NASA's Neil Gehrels Swift Observatory successfully returned to science operations Thursday, Feb. 17. The spacecraft and its three instruments are healthy and operating as expected.
The spacecraft is now operating using five reaction wheels instead of six, following a failure of a reaction wheel that caused the observatory to enter safe mode on Jan. 18.
The team is monitoring the spacecraft's performance as Swift resumes its mission to study the high-energy universe.
NASA's Neil Gehrels Swift Observatory operations team has confirmed that a failed reaction wheel caused the spacecraft to enter safe mode Jan. 18. The team believes the issue is mechanical and is moving to configure the spacecraft to operate using the other five reaction wheels, which are performing as expected.
The team has decided not to attempt recovery of the failed reaction wheel for the time being. After several more weeks of resting the wheel, the team will reassess whether to attempt its recovery.
The team is currently testing the settings for operating the spacecraft using the five operational reaction wheels. After the tests for these settings have been completed, they plan to upload them to the spacecraft next week.
Swift can fully carry out its science mission with five wheels. After careful analysis, the team has determined that the five-wheel configuration will minimally impact the movements necessary for Swift to make science observations. The team expects the change will slightly delay the spacecraft's initial response time when responding to onboard gamma-ray burst triggers, but this will not impact Swift's ability to make these observations and meet its original operational requirements.
Once the new configuration is uploaded to the spacecraft and verified in orbit, the team will begin a phased return to science operations. Stay tuned to nasa.gov/swift for updates.
On the evening of Tuesday, Jan. 18, NASA's Neil Gehrels Swift Observatory entered into safe mode, suspending pointed science observations. The mission team is investigating a possible failure of one of the spacecraft's reaction wheels as the cause.
The team has powered off the suspected wheel. The observatory and all its instruments are otherwise healthy and operating as anticipated. The observatory will remain in safe mode as a precaution while the team further investigates the issue.
Swift has a total of six reaction wheels onboard. The team is working to restore science operations using five reaction wheels. The remaining five wheels are all working as expected. This is the first time a reaction wheel has experienced a failure in Swift's 17 years of operations.
Swift studies high-energy events in the universe such as gamma ray bursts, which may come from black holes being born from dying stars. Stay tuned to nasa.gov/swift for more updates.