The Red Planet features ice caps of carbon dioxide and water, a volcano 15 miles high (Olympus Mons), a canyon 3,000 miles long and 4 miles deep (the great rift valley, Valles Marinerus), and dry river channels. Many such features were explored in 1971-72 by the Mariner-9 craft. The later Viking landers performed surface tests, looking for evidence of life.

Perhaps Mars, now locked in an ice age, once had a denser atmosphere and liquid water on its surface. But NASA's two Viking landers (1976) found no life.

The small rocky moons of Mars, Deimos and Phobos, are irregular in shape and comparable in size to the asteroid Gaspra. The three objects are shown at the same scale and almost the same lighting conditions in the image linked below. All three bodies have irregular shapes, testament to their violent histories. Their surfaces are distinctly different, most likely because of very different impact histories. The Gaspra image was taken by the Galileo spacecraft on October 29, 1991 and the images of Deimos and Phobos were taken by Viking Orbiter in 1977. The images are from NASA.