The Swift space telescope is observing the Universe again, but its time is now running out.
NASA restored two of its three scientific instruments to service on August 26. Swift can therefore resume its observations in X-rays, ultraviolet light, and visible light. Its third instrument, intended in particular to detect gamma-ray bursts, is expected to return to service in the coming weeks.
Illustration of the LINK spacecraft (left) attaching itself to NASA’s Swift observatory to modify its orbit. This operation will ultimately not take place.
Credit: Katalyst Space
Since February, NASA had deliberately reduced its activity to limit its descent toward Earth. The solar panels had in particular been oriented to reduce atmospheric drag. Although extremely thin at this altitude, the atmosphere gradually slows satellites down.
Swift has no engine capable of raising its orbit. Launched in 2004, it notably studies gamma-ray bursts, extremely powerful explosions observed throughout the Universe. It can quickly turn toward a detected event and transmit an alert to other observatories.
To extend its mission, NASA had therefore chosen an unusual solution: send another spacecraft to Swift. The LINK vehicle, developed by Katalyst Space, was supposed to reach the telescope, capture it, and then raise it to a higher orbit. It was launched in July.
The plan nevertheless failed before this operation. LINK encountered problems controlling its orientation in space. On August 19, NASA and Katalyst Space announced that it would ultimately not attempt to capture Swift.
Swift’s situation therefore remains fragile. Recent solar activity increased the drag encountered by the satellite in the upper layers of the atmosphere. Its descent then accelerated. The months spent in a configuration that reduced this drag nevertheless allowed it to buy some time.
NASA is closely monitoring the 300-kilometer altitude threshold. Below it, operations become difficult and the descent accelerates rapidly. With the return to scientific activity, Swift could now reach it within one to two months.
The LINK mission is not completely over. Even without raising Swift’s orbit, its approach should make it possible to test satellite servicing techniques directly in space. These tests could support future missions capable of intervening on spacecraft that had not been designed to receive such assistance.