The first casualty of US President George Bush's new space plan is one of NASA's success stories. A Space Shuttle flight to service the Hubble Space Telescope has been cancelled for safety reasons, and the observatory is expected to cease operations in 2007-8 and be deliberately de-orbited by 2011.
Under the Bush plan, the Shuttle will be retired in 2010 after completion of the International Space Station (ISS), and all missions after a return to flight in 2005 are expected to be dedicated to completing assembly of the orbiting base.
Additionally, a mission to Hubble would not be able to use the ISS as a safe haven in an emergency, because of their different orbits, requiring a second Shuttle to be ready for launch on a rescue mission. This would be prohibitively expensive, says NASA.The fifth servicing mission since Hubble was deployed into orbit by a Shuttle in 1990 was originally scheduled for mid-2005, and would have replaced the telescope's failing gyroscopes and installed a more-sensitive wide-field camera and ultraviolet spectrograph.
Three of Hubble's six gyroscopes are still working, the minimum for full operation. NASA is developing software to enable degraded operation on two gyroscopes, while looking at bringing forward launch of the replacement James Webb Space Telescope from 2011.
Because the 11,000kg (24,200lb) telescope is too large to burn up, NASA will have to launch a $300 million robotic mission to attach a rocket motor to Hubble to enable a controlled re-entry, preferably into an ocean.
Source: Flight International
