The Mars moon: The European Space Agency recently showed off the first in a series of extreme close-up photos of the Mars moon Phobos . The photos, which show a pock-marked but otherwise relatively smooth surface, are some of the closest shots of the Mars moon ever taken. The data and photos collected by the Mars Express satellite could help unwrap some of the mystery about the moon, the ESA said. Three scenarios are possible, one, that the moon is actually a captured asteroid. The second is that it formed at the same time as Mars formed below it. The third is that Phobos formed later than Mars, out of debris flung into Martian orbit when a large meteorite struck the red planet, according to the ESA.