NASA's Neil Gehrels Swift Observatory has resumed science observations with two of its three instruments, bringing its ultraviolet, optical and X-ray capabilities back online while the spacecraft continues to lose altitude. The restart follows a decision to scale back a commercial mission that had aimed to capture Swift and lift it into a higher orbit.
The observatory has spent more than two decades studying gamma-ray bursts and other fast-changing events in the universe. Its ability to turn quickly toward a new target and alert telescopes around the world has made it an important part of astronomy's rapid-response network.
Which instruments are operating again
NASA said the Swift team switched on the Ultraviolet/Optical Telescope and X-ray Telescope on August 26. Both instruments had been turned off in February as engineers placed the spacecraft in a low-drag configuration to preserve its orbit while preparing for the attempted boost.
The X-ray telescope has already captured an image of Tycho's supernova remnant, around 13,000 light-years away in the constellation Cassiopeia. That observation provided a practical confirmation that science work had resumed.
Swift's third instrument, the Burst Alert Telescope, remains off. It was halted in April to reduce power consumption and allow the solar panels to be positioned for lower atmospheric drag. The mission team is working toward returning it to data collection in the coming weeks.
Why Swift needs help in orbit
Swift operates in low Earth orbit and does not have a propulsion system capable of countering a long-term decline in altitude. Although space is often described as a vacuum, the outer atmosphere still creates drag on satellites in lower orbits.
Solar activity can heat and expand the upper atmosphere, increasing that drag. NASA says recent solar conditions caused Swift to descend faster than expected. Engineers therefore tried to reduce the spacecraft's exposed area and extend the time available for a rescue mission.
The challenge becomes more serious as altitude falls. NASA has used 185 miles, or about 300 kilometres, as an important operational threshold. Below it, maintaining observations becomes difficult and the rate of descent can increase.
What happened to the commercial boost mission
NASA contracted Katalyst Space in September 2025 to design a rapid mission that could meet Swift in orbit, grab it and raise its altitude. Katalyst's LINK spacecraft launched in July 2026 aboard a Northrop Grumman Pegasus rocket.
Later in July, LINK developed problems controlling its orientation. NASA and Katalyst announced on August 19 that the vehicle would no longer proceed with capturing and boosting Swift.
The mission has not been abandoned entirely. LINK is now expected to attempt a rendezvous and proximity operations without making the planned capture. Those manoeuvres could still provide useful experience for future satellite inspection and servicing missions.
How much observing time remains
Low-drag operations extended the period during which Swift was expected to remain above 300 kilometres. With science observations running again, the team now anticipates that the spacecraft may cross that altitude milestone within one to two months.
That forecast is not an exact end date. Orbital decay depends on atmospheric conditions, the spacecraft's orientation and solar activity. Mission controllers will have to balance valuable observations against the need to manage power, temperature and drag.
Why Swift still matters
Swift was launched in 2004 to study gamma-ray bursts, extremely energetic explosions that can briefly outshine entire galaxies. It can detect a burst, calculate its position and rapidly share an alert so other observatories can turn toward the same region.
The spacecraft also studies supernova remnants, black holes and other variable objects. Its observations across different wavelengths help astronomers connect a high-energy X-ray source with visible or ultraviolet light from the same event.
Even a limited final observing period can be scientifically valuable because the sky does not follow a schedule. A nearby stellar explosion or unusual burst could occur while Swift is still able to respond.
What to watch next
The immediate milestones are the attempted restart of the Burst Alert Telescope and the LINK spacecraft's proximity demonstration. NASA will also continue updating Swift's predicted altitude and operating window.
The episode highlights a wider issue for space agencies: many useful satellites were not designed to be refuelled or lifted after launch. Future servicing missions may extend spacecraft lives, but they must be able to navigate, match an orbit and interact safely with hardware that was never built for capture.
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