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Flight Status Report

Friday, 5 September 1997

Surveyor has almost completed its 10-month voyage to reach Mars. As of today, only six days remain until the spacecraft encounters the red planet. Currently, Surveyor is 1.56 million kilometers from Mars and is closing that gap at the rate of 249,350 km per day. Very few activities occurred this week as the flight team continues its preparations for the Mars orbit insertion burn that will take place next Thursday.

On Monday, the onboard flight computer was commanded to disable its ability to enter safe mode. This mode of operations is automatically triggered when Surveyor's software detects an unexpected event in one or more of the spacecraft's subsystems. An entry into safe mode would cause Surveyor to terminate all onboard command sequences, and then transition to a configuration that ensures adequate power, thermal, and communications margins.

Disabling safe mode ensures that nothing will accidentally cause Surveyor to abort the command sequence that is currently counting down toward the orbit insertion burn in six days. The lack of an automatic method to safe the spacecraft in the unlikely event of an emergency is compensated by the fact that the flight team is in constant communications contact with Surveyor. The automatic ability to enter safe mode will be restored shortly after arriving at Mars.

After a mission elapsed time of 302 days from launch, Surveyor is 248.70 million kilometers from the Earth and is moving in an orbit around the Sun with a velocity of 22.04 kilometers per second. This orbit will intercept Mars six days from now, at 6:31 p.m. PDT on September 11th (01:31 UTC, September 12th). The spacecraft is currently executing the T1 command sequence, and all systems continue to be in excellent condition.

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