NASA's Swift Space Telescope Resumes Science After Rescue Mission Fails

NASA's Neil Gehrels Swift Observatory is observing the universe again after controllers restarted two of its three science instruments — the X-ray Telescope (XRT) and the Ultraviolet/Optical Telescope (UVOT) — on Aug. 26, NASA said Aug. 28. Both were shut down in February to cut atmospheric drag and keep it aloft until another spacecraft could boost it higher.

The third instrument, the Burst Alert Telescope (BAT), remains offline; halted in April to save power and reduce drag by angling Swift's solar panels. NASA hopes to resume BAT data within weeks. "Over the last 21 years, Swift has been NASA's multitool for studying the cosmos," NASA officials said, noting it observes many kinds of light, rapidly points at short-lived outbursts, and alerts facilities to coordinate follow-ups.

The return follows NASA's decision to abandon boosting Swift's orbit using LINK, a robotic servicing spacecraft from Arizona's Katalyst Space. LINK launched July 3 on a Northrop Grumman Pegasus XL rocket to grab Swift and raise its orbit, but developed attitude-control problems in late July that caused it to spin and disrupted communications. Two of its three reaction wheels were found inoperable, and its cold-gas thruster system lost some functionality.

Engineers regained attitude control, but NASA and Katalyst announced Aug. 19 that LINK would no longer try to capture and boost Swift; it will perform proximity operations, demonstrating satellite-servicing technology. Launched in November 2004 for a two-year mission studying gamma-ray bursts, Swift lacks propulsion to fight atmospheric drag, and rising solar activity expanded Earth's upper atmosphere, causing its orbit to decay faster than expected.

NASA's low-drag operations were expected to keep Swift above about 185 miles (300 kilometers) until October. With science operations resumed and the orbital boost off the table, NASA expects Swift to reach that critical altitude within one to two months, after which it is likely to crash back to Earth later this year, mostly burning up as it reenters the atmosphere.