Last week Hubble's key camera stopped working but NASA claims it will be able to fix the problem soon.
The camera constantly beams down signals of how its subsystems are operating. And on Monday, the signals coming from its low-voltage power supply suddenly went awry.
"It was as if the power had failed to that piece of the instrument," says Bruce Margon, at the Space Telescope Science Institute (STScI) in Maryland, US, which manages Hubble's observations. "It got our attention because it's the most heavily used instrument on the spacecraft."
Mission managers believe with 90% certainty that the problem is down to a simple part on a circuit board failing earlier than expected. "Most likely, some five-cent resistor or capacitor that's supposed to last for 20 years by bad luck only lasted for six," Margon told New Scientist.