Hubble: currently comatose. Credit: NASA

Late last month, the main system for storing and transmitting data from the Hubble Telescope's science instruments failed. Operators can still send commands to the 18-year-old orbiting observatory, but they can no longer retrieve the images that have made it famous.

On 16 October, telescope engineers successfully booted up a backup for the faulty system. But as they were preparing to resume star-gazing, problems with the backup computer sent the entire spacecraft into safe-mode. NASA officials hope that Hubble will be healthy again by the end of this week, but are not certain when it will be back in action. A shuttle mission to service the telescope has been delayed until at least February so that engineers can develop fixes for the computer problems.