Hubble telescope fixed by 'jiggling it around'

The Hubble space telescope is close to resuming full operations after Nasa “jiggled it around”.

The telescope was sidelined earlier this month after a gyroscope failed, leaving it unable to point in the right direction during observations. The device had been expected to fail at some point this year, but the surprise came when a backup did not kick in properly after the initial failure. As a result, Hubble has remained in so-called safe mode and all science observations are on hold.

Gyroscopes are needed to keep Hubble pointing in the right direction as it operates 545km above Earth. Precise pointing is crucial: astronomers use the telescope to peer deep into the cosmos, revealing faraway galaxies, black holes and solar systems. Last week, astronomers said they may have discovered the first moon outside our solar system, with Hubble’s help.

The problem with the backup gyroscope was spotted when detectors in the gyroscope wrongly signalled that the wheel within the device was rotating at a much greater rate than that 19,200 revolutions per minute it should be spinning at.

Nasa expected Hubble to return to normal science operations soon after it performed a “running restart” of the gyroscope on 16 October, which turned the device off for a second. The intention was to clear any faults that may have occurred during a restart on 6 October. That did not seem to work so it was followed up on 18 October with a series of spacecraft manoeuvres – known as turns – in an attempt to clear any blockage around the sealed “float” which contains the spinning wheel in the gyroscope.

At the same time the system was switched between two modes to help with the procedure. Nasa believes that the dodgy rotation speeds could have arisen if the float was off centre in the device. Further jiggling of the telescope and twiddling of switches was performed: the issue now appears to be resolved.

The 28-year-old telescope has had trouble with its gyroscopes before. Shuttle astronauts replaced all six in 2009 during a spacewalk on the final servicing mission. Three of the devices are now considered unusable.

Source - The Guardian