Chandra X-ray Observatory to resume observations after gyro swap

The Chandra X-Ray Observatory, along with the Hubble Space Telescope, the Spitzer Space Telescope, the XMM-Newton Observatory and the Karl G. Jansky Very Large Array contributed to this spectacular image of the Crab Nebula, a supernova remnant powered by a spinning pulsar. Image: NASA, ESA, NRAO/AUI/NSF and G. Dubner (University of Buenos Aires)

NASA’s Chandra X-ray Observatory, which went into protective safe mode 10 October after a glitch with one of its stabilising gyroscopes, will resume normal science observations shortly after engineers complete software updates.

“The operations team has successfully returned the spacecraft to its normal pointing mode,” NASA said in a statement. “The safe mode was caused by a glitch in one of Chandra’s gyroscopes resulting in a 3-second period of bad data that in turn led the on-board computer to calculate an incorrect value for the spacecraft momentum. The erroneous momentum indication then triggered the safe mode.”

Engineers uplinked commands to put the suspect gyro into reserve and replaced it with a healthy unit.

“Once configured with a series of pre-tested flight software patches, the team will return Chandra to science operations which are expected to commence by the end of this week,” NASA said.

The Hubble Space Telescope, meanwhile, remains out of action while engineers troubleshoot problems with one of its gyroscopes.

Hubble was launched with six gyros but only needs three to operate normally. Two gyros failed earlier and a third suffered a fatal malfunction earlier this month. The telescope’s lone remaining backup gyro was activated, but it, too, ran into problems.

Engineers are studying whether that gyro can be restored to normal operation. If not, mission managers will implement a so-called single-gyro plan, operating Hubble in near-normal fashion with just one operational gyroscope while holding the telescope’s other healthy gyro in reserve.