In August 1999, the Jet Propulsion Laboratory’s Advanced Projects Design Team (Team X) studied a robotic mission to determine the ages of the volcanic and sedimentary rock layers in the walls of Valles Marineris, the great martian canyon system. The Mars Stratigraphy Mission (MSM), as it was called, would see a lander similar to that planned for the 2001 Mars Surveyor Program lander mission leave Earth atop a Delta 7925 rocket in April 2007 and land on Mars in October 2009. It would steer itself to a precision landing at 14° south latitude, 68° west longitude, no more than 10 kilometers from the Valles Marineris southern rim.
The MSM lander would deploy a specialized rover with three spherical inflatable “wheels.” Throughout the surface mission, the solar-powered rover would communicate with Earth via a communications satellite in equatorial Mars orbit. The rover would need no more than 50 days to travel to the canyon rim. Once there, it would anchor the end of a tether to the ground and, paying out the tether behind it, rappel into the six-kilometer-deep canyon.