The fourth and final servicing mission was scheduled to take place in 2006. However, the White House eliminated the necessary funding (over US$1 billion) and as a result several components of Hubble, most probably its batteries, are expected to stop operating in the next 2-4 years, while the whole telescope will be directed towards the Earth oceans soon after. "It will be a great loss for science", American astronomer Holland C. Ford said. (Source: Space.com).
Hubble was deployed 600km above the Earth on 25 April 1990 by the space shuttle Discovery during the STS-31 mission. The orbiting telescope cost US$1.5 billion and every year it costs an additional US$230-250 million to keep it in operation, analyse the data it transmits and develop new hardware or software. It is named in honour of Edwin Hubble and is operated by Space Telescope Science Institute (STScI) on behalf of NASA. (Sources: NASA, Space.com).
HST was designed to be maintained with servicing missions operated from space shuttles every few years, a conception that saved billions of dollars. On 2 December 1993, the first servicing mission (SM1) replaced the solar arrays, upgraded the HST computer, installed the Corrective Optics Space Telescope Axial Replacement (COSTAR) unit, and made numerous other maintenance tasks. SM1 was operated by the space shuttle Endeavour in its STS-61 flight. The second servicing mission (SM2), operated by Discovery in flight STS-82 on 11 February 1997, installed the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) and the Space Telescope Imaging Spectrograph (STIS) - which stopped operating on 3 August 2004 due to a power supply failure. The third servicing mission was completed in two phases: SM3A and SM3B. During the first phase, operated by spache shuttle Discovery in flight STS-103 on 19 December 1999, the astronauts repaired two Rate Sensor Units (RSU) which contain gyroscopes, installed a new computer (20 times faster compared to the old one) and a new space-to-ground data transmitter (replacing HST's original transmitter which had failed in 1998) before re-placing HST in orbit on Christmas Day. In the second phase, operated by space shuttle Columbia in flight STS-109 on 1 March 2002, the solar arrays were replaced again and two instruments were installed: The NICMOS Cooling System (NCS) and the Advanced Camera for Surveys (ACS). SM3B was the last servicing mission, but a fourth mission is necessary if we want to keep Hubble operational. (Source: NASA).
Will Hubble have the fate of Mir?
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