MEDIA RELATIONS OFFICE JET PROPULSION LABORATORY CALIFORNIA INSTITUTE OF TECHNOLOGY NATIONAL AERONAUTICS AND SPACE ADMINISTRATION PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011 http://www.jpl.nasa.gov Mars Polar Lander Mission Status December 3, 1999 11 a.m. PST NASA's Mars Polar Lander is performing flawlessly and poised to land on the layered terrain near the red planet's south polar region shortly after noon Pacific time today, the mission team reported. The Mars Polar Lander navigation team reported on the success of this morning's trajectory adjustment, which took place at 5:39 a.m. PST. "It seems to be coming in pretty much right on the target line," said Michael Watkins, manager of JPL's navigation and mission design section. Flight controllers opted to perform the final trajectory adjustment of the mission early this morning. "It was as smooth and clean a maneuver as we've done," said Project Manager Richard Cook. "We're a gnat's eyelash away from our target." Wind speeds at NASA's Deep Space Network complex at Goldstone, Calif., were expected to remain in an acceptable range and not force stowage of the large antennas used to receive Polar Lander's signal after landing, Cook said. Winds in the range of about 32 kilometers (20 mph) were reported. The antennas would be stowed if there were sustained winds of about 80 kilometers per hour (50 mph) or gusts from about 73 to 88 kilometers per hour (45-55 mph). The entry, descent and landing sequence is the most complex and risky part of the mission. During descent, the spacecraft will enter the Martian atmosphere traveling at 6.9 kilometers per second (15,400 miles per hour). Onboard accelerometers will sense when friction from the atmosphere causes the lander to slow. From that time, it will be approximately 5 minutes and 30 seconds until touchdown on the surface, during which time the spacecraft will experience G forces up to 12 times Earth's gravity and the temperature of the heat shield's exterior will rise to 1,650 C (3,000 degrees F). Based on images from the camera on NASA's Mars Global Surveyor, the landing site, near the south polar layered terrain is expected to be devoid of rocks, generally flat and rolling, and fields of sand or dust dunes may be present, said Polar Lander Project Scientist Dr. Richard Zurek. The Deep Space 2 microprobes, which are piggybacking on the lander, will be jettisoned to the planet about 5 minutes before the lander enters the Martian atmosphere. They will impact the Martian surface about 60 kilometers (about 35miles) northwest from spot where Mars Polar Lander will set down. The probes, called Scott and Amundsen after early Antarctic explorers, will hit the Mars surface about 1 kilometer (less than a mile) from each other. The earliest signal from the spacecraft on Mars would be received at 12:39 p.m. PST, said Cook. Mars Polar Lander is part of a series of missions in a long- term program of Mars exploration managed by JPL for NASA's Office of Space Science, Washington, D.C. JPL's industrial partner is Lockheed Martin Astronautics, Denver. JPL is a division of the California Institute of Technology in Pasadena.

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