Hubble trouble
BY DR EMILY BALDWIN
ASTRONOMY NOW

Posted: October 01, 2008

Just weeks before the Hubble repair mission was originally set to commence, a sudden anomaly with the space telescope’s data storage and transmission devices could see the mission pushed back to next year.

Hubble currently floats helplessly in space, unable to store or download any data. Image: NASA.

On Saturday, Hubble’s Control Unit/Science Data Formatter Side A malfunctioned and the telescope’s computer automatically issued commands to the payload computer and science instruments to go into safe mode. An attempt to reset the formatter and obtain a dump of the payload computer's memory has so far been unsuccessful.

Although there is a back-up system - Side B - the transition is complex since it requires five other data managing systems to also be switched to their B-sides. The B-sides of these modules were last activated during ground tests in the late 1980's, prior to the space telescope’s launch. If successful, a transition to the redundant Side B should restore full functionality to the science instruments and operations, and reconfiguration attempts will be made this week.

But this still leaves the telescope with a single point of failure, so NASA is investigating the possibility of flying a back-up replacement system, which could be installed during the servicing mission. A new Side A and Side B would therefore give Hubble a second chance should the primary data channels fail again in the future, since there are no plans to visit Hubble again after the imminent servicing mission.

Astronauts replace Hubble's Wide Field and Planetary Camera during the first servicing mission in 1993. The third generation camera will replace this in the upcoming fourth and final servicing mission. Image: NASA.

Looking at the break down with a ‘glass half full’ attitude and the telescope couldn’t have chosen a better time to break down. Had the servicing mission gone ahead as planned, the astronauts would not have had the right components to rectify the problem and the mission could have been lost within a year. This way the mission team can prepare the necessary equipment required to fix the problem should the automated reconfiguration to Side B fail.  The repair job for this new problem is thought to require just two hours of spacewalk time and could be slotted into the current repair schedule.

NASA officials say that the decision on how next to proceed will be made later next week. Currently, there is a window of opportunity for the Hubble rescue mission between February and May next year, based on other launch schedules.

The fourth and final Hubble servicing mission already plans to replace all six of the telescope’s gyroscopes, install new batteries and replacement insulation, as well as install two new instruments: the Wide Field Camera 3 and the Cosmic Origins Spectrograph, which will improve Hubble’s eyesight and increase the mission to an expected further 10 years.

You can read more about the trials and tribulations of Hubble, as well as a thorough description of the new instruments, in this month’s Astronomy Now magazine.