It’s all downhill from here! (Well not really, but it was for a little while when Opportunity was at the top of that hill!) The image above is a mosaic I assembled from six color-composites, each made from three separate images acquired in near-infrared, green, and near-ultraviolet color wavelengths on April 21, 2017 (mission sol 4707). It’s been adjusted to appear in approximate true color to what the scene might look like to a human standing on Mars. The view shows a ridge called “Rocheport” located on the western rim of Endeavour Crater (the interior of which would be toward the right in this image) which was the final segment of Opportunity’s last target region of exploration, Cape Tribulation. Opportunity’s wheel tracks can be seen at the bottom center, heading back up the ridge and zig-zagging toward the top (detail below).
Mars isn’t a planet well-known for its natural satellites but it actually does have two small moons. The larger, Phobos, is an irregularly-shaped, heavily grooved and cratered world only about 17 miles (27 km) across at its widest. It orbits Mars so closely that it completes 3 orbits every day, and isn’t even visible from some parts of the planet. But Phobos has an even smaller companion in orbit: Deimos, which at the most 7.5 miles across is half Phobos’ size. Deimos orbits Mars much further away as well, taking about 30 hours to complete one orbit.
On March 9, 2017, NASA’s Curiosity rover took this picture with its turret-mounted MAHLI camera of the calibration target installed near the “shoulder” of its robotic arm. In addition to color chips and a metric line graph, the target also includes a U.S. coin: a 1909 Lincoln penny, adhered heads-up.
Curiosity’s coin isn’t just for good luck though; it’s also a nod to geologists who typically use familiar objects in field photos to help determine scale. (Curiosity is, after all, one of only two working robot geologists on all of Mars!)
The first mission to successfully* send a rover to Mars, NASA’s Mars Pathfinder, launched on Dec. 4, 1996. It was a “budget” Discovery mission designed to demonstrate a low-cost method for delivering a set of science instruments to Mars and sent the first remote-controlled vehicle to be used on another planet. Solar-powered and only a foot in height, the little six-wheeled Sojourner was the foundation for all future Mars rovers…and, along with the Carl Sagan Memorial Station, gave us our best views of the Martian surface since the Viking 1 and 2 landers.
Mars may have an atmosphere just 1% the density of Earth’s but it can still stir up enough of a breeze to quickly cover a rover’s tracks, as evidenced in the animation above. Captured by Curiosity’s downward-looking Mars Descent Imager (MARDI) camera on Jan. 23 and 24, 2017, the two pictures show an approximately 3-foot-wide area just beneath the rover (part of one wheel is visible at upper left.) In the first image Curiosity’s wheel tracks are fresh and crisp; in the second, they’ve been blurred by wind shifting the fine Martian sand. As summertime is the windiest season within Gale Crater, one could easily imagine the rover’s tracks being completely obliterated after a week or so!
Source: NASA’s Planetary Photojournal