Part of a bulk data release from the European Space Agency’s Mars Express orbiter (available at ftp://psa.esac.esa.int/pub/mirror/MARS-EXPRESS/HRSC, posted on unmannedspaceflight.com by user peter59) this wonderful image shows Phobos, the larger of Mars’ two moons, in orbit against the backdrop of the planet’s limb. The dark, irregularly-shaped moon is shown in amazing clarity, giving a very nice sense of depth to the image. (Mars’ surface features appear slightly wavy due to motion of the spacecraft’s camera, which gathers data line-by-line rather than as a single full-frame. Also I rotated the image 90º counter-clockwise from the original.)
Mars Express last performed a close flyby of Phobos on March 7, 2010, passing by the moon at a distance of about 170 miles (278 km) and returning some great images. Previously believed to be a captured asteroid, it’s now thought that Phobos may actually be a chunk of Mars itself, reconstituted bits of the surface that were blown into orbit by a large meteorite impact…a theory strengthened by the discovery of phyllosilicates in Phobos’ composition, a substance known to exist in abundance on Mars’ surface – but not in asteroids.
The Russian space program is planning a mission to Phobos next year with their Phobos-Grunt spacecraft, which will land on its surface and return a sample back to Earth.
Thanks to peter59 (Peter Masek) for sharing these images from the release, which looks to hold a lot more goodies…read more at The Planetary Society’s blog!
Image: ESA / DLR / FU Berlin (G. Neukum).