Fuel optimization during Mars Global Surveyor aerobraking

Due to a solar array on the -y-axis side of the Mars Global Surveyor (MGS) spacecraft that was severely damaged during deployment, the MGS aerobraking mission Was significantly replanned. The aerobraking mission was extended from about 400 aeropasses to about 893 aeropasses. At 0.013 kg/aeropass, the required increase in fuel use due to the additional 493 aeropasses would be 6.4 kg. There was insufficient margin to support this increase in fuel use. As a result several techniques were analyzed to reduce the fuel use on each aeropass. Four of the techniques were employed on the spacecraft, each with favorable results. Each of these techniques is discussed in detail. The combined result was a reduction from 0.013 kg/aeropass to about 0.004 kg/aeropass. With these fuel savings, the extended aerobraking mission was accomplished with less fuel than was in the original budget, and the MGS spacecraft was able to successfully achieve the objectives of its mapping mission.