National Geographic : 1977 Jan
Massive floods, scientists agree, shaped teardrop islands (right) in the lee of impact craters in the Chryse region. Ragged outflow from the crater Yuty (above) was caused by a meteorite. Its im pact may have melted subsurface permafrost and expelled a slurry of rock and water. Puzzling scars of Phobos (left), one of two Martian moons, could have been gouged by fragments of a disintegrated comet. Orbiter 2made the picture from only 545 miles away. A long-range view of the other moon, Deimos (right), shows numerous craters. Viking pictures suggest that both moons were as teroid fragments captured by the planet eons ago.