In Search of Landing Sites on Mars
Planetary scientists have long been excited about the prospect of one day exploring the "grand canyon" of Mars. Valles Marineris is a chasm vastly larger than Earth's Grand Canyon that also has many layers of rock that serve as windows into the past. A corner of Valles Marineris known as Melas Chasma is one of 36 potential landing sites being considered for the next robotic wanderer to the red planet, the Mars Science Laboratory, to be launched in 2009.
But because Mars exploration is risky, NASA's planetary explorers are very careful about selecting a safe place to land. The proposed site is perched in a basin that rises above the canyon floor as high as a 4,000-foot mountain on Earth. Images such as this one from NASA's Odyssey orbiter help mission planners get a closer look.