NASA’s aging Swift space telescope is expected to make an uncontrolled return through Earth’s atmosphere within the next few hours.
The 3,200-pound Swift Observatory launched in 2004 to investigate gamma-ray bursts—the universe’s most powerful explosions—as well as other extraordinary cosmic objects and events.
The mission was originally designed to operate for just two years.
Instead, Swift completed 21 years of scientific observations before rising solar activity caused its low-Earth orbit to deteriorate rapidly.
The latest forecasts indicate that Swift could reenter the atmosphere sometime on Wednesday.
“Re-entry locations of any surviving components can vary from hemisphere to hemisphere and depend on when it re-enters,” NASA said in a statement.
An updated tracking map shows possible reentry paths crossing parts of Central and South America, Africa, South and Southeast Asia, and northern Australia. The projected routes also extend across large areas of the Pacific, Atlantic and Indian oceans.
The map cannot identify the precise point where debris might land. That location will depend on the exact moment Swift enters the atmosphere and begins to break apart.
The yellow and blue lines show the telescope’s repeated orbits around Earth. They do not indicate the exact location where any surviving debris will fall.
John Nousek, an astronomer at Pennsylvania State University who worked on the mission, told AP: “We’ve known this day would come since before Swift was launched.
“At least in low-Earth orbit, what goes up must come down. And that end is catastrophic.”
NASA said any surviving fragments could land within a broad belt around the equator, stretching across parts of Latin America, Africa, southern Asia and northern Australia.
That projection places the United States and Europe outside the potential debris zone.
Swift’s impending reentry comes after NASA’s unsuccessful effort to save the observatory in August.
The agency had committed $30 million to a mission intended to send another spacecraft to Swift, raise its orbit and prevent an uncontrolled fall to Earth.
The rescue spacecraft, known as Link, began spinning uncontrollably several weeks after launching in early July.
Flight controllers were able to reduce Link’s spin, but problems with its orientation and ability to hold its position in orbit persisted.
Current forecasts suggest that Swift will reenter Earth’s atmosphere sometime on Wednesday.
Swift Observatory recorded the afterglow of a gamma-ray burst. The bright rings are X-rays scattered by layers of dust in our galaxy. Several space- and ground-based telescopes observed the exceptionally bright explosion as it reached Earth.
NASA Administrator Jared Isaacman said in a statement: “This is not the outcome we were working toward, but it does not change why this mission was worth attempting.”
Swift returned to observing the universe after the rescue mission was abandoned, detecting additional gamma-ray bursts and other ultrahigh-energy events. By late October, however, the observatory had dropped too low to maintain stable scientific observations, and its systems were switched off.
During its mission, Swift detected more than 2,000 gamma-ray bursts and 1,400 exploding stars, along with numerous comets, asteroids and black holes tearing apart stars.
The telescope’s defining strength was its ability to turn rapidly toward sudden eruptions and other transient events in the sky.
NASA viewed Swift as an early-warning system for the Hubble and Webb space telescopes, as well as other observatories that could respond to its alerts and conduct more detailed investigations.
Scientists are still working out how to replace that capability.
Nousek said: “Our fervent hope is that the lessons learned from the successes of Swift can be applied to new generations of space missions and accelerate our discoveries about the universe.”