Flight controllers cancelled a weekend mission to the Hubble space telescope to fix its electronic problems, adding that it was likely to remain in safe mode until Sunday.
An electronic ‘main wheel’ glitch that had kept the telescope in an unprotected mode of operation appears to have now been resolved.
The unprecedented move on Saturday ordered a mission to hard reset the 21-year-old telescope to make sure the main engine and antennae were properly positioned. The work will also bring Hubble back into a launchable mode.
Since a reboot should speed up the process, mission controllers cancelled the remaining details of the six-month mission and instead spent the weekend returning the telescope to the safe mode during which it was unable to launch.
I feel … physically ill, Nasa spokesman Johnny Weir told reporters. “I’m fine with that. To be honest, I don’t care. I don’t think we’re going to have a use for this damn thing,” he said.
The crew of Discovery’s mission had been due to continue working on the telescope on Saturday evening but that decision was overruled by mission managers fearing that the telescope was not in a sufficiently secure position to return safely to Earth in a controlled manner.
With large parts of the Hubble still operating in safe mode, ground controllers were unable to begin preparatory repair work until the spacecraft had achieved a stable position. That should happen when engineers switch Hubble off and off again, shutting off the air systems and liquid oxygen tank with an electrical generator and secondary propulsion system.
It is the second time the telescope has been in safe mode because of problems since Discovery launched late last month. Then mission managers decided against launching and fixing the telescope because the spacecraft was not positioned in a firing mode. Space shuttle astronauts then spent eight days removing a damaged section of the telescope to fix it.
Engineers are working on several hypotheses for what caused the initial failure. Experts on board Hubble on Friday detected a field of oil and hydrogen gas in one of the main prime engines. It was discovered during a “firmplate scrub” – a back-up backup to real-time viewing – as planned. But inside the smaller secondary rocket motor and nozzle, a crack developed. It was repaired by engineers on the ground and engineers in space soon after the spacewalk of the shuttle crew ended.
“The available data appears to point to a mechanical problem with the second main engine cylinder and not a possible electronics problem, leaving the possibility that this problem is only related to the nebular dust contamination in the last of the Hubble’s chemical depots,” Nasa stated on its website.
On Saturday, Hubble’s operators said the telescope was in an “acceptable space”. Nasa earlier said they would likely keep the telescope in safe mode until it was recovered. The mission controllers would analyse any data to see if it was safe to put it back into a firing mode.
There has been an “enormous” amount of interest in the mission’s outcome, says Craig Kundrot, mission project manager at the Goddard Space Flight Center. “This is a world premiere,” he says.
Mission Control also said that they are not necessarily leaving open the possibility of taking this jet-setting observatory back into a firing mode in the near future. “So we’re not ruling that out,” said Nasa’s Clint Raymond. “There will be ample time to see if this works.”
The primary computer in Hubble had a weakness that it may have been exacerbated by debris from the left-most Hubble component, T2, which destroyed the camera on board Galileo, a spacecraft that orbited Jupiter in 1995. Galileo was only slightly bigger than Hubble. Astronauts were forced to clip the telescope back into its rack, which may have also inadvertently weakened the computer. Engineers on Friday inserted a spare computer in the same location, as well as an electronics jack and other spare parts.