Swift restores burst response with only weeks of science forecast

NASA's Swift observatory can again respond automatically when it spots a gamma-ray burst. The agency said on September 25 that its Burst Alert Telescope, the last of Swift's three instruments to restart, was calibrated and detecting gamma rays on September 18. Controllers restored the spacecraft's automatic pointing on September 21, so a burst detection can interrupt the daily observing plan and turn its X-ray and ultraviolet/optical telescopes toward the event.

That scientific capability has returned just as Swift is running out of altitude. NASA put the observatory at roughly 200 miles (325 kilometers) above Earth and said science observations will likely end once it falls below about 185 miles (300 kilometers), where operations become more difficult. The mission team estimates it could reach that threshold in early to mid-October. This is a forecast of an operational limit, not an announced date for atmospheric reentry; orbital drag can change the timing.

Why the restart shortens the remaining window

The telescope was launched to catch brief, unpredictable bursts and rapidly examine their afterglows at other wavelengths. To slow its descent while awaiting an attempted orbit boost, its operators had constrained where it pointed. NASA said the team replaced about a quarter of its planned targets with lower-drag directions in December 2025 and had moved fully to that approach by February, removing automatic burst-response slews. Two instruments returned to science observations in August; the wide-field burst detector followed in September.

Returning to normal observations and quick turns also restores the faster orbital decline, NASA said. The trade is immediate scientific use of a still-working observatory against time remaining in a very low orbit. Its current ability to detect and follow bursts should not be confused with a renewed long-term mission.

The planned rescue is over. Katalyst Space, the company operating the LINK servicing spacecraft, said LINK reentered Earth's atmosphere on September 25 without capturing or boosting Swift. Katalyst said an attitude-control anomaly left it relying more heavily on thrusters and consuming fuel too quickly for a safe capture and orbit raise. The company describes useful flight tests and a close approach, but those did not extend Swift's orbit.

The distinction now is between Swift, which is collecting science for as long as conditions allow, and LINK, whose mission has ended. NASA's Swift mission updates are the place to check for a revised operational forecast or a decision to stop observing.