Engineers race to stabilize satellite bound for NASA's Swift rescue
Katalyst Space Technologies is working to regain control of its Link satellite after an unexpected spin threatens its mission to boost NASA's Swift observatory.
A week ago, more than 200 miles above Earth, a refrigerator-sized satellite named Link suddenly began tumbling out of control while on its way to attempt a rescue of NASA's $500 million Swift gamma-ray observatory. The spacecraft was rotating on multiple axes, making it impossible to maintain a reliable communications link with the ground and complicating efforts to stop the spin. Two of the satellite's three reaction wheels, which are used for pointing, also failed. Through sporadic radio contacts, engineers discovered a problem with some of the spacecraft's cold gas thrusters that are used for fine attitude control.
Link is built, owned, and operated by Katalyst Space Technologies, a startup that won a $30 million contract from NASA to rendezvous with Swift, grab onto it, and boost its orbit before it succumbs to atmospheric drag and burns up. Time is of the essence: in a few months, Swift will be too low for Katalyst to complete the rescue. This is the first time NASA has contracted with a commercial company to service one of its satellites, and the agency gave Katalyst less than a year to prepare the mission.
The Link satellite launched on July 3 to begin its pursuit of Swift, and the mission proceeded mostly as planned until last Saturday. "When this happened, it was during one of the passes without comms," said Ghonhee Lee, CEO of Katalyst, in an interview. "We were, immediately prior, in a very stable configuration." Katalyst's ground team, working from a control center near Denver, has been working to find a fix and recover the satellite. The good news is that other systems remain healthy, including power, three xenon-fueled electric thrusters, and the rendezvous and robotics hardware needed to capture Swift.
The first step involves using the satellite's plasma engines to gradually slow the spin. These engines are primarily designed for orbit-raising, but they can also be used for attitude control because they can vector their thrust with a two-axis gimbal.
