Phobos from the European Mars Express Spacecraft. image credit ESA
15th March 2010
Phobos is the largest of Mars’ two moons, the other being Deimos. Phobos hugs the red planet, orbiting closer than any other known moon in the solar system, and travels faster around Mars than Mars itself rotates. It is destined to be torn apart by Mars’ gravity as it drops below the Roche Limit in about 11 million years time, probably ending up as a ring of rubble around Mars. This rocky lump is an irregular body with a very low density, suggesting possible internal hollow regions, and is around 27 kilometres long, 22 wide, and 19 thick.
Not to be outdone by Nasa’s Cassini Spacecraft around Saturn, and the Nasa Mars Reconnaissance Orbiter, the European Space Agency’s Mars Express Spacecrafthas come up with the goods too. After recent flybys of Phobos, the spacecraft has returned amazingly detailed images of this not yet completely understood moon. Craters litter it’s surface and strange parallel lined formations are visible.
This image is from just over 100 kilometres above the surface, and will provide valuable information for the Russian’s slightly amusingly named Phobos-Grunt Mission. The Russians will attempt to land their spacecraft on the Martian moon next year, take samples and return them to Earth.
Phobos is either a collection of rubble that has come together into one solid mass, or it could be a captured asteroid.
