NASA press releases and official statements

Sunita Williams Makes First Spacewalk in 12 Years to Repair NICER Telescope in US Spacewalk 91

Jan 16, 2025, 01:46 PM

NASA astronauts Sunita Williams and Nick Hague are conducting US Spacewalk 91 outside the International Space Station (ISS) to repair the NICER (Neutron star Interior Composition Explorer) X-ray telescope and upgrade the Alpha Magnetic Spectrometer. The spacewalk began at 8 am ET and is expected to last over six hours. This marks Williams' first spacewalk in 12 years and her eighth overall. After being in orbit for over seven months—what was originally planned as a week-long test flight—the astronauts are stepping outside to perform critical repairs and maintenance tasks. The NICER telescope, which has 56 X-ray connectors, is the first NASA observatory to be repaired on-orbit since the last servicing mission to the Hubble Space Telescope in 2009. Their work involves patching thermal shields to prevent light leaks and aims to unlock the secrets of black holes, neutron stars, and dark matter.