The space telescope Neil Gehrels Swift Observatory of NASA has temporarily resumed scientific observationsalthough it is now destined to re-enter the atmosphere terrestrial within the end of 2026. In fact, on August 26, two of its three instruments were turned back on, the XRT telescope in X-rays and that UVOT in the ultraviolet and visiblewhich had been turned off in February to minimize atmospheric drag and buy time while waiting for the rescue mission LINK. The third tool, the Burst Alert Telescope (BAT) in gamma rays, it remains off for now, but NASA hopes to bring it back to data collection in the coming weeks.
The rescue, however, will not happen. The robotic spacecraft LINKbuilt by the private company Katalyst Space to reach Swift, dock it and return it to a higher orbit, developed serious problems with the control system of the structure shortly after the July 3 launch. NASA and Katalyst have therefore given up on August 19th in an attempt to capture the telescope.
Swift will continue to conduct science observations as long as orbital conditions allow. According to NASA’s latest estimates, the telescope should reach the critical quota of approx 300km within a month or two. This is not an altitude at which the satellite will suddenly fall or automatically stop functioning, but below it thefriction with the outermost layers of the atmosphere will become increasingly important, making scientific operations more difficult and causing a rapid acceleration of orbital decayAnd. Without the possibility of raising the orbit, the most likely fate is therefore a uncontrolled reentry and disintegration in the atmosphere by the end of 2026.
Because Swift is slowly falling towards Earth
Launched on November 20, 2004Swift was initially designed for a primary mission just two yearsbut after almost 22 years old it is still one of the most important tools for studying gamma-ray bursts or GRBthe most energetic explosions known in the Universe, of supernovae, neutron stars, black holes and numerous other variable sources.
Swift is located in low earth orbit and, unlike other satellites, it does not have a propulsion system capable of autonomously compensating for the loss of altitude. Even hundreds of kilometers above the Earth’s surface, the thin atmosphere produces a small but constant friction which takes away orbital energy from the satellite and causes one slow descent in altitude.
In recent years this process has become much faster due toincrease in solar activity which heated the upper layers of the Earth’s atmosphere, causing them to expand towards higher altitudes and increasing consequentially friction than what NASA scientists had previously predicted.
How the LINK rescue mission should have worked
For this reason, NASA had assigned a Catalyst Space a contract worth approximately $30 million to design, build and launch a robotic vehicle capable of reach Swift and increase its altitude. The rescue mission LINK was launched on July 3, 2026 aboard a Northrop Grumman Pegasus XL rocket. Once it reached Swift, LINK was supposed to slowly approach the telescope, use its own robotic arms to attach it and subsequently push it to a higher orbit, approximately 600 km altitudesimilar to the initial one of the mission.
After launch, however, LINK developed a malfunction In the buoyancy controlthat is, the system that allows a satellite to precisely establish and maintain its orientation in space. The vehicle began to rotate and communications with Earth became intermittent. Katalyst engineers managed in the weeks following reduce rotation of the satellite and to recover attitude control via a flight software update. Recovery it wasn’t though sufficient to make Swift’s rescue operation safe, for which NASA and Katalyst decided the August 19th to definitively cancel the capture phase of the long-lived satellite.
Swift returned to observing the sky after months of “hibernation”
Even before LINK’s rescue attempt, at the end of 2025 NASA had placed Swift in a sort of “hibernation” state whose main objective was reduce the area of the satellite exposed to the atmospherethus minimizing friction. During this phase, the satellite’s scientific instruments were turned off to facilitate targeting that would allow Swift to be kept in more aerodynamic configurations.
The strategy has certainly borne fruit because initially it was thought that the satellite would reach the altitude of 300 km already during the summer, while the low-friction operations managed to extend the stay above this altitude until autumn. However, once it became clear that LINK would no longer attempt rescue, it no longer made sense to completely sacrifice observations to maintain orbit.
NASA has therefore turned back on XRT and UVOT on August 26thobtaining new X-ray images on the same day, including that of remnant of Tycho’s supernova in the constellation Cassiopeia. The BAT remains turned off, although the mission team has stated that it intends to try to bring it back to data collection in the coming weeks.
What will be Swift’s fate
The share of 300 km is not a clear physical boundary beyond which Swift will immediately fall, but it represents a threshold below which the scientific operations become difficult to be performed and the rate of descent increases rapidly due to the greater atmospheric density and therefore higher friction. NASA currently estimates that the satellite will reach this altitude within a month or two. There is no precise date either for the end of scientific operations or for atmospheric re-entry, because the decay it also depends on solar activity and by the variable conditions of the upper atmosphere.
However, NASA expects reentry to take place by the end of 2026. It will be a uncontrolled returnbecause Swift does not have the propulsion system necessary to choose the time and place of the fall. Most of the satellite’s 613 kg should disintegrate and burn during high-speed passage through the atmosphere, although according to NASA some components may reach the surface. The agency considers anyway the risk of harm to people is unlikely.
Because Swift’s end represents a major loss for astronomy
Swift is not only important for the amount of data collected in almost 22 years, but above all for the speed with which it reacts to transient events. The satellite was designed to locate a gamma-ray burst with BAT, quickly determine its position, rotate the vehicle and observe the afterglow with XRT and UVOTsimultaneously sending an alert to observatories on Earth and in space. This ability has become particularly important with the development ofmulti-messenger astronomyin which the same events are studied simultaneously through electromagnetic radiation, gravitational waves and other particles.
After almost 22 years of activity against the two initially planned, the failure of the LINK mission has transformed these last months of observations into a sort of satellite’s swansongin what will most likely be the final phase of his long and glorious mission.
