If the team can't bring the malfunctioning gyroscopes back, it'll switch to operating with one or two gyroscopes, Osten said. The telescope only needs three gyros for it to work properly, while the other three are held in reserve in case of failure. Thus, at this time, Hubble has two functional gyroscopes.
"There isn't much difference between 2- [gyros] and 1, and it buys lots of extra observing time", tweeted Rachel Osten, the deputy mission head for Hubble at the Space Telescope Science Institute, late October 7.
Space-watchers have been nervously watching that bit of space occupied by the Hubble Space Telescope as NASA tries to diagnose a problem with its gyroscopes. According to the telescope's activity log, Hubble conducted "no scheduled observations" on Sunday.
The Hubble telescope was launched on April 24, 1990, via the space shuttle Discovery from Kennedy Space Centre in Florida.
Ground operators put the telescope into this stable configuration after one of the three active gyros that steadies and points the telescope failed. For now, NASA hasn't offered any timeframe on when can we expect Hubble Space Telescope to come back into operation.
The Hubble Space Telescope, which suffered technical snag recently, is now on a "safe mode" and looking to resume science operations, NASA said in a statement. The space shuttle Atlantis' mission is to overhaul the Hubble Space Telescope in order to extend its working life.
Osten said the team knew the gyroscope issue was imminent, but she sounds confident about overcoming this latest obstacle to Hubble's continuing operation. There is a third gyro that might be able to work, but last time NASA tested it there were some issues.
The initial six gyros installed in the telescope when it was launched have even been completely replaced during the last service mission in 2009.
"It's not a hard decision, @astrogrant: the plan has always been to drop to 1-gyro mode when two remain".
Rachel Osten, deputy mission head for Hubble with the Space Telescope Science Institute, has dropped a few more details about the problem on Twitter.
While NASA says that reduced-gyro mode would have "relatively limited impact on the overall scientific capabilities", some astronomers are concerned that the reduced-gyro mode could adversely affect some types of observations, such as of solar system objects, that require the precision of three-gyro operations.