scope:

STS-114 experienced a very low Fuel Bias which lead to an investigation regarding possible causes. One item that was reviewed was the effect that LO2 purity would have on Space Shuttle Main Engine (SSME) performance. Investigation yielded large differences between LO2 purity requirements between Stennis Space Center (SSC) and Kennedy Space Center (KSC) and that LO2 purity was not accounted for in overall performance predictions. It was also identified that the current LO2 purity requirements were not adequate with the use of Flight Derived Dispersions to protect for an abnormally low LO2 purity day.