EXPLANATION AND HISTORY OF THE NEW SOLAR CYCLE/ATMOSPHERIC MODEL USED IN MARS PLANETARY PROTECTION ANALYSIS

摘要

In December 2000, it was decided to update the solar cycle/ Mars atmosphere model coded in the software used to do the orbit lifetime aspects of Planetary Protection (PP) analysis (Vincent, 2000). The old model was based on analysis done for the Mars Observer mission in the early to mid-1980's. Since then the atmospheric models of the scientific community have been refined. In particular, the empirical measurements obtained from the accelerometer on board the Mars Global Surveyor (MGS) mission during its aerobraking phase have been included. The new model used in the PP analysis is fitted to match the recent scientific results. This report is an expanded version of an earlier memo (Vincent 2001) written to justify the use of this model. The new model is shown to be valid while still retaining some conservatism.