The next planned Space Shuttle mission to service the Hubble Space Telescope in orbit, in December 1999, will involve repairs to damaged insulation blankets over the telescope's central equipment bays. The damage was probably caused by ultraviolet radiation and atomic oxygen.
The damage to the area of the Hubble which continually faces the Sun during daylight orbit passes was surveyed by the crew of the STS82/Discovery, which undertook a successful second servicing mission, ending on 21 February. The damage threatens to overheat vital equipment, such as the avionics, on the telescope.
Four scheduled spacewalks were completed, during which new instruments were fitted: a near infra-red camera/multi-object spectrometer and an imaging spectrograph, which replaced two similar instruments. The spacewalks were also used for servicing. This included replacing a fine guidance sensor, a data-interface unit and the solar-array electronics box; fitting a new solid-state tape recorder and electronics package; and replacing one reaction-wheel assembly.
During these walks, the crew noticed damage to the top layers of the Teflon and Kapton insulation blankets, which were cracked.
As a temporary measure, two sheets of repair insulation were fitted over the most damaged areas during the end of the fourth spacewalk. An unplanned fifth walk was added. Much of the new material had to be fashioned using items from inside the orbiter.
Two teams of two astronauts accumulated 66h of spacewalk experience during the mission, which may prove to be invaluable in preparing for the International Space Station assembly in 1998.
During the STS103 mission in 1999, the Hubble's solar arrays will be replaced by two more powerful units and a new computer and advanced camera will be fitted. Regular servicing will also be conducted. The new arrays will use gallium arsenide instead of silicon.
Another servicing mission is planned in 2002 to fit a new science instrument. In 2005, the Hubble may return to Earth. A new-generation telescope is planned.
Astronaut Catherine Coleman has been brought into mission specialist training for the next Space Shuttle mission, the STS83/ Columbia, due for launch on 3 April for the 16-day Microgravity Science Laboratory mission. She may replace Don Thomas, who broke his ankle on 29 January.
Source: Flight International
