Official Nasa Communication N99-033

Douglas Isbell/Don Savage Headquarters, Washington, DC (Phone: 202/358-1547)

May 26, 1999

Cynthia M. O'Carroll Goddard Space Flight Center, Greenbelt, MD (Phone: 301/614-5563) Mary Hardin Jet Propulsion Laboratory, Pasadena, CA (Phone: 818/354-5011) NOTE TO EDITORS: N99-33 GLOBAL MAP OF MARS' TERRAIN SHOWS WHAT'S UP, WHAT'S DOWN Members of NASA's Mars Global Surveyor science team will unveil the first global three-dimensional map of the surface of Mars at a press briefing on Thursday, May 27. The topographical map gives scientists their first detailed understanding of the relative heights of various geologic features on the red planet, including regions that shaped the flow of water early in Mars' history and what may be the largest impact basin in the Solar System. The Space Science Update will be held at 2 p.m. EDT in the James E. Webb Auditorium at NASA Headquarters, 300 E St. SW, Washington, DC. The map was produced by the Mars Orbiter Laser Altimeter (MOLA) instrument aboard Global Surveyor, which fires short pulses of infrared light at the Martian surface and measures the time it takes for the reflected light to return. Given the known orbit of Global Surveyor, the resulting times allow scientists to infer the height of the terrain below with great accuracy.

Briefing presenters will include: * Moderator Dr. John Grant, Mars Global Surveyor program scientist in the Office of Space Science at NASA Headquarters. * Dr. David Smith, principal investigator for the Mars Global Surveyor MOLA instrument from NASA's Goddard Space Flight Center, Greenbelt, MD. * Dr. Maria Zuber, co-investigator for the MOLA instrument from the Massachusetts Institute of Technology, Cambridge, MA, and NASA Goddard. * Dr. Jim Zimbelman, planetary geologist at the Center for Earth and Planetary Studies at the Smithsonian Institution's National Air and Space Museum, Washington, DC. Mars Global Surveyor carries five science instruments designed to generate a complete global portrait of Mars and its seasonal changes during a full Martian year, the equivalent of two Earth years. It is the first mission in a long-term program of Mars exploration known as the Mars Surveyor Program, which is managed by NASA's Jet Propulsion Laboratory (JPL), Pasadena, CA, for the Office of Space Science at NASA Headquarters. JPL's industrial partner is Lockheed Martin Astronautics, Denver, CO, which developed and operates the spacecraft. JPL is a division of the California Institute of Technology. The briefing will be carried live on NASA Television, which is available on transponder 9C of the GE-2 satellite at 85 degrees West longitude, vertical polarization, frequency 3880 MHz, audio of 6.8 MHz. Two-way question-and-answer capability will be available for news media at participating NASA centers. - end -