| Subject: Mars Rover science funded for 18 more months |
Author:
Betty
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Date Posted: 11:23:24 04/12/05 Tue
While Spirit and Opportunity have been roving into completely new territories up on the Red Planet, NASA has approved funding for up to 18 more months of operations for the twin rovers.
Perhaps we should send several replicas of these Rovers all over Mars & the Moon to save billions of dollars, & do real long-term science there instead of satisfying Bush's "unscientific", expensive, "cowboys in space" initiative.
The Mars Exploration Rovers have been actively exploring the planet since January 2004, extending their 'warranties' by more than four times and completing 11 months of extensions on top of their successful three-month prime missions.
That drive and robustness -- which is something the twin robots share -- have pretty much blown away engineers and scientists. If they keep on functioning, they are now guaranteed support through September 2006, and right now the future is, as they say these days, all good.
"We now have to make long-term plans for the vehicles because they may be around for quite a while," Jim Erickson, rover project manager at the Jet Propulsion Laboratory (JPL) said yesterday.
Anything, however, could happen anytime, and both rovers do have some signs of wear and exposure. "Either mission could end tomorrow with a random part failure," Erickson pointed out. "With the rovers already performing well beyond their original design lifetimes, having a part wear out and disable a rover is a distinct possibility at any time."
Troubleshooting continues for determining whether Opportunity's miniature thermal emission spectrometer (mini-TES) is still usable despite tests indicating a possibly fatal problem last month. And in recent weeks, Spirit's rock abrasion tool (RAT) shows indications that its grinding teeth might be worn away. Researchers probably won't know the extent of wear until the rover's next rock-grinding attempt, which may be weeks away. Still, Spirit's RAT was only designed to expose the interiors of just three rocks, and to date, the rover has exposed the interiors of more than five times that.
All other instruments on both rovers are still working normally, or in mission jargon, 'nominally,' and right now, "both rovers are in amazingly good shape," said Erickson. " We're going to work them hard to get as much benefit from them as we can, for as long as they are capable of producing worthwhile science results."
Spirit from Gusev Crater
Spirit is still climbing the rocky slope toward the top of Husband Hill in the Columbia Hills region of Gusev Crater and the going is getting tough again. But, as luck would have it, she's in great shape and has all the energy any robot could have hope for at this point.
A boost in power came last month when blustering winds that were whipping up dust devils cleaned the rover's solar panels, and now that her formerly gimpy right-front wheel has been working normally for the last 12 weeks or so, Spirit made some longer one-day drives last week than she had in months. "We've doubled our power," said JPL's Emily Eelkema, mission manager. "It has given us extra hours of operations every day, so we can drive longer and we've used more time for observations." [Both rovers are driving in reverse sometimes to keep all six wheels well lubricated.]
After taking panoramic camera (PanCam) images of targets dubbed Cottontail and Blanket and then completing a 79-foot [24 meter] drive on March 25, the rover conducted some remote sensing observations, including measuring the opacity of the atmosphere and looking for more dust devils, before continuing her upward climb. By last Thursday, Spirit had reached sandier terrain, slipping as much as 45% on an 11-degree slope, and by April Fool's Day it was still no joke of a climb.
The rover has confronted 11-degree slopes in the past, but has never slipped quite this much. This terrain, however, is much sandier than previous terrains Spirit has driven on. The rovers used to have a slip limit of 40 percent -- meaning that the rover would automatically stop and shut down if it slipped that much. The rover team increased the allowable slippage on Spirit to 60 percent to enable the rover to progress up the hill.
The jump in power output has taken some of urgency out of Spirit's southward climb. With Mars now beginning southern-hemisphere spring, the Sun is farther south in the sky each day. If not for the winds cleaning her solar arrays, Spirit might have faced the prospect of becoming critically short of power if she was still on the north-facing slope by early June. The goal, however, remains the same: the summit of Husband Hill.
"We still want to get to the summit of Husband Hill and then head down into the Inner Basin on the other side," said Steve Squyres, of Cornell University, principal investigator for the rovers' science instruments. "But now we have more flexibility in how we carry out the plan. Before, it was climb or die."
Even though cresting the hill is now not as crucial for solar energy, it still offers allures of potential exposures of rock layers not yet examined, plus a vista of surrounding terrain. In orbital images, the Inner Basin farther south appears to have terracing that hints of layered rock.
Spirit is currently less than two-tenths of a mile [300 meters] of the summit and is spending time today conducting some remote-sensing observations.
Opportunity from Meridiani Planum
Opportunity is now within a few football fields' length of a region called Etched Terrain, where scientists hope to find rocks exposed by gentle wind erosion rather than by disruptive cratering impacts, as well as rocks from a different time in Mars' history than any examined so far.
"This is a journey into the unknown, to something completely new," said Squyres. To reach the Etched Terrain, rover planners have been really driving the rover pretty aggressively as previously reported here.
In fact, Opportunity has now overtaken Spirit in total distance driven, roving more than 3 miles [4.9 kilometers]. That's eight times the original mission-success goal. The long drives take advantage of crossing a plain so smooth it's "like an East Coast beach," said JPL's Jeff Favretto, mission manager on the Opportunity shift in recent weeks. Although Opportunity's solar arrays are now dustier than Spirit's, they are still generating enough power to allow the rover to drive for more than three hours on some days.
Despite the 'hard driving' schedule, Opportunity did stop to smell the -- dirt, and the science team members did decide to conduct some investigations of the rippled soil patches, as Joy Crisp, project scientist told The Planetary Society week before last. They are particularly interested in comparing the chemical makeup of the ripples' troughs to that of the ripples' crests.
Opportunity stopped at a nicely defined trough last week, extended her robotic arm and investigated the soil, then drove up onto one of the ripples to examine the crest. Zeroing in on a soil target called Mobarak (in honor of Persian New Year), the rover had her head down in a trough for three sols trying to figure out the composition of the trough soil. During an observation like this, the rover uses all of the in-situ instruments, taking microscopic images (MI), alpha particle X-ray spectrometer (APXS) readings and Mössbauer spectrometer readings.
After Opportunity had looked at the soil in the trough, the rover examined the soil at the top of the ripple. With practice has come perfection and the rover planners commanded the rover to execute what turned out to be an exquisite 23-foot [7-meter] drive that placed Opportunity right at the top of that ripple. The rover then deployed her instruments there and inspected the soil, homing in on two targets, Norooz and Mayberooz, again to determine the soil properties.
Last Friday, April Fool's Day, Opportunity roved away from the soil survey spot -- no kidding -- and continued onward toward the crater dubbed Viking, which lies out on this vast plain intriguingly close to another crater called Voyager. The rover should complete studies of this crater duo today, and hit the road again tomorrow. Plans call for Opportunity to continue on for about a half mile [800 meters] to the next target on the list -- Erebus, a feature about .18 of a mile [300 meters] in diameter, which appears now to be a filled-in, largely eroded crater.
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