On October 10, Chandra X-ray Observatory entered safe mode, in which the observatory is put into a safe configuration, critical hardware is swapped to back-up units, the spacecraft points so that the solar panels get maximum sunlight, and the mirrors point away from the Sun.
The good news here is that the spacecraft entered safe mode successfully, which is what it's created to do in such circumstances, so at least that part of the observatory is functioning as intended. Chandra has made many important contributions during its almost two decades of life - helping astronomers identify a new class of "intermediate-mass" black holes, for example, and imaging the shock waves emanating from supernova explosions.
Besides Chandra and Hubble, NASA's planet-hunting Kepler space telescope is also nearly out of fuel. Together, the pair make up half of NASA's "Great Observatories" program. The erroneous momentum indication then triggered the safe mode, according to NASA.
The space agency hasn't announced why Chandra entered Safe Mode, but all systems aboard the craft functioned successfully in the transition and all of Chandra's instruments are safe and unharmed.
NASA said Hubble would still be able to provide science "well into the 2020s".
"Chandra is 19 years old, which is well beyond the original design lifetime of 5 years", NASA explains.
Just before 10 a.m. EDT on October 10, the telescope automatically entered a safe configuration, swapping critical hardware to back-up units and changing direction for optimal solar panel charging. "It is now well into its extended mission". It is now well into its extended mission and is expected to continue carrying out forefront science for many years to come, it said.
Earlier this month, the Hubble Space Telescope went from four working gyroscopes to only two fully-functional gyros.
There are also hopeful noises coming out of NASA's Hubble team. Unfortunately, the backup gyro didn't operate successfully.
Tests "showed that the gyro is properly tracking Hubble's movement, but the rates reported are consistently higher than the true rates", the update continued.