The Mars Surveyor 2001 missions will follow two other robotic Mars missions to be launched in late 1998 and early
1999. All are part of NASA's long-term, systematic exploration of Mars in which two missions are launched to the planet
approximately every 26 months. NASA's Office of Space Science has selected the following investigations for the Mars 2001 Orbiter, due for launch in March of that year, and the Mars 2001 Lander/Rover, due for launch in April:

The two robotic spacecraft scheduled for launch in mid-2001 to orbit and land on Mars will carry a descent camera, a
multispectral imager, and a robotic rover capable of traversing tens of miles across the red planet's rocky highlands. The Mars 2001 Thermal Emission Imaging System (THEMIS) will map the mineralogy and morphology of the Martian surface using a high resolution camera and a thermal infrared imaging spectrometer. Dr. Phil Christensen from Arizona State University in Tempe is the principal investigator for THEMIS.

The Mars 2001 Lander will carry a small, advanced technology rover capable of traveling several tens of miles across
the Martian highlands. The rover will be slightly larger than the Pathfinder Sojourner rover and will be designed to go farther
(100 km vs. 100 m for Sojourner) and to last longer (1 year vs. 7 days for Sojourner). The rover will carry a payload called
Athena, which is an integrated suite of instruments which will conduct in-situ scientific analyses of surface materials. It also will
be able to collect and analyze core samples for later return to Earth by a future robotic mission. Dr. Steven Squyres from
Cornell University, Ithaca, NY, is the principal investigator for Athena.

The 2001 Orbiter will be the first to use the atmosphere of Mars to slow down and directly capture a spacecraft into orbit
in one step, using a technique called aerocapture. The 2001 Lander will carry an imager to take pictures of the surrounding terrain during the lander's rocket-assisted descent to the surface. The descent imaging camera will provide images of the landing site for geologic analyses, and will aid planning for initial operations and traverses by the Athena rover. Dr. Michael Malin of Malin Space Science Systems Inc. in San Diego, CA, is the team leader for the Descent Imager science team and Dr. Ken Herkenhoff of NASA's Jet Propulsion Laboratory (JPL), Pasadena, CA is a team member.

The Orbiter also will carry the Gamma Ray Spectrometer (GRS), the last of the remaining Mars Observer science
investigations. The GRS will achieve global mapping of the elemental composition of the surface and the abundance of
hydrogen in the shallow subsurface.

An integrated team consisting of the Jet Propulsion Laboratory and Lockheed Martin Astronautics, Denver, CO, will
develop the missions, led by JPL. Both of the 2001 missions are part of an ongoing NASA series of robotic Mars exploration spacecraft that began with the launches of the Mars Global Surveyor orbiter and the Mars Pathfinder lander in November and December 1996, respectively.