A satellite built to rescue NASA's Swift gamma-ray telescope from destruction is now fighting for its own survival. Nearly one month after its launch, the Link spacecraft developed by Katalyst Space Technologies experienced serious attitude control failures over the weekend, NASA announced Tuesday.
According to Ars Technica, preliminary findings show that two of Link's three reaction wheels are no longer operable. The spacecraft's cold gas thruster system also suffered a partial loss of function. Together, those failures caused Link to begin spinning in orbit and knocked out regular communications with ground controllers.
Reaction wheels are standard components on most satellites. They work by discharging momentum to control which direction a spacecraft points, a function called attitude control. The cold gas thruster system handles finer adjustments, especially during close-approach maneuvers. Both systems would be essential when Link attempts to dock with the Swift telescope.
NASA and Katalyst had reported steady progress in Link's first weeks in orbit. The satellite launched July 3 aboard a Northrop Grumman Pegasus XL rocket, which releases its payload from the air rather than a traditional ground pad. After reaching orbit, Link successfully deployed its solar arrays and established stable contact with Katalyst's ground operations center. Its xenon-fueled electric thrusters also completed their first test firings.
Those electric thrusters are now being pressed into a role they were not designed for. Engineers are attempting to use them to stabilize Link's spinning attitude, a function normally handled by the now-failed reaction wheels and cold gas system. Whether that approach will work well enough to continue the mission remains unclear.
The stakes are high. Without a rescue, the Swift observatory is expected to reenter Earth's atmosphere and burn up within months. Swift, formally known as the Neil Gehrels Swift Observatory, is nearly 22 years old and has operated far beyond its original planned lifespan. It cannot save itself because it has no propulsion system of its own.
NASA wants to keep Swift operating because it is one of the only spacecraft in its fleet designed to detect gamma-ray bursts, which are the most powerful explosions known in the universe. NASA is paying Katalyst $30 million for the rescue service.
The mission plan calls for Link to raise its orbit to reach Swift, which flies approximately 200 miles above Earth. Once there, Link would attach to the telescope using three robotic arms, then fire its electric thrusters again to boost Swift to a higher, safer orbit. All of that now depends on engineers finding a way to stabilize a spacecraft that is currently spinning with two of its three main attitude-control wheels out of commission.
