Mars rover Curiosity has been making steady progress toward carrying out its first rock-drilling test at "Yellowknife Bay" - a geologically interesting location that, according to mission scientists this week, contains sedimentary rocks veined with calcium sulfate deposits that provide further evidence for an abundance of water in Gale Crater in Mars' ancient past. But to get to Yellowknife Bay, the nuclear-powered robot had to meander its way across the Martian landscape, a journey that has been closely watched by another robot over 160 miles overhead.
NASA's Mars Reconnaissance Orbiter (MRO) has been orbiting the red planet since 2006 and its suite of instruments have transformed our view of Mars. One camera in particular, the High-Resolution Imaging Science Experiment (HiRISE), has been keeping very close, high-resolution tabs on Mars' surface and the missions we send there. Curiosity is no different. The rover tracks of Spirit and Opportunity have been spotted by HiRISE, but Curiosity's wheels are much bigger, and therefore they can readily be spied from above. The rover itself, which is the size of a small car, can easily be picked out by the powerful camera's optics.
When the MRO flew high above Gale Crater on Jan. 2, Curiosity was spotted (the white feature, far right) with wheel tracks rolling over the undulating landscape from "Bradbury Landing," Curiosity's landing site (the dark feature, far left) on Aug. 5, 2012.
Apart from keeping tabs on Curiosity's progress, the HiRISE team can understand some of the characteristics of the Martian surface that Curiosity is rolling over. In some locations, the dark tracks are highly visible, in others, they're not. "The tracks are not seen where the rover has recently driven over the lighter-toned surface, which may be more indurated (hardened) than the darker soil," writes Alfred McEwen, lead HiRISE scientist and professor of planetary geology at the Arizona State University.
For me, whenever I see HiRISE observations of our robotic emissaries on the surface of Mars, I'm still blown away that we have robots looking out for other robots on another planet. If that's not awesome, I'm not quite sure what is.
Image credit: NASA/JPL/University of Arizona