OFFICIAL: NASA’s Neil Gehrels Swift Observatory re-entered Earth’s atmosphere Wednesday, almost 22 years after launch. At launch, Swift was a first-of-its-kind multiwavelength observatory designed to study the most powerful explosions in the cosmos using its three telescopes.
The U.S. Space Force confirmed that the Swift spacecraft re-entered Earth’s atmosphere at 7:39 a.m. EST Wednesday over the North Sumatra region of Indonesia, at approximately 3.4 degrees north latitude and 98.6 degrees east longitude. NASA expected most of the spacecraft to burn up as it traveled through the atmosphere, but some components may have survived re-entry.
NASA’s Swift launched in 2004 to explore the universe’s most powerful explosions, called gamma-ray bursts. It was originally designed for a two-year prime mission. During more than two decades of science operations, Swift served as a multi-tool for exploring the universe, observing a wide range of light, rapidly pointing at short-lived outbursts, and sending alerts to other facilities to help coordinate follow-up observations. Swift has broadened our understanding of a wide variety of cosmic objects and events, from active galaxies powered by supermassive black holes and stars undergoing X-ray flares, to supernova explosions and comets and asteroids in our own solar system.
A further look at Swift's history:
submitted by /u/ChiefLeef22Swift was not classified as a flagship observatory, like the Hubble Space Telescope or Chandra X-Ray Observatory, but it left behind a legacy that will not swiftly be forgotten.
The Swift Observatory first came onto the scene in 2004 when NASA launched it into low Earth orbit. Originally called the Swift Gamma-Ray Burst Explorer, its purpose was to move quickly to follow up on explosive events called gamma-ray bursts and their afterglows using its three onboard telescopes.
Swift’s name is not an acronym. Instead, it refers to its speed and likens the observatory to the bird. It could rotate and move quickly to observe transient events, which are events that happen quickly and fade away.
Watching for gamma-ray bursts:
Gamma-ray bursts are the most explosive and energetic events in the universe. Scientists theorize they come from the explosions of large stars or mergers of a very dense type of star called neutron stars. Gamma-ray bursts, as the name implies, release large bursts of gamma-rays, but as these explosions fade, they lose energy. Scientists can spot remnants of gamma-ray bursts by looking for X-rays and optical light as the gamma rays themselves fade.
Swift’s burst alert telescope could see light in the gamma-ray portion of the electromagnetic spectrum, so it searched directly for gamma-ray bursts. Its X-ray telescope and ultraviolet-optical telescope could measure the resulting afterglow of X-ray and UV light these events produced as they faded.
What set Swift apart was its ability to do what’s called slewing: In order to follow up on transient events, it swiveled its telescopes around quickly and could cover 50 degrees in less than 75 seconds. Comparatively, it takes Hubble about 15 minutes to turn 90 degrees.
By 2015, just 10 years after science operations started, Swift detected its 1,000th gamma-ray burst.
Beyond gamma-ray bursts:
Swift’s ability to slew quickly allowed it to detect more than just gamma-ray bursts. Its onboard instruments could detect anything that changes quickly in the sky, including supernovae and X-ray flares from binary stars, which are two stars bound by gravity that tend to interact with each other. It could also detect the electromagnetic counterparts to gravitational waves, which result from large distortions in space-time, such as the merger of dense objects such as black holes and neutron stars.
In 2008, when observing another supernova, Swift by chance detected a slight rise in X-rays, which preceded a supernova explosion. This initial increase in X-rays represented the earliest phase of supernova evolution ever observed. Swift’s extensive alert network notified astronomers all over the world who were able to point other space- and ground-based telescopes at the supernova to follow up and obtain even more data.
Then in 2017, when the IceCube Neutrino Observatory – whose principal investigator Francis Halzen won the 2026 Nobel Prize in physics – detected high-energy neutrinos, Swift was able to help localize their source. Neutrinos are massless particles that do not interact with most matter. This property makes it hard for physicists to detect them and pinpoint their source. Scientists know that astrophysical events can emit them, and they used Swift to connect these neutrinos to a very energetic supermassive black hole at the center of its galaxy.
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