NASA has given us approval to fire the spin thrusters on ISEE-3 to increase its spin from 19.16 rpm up to the mission specification of 19.75 +/- 0.2 rpm. This spin rate is required in order to properly fire the axial thrusters during the much longer trajectory correction maneuver (TCM) we need to perform to adjust the spacecraft’s course. We do not yet have a specific target date for this spin-up burn. This will also serve as our initial test of the functionality of the ISEE-3 propulsion system in preparation for the much longer TCM burn between 30 June and 2 July.
Update: we are now targeting Saturday 21 June as the date for our spin-up maneuver.
See ISEE-3 Propulsion System Overview for a more detailed description of the ISEE-3 propulsion system.