On March 7th, the European Space Agency's Mars Express spacecraft performed a flyby of Mars' larger moon, Phobos, and managed to take the most detailed pictures of the moon's surface to date.
The Mars Express orbits Mars, and its elliptical orbit brings it close to Phobos every five months. The spacecraft was taking images of a particular area that may be used as a landing site by the Russian Phobos-Grunt (meaning 'Phobos-Soil') mission planned for next year.
The new, more detailed images are being used along with other data to determine what the planet is made of, as well as its origins.
According to Science News, Gerard Neukum of the Free University of Berlin said that researchers are attempting to discover if Phobos is, "a fragile pile of rocky fragments stuck together -- what planetary scientists refer to as a rubble pile -- or solid through and through."
See the detailed pictures of Phobos below, then check out terrific images of Mars on HuffPost Tech here.