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Flight Status Report

Friday, 20 December 1996

During the morning on Monday and Tuesday of this week, the Surveyor flight team conducted more tests to collect diagnostic data regarding the spacecraft's solar array position discrepancy. On each of the two test days, the gimbal joint holding the -Y solar panel to the spacecraft was commanded to wiggle the panel back and forth several times over a time period of 18 and 84 seconds, respectively. The strongest of these two tests occurred on Tuesday during which the wiggling caused the -Y panel to move by 8 degrees before returning to its pre-test position.

Engineering telemetry transmitted back to Earth during these tests will allow the flight team to analyze the nature of the vibrations in the spacecraft that resulted from the wiggling. This data will provide valuable insight into determining the best method to clear the obstruction that is currently keeping the -Y solar panel 20.5 degrees out of position.

Preliminary results from this week's tests and the three tests that occurred last week support the theory that the obstruction is a broken shaft from the solar array's deployment mechanism. The flight team believes that the shaft broke sometime during the launch phase, or during solar array deployment, and then wedged itself in a position to keep the -Y panel from deploying into its proper position. However, both arrays are generating full power and the position discrepancy does not pose a threat to the mission.

Other activities this week included a test of the Mars Orbiter Laser Altimeter. Early Thursday morning, shortly after midnight Pacific Standard Time, Surveyor turned to point the laser altimeter at the Earth. Over the course of one hour, the laser fired pulses of light toward a receiving station at NASA's Goddard Space Flight Center in Greenbelt, Maryland. Unfortunately, snow storms and low-level clouds prevented the station from detecting the laser's pulses. The flight team may consider attempting another test next year if time permits.

After eight weeks of flight, Surveyor is 10.90 million kilometers from the Earth and is moving in an orbit around the Sun with a velocity of 32.48 kilometers per second. This orbit will intercept Mars on September 12th, 1997. All systems on the spacecraft continue to be in excellent condition.

The flight team would like to extend our best wishes to everybody for safe and happy holiday season.