Ulysses is still alive, but efforts to restart the X-band transmitter have failed. In the meantime, the fuel-bleeding technique for keeping the hydrazine fluid is still working, but the tank is running dry! Here’s the official update from Nigel Angold.
Dear Ulysses colleagues,
Well, August came and went and spacecraft operations continue. However, we now have to reduce the telemetry bit rate to 256 bps for low elevation portions of our 70m tracks. As reported in early August, a further X-band switch on attempt failed and we do not feel that approach is worth trying again. We will try a more aggressive switching scenario (involving Main Bus Undervoltage) at the first signs of fuel freezing.
We estimate that we have approximately 0.85 kg fuel remaining but there is an uncertainty of +0.6/-0.7 kg. So with our current rate of fuel usage (~0.5 kg per month), we expect to run out sometime between the end of September and December. We could use less fuel during our 2-hourly fuel bleeding activities, but that would increase the risk of freezing significantly.
Hopefully, we will be able to continue the S-band mission on a day-by-day basis until the fuel freezes or runs out. And with a bit of luck, we’ll encounter the slow speed solar wind before then.
Best regards,
Nigel
