Scientists say the most telling signs of Phobos' unfortunate fate are the long indentations extending across the surface.
The grooves were initially believed to be the aftermath of an especially brutal hit, but researchers later observed their apparent point of origin didn't match up with the impact site.
Just recently, a team concluded tidal forces are the most likely cause of the rifts.
See Mars' moons:
NASA discovers one of Mars' moons is facing destruction
March 23, 2008 - NASA's Mars Reconnaissance Orbiter took two images of the larger of Mars' two moons, Phobos, within 10 minutes of each other on March 23, 2008. This is the second, taken from a distance of about 5,800 kilometers (about 3,600 miles). It is presented in color by combining data from the camera's blue-green, red, and near-infrared channels. The illuminated part of Phobos seen in the images is about 21 kilometers (13 miles) across. The most prominent feature in the images is the large crater Stickney in the lower right. With a diameter of 9 kilometers (5.6 miles), it is the largest feature on Phobos. The color data accentuate details not apparent in black-and-white images. For example, materials near the rim of Stickney appear bluer than the rest of Phobos. Based on analogy with materials on our own moon, this could mean this surface is fresher, and therefore younger, than other parts of Phobos. A series of troughs and crater chains is obvious on other parts of the moon.
The command module, now free of the larger Phobos mission rocket, begins a close approach to Phobos. With an average diameter of less than 12 miles, irregularly shaped Phobos has a very weak gravitational field making it relatively easy for the command module to come very close without being drawn all the way to its surface. The goal is to come close enough to permit space suited astrogeologists equipped with personal manned maneuvering units (MMUs) to act as mini spaceships themselves and descend to the surface. On the surface of Mars to the right can be seen Elysium Planitia and the volcano Albor Tholus.
An artwork of the terrestrial planet Mars set against the backdrop of the Milky Way. Mars's two moons, Phobos and Deimos, are seen passing in front. In this view of Mars we can see Valles Marineris in the middle - a vast chasm compared to which the US's Grand Canyon is little but a scratch. While off to the left we can see the Tharsis rise with its four giant volcanoes, the largest of which (Olympus Mons) is the most massive volcano in the known Solar System.