NASA Prepares Repair Kit for ISS Telescope
NASA is gearing up to send a repair kit to the International Space Station (ISS) for the Neutron Star Interior Composition Explorer (NICER), a telescope that wasn’t originally designed for in-space repairs by astronauts.
NICER, which developed a light leak in May 2023, is mounted near the station’s starboard array. It was launched aboard a SpaceX Dragon resupply mission in 2017 and was initially expected to operate for 18 months. However, its mission has been extended, and it recently marked its seventh anniversary.
As its name implies, NICER focuses on studying neutron stars. Its main instrument, the X-ray Timing Instrument (XTI), consists of 56 X-ray photon detectors that record photon energies and their arrival times.
One of NICER’s primary objectives is to determine the size of neutron stars, a long-standing question in astrophysics. Everything was proceeding smoothly until May 22, 2023, when the XTI developed a visible light leak between 1300 and 1400 UTC, disrupting NICER’s measurements. While there are no issues during the orbital night, the NICER team has had to adjust its daytime observation strategy to mitigate the problem.
The team discovered that the light was entering through damage to NICER’s thermal shields, which protect the X-ray detectors by filtering out infrared, ultraviolet, and visible light while allowing X-rays to pass through. According to NASA, the largest damage is about the size of a typical US postage stamp, with other areas being closer in size to pinheads.
To fix the issue, NASA plans to send patches resembling oversized Trivial Pursuit pie pieces, which will slide into the sunshade. Astronauts will install five patches to address the most significant damage, although 12 patches will be sent on next week’s Northrop Grumman commercial resupply mission.
The turnaround time for these patches is impressive. The NICER team received approval in January from the ISS program management team to proceed with the repair effort. They considered using the ISS robotics system but ultimately decided that astronauts would need to perform the repairs during a spacewalk.
The ISS team has extensive experience repairing payloads not designed for astronaut intervention. A series of spacewalks, concluding in 2020, successfully repaired the Alpha Magnetic Spectrometer-02 (AMS-02).
“It’s incredible that in just one year, we were able to diagnose the problem and then design, build, test, and deliver a solution,” said Steve Kenyon, NICER’s mechanical lead at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We’re excited to see the patches installed during a future spacewalk, return to a more regular operating schedule, and continue groundbreaking science.”
