Five days after entering orbit around the red planet, performance from the Mars Global Surveyor spacecraft continues to be outstanding. At 10:58 a.m. this morning, the spacecraft reached the top of its third orbit and performed a five-second rocket engine firing. According to navigator Eric Graat, this small burn slowed Surveyor by 9.8 m.p.h. (4.4 meters per second) and altered the tilt of the orbit with respect to the Martian north pole by 0.05 degrees.

Today's maneuver lowered the altitude of the orbit's low point from its current value of 163 miles (263 km) down into the upper fringes of the Martian atmosphere at 93 miles (150 km). Surveyor is currently falling back toward Mars and will reach this low point at 9:22 a.m. on Wednesday morning. At that time, the onboard flight computer will configure the spacecraft for its first pass through the Martian atmosphere.

Over the next four months, the spacecraft will lose momentum as it passes through the upper atmosphere during the low point of every orbit. This aerobraking technique will be used to lower the high point of Surveyor's orbit from its current altitude of 33,555 miles (54,002 km) to less than 280 miles (450 km).

After a mission elapsed time of 313 days from launch, Surveyor is 160.41 million miles (258.15 million kilometers) from the Earth and in an orbit around Mars with a period of 45 hours. The spacecraft is currently executing the P3 command sequence, and all systems continue to be in excellent condition.

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Status report prepared by:

Office of the Flight Operations Manager
Mars Surveyor Operations Project
NASA Jet Propulsion Laboratory
California Institute of Technology
Pasadena, CA 91109
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