degree to which the proposed trajectory options are consistent with the requirements necessary to avoid the forward contamination of Europa.

In the interim, COMPLEX performed its own qualitative analysis. Based on the information supplied to the committee, an extra year of operations can be expected to increase the burden of radiation absorbed by Galileo by only about 20%. This estimate, plus the fact that Galileo retains full redundancy in all essential systems and that the radiation effects sustained thus far have not handicapped control of the spacecraft, suggests to COMPLEX that the probability of total loss of control during this extra year is relatively small. Moreover, the chances of total failure can be mitigated by prudent monitoring of the spacecraft ’s health and by a commitment on the part of NASA to retarget Galileo onto a Jupiter-bound trajectory following the loss of redundancy in any major command and control subsystem.

In summary, COMPLEX concurs with NASA’s decision that impact with Jupiter is the most appropriate means of disposing of Galileo. COMPLEX recommends that the Galileo Project perform qualitative risk assessment of the various trajectory options. Pending the completion of these calculations, the committee reached a consensus that an appropriate interim course of action is to defer the destruction of Galileo until after the completion of the Io polar flybys, in order to obtain as much science as possible from the mission.


Claude Canizares


Space Studies Board

John A. Wood



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