Mars Exploration Rovers Update: Both Spirit and Opportunity Get to Work on Mars
Posted by Amir Alexander
03-02-2004 11:00 CST
Both Mars Exploration Rovers -- Spirit and Opportunity -- are getting to work studying the Martian landscapes in which they landed.
After a good weekend, Spirit is all but fully recovered from her 'overload' breakdown a couple of weeks ago and is once again collecting science, while Opportunity has been busy collecting and returning a 'mission success' color panorama, and completing check-outs of her arm and instruments.
Today, the exploration of Mars moves forward full steam ahead, as each of the robot field geologists is manipulating one or another in her armful of sophisticated instruments to measure, as well as image, the geologic and chemical composition of the Gusev Crater and Meridiani Planum.
Meridiani in complete view
Opportunity sent home her first, 360-degree, color, stereo panorama yesterday, revealing the breadth and scope of the area of Meridiani Planum stretching out before the rover in all directions.
The picture 'snapped' by Opportunity's panorama camera, known as PanCam, reveals the trail of bounce marks coming down the inner slope of the small crater where the second MER rover came to rest, after landing nine days ago. For the scientists, the image provides "a real sense of 'you are there' at the site, and gives us a feeling for this bowl-shaped depression that we're in," said Jeff Johnson, a MER science team member from the United States Geological Survey, in Flagstaff, Arizona.
In addition to taking the hundreds of super high-resolution color pictures, the PanCams on Spirit and Opportunity have been collecting spectroscopy data in the visible and near-infrared wavelengths. The cameras feature14 filters that enable the scientists to take recordings and measurements based on specified conditions.
"Each mineral has sort of a fingerprint in the visible to near infrared spectrum," explained Johnson. "When we put together a spectrum using all of these 14 filter combinations, we can look at Mars and try to make comparisons about what we think the minerals on the soils may be composed of. The spectra we extract from Mars will give us a very good idea of the true spectral characteristics of that site. One thing that PanCam will allow us to do is take those very subtle spectral features and map them into the scene, so we can try and do some remote geology, and from there, hopefully, try to get a better understanding of both the landing sites," he said.
By looking at the brightness of areas in each of the filter to filter combinations -- or, in other words, each of the wavelengths - the scientists can begin to get an idea about the mineralogy and composition of the materials they're looking at, something that is "especially" important if we want to try and unravel the geologic history of the landing site which is really our main goal," Johnson added.
Interestingly, the scientists are seeing, "at least to the eyes of PanCam," the "same types of materials" in "typical spectra" from both the Gusev and Meridiani sites, according to Johnson. "The difference is, perhaps, the thermal emission data is sensing deeper into the material, sensing perhaps that's more sensitive to other materials that may be out there," considered Johnson. "One of the things we want to do towards the mid-to-later part of the mission is to get out of the crater and verify that for ourselves. It's a little difficult to look at distance, horizon features, and compares them to something that's directly with something that's in front of you -- there's a lot more atmosphere at the horizon than at your feet.
Opportunity is also preparing to do the up-close science. Yesterday, she successfully extended her arm for the first time since pre-launch testing and checked out the instruments: the rock abrasion tool (RAT); the microscopic imager (MI); the alpha particle X-ray spectrometer (APXS), and the Mössbauer spectrometer. "This was a great confirmation for the team," said Joe Melko, a mechanical systems engineer for the rover's arm, known as the instrument deployment device or IDD.
Mission controllers at JPL commanded Opportunity to deploy two of the instruments on her arm overnight to examine a patch of soil in right in front of her. A microscopic imager on the arm will take pictures that show in detail structures as thin as a human hair. Then, Opportunity will place the Mössbauer right down onto the soil and take readings, for 24 hours, that will identify what minerals are present in the soil.
After that, Opportunity will turn the turret at the end of her arm in order to examine the same patch of soil with the APXS, a process that also will take 24 hours to complete. At the end of the day, it will have collected the data scientists need to determine the chemical properties of the soil.
While Opportunity continues to 'ramp up' her instruments, the science teams have been debating just how they're going "to attack" studying the outcrop, said Johnson. "There's a bit of a debate in the team right now as to the best method to do that. It's a bit of a traveling salesman problem -- how do you do the best science the most quickly in the most efficient manner?"
Though nothing is yet written in stone, one prominent idea calls for Opportunity to drive over to the end of the outcrop, right in front her, "and kind of saddling up to it and taking a lot of very high-resolution pictures at increments until we end up at the end of the outcrop," Johnson said. "Then we'll have a wonderful amazing data set that maps this outcrop completely."
Some of the scientists believe that the outcrop of rock is actually just pat of the bedrock that encircles the rim of the crater in which Opportunity sits. "From what I've seen there seems to be a prevailing wind direction and that has a lot to do with why just a portion of the crater rim is an outcrop," offered Johnson. "It may be that the outcrop goes all the way around the crater rim and is just covered up on the other side. One of the things we'll be doing, hopefully, is investigating that by trenching . . . perhaps we can reach some of that other bedrock if its just only a half a wheel depth or so below the surface. Right we're trying to figure out now how far off we need to be to be able to use both PanCam and Mini-TES and not his the solar panel if we are going to kind of parallel park [up next to it].
Opportunity's stuck heater, meanwhile, is still on, confirmed Joe Melko, systems engineer for the IDD. "There's a device that was put on by our thermal people just for this particular type of case," he explained. "During the day, when it gets warmer, there's a secondary device that turns that [heater] off. During night, it's on and we've taken a look at our system and it turns out with a [few] changes, we're able to do everything we set out to do regardless of this. So it's really not affecting us much now." In the future, however, "much further in future, as it gets colder," they will be looking at other kinds of 'workarounds' to accommodate the fact that the heater remains on at night.
Back to business as usual
On the other side of the planet, Spirit got back to business as usual, picking up just about exactly where she left off a couple of weeks ago. "Spirit has made incredible progress over the weekend," reported Mission Manager Jennifer Trosper. "We are doing science on Spirit just like we were about 10 sols ago," and the rover is as good as she was on day one, she added.
Spirit team members planned to erase and reformat the rover's flash memory today, something that is being done as "a precautionary measure" to insure that glitch that prevented the rover from doing much science last week never happens again, said Trosper.
"Over the weekend, we downlinked some additional data and [that data] essentially confirmed our suspicions about why the first problem occurred," Tropser said. The breakdown Spirit suffered was the related, she reminded, "to the number of files in the file system and the amount of RAM necessary to allocate in order to manage those files."
Based on the additional data that arrived last weekend, Trosper said the Anomaly Team is convinced its suspicion of the origin of the problem was correct. "The only residual concern that we have is -- when we entered into that anomaly, we may have had side effects that we don't fully understand on the flash memory itself." That is something for which they'll continually be on the lookout. The mantra Spirit's team is passing along to Opportunity to help prevent her from experiencing the same kind of breakdown, Trosper said is: 'Keep your file number low and look at this additional data.'
Meanwhile Spirit is "moving forward" by completing its study of the rock Adirondack." First on the science agenda today, this robot field geologist was scheduled to dust off Adirondack today with the rock abrasion tool or RAT, then take some images with her microscopic imager (MI). "Then we'll place the APXS on the rock and do an overnight integration," Trosper said. Following those tasks, Spirit will employ the Mössbauer spectrometer to further characterize the composition and make-up of the rock.
Then, later in the week, the robot geologist will 'RAT' - or grind -- the surface off of a sample area on Adirondack to inspect the rock's interior and take more images with her MI.
Once the study of Adirondack is completed, Spirit will begin roving again. "Spirit is the driving mission," Trosper noted. "We are already strategizing how to drive far and fast."
As far as the long-term plan for Spirit, right now the big crater still beckons, Trosper said. "It isn't official but what we're looking toward is driving to the crater and so we will be driving quite a ways and we're working now to do that quickly." The Spirit drivers will start with instructing the rover to drive about 15 meters a day, Trosper added, and will increase the rover's daily distance "as we get more comfortable."The main task for both rovers in coming weeks and months is to find clues in rocks and soil about past environmental conditions, particularly about whether the landing areas were ever watery and possibly suitable for sustaining life. Each Martian day, or "sol" lasts about 39 minutes longer than an Earth day. Spirit begins its 31st sol on Mars at 1:23 a.m. Tuesday, Pacific Standard Time. Opportunity begins its 11th sol on Mars at 1:44 p.m. Tuesday, PST.
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