Opportunity Rover Rolls Free on Mars

[onedomino]

After fives weeks stuck in a sand trap:

Opportunity Rover Rolls Free on Mars
June 06, 2005

http://www.jpl.nasa.gov/news/news.cfm?release=2005-095

Engineers and mission managers for NASA's Mars Exploration Rover mission cheered when images from the Martian surface confirmed Opportunity had successfully escaped from a sand trap.

From about 174 million kilometers away (about 108 million miles), the rover team at NASA's Jet Propulsion Laboratory, Pasadena, Calif., had worked diligently for nearly five weeks to extricate the rover. The long-distance roadside assistance was a painstaking operation to free all six wheels of the rover, which were mired up to their rims in the soft sand of a small martian dune.

"After a nerve-wracking month of hard work, the rover team is both elated and relieved to finally see our wheels sitting on top of the sand instead of half buried in it," said Jeffrey Biesiadecki, a JPL rover mobility engineer.

Traction was difficult in the ripple-shaped dune of windblown dust and sand that Opportunity drove into on April 26. In the weeks following, the rover churned 192 meters (629 feet) worth of wheel rotations before gaining enough traction to actually move one meter (about three feet). The rover team directed the drives in cautious increments from May 13 through June 4.

"We did careful testing for how to get Opportunity out of the sand. Then we patiently followed the strategy developed from the testing, monitoring every step of the way," Biesiadecki said. "We hope to have Opportunity busy with a full schedule of scientific exploration again shortly."

Opportunity's next task is to examine the site to provide a better understanding of what makes that ripple different from the dozens of similar ones the rover easily crossed. "After we analyze this area, we'll be able to plan safer driving in the terrain ahead," said JPL's Jim Erickson, rover project manager.

Both Spirit and Opportunity have worked in harsh martian conditions much longer than anticipated. They have been studying geology on opposite sides of Mars for more than a year of extended missions since successfully completing their three-month primary missions in April 2004.

"The first thing we're going to do is simply take a hard look at the stuff we were stuck in," said Dr. Steve Squyres of Cornell University, Ithaca, N.Y. He is the principal investigator for the Mars rovers' science instruments. "After that, we will begin a cautious set of moves to get us on our way southward again. South is where we think the best science is, so that's still where we want to go."

Shortly after landing in January 2004, Opportunity found layered bedrock that bore geological evidence for a shallow ancient sea. Spirit did not find extensive layered bedrock until more than a year later, after driving more than two miles and climbing into a range of hills known as "Columbia Hills."

 

[no1tovote4]

There must be a lot of silica in the sand on mars, the tracks tend to remain quite faithful to the pattern of the tracs of the vehicle. It is either that or there is more moisture than we are being led to believe.

 

[onedomino]

There must be a lot of silica in the sand on mars, the tracks tend to remain quite faithful to the pattern of the tracs of the vehicle. It is either that or there is more moisture than we are being led to believe.

Electrostatic cohesion? Very fine particles are made cohesive by electrostatic forces between the grains.

 

[no1tovote4]

Electrostatic cohesion? Very fine particles are made cohesive by electrostatic forces between the grains.

Much like on the moon, this would only work if the sand is largely silica. Drive one of these bad boys down pismo beach and see how cohesive the sand is there, you will find that the tracks are not as clear. This was one of the "evidences" of conspiracy that the theorists use to "prove" we never were on the moon, the footprint would not work unless there was either moisture or silicates. Fortunately, we can prove that the sand on the face of the moon is largely made of silicates and that is why the footprint was so well outlined, and the tracks from the rover were so clear.

On Mars, either the sand is largely silicates as well, or there is more moisture in the sand than we are led to believe.

 

[onedomino]

Water and/or silica are not necessary for fine particle cohesion or adhesion: "In dry fine-grained granular media van der Waals forces are the dominating adhesion forces. Under loading the particles are partially deformed irreversibly, such that the effective interface between contacting particles is enlarged by flattening, which leads to enhanced cohesion. This means that the history dependence of cohesion which is due to van der Waals forces arises from plastic deformation of the particles" http://www.ica1.uni-stuttgart.de/Jahresberichte/01/node29.html . For a description of van der Waals forces see this link: http://search.eb.com/nobel/micro/617_56.html .

 

[no1tovote4]

What are the reports of what is in the sand on Mars? The reason I say that cohesion at this level would necessitate silica is because of the necessity of higher levels of static charge in the sands, silica naturally creates such cohesion. It may be that electrostatic charge builds up higher in the sand because there is little surface liquid to take the charge from the sand, but I still think it more likely that there would be a higher level of silicates in the sand, or more surface moisture than we have been led to believe.

 

[onedomino]

NASA Mars Rover's First Soil Analysis Yields Surprises
Posted on: Wednesday January 21, 2004.

http://www.physlink.com/News/011203MarsRockSamples.cfm

This image shows the Mars Exploration Rover Spirit probing its first target rock, Adirondack. At the time this picture was snapped, the rover had begun analyzing the rock with the alpha particle X-ray spectrometer located on its robotic arm. This instrument uses alpha particles and X-rays to determine the elemental composition of martian rocks and soil. The image was taken by the rover's hazard-identification camera.

The first use of the tools on the arm of NASA's Mars Exploration Rover Spirit reveals puzzles about the soil it examined and raises anticipation about what the tool will find during its studies of a martian rock.

Today and overnight tonight, Spirit is using its microscope and two up-close spectrometers on a football-sized rock called Adirondack, said Jennifer Trosper, mission manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

"We're really happy with the way the spacecraft continues to work for us," Trosper said. The large amount of data -- nearly 100 megabits -- transmitted from Spirit in a single relay session through NASA's Mars Odyssey spacecraft today "is like getting an upgrade to our Internet connection."

Scientists today reported initial impressions from using Spirit's alpha particle X-ray spectrometer, Moessbauer spectrometer and microscopic imager on a patch of soil that was directly in front of the rover after Spirit drove off its lander Jan. 15.

"We're starting to put together a picture of what the soil at this particular place in Gusev Crater is like. There are some puzzles and there are surprises," said Dr. Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the suite of instruments on Spirit and on Spirit's twin, Opportunity.

One unexpected finding was the Moessbauer spectrometer's detection of a mineral called olivine, which does not survive weathering well. This spectrometer identifies different types of iron-containing minerals; scientists believe many of the minerals on Mars contain iron. "This soil contains a mixture of minerals, and each mineral has its own distinctive Moessbauer pattern, like a fingerprint," said Dr. Goestar Klingelhoefer of Johannes Gutenberg University, Mainz, Germany, lead scientist for this instrument.

The lack of weathering suggested by the presence of olivine might be evidence that the soil particles are finely ground volcanic material, Squyres said. Another possible explanation is that the soil layer where the measurements were taken is extremely thin, and the olivine is actually in a rock under the soil.

Scientists were also surprised by how little the soil was disturbed when Spirit's robotic arm pressed the Moessbauer spectrometer's contact plate directly onto the patch being examined. Microscopic images from before and after that pressing showed almost no change. "I thought it would scrunch down the soil particles," Squyres said. "Nothing collapsed. What is holding these grains together?"

Information from another instrument on the arm, an alpha particle X- ray spectrometer, may point to an answer. This instrument "measures X-ray radiation emitted by Mars samples, and from this data we can derive the elemental composition of martian soils and rocks," said Dr. Johannes Brueckner, rover science team member from the Max Planck Institute for Chemistry, Mainz, Germany. The instrument found the most prevalent elements in the soil patch were silicon and iron. It also found significant levels of chlorine and sulfur, characteristic of soils at previous martian landing sites but unlike soil composition on Earth.

Squyres said, "There may be sulfates and chlorides binding the little particles together." Those types of salts could be left behind by evaporating water, or could come from volcanic eruptions, he said. The soil may not have even originated anywhere near Spirit's landing site, because Mars has dust storms that redistribute fine particles around the planet. The next target for use of the rover's full set of instruments is a rock, which is more likely to have originated nearby.

Spirit landed in the Connecticut-sized Gusev Crater on Jan. 3 (EST and PST; Jan. 4 Universal Time). In coming weeks and months, according to plans, it will examine rocks and soil for clues about whether the past environment there was ever watery and possibly suitable to sustaining life. Spirit's twin Mars Exploration Rover, Opportunity, will reach Mars on Jan. 25 (EST and Universal Time; 9:05 p.m., Jan. 24, PST) to begin a similar examination of a site on the opposite side of the planet.

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[no1tovote4]

I didn't think I was crazy, the silicates are what causes the bonding in the soil... And salt that binds it together and makes it almost rock. Cool, like the whole salt thing, but that is what caused it not to move when testing, leaving the impression of the tracks would be the silicates' electrostatic charge.

*whew*

 

[sagegirl]

I so love these rovers.....the teams that designed and built them must be so happy......and to think that they got this little guy out of the sand is just outstanding......I love to think about all the stuff that we are learning from their adventures. Spirit and Opportunity are providing us an alternative to some of our lesser endeavors here, on our third rock from the sun.