Mars rover Opportunity on walkabout near rim

Mars rover Opportunity on walkabout near rim
The Pancam on NASA's Mars Exploration Rover Opportunity took the component images of this enhanced-color scene during the mission's "walkabout" survey of an area just above the top of "Perseverance Valley," in preparation for driving down the valley. Credit: NASA/JPL-Caltech/Cornell/Arizona State Univ.

NASA's senior Mars rover, Opportunity, is examining rocks at the edge of Endeavour Crater for signs that they may have been either transported by a flood or eroded in place by wind.

Those scenarios are among the possible explanations rover-team scientists are considering for features seen just outside the rim's crest above "Perseverance Valley," which is carved into the inner slope of the rim.

The team plans to drive Opportunity down Perseverance Valley after completing a "walkabout" survey of the area above it. The rover's drives now use steering motors on only the rear wheels, following a temporary jam of the left-front 's steering actuator this month. Opportunity has not used its right-front wheel's steering actuator since 2005, the year after it landed on Mars.

The mission has been investigating sites on and near the western rim of Endeavour Crater since 2011. The crater is about 14 miles (22 kilometers) across.

"The walkabout is designed to look at what's just above Perseverance Valley," said Opportunity Deputy Principal Investigator Ray Arvidson of Washington University in St. Louis. "We see a pattern of striations running east-west outside the crest of the rim."

A portion of the crest at the top of Perseverance Valley has a broad notch. Just west of that, elongated patches of rocks line the sides of a slightly depressed, east-west swath of ground, which might have been a drainage channel billions of years ago.

"We want to determine whether these are in-place rocks or transported rocks," Arvidson said. "One possibility is that this site was the end of a catchment where a lake was perched against the outside of the crater rim. A flood might have brought in the rocks, breached the rim and overflowed into the crater, carving the down the inner side of the rim. Another possibility is that the area was fractured by the impact that created Endeavour Crater, then rock dikes filled the fractures, and we're seeing effects of wind erosion on those filled fractures."

In the hypothesis of a perched lake, the notch in the crest just above Perseverance Valley may have been a spillway. Weighing against that hypothesis is an observation that the ground west of the crest slopes away, not toward the crater. The science team is considering possible explanations for how the slope might have changed.

A variation of the impact-fracture hypothesis is that water rising from underground could have favored the fractures as paths to the surface and contributed to weathering of the fracture-filling rocks.

Close examination of the piles along the edges of the possible channel might help researchers evaluate these and other possible histories of the site. Meanwhile, the team is analyzing stereo images of Perseverance Valley, taken from the rim, to plot Opportunity's route. The valley extends down from the crest into the crater at a slope of about 15 to 17 degrees for a distance of about two football fields.

On June 4, during the walkabout survey, the steering actuator for Opportunity's left-front wheel stalled with the wheel turned outward more than 30 degrees. Each of the rover's six wheels has its own drive motor, which all still work after about 27.9 miles (44.9 kilometers) of driving on Mars. Each of the four corner wheels also has an independent steering actuator—including motor and gearbox. The rover has driven about 25 miles (40 kilometers) since losing use of right-front wheel steering in April 2005.

Diagnostic testing on June 17 succeeded in straightening out the left-front wheel, a more favorable orientation than it had been in for nearly two weeks.

"For at least the immediate future, we don't plan to use either front wheel for steering," said Opportunity Project Manager John Callas of NASA's Jet Propulsion Laboratory, Pasadena, California. "We can steer with two wheels, just like a car except it's the rear wheels. We're doing exactly what we should be doing, which is to wear out the rover doing productive work—to utilize every capability of the vehicle in the exploration of Mars."

The team has operated Opportunity on Mars for more than 50 times longer than the originally planned mission duration of three months.

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Mars rover Opportunity begins study of ancient valley's origin

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Jun 24, 2017
"A lack of hydrogen and hydrogen-based compounds is a very important fact for the atmosphere of Mars, but also for Mars in general. When certain smart people realize that there can be no water without hydrogen, maybe then will they stop writing about water on Mars and stop this massive, yet futile search for the fictional water. It needs to be specially noted here that the melting point of hydrogen is -259,14°C and its boiling point is -252,87°C, which means that if there were hydrogen on Mars, it should be possible to detect it in the chemical composition of the atmosphere and surface." https://www.acade...nd_Earth

Jun 24, 2017
"A lack of hydrogen and hydrogen-based compounds is a very important fact for the atmosphere of Mars, but also for Mars in general. When certain smart people realize that there can be no water without hydrogen, ...

Right, but that doesn't mean there wasn't once much more hydrogen than there is now.

+ we have various bits of very strong evidence that there must have been much water on Mars including the irrefutable detection of huge amounts of certain carbonates on Mars which can only be explained with the presence of much water;

" ...These kind of carbonates only form when there is a lot of water. ..."

And that means there could be huge amounts of frozen water below the surface of Mars In fact, this has already been proven to be true;

"...Frozen water also lies beneath the surface. "

so saying its a "futile search for the fictional water. " is nonsense.

Jun 24, 2017
Nobody jou, not defend, that you live in faith and delusion.
Now it is so, there is no (not just the evidence) is already an indication of the existence of water on Mars (except smart heads).
Science are evidence , stories are for believers who are not interested in evidence.
Lead is not in the atmosphere (there is "The chemical composition of its atmosphere is: carbon dioxide 95.97%, argon 1.93%, nitrogen 1.89%, oxygen 0.146%, carbon-monoxide 0.0557%, which in total Makes 99.9917% of the elements and compounds, present in its atmosphere. "). But when you say there are Bogey on Mars, we will believe who cares for the evidence.

Jun 24, 2017
" When certain smart people realize that there can be no water without hydrogen, maybe then will they stop writing about water on Mars and stop this massive, yet futile search for the fictional water."

From a much more reliable source than the one you cited:
"Using an imaging spectrometer on MRO, researchers detected signatures of hydrated minerals on slopes where mysterious streaks are seen on the Red Planet."
""It took multiple spacecraft over several years to solve this mystery, and now we know there is liquid water on the surface of this cold, desert planet," said Michael Meyer, lead scientist for NASA's Mars Exploration Program at the agency's headquarters in Washington."

Water on Mars is NOT fictional and the search for it is NOT futile. It is a CONFIRMED FACT.

Jun 24, 2017
@ wduckuss: The ice deposit on Utopia Planitia alone contains as much water as Lake Superior. (https://www.nasa....uperior)
And your figures on the composition of the Martian atmosphere are incorrect. The actual composition is: 95.32% CO2, 2.7% N2, 1.6% Ar, 0.13% O2, 0.08% CO and trace amounts (totalling ~0.17%) of nitrogen oxide, neon, krypton, xenon, hydrogen-deuterium-oxygen (aka heavy WATER), and WATER. (

Jun 26, 2017
"And your figures on the composition of the Martian atmosphere are incorrect."

Mars atmosphere composition[1]
Carbon dioxide 95.97%
Argon 1.93%
Nitrogen 1.89%
Oxygen 0.146%
Carbon monoxide 0.0557% or 99,9917% https://en.wikipe..._of_Mars or
Science. 341 (6143): 263. Bibcode:2013Sci...341..263M. PMID 23869014. doi:10.1126/science.1237966

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