NASA Swift rescue mission hits spin and communications problems
Katalyst Space says its LINK craft is spinning with two reaction wheels offline, threatening a time-sensitive attempt to reach Swift.
By Renata Fuchs · Policy Reporter
· 3 min read
Katalyst Space’s NASA Swift rescue mission has run into attitude-control trouble during commissioning, with the company’s LINK spacecraft in a multi-axis spin and communicating only intermittently. The issue matters because LINK is supposed to reach and capture NASA’s Neil Gehrels Swift Observatory before it re-enters Earth’s atmosphere later this year, leaving only a few months for recovery and rendezvous work.
LINK was designed with three reaction wheels for pointing, stability and attitude control. Katalyst said two of those wheels are currently not operable, though it did not say why. NASA also reported that the spacecraft’s cold-gas thruster system has lost some functionality.
The company said LINK is still in contact with controllers despite sporadic communications, and that other major subsystems are performing as expected. The problems began over the weekend, according to Katalyst, and the team is now using LINK’s electric propulsion thrusters to slow and stop the spin.
What happened to the NASA Swift rescue mission?
LINK entered commissioning after launching earlier this month on the final Northrop Grumman Pegasus XL rocket. During that phase, Katalyst deployed the spacecraft’s solar arrays, began generating power and started checking vehicle systems before the planned approach to Swift.
The commissioning campaign had already shown problems before the latest spin. On July 15, Katalyst said mission operations had identified attitude-control and communications anomalies early in flight operations. The company said it then applied flight software patches and operational changes that restored reliable communications and enabled three-axis stabilized control, allowing LINK to point and orient itself in space.
Shortly before acknowledging the latest anomaly, Katalyst said in a LinkedIn post that LINK had been extending the duration of its thruster burns to prepare for longer burns expected during rendezvous. The spacecraft is now using electric propulsion thrusters originally intended for that rendezvous phase to stabilize itself.
Why LINK’s attitude control matters
Attitude control determines whether a spacecraft can point its antennas, solar arrays, sensors and propulsion system in the right directions. For a capture mission, stable orientation is also a prerequisite for guidance, navigation and control software to execute an approach without creating additional risk.
If Katalyst can regain stable attitude, the company said it will update LINK’s guidance, navigation and control system for the spacecraft’s new configuration. Only after that would the team consider revised plans to approach and capture Swift.
The schedule is unusually compressed. LINK was built and launched less than a year after contract award, according to Katalyst, as a rescue vehicle for Swift before the observatory falls back into Earth’s atmosphere. Swift is expected to deorbit later this year, so the mission has limited margin for prolonged troubleshooting.
Katalyst said it is “seeing the intended effect” from the electric thrusters and said the mission remains active. The company also said it continues to believe that, with the changes being made, LINK has a viable path to rendezvous with Swift. It has not disclosed the root cause of the reaction wheel failures, the extent of the cold-gas thruster issue or how much schedule margin remains.
This story draws on original reporting from The Register.
