Mission Information
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MISSION_NAME |
HST
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MISSION_ALIAS |
HUBBLE SPACE TELESCOPE
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MISSION_START_DATE |
1990-04-08T12:00:00.000Z
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MISSION_STOP_DATE |
N/A (ONGOING)
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MISSION_DESCRIPTION |
Mission Overview
================
The Hubble Space Telescope is a cooperative program of the European
Space Agency (ESA) and the National Aeronautics and Space
Administration (NASA) to operate a long-lived space-based
observatory for the benefit of the international astronomical
community. HST is an observatory first dreamt of in the 1940s,
designed and built in the 1970s and 80s, and operational only in the
1990s. Since its preliminary inception, HST was designed to be a
different type of mission for NASA -- a permanent space-based
observatory. To accomplish this goal and protect the spacecraft
against instrument and equipment failures, NASA had always planned
on regular servicing missions. Hubble has special grapple fixtures,
76 handholds, and stabilized in all three axes. HST is a 2.4-meter
reflecting telescope which was deployed in low-Earth orbit (600
kilometers) by the crew of the space shuttle Discovery (STS-31) on
25 April 1990.
Responsibility for conducting and coordinating the science
operations of the Hubble Space Telescope rests with the Space
Telescope Science Institute (STScI) on the Johns Hopkins University
Homewood Campus in Baltimore, Maryland. STScI is operated for NASA
by the Association of University for Research in Astronomy,
Incorporated (AURA).
HST's current complement of science instruments include two cameras,
two spectrographs, and fine guidance sensors (primarily used for
astrometric observations). Because of HST's location above the
Earth's atmosphere, these science instruments can produce high
resolution images of astronomical objects. Ground-based telescopes
can seldom provide resolution better than 1.0 arc-seconds, except
momentarily under the very best observing conditions. HST's
resolution is about 10 times better, or 0.1 arc-seconds.
When originally planned in 1979, the Large Space Telescope program
called for return to Earth, refurbishment, and relaunch every 5
years, with on-orbit servicing every 2.5 years. Hardware lifetime
and reliability requirements were based on that 2.5-year interval
between servicing missions. In 1985, contamination and structural
loading concerns associated with return to Earth aboard the shuttle
eliminated the concept of ground return from the program. NASA
decided that on-orbit servicing might be adequate to maintain HST
for its 15-year design life. A three year cycle of on-orbit
servicing was adopted. The first HST servicing mission in December
1993 was an enormous success. Future servicing missions are
tentatively planned for March 1997, mid-1999, and mid-2002.
Contingency flights could still be added to the shuttle manifest to
perform specific tasks that cannot wait for the next regularly
scheduled servicing mission (and/or required tasks that were not
completed on a given servicing mission).
The years since the launch of HST in 1990 have been momentous, with
the discovery of spherical aberration and the search for a practical
solution. The STS-61 (Endeavour) mission of December 1993 fully
obviated the effects of spherical aberration and fully restored the
functionality of HST.
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MISSION_OBJECTIVES_SUMMARY |
Mission Objectives Overview
===========================
The objective of these observations was to get the highest spatial
resolution of the impact sites.
|
REFERENCE_DESCRIPTION |
Burrows, C.J., ed., Wide Field and Planetary Camera 2 Instrument Handbook,
Version 2.0, (Baltimore: STScI), May, 1994.
Burrows, C.J., J.A. Holtzman, S.M. Faber, P.Y. Bely, H. Hasan, C.R. Lynds, and
D. Schroeder, 'The imaging Performance of the Hubble Space Telescope', Ap. J.
Lett., 369, L21- L25, 1991.
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