The Katalyst Space-built robotic probe known as LINK, intended to dock with and stabilize the aging Swift observatory, is now spinning uncontrollably in low Earth orbit. The mission, launched in early July, is currently jeopardized by a malfunction in two of LINK’s three reaction wheels—devices used to adjust orientation in the vacuum of space.
LINK's malfunction and response
NASA’s latest update on the Neil Gehrels Swift Observatory blog confirmed that the spacecraft has problems managing its orientation, leading to intermittent communication. The issue forced LINK into an uncontrolled spin, which has complicated efforts to communicate with the probe. NASA’s ground team, however, retains contact and is preparing to use electric propulsion thrusters to halt the rotation. As of July 30, Katalyst’s mission blog said engineers reduced the rotation with engine fires from the spacecraft, and that work is ongoing to stabilize the spacecraft. LINK is now spinning at four degrees a second, instead of the previous nine. "Over the last 48 hours, the Katalyst team has worked to reduce LINK’s rotation while assessing current spacecraft functionality and its control system," Katalyst representatives wrote.
Swift observatory’s precarious situation
The Swift observatory has been experiencing an accelerated orbital decay due to increased solar activity, causing more atmospheric drag than expected. Without intervention, it is set to re-enter the atmosphere this year. LINK was designed to dock with the observatory and lift it to a higher orbit, prolonging its scientific use. Swift must stay above a minimum rescue altitude of 185 miles (298 kilometers) for the mission to succeed, agency models suggest. For comparison, the International Space Station typically operates at about 250 miles (400 kilometers) in altitude.
Path forward remains uncertain
After stabilizing LINK, NASA and Katalyst must reset its guidance system to account for the changed configuration. Only then can a revised evaluation of the mission’s viability take place. Despite the setbacks, Katalyst remains optimistic that the spacecraft can still achieve its objective. NASA has noted that other systems on LINK are working well. "The spacecraft remains power positive and in communication with the Katalyst team," NASA officials wrote in a Tuesday (July 28) update. Assuming LINK’s attitude stabilizes and the spacecraft is healthy enough, teams "will then evaluate revised plans to approach and capture Swift," NASA stated.