NASA's Swift Observatory rescue mission faces delays after service satellite spins out of control
NASA's effort to boost the aging Swift space telescope has been set back after the rescue satellite LINK developed a spin problem, but engineers say the issue is being addressed.
NASA’s Swift observatory, launched in 2004 and used to monitor high-energy cosmic events, is projected to re-enter Earth’s atmosphere this fall unless its orbit is raised. To prevent that outcome, the agency contracted Arizona-based Katalyst Space Technologies to build and launch a robotic spacecraft, LINK, that would rendezvous with Swift and lift it to a safer altitude.
LINK was launched on July 3 aboard a Northrop Grumman Pegasus XL rocket released from the Stargazer aircraft. Initial operations proceeded as planned, with the satellite deploying solar arrays, firing thrusters and completing health checks. However, around July 25 the spacecraft entered a multi-axis spin, leading to a temporary loss of communications.
"I think one of the difficult things to convey is how amazing it is that we’ve gotten this far," said Shawn Domagal-Goldman, NASA’s division director of astrophysics.
Katalyst reported that two of LINK’s three reaction wheels were inoperable and that its cold-gas thruster system had degraded performance. The team used electric propulsion thrusters to reduce the spin from roughly 9 degrees per second to 4 degrees per second, and later to 1.47 degrees per second, consuming less than 100 grams of propellant to preserve fuel for the planned boost.
"All of this is challenging and risky," said Kieran Wilson, principal investigator for LINK at Katalyst.
NASA and Katalyst are now working on a flight-software update intended to restore full attitude control and enable the maneuvers needed to align LINK with Swift. The original schedule called for a survey of Swift in late July to identify grappling points, followed by a multi-month ion-thruster boost. The spin issue has pushed the survey to a later date, and the impact on the overall timeline remains uncertain.
If successful, LINK will capture Swift, fire its ion thrusters and raise the telescope’s orbit over two to three months, allowing the observatory to resume scientific observations before its projected re-entry.