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Mars Pathfinder Mission Status

24 January 1997

The spacecraft continues to function well and is currently 14 million kilometers from Earth. The major activity for last week was starting the performance testing of the K=15 R=1/6 convolutional code. Early tests results indicate that the Block III MCD is operating as expected and that the expected telecom link improvements match predicts.

The project is investigating some minor anomalies which occurred this week involving the spacecraft Command Detector Unit. The most serious of these occured on Monday, January 20 when the CDU transitioned to a lock state during a period when we were not uplinking to the spacecraft. The CDU lost lock as expected when we transmitted an uplink signal, but this "self-lock" behavior is not expected. In addition, we experienced two other episodes where commands were rejected by the spacecraft uplink hardware for unexplained reasons. The project has started a tiger team activity to further investigate these problems and determine potential causes. The possibility of solar flare induced SEUs is being assessed, but we are not ruling out other potential causes.

The flight team is also investigating an attitude control fault that we experienced on Sunday, January 19. This fault occured when estimates of the attitude covariance matrix inexplicably jumped by several orders of magnitude. The resulting fault response reinitialized attitude control flight software and turned off the Propulsion Drive Electronics. Analysis of telemetry before and after the fault did not show a definitive cause. We are currently planning to perform additional diagnostic tests to assess memory and software integrity in case SEUs or numerical divergence problems may have caused this problem.

Continuing EDL and surface operations planning. The Rover team completed a successful Rover Operations Readiness Test, and planning is nearly complete for the first full team Surface Operations Readiness Test on January 27-28.

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