries. This was needed to keep some systems operational during the Martian winter. [65] On March 30, 2010, Spirit skipped a planned communication session and as anticipated from recent power-supply projections, had probably entered a low-power hibernation mode. [66]

The last communication with the rover was March 22, 2010 (sol 2208) [67] and there is a strong possibility the rover's batteries lost so much energy at some point that the mission clock stopped. In previous winters the rover was able to park on a Sun-facing slope and keep its internal temperature above −40 °C (−40 °F), but since the rover was stuck on flat ground it is estimated that its internal temperature dropped to −55 °C (−67 °F). If Spirit had survived these conditions and there had been a cleaning event, there was a possibility that with the southern summer solstice in March 2011, solar energy would increase to a level that would wake up the rover. [68]

Communication attempts Edit

Spirit remains silent at its location, called "Troy," on the west side of Home Plate. There was no communication with the rover after March 22, 2010 (sol 2208). [69]

It is likely that Spirit experienced a low-power fault and had turned off all sub-systems, including communication, and gone into a deep sleep, trying to recharge its batteries. It is also possible that the rover had experienced a mission clock fault. If that had happened, the rover would have lost track of time and tried to remain asleep until enough sunlight struck the solar arrays to wake it. This state is called "Solar Groovy." If the rover woke up from a mission clock fault, it would only listen. Starting on July 26, 2010 (sol 2331), a new procedure to address the possible mission clock fault was implemented.

Each sol, the Deep Space Network mission controllers sent a set of X-band "Sweep & Beep" commands. If the rover had experienced a mission clock fault and then had been awoken during the day, it would have listened during brief, 20-minute intervals during each hour awake. Due to the possible clock fault, the timing of these 20-minute listening intervals was not known, so multiple "Sweep & Beep" commands were sent. If the rover heard one of these commands, it would have responded with an X-band beep signal, updating the mission controllers on its status and allowing them to investigate the state of the rover further. But even with this new strategy, there was no response from the rover.

The rover had driven 7,730.50 metres (4.80351 mi) until it became immobile. [70]

2011 Edit

Mission end Edit

JPL continued attempts to regain contact with Spirit until May 25, 2011, when NASA announced the end of contact efforts and the completion of the mission. [13] [15] [71] According to NASA, the rover likely experienced excessively cold "internal temperatures" due to "inadequate energy to run its survival heaters" that, in turn, was a result of "a stressful Martian winter without much sunlight." Many critical components and connections would have been "susceptible to damage from the cold." [15] Assets that had been needed to support Spirit were transitioned to support Spirit's then still-active Opportunity rover, [13] and Mars rover Curiosity which is exploring Gale Crater and has been doing so for more than six years. [72]

The rocks on the plains of Gusev are a type of basalt. They contain the minerals olivine, pyroxene, plagioclase, and magnetite, and they look like volcanic basalt as they are fine-grained with irregular holes (geologists would say they have vesicles and vugs). [73] [74]

Much of the soil on the plains came from the breakdown of the local rocks. Fairly high levels of nickel were found in some soils probably from meteorites. [75]

Analysis shows that the rocks have been slightly altered by tiny amounts of water. Outside coatings and cracks inside the rocks suggest water deposited minerals, maybe bromine compounds. All the rocks contain a fine coating of dust and one or more harder rinds of material. One type can be brushed off, while another needed to be ground off by the Rock Abrasion Tool (RAT). [76]

There are a variety of rocks in the Columbia Hills, some of which have been altered by water, but not by very much water.

The dust in Gusev Crater is the same as dust all around the planet. All the dust was found to be magnetic. Moreover, Spirit found the magnetism was caused by the mineral magnetite, especially magnetite that contained the element titanium. One magnet was able to completely divert all dust hence all Martian dust is thought to be magnetic. [77] The spectra of the dust was similar to spectra of bright, low thermal inertia regions like Tharsis and Arabia that have been detected by orbiting satellites. A thin layer of dust, maybe less than one millimeter thick covers all surfaces. Something in it contains a small amount of chemically bound water. [78] [79]

Plains Edit

Observations of rocks on the plains show they contain the minerals pyroxene, olivine, plagioclase, and magnetite. These rocks can be classified in different ways. The amounts and types of minerals make the rocks primitive basalts—also called picritic basalts. The rocks are similar to ancient terrestrial rocks called basaltic komatiites.

Rocks of the plains also resemble the basaltic shergottites, meteorites that came from Mars. One classification system compares the amount of alkali elements to the amount of silica on a graph in this system, Gusev plains rocks lie near the junction of basalt, picrobasalt, and tephrite. The Irvine-Barager classification calls them basalts. [73] Plains rocks have been very slightly altered, probably by thin films of water because they are softer and contain veins of light colored material that may be bromine compounds, as well as coatings or rinds. It is thought that small amounts of water may have gotten into cracks inducing mineralization processes). [73] [74] Coatings on the rocks may have occurred when rocks were buried and interacted with thin films of water and dust. One sign that they were altered was that it was easier to grind these rocks compared to the same types of rocks found on Earth.

Cross-sectional drawing of a typical rock from the plains of Gusev crater. Most rocks contain a coating of dust and one or more harder coatings. Veins of water-deposited minerals are visible, along with crystals of olivine. Veins may contain bromine salts.

Columbia Hills Edit

Scientists found a variety of rock types in the Columbia Hills, and they placed them into six different categories. The six are: Clovis, Wishbone, Peace, Watchtower, Backstay, and Independence. They are named after a prominent rock in each group. Their chemical compositions, as measured by APXS, are significantly different from each other. [80] Most importantly, all of the rocks in Columbia Hills show various degrees of alteration due to aqueous fluids. [81] They are enriched in the elements phosphorus, sulfur, chlorine, and bromine—all of which can be carried around in water solutions. The Columbia Hills' rocks contain basaltic glass, along with varying amounts of olivine and sulfates. [82] [83] The olivine abundance varies inversely with the amount of sulfates. This is exactly what is expected because water destroys olivine but helps to produce sulfates.

Acid fog is believed to have changed some of the Watchtower rocks. This was in a 200 metres (660 ft) long section of Cumberland Ridge and the Husband Hill summit. Certain places became less crystalline and more amorphous. Acidic water vapor from volcanoes dissolved some minerals forming a gel. When water evaporated a cement formed and produced small bumps. This type of process has been observed in the lab when basalt rocks are exposed to sulfuric and hydrochloric acids. [84] [85] [86]

The Clovis group is especially interesting because the Mössbauer spectrometer (MB) detected goethite in it. [87] Goethite forms only in the presence of water, so its discovery is the first direct evidence of past water in the Columbia Hills's rocks. In addition, the MB spectra of rocks and outcrops displayed a strong decline in olivine presence, [82] although the rocks probably once contained much olivine. [88] Olivine is a marker for the lack of water because it easily decomposes in the presence of water. Sulfate was found, and it needs water to form. Wishstone contained a great deal of plagioclase, some olivine, and anhydrate (a sulfate). Peace rocks showed sulfur and strong evidence for bound water, so hydrated sulfates are suspected. Watchtower class rocks lack olivine consequently they may have been altered by water. The Independence class showed some signs of clay (perhaps montmorillonite a member of the smectite group). Clays require fairly long term exposure to water to form. One type of soil, called Paso Robles, from the Columbia Hills, may be an evaporate deposit because it contains large amounts of sulfur, phosphorus, calcium, and iron. [81] Also, MB found that much of the iron in Paso Robles soil was of the oxidized, Fe 3+ form, which would happen if water had been present. [78]

Towards the middle of the six-year mission (a mission that was supposed to last only 90 days), large amounts of pure silica were found in the soil. [89] The silica could have come from the interaction of soil with acid vapors produced by volcanic activity in the presence of water or from water in a hot spring environment. [90]

After Spirit stopped working scientists studied old data from the Miniature Thermal Emission Spectrometer, or Mini-TES and confirmed the presence of large amounts of carbonate-rich rocks, which means that regions of the planet may have once harbored water. The carbonates were discovered in an outcrop of rocks called "Comanche." [91] [92]

In summary, Spirit found evidence of slight weathering on the plains of Gusev, but no evidence that a lake was there. However, in the Columbia Hills there was clear evidence for a moderate amount of aqueous weathering. The evidence included sulfates and the minerals goethite and carbonates that only form in the presence of water. It is believed that Gusev crater may have held a lake long ago, but it has since been covered by igneous materials. All the dust contains a magnetic component that was identified as magnetite with some titanium. Furthermore, the thin coating of dust that covers everything on Mars is the same in all parts of Mars.

Spirit pointed its cameras towards the sky and observed a transit of the Sun by Mars' moon Deimos (see Transit of Deimos from Mars). It also took the first photo of Earth from the surface of another planet in early March 2004.

In late 2005, Spirit took advantage of a favorable energy situation to make multiple nighttime observations of both of Mars' moons Phobos and Deimos. [93] These observations included a "lunar" (or rather phobian) eclipse as Spirit watched Phobos disappear into Mars' shadow. Some of Spirit's star gazing was designed to look for a predicted meteor shower caused by Halley's Comet, and although at least four imaged streaks were suspect meteors, they could not be unambiguously differentiated from those caused by cosmic rays. [93]

A transit of Mercury from Mars took place on January 12, 2005 from about 14:45 UTC to 23:05 UTC. Theoretically, this could have been observed by both Spirit and Opportunity however, camera resolution did not permit seeing Mercury's 6.1" angular diameter. They were able to observe transits of Deimos across the Sun, but at 2' angular diameter, Deimos is about 20 times larger than Mercury's 6.1" angular diameter. Ephemeris data generated by JPL Horizons indicates that Opportunity would have been able to observe the transit from the start until local sunset at about 19:23 UTC Earth time, while Spirit would have been able to observe it from local sunrise at about 19:38 UTC until the end of the transit. [ clarification needed ] [94]

Both rovers passed their original mission time of 90 sols many times over. The extended time on the surface, and therefore additional stress on components, resulted in some issues developing. [69]

On March 13, 2006 (sol 778), the right front wheel ceased working [95] after having covered 4.2 mi (7 km) on Mars. Engineers began driving the rover backwards, dragging the dead wheel. Although this resulted in changes to driving techniques, the dragging effect became a useful tool, partially clearing away soil on the surface as the rover traveled, thus allowing areas to be imaged that would normally be inaccessible. However, in mid-December 2009, to the surprise of the engineers, the right front wheel showed slight movement in a wheel-test on sol 2113 and clearly rotated with normal resistance on three of four wheel-tests on sol 2117, but stalled on the fourth. On November 29, 2009 (sol 2098), the right rear wheel also stalled and remained inoperable for the remainder of the mission.

Scientific instruments also experienced degradation as a result of exposure to the harsh Martian environment and use over a far longer period than had been anticipated by the mission planners. Over time, the diamond in the resin grinding surface of the Rock Abrasion Tool wore down, after that the device could only be used to brush targets. [96] All of the other science instruments and engineering cameras continued to function until contact was lost however, towards the end of Spirit's life, the MIMOS II Mössbauer spectrometer took much longer to produce results than it did earlier in the mission because of the decay of its cobalt-57 gamma ray source that has a half life of 271 days.

To rover Edit

To commemorate Spirit's great contribution to the exploration of Mars, the asteroid 37452 Spirit has been named after it. [97] The name was proposed by Ingrid van Houten-Groeneveld who along with Cornelis Johannes van Houten and Tom Gehrels discovered the asteroid on September 24, 1960.

Reuben H. Fleet Science Center and the Liberty Science Center also have an IMAX show called Roving Mars that documents the journey of both Spirit and Opportunity, using both CG and actual imagery.

January 4, 2014 was celebrated as the tenth anniversary of its landing on many news sites, despite nearly four years since loss of communications. [98]

To honor the rover, the JPL team named an area near Endeavour Crater explored by the Opportunity rover, 'Spirit Point'. [99]

From rover Edit

On January 27, 2004 (sol 22) NASA memorialized the crew of Apollo 1 by naming three hills to the north of "Columbia Memorial Station" as the Apollo 1 Hills. On February 2, 2004 (sol 28) the astronauts on Space Shuttle Columbia ' s final mission were further memorialized when NASA named a set of hills to the east of the landing site the Columbia Hills Complex, denoting seven peaks in that area as "Anderson", "Brown", "Chawla", "Clark", "Husband", "McCool", and "Ramon" NASA has submitted these geographical feature names to the IAU for approval.

The rover could take pictures with its different cameras, but only the PanCam camera had the ability to photograph a scene with different color filters. The panorama views were usually built up from PanCam images. Spirit transferred 128,224 pictures in its lifetime. [100]


Science objectives Edit

The Perseverance rover has four science objectives that support the Mars Exploration Program's science goals: [11]

  • Looking for habitability: identify past environments that were capable of supporting microbial life.
  • Seeking biosignatures: seek signs of possible past microbial life in those habitable environments, particularly in specific rock types known to preserve signs over time.
  • Caching samples: collect core rock and regolith ("soil") samples and store them on the Martian surface.
  • Preparing for humans: test oxygen production from the Martian atmosphere.

Despite the high-profile success of the Curiosity rover landing in August 2012, NASA's Mars Exploration Program was in a state of uncertainty in the early 2010s. Budget cuts forced NASA to pull out of a planned collaboration with the European Space Agency which included a rover mission. [12] By the summer of 2012, a program that had been launching a mission to Mars every two years suddenly found itself with no missions approved after 2013. [13]

In 2011, the Planetary Science Decadal Survey, a report from the National Academies of Sciences, Engineering, and Medicine containing an influential set of recommendations made by the planetary science community, stated that the top priority of NASA's planetary exploration program in the decade between 2013 and 2022 should be to begin a Mars Sample Return campaign, a three-mission project to collect, launch, and safely return samples of the Martian surface to Earth. The report stated that NASA should invest in a sample-caching rover as the first step in this effort, with the goal of keeping costs under US$2.5 billion. [14]

After the success of the Curiosity rover and in response to the recommendations of the decadal survey, NASA announced its intent to launch a new Mars rover mission by 2020 at the American Geophysical Union conference in December 2012. [15]

Though initially hesitant to commit to an ambitious sample-caching capability (and subsequent follow-on missions), a NASA-convened science definition team for the Mars 2020 project released a report in July 2013 that the mission should "select and store a compelling suite of samples in a returnable cache." [16]

Design Edit

The Perseverance design evolved from its predecessor, the Curiosity rover. The two rovers share a similar body plan, landing system, cruise stage, and power system, but the design was improved in several ways for Perseverance. Engineers designed the rover wheels to be more robust than Curiosity 's wheels, which have sustained some damage. [17] Perseverance has thicker, more durable aluminum wheels, with reduced width and a greater diameter, 52.5 cm (20.7 in), than Curiosity 's 50 cm (20 in) wheels. [18] [19] The aluminum wheels are covered with cleats for traction and curved titanium spokes for springy support. [20] The heat shield for the rover was made out of phenolic-impregnated carbon ablator (PICA), to allow it to withstand up to 2400°F (1300°C) of heat. [21] Like Curiosity, the rover includes a robotic arm, although Perseverance ' s arm is longer and stronger, measuring 2.1 m (6 ft 11 in). The arm hosts an elaborate rock-coring and sampling mechanism to store geologic samples from the Martian surface in sterile caching tubes. [22] There is also a secondary arm hidden below the rover that helps store the chalk-sized samples. This arm is known as the Sample Handling Assembly (SHA), and is responsible for moving the soil samples to various stations within the Adaptive Caching Assembly (ACA) on the underside of the rover. These stations include volume assessment, imaging, seal dispensing, and hermetic seal station, among others. [23] Due to the small space in which the SHA must operate, as well as load requirements during sealing activities, the Sample Caching System "is the most complicated, most sophisticated mechanism that we have ever built, tested and readied for spaceflight." [24]

The combination of larger instruments, new sampling and caching system, and modified wheels makes Perseverance heavier, weighing 1,025 kg (2,260 lb) compared to Curiosity at 899 kg (1,982 lb)—a 14% increase. [26]

The rover's radioisotope thermoelectric power generator (MMRTG) has a mass of 45 kg (99 lb) and uses 4.8 kg (11 lb) of Plutonium-238 oxide as its power source. The natural decay of plutonium-238, which has a half-life of 87.7 years, gives off heat which is converted to electricity—approximately 110 watts at launch. [27] This will decrease over time as its power source decays. [27] The MMRTG charges two lithium-ion rechargeable batteries which power the rover's activities, and must be recharged periodically. Unlike solar panels, the MMRTG provides engineers with significant flexibility in operating the rover's instruments even at night, during dust storms, and through winter. [27]

The rover's computer uses the BAE Systems RAD750 radiation-hardened single board computer based on a ruggedized PowerPC G3 microprocessor (PowerPC 750). The computer contains 128 megabytes of volatile DRAM, and runs at 133 MHz. The flight software runs on the VxWorks Operating System, is written in C and is able to access 4 gigabytes of NAND non-volatile memory on a separate card. [28] Perseverance relies on three antennas for telemetry, all of which are relayed through craft currently in orbit around Mars. The primary Ultra High Frequency (UHF) antenna can send data from the rover at a maximum rate of two megabits per second. [29] Two slower X-band antennas provide communications redundancy.

JPL built a copy of the Perseverance that stayed on Earth, called OPTIMISM (Operational Perseverance Twin for Integration of Mechanisms and Instruments Sent to Mars). It is housed at the JPL Mars Yard and is used to test operational procedures and to aid in problem solving should any issues arise with Perseverance. [30]

Mars Ingenuity helicopter experiment Edit

Also traveling with Perseverance is the Mars helicopter experiment named Ingenuity. This solar-powered helicopter drone has a mass of 1.8 kg (4.0 lb). It is demonstrating flight stability in the rarefied Martian atmosphere and the potential to scout for ideal driving routes for the rover over its planned 30-Martian-day (31-Earth-day) experimental flight test window. Other than a camera, it carries no scientific instruments. [31] [32] [33] The helicopter communicates with Earth via a base station onboard Perseverance. [34] First takeoff was attempted on 19 April 2021 at 07:15 UTC, with livestreaming three hours later at 10:15 UTC confirming the flight. [35] [36] [37] [38] [39] It is the first powered flight on another planet. [10] Ingenuity has made additional, incrementally more ambitious flights, all of which were recorded using Perseverance ' s cameras.

Name Edit

Associate Administrator of NASA's Science Mission Directorate, Thomas Zurbuchen selected the name Perseverance following a nationwide K-12 student "name the rover" contest that attracted more than 28,000 proposals. A seventh-grade student, Alexander Mather from Lake Braddock Secondary School in Burke, Virginia, submitted the winning entry at the Jet Propulsion Laboratory. In addition to the honor of naming the rover, Mather and his family were invited to NASA's Kennedy Space Center to watch the rover's July 2020 launch from Cape Canaveral Air Force Station (CCAFS) in Florida. [40]

Mather wrote in his winning essay:

Curiosity. InSight. Spirit. Opportunity. If you think about it, all of these names of past Mars rovers are qualities we possess as humans. We are always curious, and seek opportunity. We have the spirit and insight to explore the Moon, Mars, and beyond. But, if rovers are to be the qualities of us as a race, we missed the most important thing. Perseverance. We as humans evolved as creatures who could learn to adapt to any situation, no matter how harsh. We are a species of explorers, and we will meet many setbacks on the way to Mars. However, we can persevere. We, not as a nation but as humans, will not give up. The human race will always persevere into the future. [40]

Mars transit Edit

The Perseverance rover lifted off successfully on 30 July 2020, at 11:50:00 UTC aboard a United Launch Alliance Atlas V launch vehicle from Space Launch Complex 41, at Cape Canaveral Air Force Station (CCAFS) in Florida. [41]

The rover took about seven months to travel to Mars and made its landing in Jezero Crater on 18 February 2021, to begin its science phase. [42]

Landing Edit

One such new technology is Terrain Relative Navigation (TRN), a technique in which the rover compares images of the surface taken during its descent with reference maps, allowing it to make last minute adjustments to its course. The rover also uses the images to select a safe landing site at the last minute, allowing it to land in relatively unhazardous terrain. This enables it to land much closer to its science objectives than previous missions, which all had to use a landing ellipse devoid of hazards. [44]

The landing occurred in the late afternoon, with the first images taken at 15:53:58 on the mission clock (local mean solar time). [46] The landing took place shortly after Mars passed through its northern vernal equinox (Ls = 5.2°), at the start of the astronomical spring, the equivalent of the end of March on Earth. [47]

The parachute descent of the Perseverance rover was photographed by the HiRISE high-resolution camera on the Mars Reconnaissance Orbiter (MRO). [48]

Jezero Crater is a paleolake basin. [49] [50] It was selected as the landing site for this mission in part because paleolake basins tend to contain perchlorates. [49] [50] Astrobiologist Dr. Kennda Lynch's work in analog environments on Earth suggests that the composition of the crater, including the bottomset deposits accumulated from three different sources in the area, is a likely place to discover evidence of perchlorates-reducing microbes, if such bacteria are living or were formerly living on Mars. [49] [50]

A few days after landing, Perseverance released the first audio recorded on the surface of Mars, capturing the sound of Martian wind [51] [52]

NASA considered nearly 60 proposals [53] [54] for rover instrumentation. On 31 July 2014, NASA announced the seven instruments that would make up the payload for the rover: [55] [56]

    (MOXIE), an exploration technology investigation to produce a small amount of oxygen ( O
    2 ) from Martian atmospheric carbon dioxide ( CO
    2 ). On 20 April 2021, 5.37 grams of oxygen were produced in an hour, with nine more extractions planned over the course of two Earth years to further investigate the instrument. [57] This technology could be scaled up in the future for human life support or to make the rocket fuel for return missions. [58][59]
    (PIXL), an X-ray fluorescencespectrometer to determine the fine scale elemental composition of Martian surface materials. [60][61][62]
    (RIMFAX), a ground-penetrating radar to image different ground densities, structural layers, buried rocks, meteorites, and detect underground water ice and salty brine at 10 m (33 ft) depth. The RIMFAX is being provided by the Norwegian Defence Research Establishment (FFI). [63][64][65][66]
    (MEDA), a set of sensors that measure temperature, wind speed and direction, pressure, relative humidity, radiation, and dust particle size and shape. It is provided by Spain's Centro de Astrobiología. [67]
    , an instrument suite that can provide imaging, chemical composition analysis, and mineralogy in rocks and regolith from a distance. It is an upgraded version of the ChemCam on the Curiosity rover but with two lasers and four spectrometers that will allow it to remotely identify biosignatures and assess the past habitability. Los Alamos National Laboratory, the Research Institute in Astrophysics and Planetology (IRAP) in France, the French Space Agency (CNES), the University of Hawaii, and the University of Valladolid in Spain cooperated in the SuperCam's development and manufacture. [68][69]
    , a stereoscopic imaging system with the ability to zoom. [70][71] Many photos were included in the published NASA photogallery. (Including Raw)
    (SHERLOC), an ultravioletRaman spectrometer that uses fine-scale imaging and an ultraviolet (UV) laser to determine fine-scale mineralogy and detect organic compounds. [72][73]

There are additional cameras and two audio microphones (the first working microphones on Mars), that will be used for engineering support during landing, [74] driving, and collecting samples. [75] [76] For a full look at Perseverance ' s components look at Learn About the Rover.

Perseverance is planned to visit the bottom and upper parts of the 3.4 to 3.8 billion-year-old Neretva Vallis delta, the smooth and etched parts of the Jezero Crater floor deposits interpreted as volcanic ash or aeolian airfall deposits, emplaced before the formation of the delta the ancient shoreline covered with Transverse Aeolian Ridges (dunes) and mass wasting deposits, and finally, it is planned to climb onto the Jezero Crater rim. [77]

In its progressive commissioning and tests, Perseverance made its first test drive on Mars on 4 March 2021. NASA released photographs of the rover's first wheel tracks on the Martian soil. [78]

NASA plans to invest roughly US$2.75 billion in the project over 11 years, including US$2.2 billion for the development and building of the hardware, US$243 million for launch services, and US$291 million for 2.5 years of mission operations. [9] [79]

Adjusted for inflation, Perseverance is NASA's sixth-most expensive robotic planetary mission, though it is cheaper than its predecessor, Curiosity. [80] Perseverance benefited from spare hardware and "build-to print" designs from the Curiosity mission, which helped reduce development costs and saved "probably tens of millions, if not 100 million dollars" according to Mars 2020 Deputy Chief Engineer Keith Comeaux. [81]

"Send Your Name to Mars" Edit

NASA's "Send Your Name to Mars" campaign invited people from around the world to submit their names to travel aboard the agency's next rover to Mars. 10,932,295 names were submitted. The names were etched by an electron beam onto three fingernail-sized silicon chips, along with the essays of the 155 finalists in NASA's "Name the Rover" contest. The first name to be engraved was "Angel Santos". [ citation needed ] The three chips share space on an anodized plate with a laser engraved graphic representing Earth, Mars, and the Sun. The rays emanating from the Sun contain the phrase "Explore As One" written in Morse code. [82] The plate was then mounted on the rover on 26 March 2020. [83]

Geocaching in Space Trackable Edit

Part of Perseverance ' s cargo is a geocaching trackable item viewable with the SHERLOC's WATSON camera. [84]

In 2016, NASA SHERLOC co-investigator Dr. Marc Fries — with help from his son Wyatt — was inspired by Geocaching's 2008 placement of a cache on the International Space Station to set out and try something similar with the rover mission. After floating the idea around mission management, it eventually reached NASA scientist Francis McCubbin, who would join the SHERLOC instrument team as a collaborator to move the project forward. The Geocaching inclusion was scaled-down to a trackable item that players could search for from NASA camera views and then log on to the site. [85] In a manner similar to the "Send Your Name to Mars" campaign, the geocaching trackable code was carefully printed on a one-inch, polycarbonate glass disk serving as part of the rover's calibration target. It will serve as an optical target for the WATSON imager and a spectroscopic standard for the SHERLOC instrument. The disk is made of a prototype astronaut helmet visor material that will be tested for its potential use in manned missions to Mars. Designs were approved by the mission leads at NASA's Jet Propulsion Laboratory (JPL), NASA Public Affairs, and NASA HQ, in addition to Groundspeak Geocaching HQ. [86] [87]

Tribute to healthcare workers Edit

Perseverance launched during the COVID-19 pandemic, which began to affect the mission planning in March 2020. To show appreciation for healthcare workers who helped during the pandemic, an 8 cm × 13 cm (3.1 in × 5.1 in) plate with a staff-and-serpent symbol (a Greek symbol of medicine) was placed on the rover. The project manager, Matt Wallace, said he hoped that future generations going to Mars would be able to appreciate healthcare workers during 2020. [88]

Parachute with coded message Edit

The orange-and-white parachute used to land the rover on Mars contained a coded message that was deciphered by Twitter users. NASA's systems engineer Ian Clark used binary code to hide the message "dare mighty things" in the parachute color pattern. The 70-foot-wide parachute consisted of 80 strips of fabric that form a hemisphere-shape canopy, and each strip consisted of four pieces. Dr. Clark thus had 320 pieces with which to encode the message. He also included the GPS coordinates for the Jet Propulsion Laboratory's headquarters in Pasadena, California (34°11’58” N 118°10’31” W). Clark said that only six people knew about the message before landing. The code was deciphered a few hours after the image was presented by Perseverance ' s team. [89] [90] [91]

NASA History: Mars Exploration Rover Spirit Lands On The Red Planet 13 Years Ago

On January 3, 2004, Mars Exploration Rover Spirit landed at Gusev Crater on the Red Planet. Spirit launched on June 10, 2003, and spent nearly 6 months journeying to Mars. (NASA Image)

NASA – On January 3, 2004, Mars Exploration Rover Spirit landed at Gusev Crater on the Red Planet. Spirit launched on June 10, 2003, and spent nearly 6 months journeying to Mars.

Although originally baselined for only a 90-day mission, the Spirit rover exceeded its parameters by more than 28 times.

The mission finally ended more than 7 years later on May 25, 2011, after Spirit became mired in the sands of Mars.

This mosaic image was taken by Spirit’s navigation camera shortly after landing and shows a 360 degree panoramic view of the rover on the surface of Mars.

Mars Exploration Rover heads toward 'Spirit Point'

When NASA's Mars Exploration Rover Opportunity reaches the rim of a large crater it is approaching, its arrival will come with an inspiring reminder.

This crater, Endeavour, became the rover's long-term destination nearly three years ago. Opportunity has driven about 11 miles (18 kilometers) since climbing out of Victoria crater in August 2008, with Endeavour crater beckoning to the southeast. The rover has about 2 miles (about 3 kilometers) to go before reaching the rim of Endeavour.

Rover team members last week selected "Spirit Point" as the informal name for the site on the rim where Opportunity will arrive at Endeavour crater. The choice commemorates Opportunity's rover twin, Spirit, which has ended communication and finished its mission.

"Spirit achieved far more than we ever could have hoped when we designed her," said Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the rovers. "This name will be a reminder that we need to keep pushing as hard as we can to make new discoveries with Opportunity. The exploration of Spirit Point is the next major goal for us to strive for."

Endeavour offers the setting for plenty of productive work by Opportunity. The crater is 14 miles (22 kilometers) in diameter -- more than 20 times wider than Victoria crater, which Opportunity examined for two years. Orbital observations indicate that the ridges along its western rim expose rock outcrops older than any Opportunity has seen so far. Spirit Point is at the southern tip of one of those ridges, "Cape York," on the western side of Endeavour.

Opportunity and Spirit completed their three-month prime missions on Mars in April 2004. Both rovers continued for years of bonus, extended missions. Both have made important discoveries about wet environments on ancient Mars that may have been favorable for supporting microbial life.

Mars Exploration Rovers Update: Spirit Cruises to New Target, 'White Boat' Opportunity Uncovers Mystery Spheres

Both Mars rovers -- Spirit and Opportunity -- are roving on the Red Planet and doing exactly what they were programmed to do as robot field geologists, explore their surrounding areas.

Each rover is now driving to defined targets, closely inspecting chosen patches of soil and rocks to gather clues necessary to uncover the geological history of Gusev Crater and Meridiani Planum, and determine if either environment ever featured a body of water and was capable of supporting life as we know it.

Spirit finished her study of Adirondack last weekend, and has been allowed to shift to her 'AutoNav' system so that she can make some of her own driving decisions. Today, this rover broke the record for the farthest distance driven in one sol [day] on Mars, traveling 69.6 feet (21.2 meters). This distance shattered the Sojourner's previous record of 23 feet (7 meters) in one sol, back in 1997.

On the other side of the planet, her twin, Opportunity, has returned a host of data on the intriguing, tiny rounded spheres discovered embedded in the rock outcrop and dotting the surface nearby in Meridiani Planum where she landed last month.

From Gusev Crater

Last weekend, Spirit completed her study of Adirondack by using her rock abrasion tool to grind off the surface of a patch about 1.8 inches (45.5 millimeters) in diameter and 0.1 inch (2.65 millimeters) deep. It was the first artificial hole ever drilled in a rock on Mars, giving Spirit yet another 'first' in an ever-growing list of 'firsts.'

Opening a window

"It has really opened up a window into the interior," said MER lead scientist Steve Squyres, of Cornell University.

Spirit's ensuing examination of the freshly exposed interior included taking pictures with the microscopic imager, and measurements with the mini-thermal emission spectrometer, as well as the Mössbauer and alpha particle x-ray (APXS) spectrometers. The data returned and analyzed so far has indicated that the rock is volcanic basalt.

"What [we're seeing] is a beautifully cut, almost polished rock surface and it looks very much like an image of volcanic rock," Squyres said. "In fact, when we look at this with the APXS and with the Mössbauer spectrometer, we find compelling compositional evidence that it is volcanic basaltic rock."

After completing her examination of the rock late Sunday, Spirit drove right over Adirondack - not to be rude, but efficient - arriving at her next target about 21 feet (6.37 meters) away, a rock called White Boat.

Baby, you can drive yourself

Along the way, Spirit tested out her autonomous navigation ability -- a built-in navigation software and hazard avoidance system that enables her to make her own decisions about how to get to a specified point of interest. It marked yet another 'first' for the Mars Exploration Rover.

"We're in a new phase of the mission," said Mark Maimone, rover mobility software engineer, at a morning news briefing yesterday at the Jet Propulsion Laboratory (JPL). "We're going to let the rover decide how to get to where it's going."

Spirit switches to her autonomous mode when she receives the commands from the mission team on Earth that instruct her to do so. In that series of commands, the rover is directed to drive to a specific destination. As the rover proceeds, she evaluates the terrain with stereo imaging as she goes, choosing the best way to get to her destination, while avoiding anything she identifies as an obstacle that might be in her path.

This autonomous navigation ability "opens up new opportunities and lets us drive farther distances," explained Maimone. Most significantly, it frees Spirit up from the step-by-step navigation commands that have directed her since egress from her lander January 15.

Last night, this robot field geologist was commanded to drive farther on a northeastward course toward Bonneville Crater, about 820 feet (250 meters) away, where she will study the rocks thrown outward by the crater-forming impact. "This is the beginning of a very long drive, and we're looking forward to letting Spirit do her thing and deciding for herself decide for herself if it's safe and how far to go," Maimone said.

The general plan for this weeks calls for Spirit to begin her examination of the rock White Boat today, and continue on the route to Bonneville, stopping along the way, here and there, to study rocks of interest.

From Meridiani Planum

MER mission team members also announced at the news briefing the results of the triangulated data that has allowed them to pinpoint the location of Opportunity's landing site crater. Just as with Spirit, the team relied on radio-tracking data, descent images, post-landing images from the surface, and orbital images to home in on the rover's exact position at Meridiani Planum.

Opportunity -- where are you?

Radio signals gave the team a preliminary location for Opportunity about 35 minutes after landing, and additional information from communications with the Mars Odyssey orbiter soon narrowed the estimate, said Tim McElrath, deputy chief of the navigation team.

As Opportunity neared the ground, winds changed its course from eastbound to northbound, according to analysis of data recorded during the landing, to wind up in the tiny crater that she is about to crawl out of. "It's as if the crater were attracting us somehow," said Andrew Johnson, an engineer on the Descent Image Motion Estimation System (DIMES) camera team. The DIMES systems -- which were installed on the bottom of both MER rovers' landers -- estimate the spacecraft's horizontal motion during the landing.

The spacecraft bounced 26 times and rolled for more than 1 minute for about one-eighth of a mile or 219 yards (200 meters) before coming to rest inside the small crater, which is about 72 feet (22 meters) in diameter. As Squyres put it January 24, the night Opportunity landed: ""We scored a 300-million-mile, interplanetary hole in one."

JPL geologist Tim Parker was able to correlate a few features on the horizon above the crater rim with features identified by Mars orbiters, while imaging scientist Justin Maki, also of JPL, identified the spacecraft's jettisoned backshell and parachute in another Opportunity image showing the outlying plains. "This was a difficult location effort, because the crater is so small that we can't identify features on the rim that we were triangulating to, and compare views," explained Parker.

The location determined from the triangulation of data proved to be almost right on the mark when the tour de force image arrived from the Mars Orbital Camera (MOC) onboard Mars Global Surveyor (MGS). The MOC image actually shows the Opportunity lander as a bright little splotch in the crater. A darker feature near the lander may be the rover. "I won't know if it's really the rover until I take another picture after the rover moves," said Michael Malin of Malin Space Science Systems.

MGS passes over Opportunity's landing site twice a day, morning and afternoon, and images from the MOC are generally about 4.9 feet (1.5 meters) per pixel [picture element], although they can utilize a super-resolution feature on the camera and reduce that to 1.6 feet (.5 meters) per pixel, to really home in on an object, said Malin, a member of the rovers' science team and principal investigator for the MOC.

In the final report, the team announced that Opportunity's crater is at 1.95 degrees south latitude and 354.47 degrees east longitude, the opposite side of the planet from Spirit's landing site, which is at 14.57 degrees south latitude and 175.47 degrees east longitude.

Slip, Sliding Away

Meanwhile, the second Mars Exploration Rover was getting on with her job of collecting science in her little landing crater.

Yesterday, engineers woke up Opportunity with a lighthearted wake-up tune, Paul Simon's "Slip Sliding Away." They chose the song because this Mars rover had experienced quite a bit of slippage in the loose soil on her way to the outcrop last weekend. That's why it took her just a little bit longer to get to Stone Mountain, the rock at the edge of the outcrop formerly known as Snout. ["We tend to come up with names quickly in 'the heat of battle,'" Squyres noted of the name change. And, obviously, the initial names don't always stick.]

"We actually had quite a bit of slippage," Maimone told The Planetary Society. "In fact, the crater where Opportunity is, is quite a bowl and as we were going farther up the side of the bowl, we were slipping more and more. During one of the set of moves there, we drove 97 centimeters [about 3 feet] slipping on the order of 40 to 50 percent. We told it to go so far, and it actually went a little more than half that distance."

Considering that the soil appears to be composed of very loose sand-like materials the slipping came as no real surprise. The MER team has spent months testing the rovers' capabilities in all types of soil and sand and are prepared for pretty much any kind of ground materials they have been able to envision encountering either in Gusev Crater or on Meridiani Planum.

For Opportunity, driving to the outcrop was a bit like "trying to walk up hill on a sand dune," Maimone said. "It takes more energy and it takes you a while to get there." So what they have to do on the ground for now, he explained, "is manually look and see how far the rover has gone and determine where it really is. We have tried to characterize it and compare it with tests we did here on Earth in different soil and we've measured the slip on those and we're getting the right model."

That said, Maimone also explained that the rovers each feature software technology that allow them to incorporate their cameras and determine the distance traveled. This feature, he said, will be tested out on Opportunity at some point in the next few days. "That's going to actually let the rover look with its cameras and figure out how far it's really traveled, and then use that information to tell itself how far it's gone, so even though it may be slipping, pretty soon it will be smart enough to know how far it's gone," and when it reaches its destination.

Despite the loose soil, Opportunity pressed on and drove another 13 feet (4 meters) yesterday, to a second point in what is a counterclockwise survey of the rock outcrop along the inner wall of the rover's landing-site crater.

The outcrop -- dubbed Opportunity Ledge -- is the first outcrop ever seen and explored on Mars, or any other planet for that matter, and it represents a veritable bonanza for geologists working on the mission.

Blueberries in a muffin

Pictures taken at the first point in the outcrop survey have revealed perfectly rounded gray spherules, or tiny spheres, within the layered rocks and also loose on the ground nearby that have the scientists excited.

"We had a big weekend -- probably the biggest 2 or 3 days for science since we landed," enthused Squyres, as he prepared to display a series of "tantalizing" new pictures from the PanCam and microscopic imager.

"The deeper we get into Meridiani, the more it's reminding me of a mystery novel. When you start into a mystery novel, you start getting clues and you get them one at a time, chapter by chapter. Some of the clues mean something. Some of them are probably red herrings -- and you don't know which is which. We're working our way through these," he explained.

The outcrop is "tan or buff-colored," composed of "finely-layered" materials, and in the process of being eroded by windblown sand. "The thickness of the individual layers is a few millimeters," Squyres specified. "[The outcrop] is very, very finely grained and then embedded in it -- like blueberries in a muffin - are these little spherical grains -- I call them spherules -- because we don't know what they are."

The spherules are different in color -- "very, very gray," and very different from the stuff that was in the matrix [whole of the outcrop]," Squyres continued as he showed a microscopic image that showed the gray spherules in various stages of being released from the rock. "This is wild looking stuff. The rock is being eroded away and these spherical grains are dropping out," he noted.

"What's happened is [this]: [the outcrop] is sitting there for a very long period of time and has been sandblasted . . . the wind blows and the grains are striking it. Some portions of the rock are softer and some portions are harder, and the portions that are softer get worn away more rapidly. The intricate texture is telling [us] something about how well this stuff is stuck together -- geologists use the word indurated.

The gray spherules, Squyres added, "seem to be pretty tough." In many cases, as the rock erodes away, these "little blueberries in a muffin" drop out and roll down the slope of the crater.

The new data has helped the science team to winnow down its list of hypotheses about what the outcrop rock is made of, and what the tiny spherules might be. "For the matrix [outcrop], the tan colored rock itself, there are really only two ideas that we think are still holding up, Squyres said. Those theories are that the outcrop is either made up of volcanic ash or Martian windblown dust -- "the same dust you see everywhere else on the planet, compacted into sedimentary rock."

As for the gray spherules, "there are three hypotheses still standing, but one is fading fast," Squyres said. Those three hypotheses are that these perfectly round little spheres are:

"The one [hypothesis] that is fading fast is the idea that these are lapilli," offered Squyres. "We go back and forth on this to be honest. The thing about lapilli -- though they can be very round and just this size -- they tend to be made of the same stuff as the matrix of the stuff they're embedded in."

That's not what the evidence shows at the outcrop. In fact, a false color image "emphasizes that they are different in color and that's a hint that they may be different in composition too," he explained. That duly noted, however, Squyres added that they have not yet been able to complete separate Mössbauer measurements on the spherule and the matrix -- "on the blueberries and the muffin," as he described it. "We are going to do that and I think that will nail down whether or not these two are made of the same stuff or not, but the fact that their colors, their spectra are so different suggests that the little spherules are made of something different from the matrix stuff.

The notion that the spherules are formed from molten rock is a strong, perhaps the strongest contender in terms of the hypotheses right now. "Spherical grains can form when molten rock is sprayed into the air and freezes while it's still in mid-air -- solidifying [into] 'rocklets.' "Then, with these frozen 'rocklets' in the air you get these little glass beads that fall down to the surface."

The theory that these may be concretions is also a prime contender -- and these sedimentary objects form in a process involving water. On Earth, geologists discovered long ago that concretions form when fluids -- water -- carrying dissolved stuff precipitates through a rock. "This stuff diffuses through the rock, and precipitates around the nucleation sites, then grows into these spherical granule," Squyres said.

The most varied-shaped rocks on the sedimentary scene, concretions are formed and found in many places on our home planet. By definition, a concretion is a compact mass of mineral matter, usually spherical or disk-shaped, and embedded in a host rock of a different composition. These little spheres tend to form when a considerable amount of cementing material precipitates locally around a nucleus, often organic material, such as a leaf, or piece of shell or fossil.

Concretions vary in size, shape, hardness, and color -- from tiny little balls that require a magnifying lens to be clearly visible to huge bodies 10-feet in diameter and weighing several hundred pounds. Most importantly with regard to the quest at Meridiani, however, these hard, round masses of sedimentary rock 'cement' are ferried to their hiding places by groundwater.

Although the team is only on chapter two of the Mystery at Meridiani novel, "we think we should be able to test all of those hypotheses," Squyres said.

"I don't believe that the only spherules that we're seeing in the soil came from the outcrop," Squyres told The Planetary Society later. "I really think there is another source higher up."

They'll find out soon enough, and the traverses across the featureless, flat topography of Meridiani Planum is going to make for "smooth sailing" for the rover. At this point, Squyres pointed out, the only thing you can see for hundreds of meters is the backshell and harness. "If we were to drive in that direction, the first obstacle we would get to is the backshell."

The trip out of her landing crater will come once this rover completes her work on Opportunity Ledge.

Shoot 'n Scoot

For now, the agenda for the next week or so, is for Opportunity to complete the thorough survey of the outcrop, following follow a systematic plan. The rover will progress from point to point -- arriving, shooting pictures of the terrain, and acquiring new scientific measurements of the rocks, then moving on to the next chosen location where she will follow the same procedure. She will continue to investigate Opportunity Ledge in that manner until all levels of the outcrop up, down, and across have been investigated.

"We 're calling it a shoot'n scoot -- where we shoot a bunch of pictures and scoot to the next site about 3 meters over, shoot a bunch more pictures, then scoot again and do that for several sols, working our way across the outcrop," said Squyres.

All along the way, the team will instruct Opportunity to take high-resolution PanCam images of the entire outcrop, as well as taking Mini-TES measurements and using the other spectrometers and instruments as deemed necessary.

"We're going to find a couple of the best places -- a place where finely layered stuff in this matrix is really well exposed so we can go in there with the RAT and grind away at this stuff and then see what those layers are really like . . . and a place where there are a whole bunch of these spherules and if we could RAT those, see what they look like in cross-section and then stick the Mössbauer on them to figure out what they're really made of," Squyres added. "That's stuff that is yet to come."

Although the spectrometers data is still being analyzed, Squyres did say yesterday that the APXS measure on the rock outcrop indicates that there's a lot of sulfur, "more sulfur than we've found in any other location on Mars." It's yet another clue in the Mystery at Meridiani, but like many of the other recent clues, they don't know what it means.

And what about the hematite -- the mineral that on Earth usually forms in water -- which is what originally enticed Mars scientists and drove them to pick Meridiani Planum as a choice landing site?

"When we look hard at the outcrop we don't see high concentrations of hematite, so the matrix itself doesn't appear to be hematite bearing," Squyres said. "That does not rule the possibility that the spherules contain hematite - they could on the basis of Mini-TES." But the Mini-TES measurements are definitive, he added, because they have not yet found a place filled with spherules that Mini-TES can homes directly in on.

"The key to answering that [hematite question] is going to be to use the PanCam on a lot of these spherules," Squyres contended. "There's no question though that the highest concentration is actually above the outcrop -- and we don't know what's up there," he said. "Everything that we're seeing so far is either the outcrop itself or stuff that has fallen down. The evidence suggests that the highest concentration of hematite is in the stuff up above the outcrop layer, which we're not going to see until we start going at it."

The Mars Rovers: Spirit and Opportunity

After the success of the Sojourner rover, NASA wanted to send more rovers to learn about Mars. So, in 2003, they sent two rovers to the Red Planet. The rovers were named Spirit and Opportunity. Together, they were part of the Mars Exploration Rover mission.

Spirit and Opportunity were made as twins. They both carried all of the same scientific instruments. And each was about the size of a golf cart.

On Earth, where there is water, there is life. Spirit and Opportunity were sent to Mars to find more clues about the history of water there, and to see if the Red Planet could ever have supported life. To do this, scientists sent the two rovers to two different landing sites. The rovers landed on opposite sides of the planet.

The landing sites of all four Mars rovers on a map of Mars. Credit: National Geographic Society, MOLA Science Team, MSS, JPL, NASA

Spirit landed in a region called Gusev Crater. Scientists wanted to explore the crater because they thought it could have held water long ago. From pictures taken by satellites, scientists thought it looked like several large rivers flowed into Gusev Crater.

Opportunity landed on the other side of Mars in an area called Meridiani Planum. This region was nice because it was a flat, safe spot for the rover to land. Also, studies with a satellite around Mars showed that it might contain a mineral called grey hematite. On Earth, grey hematite is often found in the presence of water.

Opportunity found grey hematite in sphere-like grains in Meridiani Planum. Scientists called these grains “blueberries.” On Earth, hematite forms near water. Credit: NASA/JPL-Caltech/Cornell

On its journey, Spirit took many photos of Mars with its camera. They were the first color photos taken by a rover on another planet. Spirit also found several signs of past water, and evidence of geothermal, or volcanic activity. It explored sites that may have been hot springs millions of years ago.

In this photo, you can see where Spirit dragged one of its wheels and churned up some soil. Here, it found a light-colored mineral called silica. On Earth, this kind of silica usually exists in hot springs, where life as we know it often finds a hot, happy home. Perhaps ancient microbes on Mars did as well! Credit: NASA/JPL-Caltech/Cornell

Not to be outdone by its twin, Opportunity also took many color photos of the Martian landscape. It found evidence of water, too.

Opportunity studied layers of minerals in the rock near its landing site. The evidence it collected suggested that its landing site was once the shoreline of a salty sea.

Opportunity’s landing site in the flat Meridiana Planum. The shiny metal structure on the left is the rover’s heat shield that popped off during landing. Credit: Mars Exploration Rover Mission, JPL, NASA

The rocks that Spirit and Opportunity studied showed scientists that a long time ago, water on Mars may have looked a lot like water on Earth. Mars once had lakes and rivers on the surface. Like Earth, it also had water below the ground, as well as water vapor in the atmosphere.

Watch the video: NASAs Perseverance rover spotted a Pond on Mars (January 2022).