NASA’s Swift telescope fell over Indonesia. Astronomers have no like-for-like replacement

A final descent over Sumatra

NASA’s Neil Gehrels Swift Observatory re-entered Earth’s atmosphere over Indonesia’s North Sumatra region at 12:39 UTC on November 4, ending nearly 22 years in orbit. The U.S. Space Force confirmed the re-entry; NASA expected most of the spacecraft to burn up, but said some components may have survived. It was not immediately clear whether debris reached land.science +1

The loss removes an unusually agile tool for catching fleeting cosmic explosions. Other observatories can take over portions of Swift’s work, but none is lined up to replace its full combination of rapid pointing and instruments, according to Science News.sciencenews

Why seconds mattered

Swift launched in 2004 to study gamma-ray bursts, powerful flashes that often faded before earlier telescopes could respond. Its burst-alert instrument could spot and locate a flash, then the spacecraft could pivot its X-ray and ultraviolet/optical telescopes toward the fading source and alert other observatories. NASA says that sequence typically took about a minute.sciencenews +1

The speed opened a window on short gamma-ray bursts, which reach peak brightness in under two seconds. In 2005 Swift detected the X-ray afterglow of one such burst for the first time, supporting the idea that these events can come from merging neutron stars.science

Swift later became a versatile tool for astronomers studying other changes in the sky. In 2017 it took part in efforts to study light associated with a neutron-star merger and to trace a high-energy neutrino to its source, Science News reports.sciencenews

A rescue ran out of time

Swift had no engine to raise its own orbit, and increased solar activity expanded the upper atmosphere, increasing drag. NASA commissioned Katalyst Space to send a robotic craft, LINK, to grapple the telescope and lift it higher, but LINK lost control of its orientation after its July launch. The rescue was abandoned in August, and LINK itself re-entered in September.spaceflightnow +1

Swift resumed observations after the rescue attempt was called off, but made its final observation on October 20 as worsening drag prevented it from holding its telescopes steady.science +1

The work after Swift

NASA’s Fermi Gamma-ray Space Telescope remains in operation, but has different strengths. Researchers told Science News that the loss of Swift’s particular combination of capabilities could mean missing rare events as well as more common ones.sciencenews

NASA says it is exploring ways to respond quickly to future cosmic events using existing telescopes and possible new capabilities. Swift’s public archive, meanwhile, contains nearly 22 years of observations for researchers to keep analyzing.science