SOHO Recovery Updates

Yesterday, there was an attempt to transition the spacecraft from ESR to ISA, then to FSA and on to RMW mode. However, it was not successful for the following two reasons.

While on ISA mode and preparing the transition to FSA, a Mode 3 command with data words to change the limit for RRAD was sent to the spacecraft. Unfortunately, while building the command, the CMS on the ground shifted the value of this limit 8 bits to the right, dividing it by 256, and making it very close to zero. As soon as this command was uplinked, a roll rate anomaly was triggered on board and the spacecraft transitioned itself to ESR mode again.

Later in the afternoon, when running the script again, a DHSS error, under investigation, prevented the completion of the activities when it caused a COBS warm start up. This event had no effect on the spacecraft thermal configuration.

Today, a spacecraft emergency was declared in order to secure DSN coverage until SOHO is, once again, in nominal mode.

Thrusters 7 and 8 (B side) were successfully tested when SOHO was on ISA mode. This completed the tests of the propulsion subsystem.