NASA\u2019s Neil Gehrels Swift Observatory has ended its science mission now that the spacecraft is orbiting less than 171 miles (275 kilometers) above Earth\u2019s surface. The greater atmospheric drag at this height prevents the satellite\u2019s telescopes from steadily gazing at their astronomical targets. <\/p>\n
Swift conducted its final observation on Oct. 20. It is expected to re-enter the atmosphere in the next few weeks.<\/p>\n
\u201cSwift delivered an incredible, lasting return on investment for the nation, designed for a two-year primary mission but productive for more than 10 times as long,\u201d said Shawn Domagal-Goldman, director,\u00a0Astrophysics Division at\u00a0NASA Headquarters<\/a>\u00a0in Washington. \u201cIn that time, Swift played a major role in advancing our understanding of the changing universe and was part of a revolution in astrophysics that showed how critical rapid-response observations are to the entire community. To support rapid response to cosmic events in a post-Swift world, we\u2019re exploring our ability to use and augment NASA\u2019s fleet of existing space telescopes, from fast-to-orbit commercial capabilities to efficient, innovative new missions. And Swift leaves us with an extraordinary archive of multiwavelength observations that will fuel new discoveries for decades more.\u201d<\/p>\n In its storied career, Swift has observed more than 2,000 gamma-ray bursts<\/a>, the most powerful explosions in the cosmos. It has studied more than 1,400 supernova explosions, witnessed stars shredded by black holes<\/a>, monitored active galaxies<\/a>, conducted an all-sky X-ray survey, studied asteroids<\/a> and comets<\/a>, and more. Swift data has contributed to about 7,000 published scientific papers.<\/p>\n \u201cSwift was designed as a satellite dedicated to studying gamma-ray bursts, outbursts that came and went so quickly that no one could target them with large telescopes to learn more,\u201d said S. Bradley Cenko, the mission\u2019s principal investigator at NASA\u2019s Goddard Space Flight Center in Greenbelt, Maryland. \u201cSwift needed to detect and locate gamma-ray bursts, communicate their position to other observatories, and then swing its telescopes around to image the burst locations before their afterglows faded out. This typically took Swift about a minute to do.\u201d<\/p>\n Led by its first principal investigator, Neil Gehrels, Swift was born as a multiwavelength observatory, with co-aligned Optical\/Ultraviolet and X-ray telescopes that could quickly image and refine a burst\u2019s position. The mission launched into orbit on Nov. 20, 2004, and went to work the following month. In 2018, NASA renamed the mission<\/a> to honor Gehrels following his death.<\/p>\n Speed was especially important for an elusive population called short gamma-ray bursts, which reach peak brightness in less than two seconds. Until Swift, it had been impossible to locate these bursts rapidly and precisely enough to observe their afterglows. In May 2005, Swift\u00a0achieved this milestone with GRB 050509B<\/a>, which lasted just 0.03 seconds. Swift turned to the burst fast enough to detect 11 X-ray photons, making this the first short burst with a detected afterglow. These observations validated long-standing theoretical models, showing that short gamma-ray bursts likely come from mergers of two neutron stars \u2014 objects with the mass of the Sun that have been crushed to the size of a city.<\/p>\n Another factor led to Swift\u2019s success as a kind of astronomical multitool. Its flexible planning system enabled astronomers to request “target-of-opportunity” observations that could be commanded from the ground in as little as a few minutes, or to set up monitoring programs for observing specific sources lasting from as little as a few minutes to months. The system could schedule up to 75 independent targets a day.<\/p>\n “The unique speed of response of the Swift hardware, the extraordinary success of the rapid mission operations, and the closely knit teamwork of the Swift Flight and Science Operations teams placed Swift at the crossroads of burgeoning areas of research,” said John Nousek, the mission\u2019s operations director and professor of astronomy and astrophysics in the Eberly College of Science at Penn State in University Park, Pennsylvania.<\/p>\n The Swift archive contains nearly 22 years of brightness measurements of all kinds of cosmic outbursts, multiwavelength spectra, more than 1.5 million images from its Ultraviolet\/Optical Telescope, and much more. The full dataset, publicly available as part of NASA\u2019s commitment to open, gold standard science, spans approximately 12 terabytes, the storage equivalent of about 600 high-definition movies.\u00a0\u00a0<\/p>\n As part of the agency\u2019s previous planning for Swift\u2019s end of mission, NASA will continue to prioritize finding new options to react rapidly to cosmic events, using current missions to help fill the gap in the meantime.<\/p>\n To learn more about the Swift mission, visit:<\/p>\n