NASA aims to save a sinking space telescope with a rendezvous in orbit

NASA on Tuesday plans to launch a mission to save one of its workhorse space telescopes.

For more than two decades, the agency's Neil Gehrels Swift Observatory has been circling Earth studying gamma-ray bursts, the most powerful explosions in the universe, which are triggered by events like births of black holes and collisions between ultra-dense stars at the ends of their lives.

But Swift is at imminent risk of sinking back into the atmosphere, where it would break apart upon re-entry. NASA's prediction models suggest that the telescope's orbit could drop to an altitude considered critically low — below 185 miles — in October.

"It is a swift observatory that can quickly pivot across the night sky to find things that go boom in the night," Dr. Shawn Domagal-Goldman, director of NASA's astrophysics division, said during a news conference on June 17, pausing to emphasize the pun with Swift's name. "So we decided, yeah, we want to go save this one this time because of how special it is."

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To stave off the observatory's demise, NASA plans to launch a robotic spacecraft to boost Swift's orbital path. The agency last year awarded a $30 million contract to the Arizona-based company Katalyst Space Technologies to build the spacecraft, with aerospace giant Northrop Grumman providing the plane and rocket that will send it into orbit.

The plan calls for Northrop Grumman's Stargazer airplane to take off from the Marshall Islands no earlier than Tuesday at 6:23 a.m. Once it reaches 40,000 feet, the aircraft is expected to deploy the company's Pegasus XL rocket, carrying the 6-foot, 880-pound robotic spacecraft called LINK.

The rocket should then launch LINK into orbit, where it would attempt to capture the Swift observatory and raise its orbit over a period of several months.

All satellites in low-Earth orbit slowly lose altitude as they experience atmospheric drag. That process had affected Swift, but then came a period of intense solar activity in 2024, a phase in the sun's natural 11-year cycle known as solar maximum, which is characterized by increased flares and solar storms. When the sun's activity ramps up, it heats Earth's atmosphere, which increases drag on satellites in low-Earth orbit as they fly through "thicker" air, similar to the increased effort required to fly into strong headwinds.

John Nousek, a professor of astronomy and astrophysics at Penn State University, said saving Swift could yield benefits beyond extending its time to conduct observations.

"In addition to the scientific return, the new ability to retrieve a satellite (which was never planned to be serviced in orbit) will give NASA or other customers the capability to reuse, extend or add functions to existing spacecraft at a small fraction of the cost of a new mission," Nousek wrote in an email to NBC News. "If the LINK mission succeeds it will restore a $300 million (in 2004 dollars) satellite to full capability for only $30 million (in 2026 dollars)."

Kieran Wilson, vice president of technology at Katalyst Space Technologies, said he hopes the Swift Boost mission will change how astronomers think about satellites' lifespans.

"For years and years, folks have thought about space as something where you build a satellite, you launch a satellite, it does its mission, and at the end of the mission, it gets disposed of, either it re-enters or it goes to a graveyard orbit at some point," he said during the June 17 news conference, adding, "You should be able to refuel, reposition, repurpose, repair, and even upgrade satellites, even if they were never prepared for it."

NASA launched the Swift observatory in 2004 with an original mission duration of two years. The data Swift has gathered since then has helped scientists study more than 1,400 gamma-ray bursts and other high-energy events in the universe in stunning detail, including the most distant one ever detected, from an exploding star around 13 billion light-years away.

NASA awarded Katalyst Space Technologies the contract to build and launch the LINK spacecraft in September 2025 — a tight turnaround. Although that timeline has been met, Wilson said, successfully meeting up with Swift in orbit and getting the satellite into a more stable orbit are still major undertakings. Swift was not designed to be serviced in space, so lacks onboard thrusters to raise its own orbit or rendezvous with another spacecraft.

"We still have to operate the spacecraft there successfully, and as we've all seen before, that's a very challenging thing to do," he said. "Rendezvous is going to be a challenge, it's always a technical challenge, but we think we're ready to handle that."

This article was originally published on NBCNews.com