Mars Global Surveyor will be a polar-orbiting spacecraft at Mars designed to provide global maps of surface topography, distribution of minerals and monitoring of global weather.
Launched with a Delta II expendable vehicle from Cape Canaveral, in November 1996, the spacecraft will cruise 10 months to Mars, where it will be initially inserted into an elliptical capture orbit. During the following four months, thruster firings and a erobraking techniques will be used to reach the nearly circular mapping orbit over the Martian polar caps. Aerobraking, a technique which uses the forces of atmospheric drag to slow the spacecraft into its final mapping orbit, will provide a means of min imizing the amount of fuel required to reach the low Mars orbit. Mapping operations are expected to begin in late January 1998.
The spacecraft will circle Mars once every two hours, maintaining a "sun synchronous" orbit that will put the sun at a standard angle above the horizon in each image and allow the mid-afternoon lighting to cast shadows in such a way that surface features will stand out. The spacecraft will carry a portion of the Mars Observer instrument payload and will use these instruments to acquire data of Mars for a full Martian year, the equivalent of about two Earth years. The spacecraft will then be used as a da ta relay station for signals from U.S. and international landers and low-altitude probes for an additional three years.
Mars Global Surveyor is the first mission of a new, decade-long program of robotic exploration of Mars, called the Mars Surveyor program. This will be an aggressive series of orbiters and landers to be launched every 26 months, as Mars moves into ali gnment with Earth. The program will be affordable, costing about $100 million per year; engaging to the public, providing fresh new global and close-up images of Mars; and have high scientific value obtained with the development of leading-edge space tec hnologies.
International participation, collaboration and coordination will enhance all missions of the program. Landers in future years -- 1998, 2001, 2003 and 2005 -- will capitalize on the experience of the Mars Pathfinder lander mission to be launched in 1 996. Small orbiters launched in the 1998 and 2003 opportunities will carry other instruments from the Mars Observer payload and will serve as data relay stations for international missions of the future.
The Mars Global Surveyor science payload will be provided as government-furnished equipment that was built to duplicate the instruments flown on Mars Observer. The payload includes the Mars orbital camera, thermal emission spectrometer, ultra-stable osci llator, laser altimeter, magnetometer/electron reflectometer and Mars relay system.
Project costs for the Mars Global Surveyor through 30 days after launch will be approximately $155 million.