Photos by Hubble Space Telescope

1. Two astronauts work in the payload bay of space shuttle Columbia in March of 2002, completing upgrades to the Hubble Space Telescope. The mission was the fourth visit to Hubble since its launch in 1990. A crew of seven astronauts performed five spacewalks, adding an advanced camera, new solar panels, new steering equipment, and a more efficient power system to the orbiting telescope.
2. The Hubble telescope drifts back into space with Earth as its backdrop on Christmas Day 1999 following a successful servicing mission. Seven astronauts aboard space shuttle Discovery completed three spacewalks over six days to replace the telescope's worn and outdated equipment, including its failing gyroscopes, and perform several maintenance upgrades. Astronauts had a firm return day for this mission—they needed to finish their work and return to Earth before New Year's Day to avoid possible Y2K problems. They landed safely on December 27.

3. Sunlight glints off the Hubble Space Telescope as it sits suspended over the cargo bay of space shuttle Discovery during a February 1997 servicing mission. It was during this mission that astronauts installed Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS), which used technology not available when Hubble was launched in 1990 to provide some of the most stunningly detailed images of faraway galaxies and nebulae.

4. At 43.5 feet (13.2 meters) tall, the Hubble Space Telescope towers over space shuttle Endeavour's payload bay during the first mission to upgrade the telescope's systems in December 1993. The mission's most important objective was to fix Hubble's infamous vision problem. An incorrectly shaped primary mirror meant the telescope could not focus all the light from an object to a single sharp point, which left a fuzzy halo around images. Two devices that acted as corrective eyeglasses were installed, and a clear-seeing Hubble has been making remarkable cosmic discoveries ever since.

5. Space shuttle Columbia and the Hubble Space Telescope drift 360 miles (579 kilometers) over the Earth's surface during a servicing mission in March 2002. During the mission, astronauts installed a new refrigeration system in Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS), which had been inactive since 1999, when it depleted the nitrogen ice that had cooled it since 1997.

6. During the first Hubble servicing mission in December 1993, astronauts installed new solar arrays (left) designed to reduce the thermal "jitters" experienced when the telescope transitioned from cold darkness into warm daylight.

7. Astronaut Story Musgrave moves through space shuttle Endeavour's cargo bay (center) during deployment of the Hubble Space Telescope's new solar array panels. Musgrave was on the last of five spacewalks in the 1993 mission, the first service flight to Hubble. Astronaut Jeffrey Hoffman's arm is visible in the lower left corner.

8. With the Hubble Space Telescope looming behind him, astronaut Steve Smith prepares to use a specially designed ratchet during the telescope's second servicing mission in 1997. Astronauts performed four days of spacewalks during the ten-day mission, installing new instruments and making repairs.

9. After a 2002 servicing mission, the Hubble Space Telescope sports new solar arrays on its outside and new instruments inside.

(Courtesy: NASA & National Geographic)