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Chandra Resumes Observations

For Release: February 28, 2023



NASA’s Chandra X-ray Observatory has fully recovered from the safe mode it entered on Feb. 13. The spacecraft resumed science operations at 2:18 p.m. EST on Feb. 24, with an observation of the supermassive black hole in the center of the galaxy UGC 5745.

Chandra entered safe mode when a sensor that monitors the position of the Sun provided incorrect data. In safe mode, Chandra protects its critical hardware by switching to back-up units and changing its orientation so that it points perpendicular to the direction to the Sun. Once in that mode, Chandra awaits analysis by the operations team to identify and mitigate the fault that caused the safe mode and issue ground commands to restore normal operations.

To return Chandra to science, the team worked to address elevated temperatures and reduced sensitivity of the camera the spacecraft uses to find stars and orient itself (known as the "aspect camera"). On Feb. 17, the operations team succeeded in acquiring stars and establishing an accurate pointing direction for the spacecraft, which was followed by maneuvers to a series of different pointings for cooling of the aspect camera and other critical components over several days. A set of commands that incorporate approximately a week of science observations, plus additional restrictions to reduce the likelihood of further safe mode events, were uplinked to the spacecraft on Feb. 24 to return Chandra to normal science operations.

Previous update (posted February 17, 2023)

On Feb. 13, NASA’s Chandra X-ray Observatory entered safe mode, likely because a sensor that monitors the position of the Sun provided incorrect data. The Chandra team is working toward full recovery of the spacecraft and a return to science observations. NASA will provide more information as it becomes available. Chandra has been operational and exploring the X-ray universe since 1999. To learn more about Chandra’s discoveries, visit

Media Contacts:

Megan Watzke
Chandra X-ray Center, Cambridge, Massachusetts

Molly Porter
Marshall Space Flight Center, Huntsville, Alabama