STS-31 Crew by NASASmithsonian's National Air and Space Museum
On April 24, 1990, Space Shuttle Discovery launched from Kennedy Space Center carrying the Hubble Space Telescope for NASA’s STS-31 mission. The crew of five—Loren J. Shriver, Charles F. Bolden, Jr., Bruce McCandless II, Steven A. Hawley, and Kathryn D. Sullivan—had one major goal, deploy the Hubble Space Telescope.
Deployment of Hubble Space Telescope by NASASmithsonian's National Air and Space Museum
The telescope was released at a record height (approximately 370 miles), an orbit that would help ensure Hubble’s longevity. There was one small hiccup during deployment. One of Hubble’s solar arrays was jammed. Astronauts Kathryn Sullivan and Bruce McCandless prepared for a spacewalk to fix the array as the telescope’s batteries ran down, but Mission Control fixed the problem just in time.
Hubble Trouble: Repairing the Hubble Space TelescopeSmithsonian's National Air and Space Museum
This was not the first issue to befall the telescope. Within a matter of weeks Hubble began sending back fuzzy images. Astronomers realized something was wrong with the telescope’s optical system. In fact, Hubble suffered from a spherical aberration. The mirror’s shape was off by less than 1/50th the thickness of a human hair, but this tiny flaw proved devastating.
This was a serious, but not fatal flaw. Unlike other astronomical instruments, Hubble was designed to be serviced by astronauts traveling on the Space Shuttle.
NASA already had an upgraded Wide-Field/Planetary Camera (WF/PC) replacement available and engineers knew how to adjust the optics within the new WFPC2 to compensate for the aberration in the primary mirror.
COSTARSmithsonian's National Air and Space Museum
For the other instruments, engineers created an optical box called COSTAR (Corrective Optics Space Telescope Axial Replacement). It contained a set of five pairs of small mirrors on deployable arms that corrected the light beams entering Hubble’s Faint Object Camera, Faint Object Spectrograph, and Goddard High Resolution Spectrograph.
COSTAR contained 10 optical elements, 12 motors, and over 5,000 individual parts. It performed well beyond its original specifications.
Discovery astronaut servicing the Hubble Space Telescope (1997-02-21) by NASASmithsonian's National Air and Space Museum
After several more servicing missions through the 1990s, all the new instruments onboard Hubble had their own corrections for the flaw in the main mirror. Therefore COSTAR was no longer needed, and, given the rapid advance of solid state detector technologies through the decade, WFPC2 was no longer state of the art.
NASA planned another servicing mission to replace them with new more powerful cameras and detectors. However, the shock of the Columbia accident in February 2003 was deeply felt worldwide, making NASA cautious about flights that did not go to the International Space Station.
In 2004, NASA cancelled further servicing missions. Without a new servicing mission, the telescope’s life was projected to end by 2007. The decision incited uproar from scientists, the public, and Congress. Twenty-six former astronauts signed a petition in favor of keeping the Hubble alive.
Finally, in 2009 Hubble’s fifth and final servicing mission took place. It was the most complex and demanding yet—during five spacewalks astronauts installed two new instruments, repaired two others, performed extensive maintenance, removed COSTAR and WFPC2, and installed a new Wide Field Camera (WFPC3).
Image: Full-scale mock up of the Hubble Space Telescope on display at the Smithsonian's National Air and Space Museum.
New Panoramic Picture Taken By Hubble Space Telescope Of Pillars Of Creation (2002-06-12)LIFE Photo Collection
Hubble is still sending back images today.
The telescope changed our understanding of the universe revealing more galaxies than astronomers thought existed. Over its lifespan, Hubble helped determine the expansion rate of the universe, estimated the age of the universe, determined that quasars are powered by supermassive black holes, tracked changes in the atmosphere of planets like Jupiter, and captured what was at the time (1999) the most powerful explosion ever recorded.