During our session with Arecibo today we came very, very close to firing the thrusters on ISEE-3 for its spin-up maneuver. But we were not able to complete the process and fire the thrusters. The spacecraft was completely configured for a thruster firing during today’s pass. We reduced the number of pulses from 11 to 1 to make certain that we had the proper commands in place. If that engine firing proceeded successfully we’d follow with the remaining 10 pulses so as to spin up the spacecraft to the required rotation rate. As it happened we were unable to get confirmation on the very last command and put a halt to the procedure.
The spacecraft is in a safe mode – one that has been verified by telemetry. You can follow the real time Tweets of this session by looking at our Twitter account at @ISEE3Reboot. We are waiting for word of our next window at Arecibo. We are now confident that we will be able to perform the required thruster firings to spin up the spacecraft during the next opportunity.
In order to get a more precise location on ISEE-3 we will be making another pass using the DSN on Wednesday starting at 19:45 UTC. With this information on the location of ISEE-3, and the experience of firing the thrusters for the spin-up maneuver, we are now confident that we will be able to perform our Trajectory Correction Maneuver between 30 June and 2 July.
– ISEE-3 Propulsion System Overview
– ISEE-3 Status Report 13 June 2014 – Green Light For Spin-up
– ISEE-3 Reboot Project Scheduled for DSN Doppler and Ranging Activity
– ISEE-3 Status Report 23 June 2014: DSN Ranging & Spin Up Update