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| "When Hubble reached the point of having no back-up gyros, our flight rules said we must look at what we term a 'call-up mission' to correct the situation," said Dr. John H. Campbell, the telescope's Project Director at NASA's Goddard Space Flight Center, Greenbelt, MD. "Since we are already involved in preparations for the scheduled third servicing mission next year, we essentially decided to divide the planned mission into two flights and reduce the workload on each." |
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A team of veteran astronauts had already begun training to
install the new instruments and upgrade the telescope's systems.
NASA astronauts Steven L. Smith, C. Michael Foale, John M.
Grunsfeld and European Space Agency astronaut Claude Nicollier
will perform the spacewalks on both servicing missions. Smith is
the payload commander for the missions, coordinating the
astronauts' space-walking activities. A flight crew for the
servicing missions will be selected in the near future.
Left: Scientists hope to avoid
even a brief shutdown of the Hubble Space Telescope, which has
recently returned
startling images of planet-forming regions around other stars.
This Hubble photo, for example, shows a newborn
binary star system, CoKu Tau/1, lying at the center of four "wings"
of light extending as much as 75 billion miles from the pair.
The "wings" outline the edges of a region in the stars'
dusty surroundings, which have been cleared by outflowing gas.
A thin, dark lane extends to the left and to right of the binary,
suggesting that a disk or ring of dusty material encircles the
two young stars.
In addition to replacing all six gyroscopes on the October flight, the crew will replace a guidance sensor and the spacecraft's computer. The new computer will reduce the burden of flight software maintenance and significantly lower costs. A voltage/temperature kit will be installed to protect spacecraft batteries from overcharging and overheating when the spacecraft goes into safe mode. A new transmitter will replace a failed spare currently aboard the spacecraft, and a spare solid state recorder will be installed to allow efficient handling of high- volume data. Both missions will replace telescope insulation that has degraded. The insulation is necessary to control the internal temperature on the Hubble. The later servicing mission will focus on installing the Advanced Camera for Surveys. With its new imaging capabilities, this camera will be 10 times more powerful than the present Faint Object Camera. New efficient rigid solar arrays will replace the existing solar arrays. Astronauts also will install the Aft- Shroud Cooling System. This new system is designed to carry heat away from the scientific instruments and to allow the instruments to operate better at lower temperatures. The cooling system allows multiple instruments to operate simultaneously, helping the science team maintain the program's high productivity. In addition, an advanced cooling system will be installed on the Near-Infrared Camera and Multiobject Spectrometer, which became dormant after its solid nitrogen coolant was exhausted in January 1999. |
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NASA Press Release-- Mar. 9, 1999 Spinning planets out of Stardust-- Feb. 9, 1999 NASA Space Science Update Hubble photos of 6 protoplanetary disks - from STScI |
Hubble Space Telescope-- home page NASA - home page NASA Office of Space Science - news and research |
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