Mars Rover Says Goodbye to Marathon Valley: Photos

Here are some of the best shots from Opportunity's exploration of "Marathon Valley" on Mars, where the rover has been wandering since July 2015.

NASA's prolific Opportunity rover has been travelling on Mars since 2004 and traveled more than a marathon's distance during that time. Since July 2015, it's been exploring an area nicknamed "Marathon Valley" to learn more about the Red Planet's ancient, wet past. NASA says the rover will likely leave the area soon to look at another spot.

Opportunity confirmed some clay rocks that were first spotted from orbit, and also saw some reddish material that was later revealed to be sulfur (magnesium sulfate, which is a substance that likely precipitated from water). But science isn't all it's doing; the rover also took some spectacular shots of its journey around the valley. Check out some of them in this slideshow.

You can see Endeavour Crater here in this panoramic picture from NASA rover Opportunity, combining images taken between April 16 and May 15, 2016. At right is a peak nicknamed "Knudson Ridge" and in the foreground is the floor of Marathon Valley, which is strewn with rocks.

This image has been nicknamed "Sacagawea Panorama" to honor a Lemhi Shoshone woman who helped the Lewis and Clark expedition (which took place between 1804 and 1806). This view actually combines three exposures of near-infrared, green and violet and is shown in what is close to true color.

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Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.

You can see the Opportunity rover still working hard through the Martian winter in this image, which was taken by its front hazard avoidance camera on Jan. 5, 2016. You can see the rover's robotic arm reaching towards a target nicknamed "Private John Potts", after a member of one of Lewis and Clark's expedition.

As part of examining the rock to learn more about the area's past, Opportunity used its microscopic imager on the target (pictured here). The rover also scraped off the crust using a rock abrasion tool, and looked at the chemical elements using the alpha particle X-ray spectrometer.

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Credit: NASA/JPL-Caltech

This is quite the view for Opportunity! Not only do you see tracks from the long-running rover, but in the distance is a dust devil moving through Marathon Valley. Opportunity has seen fewer dust devils on Mars than its twin, Spirit, who died in a sand trap in March 2010.

"Just as on Earth, a dust devil is created by a rising, rotating column of hot air. When the column whirls fast enough, it picks up tiny grains of dust from the ground, making the vortex visible," NASA wrote in a press release at the time.

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Credit: NASA/JPL-Caltech

This is a fun image of sand streaks on Opportunity's solar panels after the rover went through an extreme tilt; it was roving up the steepest slope ever attempted on Mars. Opportunity's tilt reached as far as 32 degrees on March 10 while it was moving up "Knudsen Ridge."

The team tried three times to reach the target, but found that the slippage was too high. In the final attempt, the wheels rotated enough to move the rover 66 feet (20 meters). But in reality, the rover only moved 3.5 inches (9 centimeters). The team instead moved on to another target in the area that, like the original one, was suspected to have clay minerals. (Clay forms in water, which makes it an interesting substance on Mars).

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Credit: NASA/JPL-Caltech

This shows the rover's shadow perched about half a football field away from Marathon Valley, in July 2015. The rover had just started driving again on June 27 after waiting three weeks for solar conjunction to pass (a period when it's hard to communicate with Mars due to the position of the sun between Earth and the Red Planet).

The team decided to move into Marathon Valley for the Martian winter because there was a slope there -- conveniently facing the sun -- which was believed to hold clay minerals. Opportunity was intended, NASA wrote at the time, "to investigate relationships among these clay-bearing deposits."

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Credit: NASA/JPL-Caltech