Apple attitude acquisition with one solar panel undeployed

The problem analysis steps, actions taken, and results of a sequence of commands necessary to deploy the one functioning solar panel on the Indian Apple satellite are discussed in terms of the effects on the attitude control system. Sun acquisition of the spin-stabilized spacecraft was accomplished by using a fine sun sensor on another part of the satellite, since the undeployed panel covered part of the primary sun sensor. It was necessary to despin the spacecraft first in order to compensate for a spin rate increase in the controls initiated in response to any positive initial spin rate. Torque pulses then brought the earth within the field of view of the earth sensor. Further compensation was necessary due to the earth image being at the edge of the sensor field as the lock-on was initiated, thereby increasing the pitch rate. Rerunning the entire sequence produced an earth lock-on, which was stabilized when the primary momentum wheel was started and run up to 3500 rpm.