Flight performance of Skylab attitude and pointing control system

Abstract

I SUPPLEMENTARY NOTES1s. ABSTRACT IThis note briefly reviews the Skylab attitude and pointing control system (APCS) requirements and the way in which they became altered during the prelaunch phase of development. The actual flight mission (including mission alterations during flight) is described. The serious hardware failures that occurred, beginning during ascent through the atmosphere, also are described. The APCS's ability to overcome these failures and meet mission changes are presented. The large around-the-clock support effort on the ground is discussed. Finally, salient design points and software flexibility that should afford pertinent experience for future spacecraft attitude and pointing control system designs are included.

Earth observation from the manned low Earth orbit platforms

“…Also, microwave active sensors were used for the first time for Earth observation from space, which included an L-band radiometer (S-194), a Ku-band scatterometer measuring the fraction of transmitted microwave radiation backscattered by the ocean and land, and a Ku-band radar altimeter . To ensure proper operation, Skylab was controlled to hold an earth-pointing (Z-LV) attitude such that the Zaxis of Skylab was maintained perpendicular to the global geoid directly beneath the spacecraft (Chubb et al, 1975;Fearnsides, 1970).…”

Formulation of Torque-Optimal Guidance Trajectories for a CubeSat with Degraded Reaction Wheels

“…Related work on the use of environmental torques for actuator desaturation dates back to the Skylab program, where gravity gradient torque was used to desaturate momentum accumulated during the daylight portion of an orbit. 20,21 Additional applications regarding the use of gravity gradient torque to desaturate CMG momentum have been previously proposed by Powell 22 and Tong. 23 Tong showed in his study that despite complete momentum dumping not being achieved, a significant attitude maintenance CMG desaturation fuel saving of over 40% was attainable, thus demonstrating the potential for extending the life span of a spacecraft.…”

Skylab Attitude Control System

“…The TACS was utilized beyond premission planning because of the unexpected events that occurred during the beginning of the mission (meteoroid shield failure during liftoff) and was exclusively used to desaturate the CMG system in an un-63 planned manner during the first 12 days of the mission since the Skylab orientation was constrained by thermal and power considerations that prevented desaturation of the CMGs by vehicle maneuvers [8].…”