Mars Climate Orbiter Incident

Overview

• Incident: Loss of NASA's Mars Climate Orbiter
• Launch Date: December 11, 1998
• Mission Objective: To orbit Mars, gather climate data, serve as a relay for Mars Polar Lander

Importance of Monitoring

• Spacecraft require continuous monitoring to ensure proper trajectory
• Reaction wheels are commonly used for orientation
• Navigation teams adjust trajectory based on angular momentum

Trajectory Monitoring Process

1. Telemetry Data Transfer:

   • Data sent from spacecraft to ground
   • Processed by software and stored in angular momentum desaturation file

2. Trajectory Adjustments:

   • Changes made by firing spacecraft thrusters
   • Velocity changes measured by two systems:
     • Spacecraft software (newton seconds)
     • Ground software (pound seconds)

Root Cause of Failure

• Measurement Error:
  • Different units used by systems (metric vs. imperial)
  • Ground computer's data used for trajectory updates
  • Conversion: 1 pound to 4.45 newtons
  • Adjustments were off by a factor of 4.45

Consequences of Errors

• Trajectory Implications:
  • Errors accumulated during the nine-month cruise
  • Orbiter reached Mars 105 miles lower than expected
  • This altitude was too low for survivability

Final Outcome

• Loss of Communication:
  • Engine burn for orbit insertion failed
  • NASA lost contact with the spacecraft

Conclusion

• The precise cause of the Mars Climate Orbiter's loss is known, but the exact fate remains unknown.
• Highlights the importance of consistency in measurements in aerospace missions.