The National Aeronautics and Space Administration (NASA) said Hubble went into "safe mode" on Friday. But after the failure last week, the Hubble is now left with only two fully-operational gyros.
Osten said the team knew the gyroscope issue was imminent, but she sounds confident about overcoming this latest obstacle to Hubble's continuing operation.
Gyroscopes are needed to keep the 340-mile-high (540-kilometer-high) Hubble pointed in the right direction during observations.
Today NASA confirmed reports that Hubble scientists such as deputy mission head Rachel Osten were passing along over the weekend: One of the telescope's three active gyros had failed on Friday, which hampered the telescope's ability to point at astronomical targets for long periods. The telescope only needs three gyros for it to work properly, while the other three are held in reserve in case of failure. Two other gyro of the same type was already out of service in April of this year.
If the problematic gyroscope can't be successfully brought back online - and if the most recent failure proves permanent - Hubble may be forced to operate on a single gyroscope for the foreseeable future. The James Webb Space Telescope, Hubble's powerful successor (at least, in the infrared regime), is now set to launch in 2021.
Ken Sembach, director of the Space Telescope Science Institute at Johns Hopkins University in Baltimore, said the Hubble team is optimistic the problem can be resolved. Although science operations are expected to resume fairly soon, the current issues raise concerns about the future of the invaluable scientific instrument. Spacewalking shuttle astronauts replaced all six in 2009.
"While reduced-gyro mode offers less sky coverage at any particular time, there is the relatively limited impact on the overall scientific capabilities", NASA said. "If the outcome of this investigation results in recovery of the malfunctioning gyro, Hubble will resume science operations in its standard three-gyro configuration", the agency stated.
This photo of the Hubble Space Telescope was taken on the 5th servicing mission to the observatory in 2009.
The plan "has always been to drop to 1-gyro mode when two remain", Osten said, adding "there isn't much difference between 2- and 1, and it buys lots of extra observing time".