April 10, 2008 -- Taking a break from scouting landing sites for NASA's next Mars rover, a sharp-eyed orbiter took a look at the planet's tiny inner moon Phobos and uncovered unprecedented details about the potato-shaped world.
Scientists are keen to dissect the images to better understand the moon's origins, but the pictures, which were released on Wednesday, were pieced together with aesthetics in mind.
Blue-green, red and near-infrared filters on the Mars Reconnaissance Orbiter's (MRO's) high-resolution camera were used to produce three-dimensional images of Phobos and its most prominent feature, a 5.5-mile diameter crater, named Stickney.
Scientists believe that the asteroid or meteoroid impact that formed Stickney nearly broke Phobos apart. The MRO images show the crater's rim ringed with different material than the surrounding vista.
"Based on analogy with material on our own moon, [it] could mean that the material is fresher, or hasn't been exposed to space as long as the rest of Phobos' surface has," said Nathan Bridges, an MRO scientist at the Jet Propulsion Laboratory in Pasadena, Calif.
MRO also caught landslides along the walls of Stickney and other craters, including some previously undetected formations on the dark side of the moon that were illuminated by light reflected off Mars.
Like Earth's moon, Phobos and its sister, Deimos, are tidally locked to their parent body, leaving half of each moon shrouded in darkness.
Though other spacecraft have flown closer to Phobos, the MRO images are the highest quality ever obtained, Bridges said. Scientists suspect Phobos harbors water ice and carbon-rich materials that may be of use for future Mars settlements.
Phobos was about 4,200 miles away when MRO snapped the pictures on March 23. At that distance, the camera was able to resolve features as small as about 50 feet in diameter.
The moon itself is only 13.5 miles in diameter. Scientists suspect it may be an asteroid that was plucked from orbit by Mars' gravity.
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