NASA Puts 21-Year-Old Spacecraft on Pause to Keep It From Crashing Into Earth

NASA is racing to save an aging space telescope before it burns up in Earth’s atmosphere. To do that, the space agency has recently limited the mission’s operations in orbit to keep it from moving around so much.

NASA suspended most of Neil Gehrels Swift Observatory’s science operations on Wednesday in an effort to reduce the effects of atmospheric drag on the spacecraft and slow down its orbital decay, the space agency announced. Swift is due for an orbit boost, with a mission planned for later this summer set to raise it to a higher altitude. In the meantime, NASA is working on keeping Swift from dropping further.

On hold

Swift launched into low-Earth orbit on a Delta 7320 rocket on November 20, 2004. The satellite is designed to study the most powerful explosions in the cosmos, known as gamma-ray bursts. It does so using three on-board telescopes, collecting data in visible, ultraviolet, X-ray, and gamma-ray light.

In order to keep the spacecraft in an orientation that minimizes drag effects, NASA has put some of Swift’s science activities on hold. “Normally, Swift quickly turns to view its targets — especially the fleeting, almost daily explosions called gamma-ray bursts — with multiple telescopes,” S. Bradley Cenko, the mission’s principal investigator at NASA’s Goddard Space Flight Center, said in a statement. “Swift’s Burst Alert Telescope will continue to detect gamma-ray bursts, but the spacecraft will no longer slew to observe targets with its other telescopes.”

Gradual decay

In the two decades since it launched, Swift has gradually lost altitude. This happens to all satellites over time. Due to recent spikes in solar activity, however, Swift has been experiencing more atmospheric drag than originally anticipated. At its current rate, the observatory has a 50% chance of uncontrolled reentry by mid-2026.

To avoid Swift being dragged down low enough to hit Earth’s atmosphere, NASA tapped an Arizona-based startup to launch a rescue mission. Late last year, NASA awarded Katalyst Space Technologies $30 million to develop a spacecraft designed to boost Swift’s orbit.

With a launch deadline in June, LINK is designed to rendezvous with Swift and nudge the spacecraft to a more stable orbit, thereby extending its lifespan. To maximize the rescue mission’s success, Swift’s average altitude needs to be above about 185 miles (300 kilometers), according to NASA. As of early February, the spacecraft’s average altitude had fallen below around 250 miles (400 kilometers).

By halting Swift’s science operations, NASA is hoping to slow down the spacecraft’s descent long enough for it to be shoved to a higher altitude. “We’re transitioning operations now to give it the best margin we possibly can,” Cenko said.