Washington –
Unbound by Earth’s atmospheric distortion, the
Hubble Space Telescope was deployed into low Earth orbit with the promise of delivering unprecedented clarity of the universe. But a design flaw in the multibillion-dollar observatory’s primary mirror dampened that promise.


Hubble, a joint project of NASA and the European Space Agency (ESA), was carried into space by
the Space Shuttle Discovery
, which
launched from Kennedy Space Center, Fla., April 24, 1990.


Shortly after
a slight flaw in Hubble’s 2.4-meter primary mirror was found, which
caused the telescope to focus improperly –
Hubble became
near-sighted. Promoted as
a wondrous device,
the telescope would for a time become the punchline
of jokes by late-night TV show hosts.

However, Hubble’s optical problems were less problematic than the general public knew, space consultant James Oberg said. “A lot of the [optical] distortion could be taken out computationally,” through a painstaking process called inverse Fourier transform methods, he said in an April 14 phone interview.


Despite the adjustment, the optical problem still weighed heavily on

During a panel discussion
at the National Space Symposium in Colorado Springs, Colo.,
April 9,
former NASA administrators Robert Frosch and Jim Beggs said not testing the primary mirror was one of the worst decisions
they made during their respective tenures.

sch, Beggs’ predecessor, said he was not comfortable with NASA’s plans to split responsibility for Hubble between Lockheed Martin, which built the casing and assembled the observatory, and Perkin-Elmer, which developed the optics.
Forsch said he was concerned that if something went wrong, each contractor would blame the other. But rather than insist on a clear prime, Frosch said he went along with the co-prime approach.


Beggs, who led the agency between 1981 and 1985, went further saying his “worst mistake” was “not requesting a test of the
mirror that Perkin-Elmer was grinding for us.”

NASA astronauts
Shuttle Endeavour installed corrective lenses that fixed the mirror’s focusing problem in December 1993 during the STS-61 mission.


With the correction made, Hubble met its lofty billing and at times has exceeded it. Hubble data has been responsible for thousands of scientific papers
in which scientists have proven the existence of black holes, located the origin of gamma-rays and measured the universe’s rate of expansion, the NASA Web site said.


Redemption had come for the space-based observatory. Formerly known as the Large Space Telescope, the concept
was conceived by U.S. physicist Lyman Spitzer in a 1946 study, although German rocket pioneer Hermann Oberth is credited with the idea of an orbiting telescope in 1923, according to NASA’s Web site. Spitzer advocated heavily for the project, and in 1965 he headed the U.S. National Academy of Sciences committee that defined the scientific objectives for the Large Space Telescope, the ESA Web site said.

ESA joined the project in 1975, providing partial
funding of the project in exchange for a share of usage time, NASA’s Web site said.


Funding for the Large Space Telescope was approved by the U.S. Congress in 1977 after the size of the primary mirror was reduced.

NASA renamed the space observatory
for U.S. astronomer Edwin Hubble, who discovered other galaxies and the expansion of the universe, the NASA Web site said.


Originally scheduled to launch
in December 1983, the agency underestimated the cost of the project and engineering requirements weren’t met, which pushed the launch date
to 1986,

according to the NASA Web site. But then the explosion of the Space Shuttle Challenger further delayed Hubble’s deployment another four years,
the Web site said.


Hubble’s cost at launch was near $1.6 billion, Hubble technical deputy program manager Mike Weiss said in an April 17 interview. That was far from the $200-$300 million cost estimate Congress approved, the NASA Web site said.

Several Hubble systems were upgraded during the seven-year
launch delay
The telescope’s
ground and onboard computer systems, the solar panels and the hull were all improved, according to the book “Hubble Wars,” written by the Tufts University professor
Eric Chaisson.

“As a result, the Hubble Space Telescope today is a more efficient spacecraft than it would have been had it been launched as originally scheduled in December 1983,” according to the book.


Today all five original scientific instruments have been replaced on three servicing missions, NASA’s Web site said.


Hubble will get two new scientific instruments, the Wide Field Camera 3 and Cosmic Origins Spectrograph, during its last servicing mission slated for August, NASA Administrator Mike Griffin announced in
October 2006.
Griffin reversed
a decision made by his predecessor, Sean O’Keefe, in the wake of the Space Shuttle Columbia


Griffin’s decision was a popular one, reflecting the affection the U.S. public
now has
for Hubble, a far cry from the late-night comedy fodder it once was.


“Hubble was not just a new eye on the universe but a new challenge to ground-based astronomy,” Oberg said. Now some newer ground-based telescopes are capable of providing images that equal or surpass Hubble, he said.


Oberg offered Hubble the highest praise both for the science it has helped and the technology it has inspired, saying it is the “single greatest scientific instrument ever built.”

Brian Berger contributed to this article from Colorado Springs, Colo. |Comments: cparks@space.com




April 21


1999: The first Russian and Ukrainian-built Dnepr rocket launches from Baikonur Cosmodrome,
lofting UoSat-12,
Surrey Satellite Technology Ltd.’s experimental remote sensing satellite,
into orbit.


April 23


1965: The Soviet Union launches the Molniya 1-1 on its modified ss-6 rocket from Baikonur Cosmodrome. The experimental communbications satellite tested satellite-based radio and TV broadcasting.


1967: The Soviet Union launches a new manned space vehicle, Soyuz 1. After suffering from several in-orbit problems cosmonaut V
ladimir Komarov was killed during descent the following day after the Soyuz’s parachute failed to deploy properly.


April 24


1947: The French government establishes a rocket testing site at Colomb Bechar, Algeria.

1970: In the country’s first rocket launch, China’s experimental China 1 satellite launches on a
Long March rocket from Shuang Cheng-Tzu.
The launch made
China the fifth nation capable of placing satellites in orbit.


2007: The U.S. Missile Defense Agency’s Near Field Infrared Experiment (NFIRE) missile-warning spacecraft is launched on a Minotaur rocket from Wallops Island, Va. NFIRE was designed to enable missile interceptors to distinguish between an incoming missile’s body and
its exhaust plume.

April 25


1961: An unmanned Mercury capsule launches on an Atlas rocket (MA-3) from Cape Canaveral, Fla. After failing to follow the correct trajectory, MA-3 was destroyed by the range safety officer 40 seconds after liftoff.

April 27


1960: The U.S. Air Force space plane, the Dyna-Soar, completed its first technical review. The program was cance
led in December 1963.