The Hubble Space Telescope has been offline for more than a week, and NASA isn't sure why

Astronauts have visited the Hubble Space Telescope for repairs and maintenance on five occasions.
NASA
NASA's Hubble Space Telescope has gone offline for the second time this year.
Hubble's science instruments were registering errors after losing critical synchronization messages.
NASA says it's "too early" to say what is causing the problem or how long it may take to fix it.
NASA's iconic Hubble Space Telescope is experiencing another mysterious glitch. Already, it's been offline and in "safe