Category: Missions

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The scientists and engineers working with the Spirit rover on Mars were hoping the aging rover could take the short route over the top of a small plateau called “Home Plate;” she could get to her next destination quicker and easier. But with the rover’s right front wheel not working, the rover was unable to make the climb from the side of the plateau where Spirit spent the majority of the Martian winter (with her solar panels tilted towards the sun) up to the top. So, Spirit is now making her way around Home Plate, where the less desirable path may have led to a serendipitous discovery. The rover’s immobile right-front wheel has churned up a long stripe of bright soil. Could this bright soil be sulfur or silica, providing evidence of past action of water at this site? The rover will test the soil today with it’s alpha particle X-ray spectrometer. And this isn’t the first time Spirit’s bum wheel has churned up something interesting.

In 2006, Spirit uncovered another patch of bright soil. The material was found to be sulfur-rich and consisted of sulfate salts associated with iron, and likely calcium. “This material could have been left behind by water that dissolved these minerals underground, then came to the surface and evaporated, or it could be a volcanic deposit formed around ancient gas vents,” said Dr. Ray Arvidson back in 2006. He is the deputy principal investigator for NASA’s twin Mars rovers, Spirit and Opportunity.

“These salts could have been concentrated by hydrothermal liquid or vapor moving through the local rocks,” said rover science team member Dr. Albert Yen, a geochemist at JPL. Two other patches of bright soil uncovered by Spirit before were also sulfur-rich, but each had similarities to local rock compositions that were different at the three sites, suggesting localized origins.

This most recent discovery was made on the 1,861st Martian day, or sol, of Spirit’s mission on Mars (March 28, 2009). After the drive, the rover took the image above with its front hazard-avoidance camera, looking back at the tracks from the drive.

As usual since losing the use of its right-front wheel in 2006, Spirit drove backwards, and the immobile right-front wheel turned up the soil.

The Sol 1861 drive took the rover past the northwest corner of the low plateau called “Home Plate,” making progress on a route around the western side of Home Plate. The edge of Home Plate forms the horizon on the right side of this image. Husband Hill is on the horizon on the left side. For scale, the parallel rover wheel tracks are about 1 meter (40 inches) apart. The rover’s hazard-avoidance cameras take “fisheye” wide-angle images.

Source: JPL’s Photojournal

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Dark pits on Mars are fascinating – probably because they provide mysteries and possibilities. Could anything be inside? Or could this be a place where humans could set up a base since it would provide shelter from Mars’ harsh environment? Some of the pits found earlier have been speculated to be entrances into caves, but more likely this is a collapse pit. Pits like this form by collapse into underground voids, such as those left by propagating magma-filled dikes. The pit in this image has very steep walls, and so only a narrow arc is illuminated by sunlight. The rest of the pit is in dark shadow. However, the HiRISE teams created a stretched version of the image, which shows details of the pit floor, due to a small amount of scattered sunlight. Anything interesting inside?

This pit is essentially a vertical shaft cut through the lava flows on the flank of the volcano. Such pits form on similar volcanoes in Hawaii and are called ‘pit craters.’ They generally do not connect to long open caverns but are the result of deep underground collapse.

The fossae, or troughs, occur on the Tharsis volcanic rise, a giant region of enhanced volcanic activity that includes the three large volcanoes Ascraeus Mons, Pavonis Mons and Arsia Mons.

Source: HiRISE

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The journey seems almost impossible and endless for the Opportunity rover, heading through the dunes of Meridiani Planum on its way to a distant crater. But now the rover’s Panoramic Camera has caught the first glimpse on the horizon of the uplifted rim of Endeavour Crater, providing optimism for the MER team and rover fans alike, that Opportunity can perhaps complete the journey. “We can now see our landfall on the horizon,” said Steve Squyres, principal investigator for the rovers’ science instruments.”It’s far away, but we can anticipate seeing it gradually look larger and larger as we get closer to Endeavour. We had a similar experience during the early months of the mission watching the Columbia Hills get bigger in the images from Spirit as Spirit drove toward them.”

Opportunity has been ‘on the road’ for six months, heading toward the huge crater, which is 22 kilometers (14 miles) in diameter. Endeavour Crater is still 12 kilometers (7 miles) away from Opportunity as the crow flies, and at least 30 percent farther away on routes mapped for evading dune hazards on the plain. Opportunity has already driven about 3.2 kilometers (2 miles) since it climbed out of Victoria Crater last August after two years of studying Victoria, which is less than one-twentieth the size of Endeavour.

“It’s exciting to see our destination, even if we can’t be certain whether we’ll ever get all the way there,” said John Callas of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., project manager for the twin Mars rovers, Opportunity and Spirit. “At the pace we’ve made since leaving Victoria, the rest of the trek will take more than a Martian year.” A Martian year lasts about 23 months.

“We’re stopping to taste the terrain at intervals along our route so that we can watch for trends in the composition of the soil and bedrock,” Squyres said. “It’s part of systematic exploration.”

The pause for using the tools on the arm also provides two other benefits. Opportunity’s right-front wheel has been drawing more electric current than usual, an indication of friction within the wheel. Resting the wheel for a few days is one strategy that has in the past helped reduce the amount of current drawn by the motor.

Also, on March 7, the rover did not complete the backwards-driving portion of its commanded drive due to unanticipated interaction between the day’s driving commands and onboard testing of capabilities for a future drive. The team is analyzing that interaction before it will resume use of Opportunity’s autonomous-driving capabilities.

Callas said, “After several attempts to drive up-slope in loose material to get around the northeast corner of Home Plate, the team judged that route to be impassable.”

The new route to get toward science targets south of Home Plate is to go around the west side of the plateau.

Squyres said, “The western route is by no means a slam dunk. It is unexplored territory. There are no rover tracks on that side of Home Plate like there are on the eastern side. But that also makes it an appealing place to explore. Every time we’ve gone someplace new with Spirit since we got into the hills, we’ve found surprises.”

Source: JPL