#### Session

Session IV: Recent and Future Missions

#### Abstract

The low Earth orbit (LEO) Pico Satellite Solar Cell Testbed spacecraft (PSSCT; also known as the PSSC Testbed) was ejected from the Space Shuttle Endeavour at 12:34 PM, PST, on November 29 , 2008. The LEO PSSCT is a 6.5-kg mass, 5” x 5” x 10”, fairly rigid, box-shaped nanosatellite designed to provide space flight data on radiation degradation of multi-junction solar cells. The LEO PSSCT was ejected from the shuttle with the long axis (Z axis) perpendicular to the instantaneous sun-spacecraft line. It has an internal momentum wheel that was spun up before ejection, thus determining the angular momentum vector in inertial space. After ejection, the momentum wheel took 5 minutes to slow down, thus imparting a 507 degree/second rotation rate for the spacecraft body about the Z axis. MEMS rate gyros from Analog Devices were used to monitor the rotation rates about the X, Y, and Z axes, with Earth and sun sensors providing additional information for on-orbit spin rate calibration. The Z axis has the minimum moment-of-inertia, so we expected the spacecraft to transfer energy from the Z axis to the X and Y axes over the course of several months. We obtained over three months of on-orbit spin rate data.

*Presentation Slides*

Spin Dynamics of the Pico Satellite Solar Cell Testbed Spacecraft

The low Earth orbit (LEO) Pico Satellite Solar Cell Testbed spacecraft (PSSCT; also known as the PSSC Testbed) was ejected from the Space Shuttle Endeavour at 12:34 PM, PST, on November 29 , 2008. The LEO PSSCT is a 6.5-kg mass, 5” x 5” x 10”, fairly rigid, box-shaped nanosatellite designed to provide space flight data on radiation degradation of multi-junction solar cells. The LEO PSSCT was ejected from the shuttle with the long axis (Z axis) perpendicular to the instantaneous sun-spacecraft line. It has an internal momentum wheel that was spun up before ejection, thus determining the angular momentum vector in inertial space. After ejection, the momentum wheel took 5 minutes to slow down, thus imparting a 507 degree/second rotation rate for the spacecraft body about the Z axis. MEMS rate gyros from Analog Devices were used to monitor the rotation rates about the X, Y, and Z axes, with Earth and sun sensors providing additional information for on-orbit spin rate calibration. The Z axis has the minimum moment-of-inertia, so we expected the spacecraft to transfer energy from the Z axis to the X and Y axes over the course of several months. We obtained over three months of on-orbit spin rate data.