“Trying to do stellar
observations from Earth is like trying to do birdwatching from the bottom of a
lake.” - James B. Odom, Hubble program manager, 1983-1990.*
The first concrete plan for placing an optical telescope in
space, above the obscuring and distorting effects of Earth’s atmosphere,
originated with Princeton University astronomer Lyman S. Spitzer in 1946. Although others had floated the idea of
orbital telescopes, Spitzer’s paper, entitled “Astronomical
advantages of an extra-terrestrial observatory,” described in detail
the scientific advantages of placing a telescope in space. This was 11 years
before the launch of Sputnik, the first artificial Earth satellite.
Spitzer continued to lobby for a space telescope and, in
1962, the U.S. National Academy of Sciences recommended development of
Earth-orbital telescopes. NASA launched four Orbiting Astronomical Observatories
(OAO) between 1966 and 1972, of which only two were successful. The final OAO
mission, called Copernicus, carried a 32-inch (80-centimeter) telescope that
made ultraviolet observations between 1972 and 1981. NASA first proposed a plan
to launch a Large Space Telescope (LST) in 1972. Five years later, Congress
approved the funding.
Left: Astronomer Lyman
Spitzer. Middle: OAO-3 Copernicus
satellite undergoes preflight testing. Right:
Cutaway of the LST/Hubble showing its major components.
As envisioned, the LST would contain a 94-inch (2.4-meter)
diameter primary mirror and use the space shuttle, then still under
development, for launch in 1983. With an expected on-orbit lifetime of 15
years, the LST’s instruments would make observations primarily in the visible
and ultraviolet parts of the electromagnetic spectrum.
In 1983, managers abandoned the original plan to use the space
shuttle to return the telescope to Earth for refurbishment and relaunch in
favor of in-orbit maintenance and upgrades by astronauts during spacewalks in
the shuttle’s payload bay. That same year, NASA renamed the LST after
astronomer Edwin P. Hubble, setting the launch for October 1986. However, the Challenger accident in January 1986
placed all shuttle flights on hold and delayed the launch of the Hubble Space
Telescope to April 1990.
construction of the frame of the Hubble Space Telescope. Middle: Engineers work
on the primary mirror for Hubble. Right: Astronomer Edwin Hubble.
The launch of the Hubble Space Telescope took place on April
24, 1990, during the STS-31 mission. The shuttle flew to an unusually high
380-mile orbit to ensure that the LST would operate above as much of the
Earth’s atmosphere as possible. Tucked inside the payload bay of Space Shuttle Discovery, the 24,000-pound telescope
carried five science instruments: the Wide Field/Planetary Camera (WF/PC), Faint
Object Camera (FOC), Goddard High Resolution Spectrograph (GHRS), Faint Object
Spectrograph (FOS) and High-Speed Photometer (HSP).
The crew for the mission included Commander Loren
J. Shriver, Pilot Charles
F. Bolden and Mission Specialists Bruce McCandless, Steven
A. Hawley and Kathryn
D. Sullivan. Once in orbit, Hawley grappled Hubble with the shuttle’s
robotic arm, carefully lifted it out of the payload bay and, after ensuring
that the telescope’s two solar arrays and antennas had properly deployed,
released it to fly free. McCandless and Sullivan had donned their spacesuits in
preparation to conduct spacewalks in the event that anything went wrong with
the deployment. As it turns out, their skills were not needed, and because they
were in the shuttle’s airlock — were probably the only two interested parties
who did not see the release of the
Hubble Space Telescope.
For the next three days, the shuttle remained in a
station-keeping position 50 miles from Hubble in case any problems during
activation required them to return to the telescope for possible repairs or to
return it to Earth. The initial checkout did not require such a rescue.
Left: Crew of STS-31
(left to right): Charles Bolden, Steven Hawley, Loren Shriver, Bruce McCandless
and Kathryn Sullivan. Middle: Launch of STS-31. Right: Release of the Hubble
Space Telescope during the STS-31 mission.
Left and middle: STS-31
astronauts McCandless and Sullivan suit up for a spacewalk. Right: Image from
WF/PC showing the blurred image of a star that should have appeared as a single
point of light.
After initial on-orbit activation and checkout of the
telescope’s systems, it was time for the much-anticipated “first light” images.
The initial images, however, puzzled scientists, as they showed stars not as
single, well-focused points of light, but as blurred and fuzzy. Investigators
learned that the telescope’s primary mirror had suffered a production error — its
edges too flat by 0.003 millimeters, resulting in an optical problem called
spherical aberration. While this significantly degraded the capability of several
of Hubble’s instruments to return exceptionally detailed photographs, the
telescope still produced some good images. NASA put in place a plan to fix the
Hubble’s optical problems without resorting to actually repairing the mirror,
which was an impossible task. Since the magnitude of the spherical aberration
was well-defined, engineers designed a set of mirrors that astronauts could
place aboard Hubble during the previously planned first servicing mission.
Left: Hubble image of
Saturn from 1990. Right: Hubble image of Jupiter from 1991.
The task of fixing Hubble’s degraded optics and also
replacing its solar arrays that caused unexpected vibrations fell to the crew
of STS-61, the first Hubble servicing mission in December 1993. The crew
consisted of Commander Richard
O. Covey, Pilot Kenneth D. Bowersox and Mission Specialists Kathryn C.
Thornton, Claude Nicollier, Jeffrey
A. Hoffman, F. Story Musgrave and Thomas D. Akers.
Two days after launch, Nicollier grappled Hubble and secured
it in the payload bay of Space Shuttle Endeavour.
During the next five days, the spacewalking teams of Hoffman/Musgrave and
Thornton/Akers alternated in conducting an unprecedented five spacewalks to
accomplish the repairs. They installed
the Corrective Optics Space Telescope Axial Replacement (COSTAR) in place of
the HSP, sacrificing the one instrument to enable the telescope to achieve its
full potential. They replaced the original WF/PC with an upgraded WF/PC-2 and
replaced the original solar arrays with a new pair with stiffer properties to
eliminate unwanted vibrations. Within a month, new images from Hubble indicated
the repairs returned the telescope to its expected capabilities, providing
astronomers with a unique observation platform.
Left: STS-61 crew
(front, left to right) Kenneth Bowersox, Kathryn Thornton, Story Musgrave and Claude
Nicollier; (back, left to right) Richard Covey, Jeffrey Hoffman and Thomas Akers.
Middle: Thornton and Akers install the COSTAR to restore Hubble’s optical
capabilities. Right: Hoffman and Musgrave install the WF/PC-2 instrument.
Left: Hubble Space
Telescope just prior to release during STS-61. Middle and right: Images of M100
galactic nucleus before and after the first servicing mission, showing the
improved optical qualities.
Left: Hubble image of
NGC 6543, The Cat’s Eye Nebula, from 1995. Middle: Hubble image of Mars from
1995. Right: Hubble image of Eta Carinae from 1996.
The second Hubble servicing mission took place in February
1997 during the STS-82 mission of Space Shuttle Discovery. The crew of STS-82 included Commander Kenneth D.
Bowersox, Pilot Scott
J. Horowitz and Mission Specialists Joseph R. Tanner, Steven
A. Hawley, Gregory J. Harbaugh, Mark C. Lee and Steve L. Smith. Shuttle
arm operator Hawley grappled Hubble, and the two spacewalking teams of Smith/Lee
and Tanner/Harbaugh alternated to conduct five spacewalks over the next five
days. They replaced the GHRS instrument with the Space Telescope Imaging
Spectrograph (STIS) and the FOS with the Near-Infrared Camera and Multi-Object
Spectrometer (NICMOS), also replacing a science data tape recorder with a
solid-state version and repairing some thermal insulation. The crew raised
Hubble’s orbit nearly six miles using the shuttle’s steering thrusters. After
release, Hubble resumed its mission of providing unprecedented views of the
universe to astronomers.
Left: Crew of STS-82
(front, left to right) Bowersox, Hawley and Scott Horowitz; (back, left to
right) Joseph Tanner, Gregory Harbaugh, Mark Lee and Steve Smith. Right: Smith
and Lee during the first STS-82 spacewalk.
Left: Tanner and
Harbaugh during the fourth STS-82 spacewalk. Right: Hubble after release during
Left: Hubble image of
NGC 4314 from 1998. Middle: Hubble image of the Stingray Nebula from 1998. Right: Hubble image of Neptune from 1998.
Managers split the next planned third servicing mission to
Hubble into two flights, since three of the telescope’s stabilizing gyroscopes
had failed. (A fourth failed shortly before the shuttle’s launch.) Servicing
Mission 3A took place in December 1999 during Discovery’s STS-103 mission. The crew included Commander Curtis L.
Brown, Pilot Scott J. Kelly and Mission Specialists Steven L. Smith, Jean-François
A. Clervoy, John
M. Grunsfeld, C. Michael
Foale and Claude Nicollier. Clervoy captured Hubble using the shuttle’s
robot arm and secured it in the payload bay. The spacewalking teams of
Smith/Grunsfeld and Foale/Nicollier alternated days to perform three spacewalks
to replace all six gyroscopes, a fine guidance sensor, the computer and
thermal insulation. Clervoy released the refurbished telescope to continue its scientific
Left: STS-103 crew
(left to right) Michael Foale, Nicollier, Scott Kelly, Curtis Brown, Jean-François
Clervoy, John Grunsfeld and Steven Smith. Right: Foale and Nicollier during the second STS-103
Left: Smith and
Grunsfeld during the third STS-103 spacewalk. Right: Hubble after release
Left: Hubble image of
the Eskimo Nebula NGC 2392 from 2000. Middle: Hubble image of planetary nebula
NGC 6751 from 2000. Right: Hubble image of a cosmic collision between two
galaxies, UGC 06471 and UGC 06472, from 2001.
Hubble Servicing Mission 3B took place in March 2002 during
the STS-109 mission of Space Shuttle Columbia.
The crew for this mission included Commander Scott D. Altman, Pilot Duane G.
Carey and Mission Specialists John M. Grunsfeld, Nancy J. Currie, Richard M.
Linnehan, James H. Newman and Michael J. Massimino. Currie grappled Hubble to
place it securely in Columbia’s
payload bay. The two spacewalking duos of Grunsfeld/Linnehan and Newman/Massimino
completed five spacewalks to replace the FOC with the new Advanced Camera for
Surveys (ACS) and install new, more durable and efficient solar arrays. They
also replaced the Power Control Unit and installed a new cooling system to
revive the NICMOS instrument, dormant since 1999. Currie released the upgraded
telescope to continue its unprecedented scientific mission.
Left: Crew of STS-109
(left to right) Michael Massimino, Richard Linnehan, Duane Carey, Scott Altman,
Nancy Currie, Grunsfeld and James Newman. Right: Massimino and Newman work with
the Reaction Wheel Assembly during the second STS-109 spacewalk.
Left: Grunsfeld and
Linnehan install the NICMOS cryocooler during the fifth STS-109 spacewalk.
Right: Hubble after release during
STS-109, showing the newly installed solar arrays.
Left: Hubble image of
barred spiral galaxy NGC 1300 from 2005. Middle: Hubble image of dark spot in
the clouds of Uranus from 2006. Right: Hubble image of The Whirlpool Galaxy M51
and companion galaxy from 2005.
Hubble image of
interacting spiral galaxies, NGC 2207 and IC 2163, from 2004.
The fifth and final Hubble servicing mission originally
planned for 2005 almost didn’t happen. In the wake of the 2003 Columbia accident, NASA managers only
approved space shuttle missions that flew to the safe haven of the
International Space Station. Following recommendations from the National
Academy of Sciences, NASA reversed the decision in 2005 and authorized the
flight that took place in May 2009, already four years past the telescope’s
originally expected 15-year lifespan.
The crew for the STS-125 mission of Atlantis included Commander Scott D. Altman, Pilot Gregory C. Johnson
and Mission Specialists Michael T. Good, Megan K. McArthur, John M. Grunsfeld,
Michael J. Massimino and Andrew J. Feustel. On this final visit to Hubble,
McArthur grappled the telescope and secured it in the shuttle’s payload bay. The
two spacewalking teams of Grunsfeld/Feustel and Massimino/Good performed five
spacewalks to complete final maintenance for the telescope. Their tasks
included replacing the WF/PC-2 with the Wide Field Camera 3 (WFC-3), replacing
COSTAR with the Cosmic Origins Spectrograph (COS), replacing the data-handling
unit, repairing the ACS and STIS instruments and installing improved nickel-hydrogen
batteries. The repairs and upgrades to the telescope completed and Hubble fully
operational, McArthur released the telescope for the final time. This last visit was expected to keep Hubble
working through 2014. But … now six years later and on its 30th anniversary … the
telescope is still going strong!
Left: Crew of STS-125,
the final Hubble servicing mission (left to right) Massimino, Michael Good, Gregory
Johnson, Altman, Megan McArthur, Grunsfeld and Andrew Feustel. Right: Massimino
and Good repair the STIS instrument during the fourth STS-125 spacewalk.
Left: Grunsfeld and
Feustel as they are about to re-enter the shuttle’s airlock at the end of the
final STS-125 spacewalk. Right: Hubble after release during STS-125.
To summarize the discoveries made by scientists using data
from the Hubble Space Telescope is well beyond the scope of this article; suffice
it to say that during its 30 years of operation, information and images returned
by Hubble have revolutionized astronomy, literally causing scientists to
rewrite textbooks, and dramatically altered how the public views the wonders of
the universe. On the technical side, the launch of Hubble and the servicing
missions to maintain and upgrade its capabilities have proven conclusively the value
of maintainability for space-based scientific platforms. During the five
servicing missions, 16 spacewalking astronauts conducted 23 excursions totaling
more than 165 hours, or just under seven days, to make repairs or improvements
to the telescope’s capabilities.
anniversary image of the Carina Nebula. Middle: Twenty-fifth anniversary image
of the star cluster Westerlund 2. Right: One of the 30th anniversary images of spiral
galaxy UGC 2885.
For more on the Hubble Space Telescope, visit: https://www.nasa.gov/content/hubbles-30th-anniversary
*From Kathryn D.
Sullivan, “Handprints on Hubble – An Astronaut’s Story of Invention.”
Smithsonian Institution, 2019:83.