PRECURSOR Attitude Concept

The PRECURSOR satellite is scheduled to be launched into a sun synchronous orbit with an 10:30 right ascending node. The attitude profile needs to fullfill these high level requirements:

  • Point solar generator toward sun when outside eclipse. Also minimize angle between downlink antenna and nadir
  • During eclipse point antenna toward nadir for best communication and point thrust vector along orbit velocity
  • When in line of sight, point antenna directly to base ground station
Attitude Mode Transitions

This concept has been simulated with GMAT. A short visualization demonstrates the concept and shows the attitude transitions:

For comparision 2 more orbits are simulated. First a 06:00 orbit where the orbital plane is rougly perpendicular to the sun direction which means the satellite is always illuminated. This would be the ideal orbit where the battery can always be charged and the antenna can always pointed directly to Earth.

Third 3rd simulation shows a 12:00 orbit. This is the other extreme where the sun is parallel to the orbital plane. This causes the longest eclipse period and also results in an aggressive yaw flip when the sun passes overhead.