Swift: re-entry expected on 4 November, but its data remain
· BehindLines newsroom
The Neil Gehrels Swift Observatory has stopped observing, but its data remain available. According to NASA, it is expected to re-enter the atmosphere on Wednesday, 4 November. Updated 3 November: none of the sources checked that day reports a re-entry yet.
Expected, not yet confirmed
In its 2 November post, NASA says Swift is expected to re-enter Earth's atmosphere on 4 November. As of Monday, the US Space Force estimated about 3:30 a.m. Eastern Standard Time (EST), which is 08:30 UTC, with an uncertainty of 11 hours. NASA says it and the Space Force will keep monitoring the re-entry and updating predictions, which are posted on the mission blog.
That time is an estimate, not an observation. Other organisations publish different forecasts, and both date and time may still shift. This article will be updated once NASA confirms the re-entry.
A risk judged low
NASA describes the risk of harm to anyone on Earth as unlikely, about 1 in 2,100. The spacecraft weighs roughly 3,200 pounds (about 1,450 kg). The agency expects most of it to burn up on the way down, though some components may survive. Because of Swift's low-inclination orbit, any surviving fragments could land only between 20.6 degrees south and 20.6 degrees north latitude.
How the mission ended
According to NASA's 23 October mission log, solar activity increased atmospheric drag and Swift lost altitude. The commercial effort to raise its orbit did not succeed. On 20 October, at about 275 kilometres altitude, the spacecraft entered safe mode; the ground team then sent the command that ended operations.
An archive that keeps working
Launched on 20 November 2004 for a two-year prime mission, Swift operated for nearly 22 years. It spotted gamma-ray bursts, relayed their positions and pointed its X-ray and ultraviolet-optical instruments at the same patch of sky. NASA's summary cites more than 2,000 bursts observed and over 1.5 million ultraviolet and optical images. The archive stays open to new analysis even though the satellite will produce no new measurements.