Whether awaiting liftoff from Kennedy Space Center's launch pads or undergoing space-age upgrades, NASA's space shuttle orbiters were majestic in appearance, intricate in design, and advanced in the possibilities they offered mankind in the exploration of our universe.
OV-102 Columbia
OV-102 Columbia
On April 12, 1981, a bright white Columbia roared into a deep blue sky as the nation's first reusable Space Shuttle. Named after the first American ocean vessel to circle the globe and the command module for the Apollo 11 Moon landing, Columbia continued this heritage of intrepid exploration. The heaviest of NASA's orbiters, Columbia weighed too much and lacked the necessary equipment to assist with assembly of the International Space Station. Despite its limitations, the orbiter's legacy is one of groundbreaking scientific research and notable "firsts" in space flight.

Image right: Columbia lifts off for the first time from Kennedy Space Center on April 12, 1981. Credit: NASA

Space Shuttle mission STS-9, launched in late November 1983, was the maiden flight for Spacelab. Designed to be a space-based science lab, Spacelab was installed inside the orbiter's cargo bay. Spacelab featured an enclosed crew work module connected to an outside payload pallet, which could be mounted with various instruments and experiments. From inside the lab, astronauts worked with the experiments on the pallet and within the crew module itself. The lab would go on to fly aboard the rest of the fleet, playing host throughout its accomplished lifetime to unprecedented research in astronomy, biology and other sciences. Spacelab ultimately finished where its career began; its 16th and final mission was hoisted into space aboard Columbia in 1998.

In addition to Columbia's STS-1 flight and Spacelab, the orbiter was also the stage for many other remarkable firsts. Germany's Dr. Ulf Merbold became the first European Space Agency astronaut when he flew aboard 1983's STS-9. The Japanese Space Agency and STS-65's Chiaki Mukai entered history as the first Japanese woman to fly in space in 1994. In a display of national pride, the crew of STS-73 even "threw" the ceremonial first pitch for game five of the 1995 baseball World Series, marking the first time the pitcher was not only outside of the stadium, but out of this world.

Perhaps Columbia's crowning achievement was the deployment of the gleaming Chandra X-ray Observatory in July 1999. Carried into space inside the orbiter's payload bay, the slender and elegant Chandra telescope was released on July 23. Still in flight today, the X-ray telescope specializes in viewing deep space objects and finding the answers to astronomy's most fundamental questions.

Columbia and its crew were tragically lost during STS-107 in 2003. As the Space Shuttle lifted off from Kennedy Space Center in Florida on January 16, a small portion of foam broke away from the orange external fuel tank and struck the orbiter's left wing. The resulting damage created a hole in the wing's leading edge, which caused the vehicle to break apart during reentry to Earth's atmosphere on February 1.

Construction Milestones

July 26, 1972 Contract Award March 25, 1975 Start long lead fabrication aft fuselage November 17, 1975 Start long-lead fabrication of crew module June 28, 1976 Start assembly of crew module September 13, 1976 Start structural assembly of aft-fuselage December 13, 1976 Start assembly upper forward fuselage January 3, 1977 Start assembly vertical stabilizer August 26, 1977 Wings arrive at Palmdale from Grumman October 28, 1977 Lower forward fuselage on dock, Palmdale November 7, 1977 Start of Final Assembly February 24, 1978 Body flap on dock, Palmdale April 28, 1978 Forward payload bay doors on dock, Palmdale May 26,1978 Upper forward fuselage mate July 7, 1978 Complete mate forward and aft payload bay doors September 11, 1978 Complete forward RCS February 3, 1979 Complete combined systems test, Palmdale February 16, 1979 Airlock on dock, Palmdale March 5, 1979 Complete postcheckout March 8, 1979 Closeout inspection, Final Acceptance Palmdale March 8, 1979 Rollout from Palmdale to Dryden (38 miles) March 12, 1979 Overland transport from Palmdale to Edwards March 20, 1979 SCA Ferry Flight from DFRF to Bigs AFB, Texas March 22, 1979 SCA Ferry flight from Bigs AFB to Kelly AFB, Texas March 24, 1979 SCA Ferry flight from Kelly AFB to Eglin AFB, Florida March 24, 1979 SCA Ferry flight from Eglin, AFB to KSC November 3, 1979 Auxiliary Power Unit hot fire tests, OPF KSC December 16, 1979 Orbiter integrated test start, KSC January 14, 1980 Orbiter integrated test complete, KSC February 20, 1981 Flight Readiness Firing April 12, 1981 First Flight (STS-1)
Upgrades and Features

Columbia is commonly referred to as OV-102, for Orbiter Vehicle-102. The orbiter weighed 178,000 pounds with its main engines installed.

Columbia was the first orbiter to undergo the scheduled inspection and retrofit program. In 1991, Columbia returned to its birthplace at Rockwell International's Palmdale, Calif., assembly plant. The spacecraft underwent approximately 50 upgrades there, including the addition of carbon brakes and a drag chute, improved nose wheel steering, removal of instrumentation used during the test phase of the orbiter, and an enhancement of its Thermal Protection System. The orbiter returned to Florida in February 1992 to begin processing for mission STS-50, launching in June of that year.

In 1994, Columbia was transported back to Palmdale for its first major tear-down and overhaul, known as the Orbiter Maintenance Down Period (OMDP). This overhaul typically lasts one year or longer and leaves the vehicle in "like-new" condition.

Its second OMDP came in 1999, when workers performed more than 100 modifications on the vehicle. The orbiter's most impressive upgrade likely was the installation of a state-of-the-art, Multi-functional Electronic Display System (MEDS), or "glass cockpit." The MEDS replaced traditional instrument dials and gauges with small, computerized video screens. The new system improved crew interaction with the orbiter during flight and reduced maintenance costs by eliminating the outdated and tricky electromechanical displays.

OV-099 Challenger
OV-099 Challenger
First called STA-099, Challenger was built to serve as a test vehicle for the Space Shuttle program. But despite its Earth-bound beginnings, STA-099 was destined for space.

In the late 1970s, NASA strived for a lighter weight orbiter, but a test vehicle was needed to ensure the lighter airframe could handle the stress of space flight. Computer software at the time wasn't yet advanced enough to accurately predict how STA-099's new, optimized design would respond to intense heat and stress. The best solution was to submit the vehicle to a year of intensive vibration and thermal testing.

In early 1979, NASA awarded Space Shuttle orbiter manufacturer Rockwell a contract to convert STA-099 to a space-rated orbiter, OV-099. The vehicle's conversion began late that year. Although the job was easier than it would have been to convert NASA's first orbiter, Enterprise, it was a major process that involved the disassembly and replacement of many parts and components.

The second orbiter to join NASA's Space Shuttle fleet, OV-099 arrived at NASA's Kennedy Space Center in Florida in July 1982, bearing the name "Challenger."

Space Shuttle orbiter Challenger was named after the British Naval research vessel HMS Challenger that sailed the Atlantic and Pacific oceans during the 1870s. The Apollo 17 lunar module also carried the name of Challenger. Like its historic predecessors, Challenger and her crews made significant scientific contributions in the spirit of exploration.

Challenger launched on her maiden voyage, STS-6, on April 4, 1983. That mission saw the first spacewalk of the Space Shuttle program, as well as the deployment of the first satellite in the Tracking and Data Relay System constellation. The orbiter launched the first American woman, Sally Ride, into space on mission STS-7 and was the first to carry two U.S. female astronauts on mission STS 41-G.

The first orbiter to launch and land at night on mission STS-8, Challenger also made the first Space Shuttle landing at Kennedy Space Center, concluding mission STS 41-B. Spacelabs 2 and 3 flew aboard the ship on missions STS 51-F and STS 51-B, as did the first German-dedicated Spacelab on STS 61-A. A host of scientific experiments and satellite deployments were performed during Challenger's missions.

Challenger's service to America's space program ended in tragedy on Jan. 28, 1986. Just 73 seconds into mission STS 51-L, a booster failure caused an explosion that resulted in the loss of seven astronauts, as well as the vehicle.

The loss of Challenger does not overshadow her legacy in NASA's storied history. The discoveries made on her many successful missions continue to better mankind in space flight and in life on Earth.

Construction Milestones - STA-099

July 26, 1972 Contract Award Nov. 21, 1975 Start structural assembly of crew module June 14, 1976 Start structural assembly of aft-fuselage March 16, 1977 Wings arrive at Palmdale from Grumman Sept. 30, 1977 Start of Final Assembly Feb. 10, 1978 Completed final assembly Feb. 14, 1978 Rollout from Palmdale
Construction Milestones - OV-099

Jan. 1, 1979 Contract Award Jan. 28, 1979 Start structural assembly of crew module June 14, 1976 Start structural assembly of aft-fuselage March 16, 1977 Wings arrive at Palmdale from Grumman Nov. 3, 1980 Start of Final Assembly Oct. 21, 1981 Completed final assembly June 30, 1982 Rollout from Palmdale July 1, 1982 Overland transport from Palmdale to Edwards July 5, 1982 Delivery to Kennedy Space Center Dec. 19, 1982 Flight Readiness Firing April 4, 1983 First Flight (STS-6)
OV-103 Discovery
OV-103 Discovery
Discovery (OV-103) was NASA's third space shuttle orbiter to join the fleet, arriving for the first time at the Kennedy Space Center in Florida in November 1983.

After checkout and processing, it was launched on Aug. 30, 1984, for its first mission, 41-D, to deploy three communications satellites.

Since that inaugural flight, Discovery has completed more than 30 successful missions, surpassing the number of flights made by any other orbiter in NASA's fleet. Just like all of the orbiters, it has undergone some major modifications over the years. The most recent began in 2002 and was the first carried out at Kennedy. It provided 99 upgrades and 88 special tests, including new changes to make it safer for flight.

Discovery has the distinction of being chosen as the Return to Flight orbiter twice. The first was for STS-26 in 1988, and the second when it carried the STS-114 crew on NASA's Return to Flight mission to the International Space Station in July 2005.

The choice of the name "Discovery" carried on a tradition drawn from some historic, Earth-bound exploring ships of the past. One of these sailing forerunners was the vessel used in the early 1600s by Henry Hudson to explore Hudson Bay and search for a northwest passage from the Atlantic to the Pacific.

Another such ship was used by British explorer James Cook in the 1770s during his voyages in the South Pacific, leading to the discovery of the Hawaiian Islands. In addition, two British Royal Geographical Society ships have carried the name "Discovery" as they sailed on expeditions to the North Pole and the Antarctic.

Destined for exploring the heavens instead of the seas, it was only fitting that NASA's Discovery carried the Hubble Space Telescope into space during mission STS-31 in April 1990, and provided both the second and third Hubble servicing missions (STS-82 in February 1997 and STS-103 in December 1999).

During its many successful trips to space, Discovery has carried satellites aloft, ferried modules and crew to the International Space Station, and provided the setting for countless scientific experiments.

Construction Milestones

January 29, 1979 Contract Award August 27, 1979 Start long lead fabrication of Crew Module June 20, 1980 Start fabrication lower fuselage November 10, 1980 Start structural assembly of aft-fuselage December 8, 1980 Start initial system installation aft fuselage March 2, 1981 Start fabrication/assembly of payload bay doors October 26, 1981 Start initial system installation, crew module, Downey January 4, 1982 Start initial system installation upper forward fuselage March 16, 1982 Midfuselage on dock, Palmdale March 30, 1982 Elevons on dock, Palmdale April 30, 1982 Wings arrive at Palmdale from Grumman April 30, 1982 Lower forward fuselage on dock, Palmdale July 16, 1982 Upper forward fuselage on dock, Palmdale August 5, 1982 Vertical stabilizer on dock, Palmdale September 3, 1982 Start of Final Assembly October 15, 1982 Body flap on dock, Palmdale January 11, 1983 Aft fuselage on dock, Palmdale February 25, 1983 Complete final assembly and closeout installation, Palmdale February 28, 1983 Start initial subsystems test, power-on, Palmdale May 13, 1983 Complete initial subsystems testing July 26, 1983 Complete subsystems testing August 12, 1983 Completed Final Acceptance October 16, 1983 Rollout from Palmdale November 5, 1983 Overland transport from Palmdale to Edwards November 9, 1983 Delivery to Kennedy Space Center June 2, 1984 Flight Readiness Firing August 30, 1984 First Flight (41-D)
Upgrades and Features

Discovery benefited from lessons learned in the construction and testing of Enterprise, Columbia and Challenger. At rollout, its weight was some 6,870 pounds less than Columbia.

Beginning in the fall of 1995, the orbiter underwent a nine-month Orbiter Maintenance Down Period (OMDP) in Palmdale California. The vehicle was outfitted with a 5th set of cryogenic tanks and an external airlock to support missions to the International Space Station. It returned to the Kennedy Space Center, riding piggy-back on a modified Boeing 747, in June 1996.

Following STS-105, Discovery became the first of the orbiter fleet to undergo Orbiter Major Modification (OMM) period at the Kennedy Space Center. Work began in September 2002, and along with the scheduled upgrades, additional safety modifications were added as part of the preparations for Return to Flight.

OV-104 Atlantis
OV-104 Atlantis
NASA's fourth space-rated space shuttle, OV-104 "Atlantis," was named after the two-masted boat that served as the primary research vessel for the Woods Hole Oceanographic Institute in Massachusetts from 1930 to 1966. The boat had a 17-member crew and accommodated up to five scientists who worked in two onboard laboratories, examining water samples and marine life. The crew also used the first electronic sounding devices to map the ocean floor.

Construction of the orbiter Atlantis began on March 3, 1980. Thanks to lessons learned in the construction and testing of orbiters Enterprise, Columbia and Challenger, Atlantis was completed in about half the time in man-hours spent on Columbia. This is largely attributed to the use of large thermal protection blankets on the orbiter's upper body, rather than individual tiles requiring more attention.

Weighing in at 151,315 pounds when it rolled out of the assembly plant in Palmdale, Calif., Atlantis was nearly 3.5 tons lighter than Columbia. The new orbiter arrived at NASA's Kennedy Space Center in Florida on April 9, 1985, and over the next seven months was prepared for her maiden voyage.

Like her seafaring predecessor, orbiter Atlantis \carried on the spirit of exploration with several important missions of her own. On Oct. 3, 1985, Atlantis launched on her first space flight, STS 51-J, with a classified payload for the U.S. Department of Defense. The vehicle went on to carry four more DOD payloads on later missions.

Atlantis also served as the on-orbit launch site for many noteworthy spacecraft, including planetary probes Magellan and Galileo, as well as the Compton Gamma Ray Observatory. An impressive array of onboard science experiments took place during most missions to further enhance space research in low Earth orbit.

Starting with STS-71, Atlantis pioneered the Shuttle-Mir missions, flying the first seven missions to dock with the Russian space station. When linked, Atlantis and Mir together formed the largest spacecraft in orbit at the time. The missions to Mir included the first on-orbit U.S. crew exchanges, now a common occurrence on the International Space Station. On STS-79, the fourth docking mission, Atlantis ferried astronaut Shannon Lucid back to Earth after her record-setting 188 days in orbit aboard Mir.

In recent years, Atlantis has delivered several vital components to the International Space Station, including the U.S. laboratory module, Destiny, as well as the Joint Airlock Quest and multiple sections of the Integrated Truss structure that makes up the station's backbone.

Construction Milestones - OV-104

Jan. 29, 1979 Contract Award March 30, 1980 Start structural assembly of crew module Nov. 23, 1981 Start structural assembly of aft-fuselage June 13, 1983 Wings arrive at Palmdale from Grumman Dec. 2, 1983 Start of Final Assembly April 10, 1984 Completed final assembly March 6, 1985 Rollout from Palmdale April 3, 1985 Overland transport from Palmdale to Edwards April 13, 1985 Delivery to Kennedy Space Center Sept. 12, 1985 Flight Readiness Firing Oct. 3, 1985 First Flight (STS 51-J)
Upgrades and Features

By early 2005, Atlantis had undergone two overhauls known as Orbiter Maintenance Down Periods. Some of the most significant upgrades and new features included: Installation of the drag chute New plumbing lines and electrical connections configuring the orbiter for extended duration missions New insulation for the main landing gear doors Improved nosewheel steering Preparations for the Mir Orbiter Docking System unit later installed at Kennedy Installation of the International Space Station airlock and Orbiter Docking System Installation of the Multifunction Electronic Display System, or "glass cockpit"
OV-105 Endeavour
OV-105 Endeavour
Authorized by Congress in August 1987 as a replacement for the Space Shuttle orbiter Challenger, Endeavour (OV-105) arrived at Kennedy Space Center's Shuttle Landing Facility on May 7, 1991, piggy-backed on top of NASA's new Space Shuttle Carrier Aircraft.

For the first time, an orbiter was named through a national competition involving students in elementary and secondary schools. They were asked to select a name based upon an exploratory or research sea vessel. In May 1989, President George Bush announced the winning name.

Endeavour was named after a ship chartered to traverse the South Pacific in 1768 and captained by 18th century British explorer James Cook, an experienced seaman, navigator and amateur astronomer. He commanded a crew of 93 men, including 11 scientists and artists.

Cook's main objective, tasked by the British Admiralty and the Royal Society, was to observe the Transit of Venus at Tahiti. This reading enabled astronomers to find the distance of the Sun from the Earth, which then could be used as a unit of measurement in calculating the parameters of the universe.

Cook's achievements on Endeavour were numerous, including the accurate charting of New Zealand and Australia and successfully navigating the Great Barrier Reef. Thousands of new plant specimens and animal species were observed and illustrated on this maiden voyage. Cook also established the usefulness of including scientists on voyages of exploration.

Space Shuttle Endeavour embodies similar experiences. Its first launch, the STS-49 mission, began with a flawless liftoff on May 7, 1992, beginning a journey filled with excitement, anticipation and many firsts.

One of Endeavour's primary assignments was to capture INTELSAT VI, an orbiting, but not functioning, communications satellite, and replace its rocket motor. Unfortunately, the Space Shuttle wasn't designed to retrieve the satellite, which created many repair challenges.

The project sparked public interest in the mission and NASA received a deluge of suggestions on possible ways for the crew to grab onto the satellite. It took three attempts to capture the satellite for repairs to be made. An unprecedented three-person spacewalk took place after the procedure was evaluated by the astronauts and ground team.

Between rescue attempts, the STS-49 crew was busy with a variety of activities. They conducted medical tests assessing the human body's performance in microgravity, and recorded footage for an educational video comparing Cook's first voyage on Endeavour with the Space Shuttle orbiter's maiden voyage.

Once the new motor was attached, it propelled the satellite into the correct orbit, providing a relay link for the equivalent of 120,000 two-way simultaneous telephone calls and three television channels.

This was the first time four spacewalks were conducted on a Space Shuttle mission and one of them was the longest in space history, lasting more than eight hours.

The crew also took part in the Commercial Protein Crystal Growth experiment. The research tested the production of protein crystals grown in microgravity.

Because of Endeavour's excellent performance, NASA decided to extend the flight two days to complete more mission objectives and allow the crew enough time to prepare for landing.

OV-105 became the first Space Shuttle orbiter to use a drag chute during a landing -- only one of many technical improvements made to Endeavour.

Just as James Cook set the standard with his seafaring Endeavour voyage, the Space Shuttle Endeavour missions have continued to uphold and surpass the standards set by its namesake, more than 200 years later.

Construction Milestones

February 15, 1982 Start structural assembly of Crew Module July 31, 1987 Contract Award September 28, 1987 Start structural assembly of aft-fuselage December 22, 1987 Wings arrive at Palmdale, Calif. from Grumman August 1, 1987 Start of Final Assembly July 6, 1990 Completed final assembly April 25, 1991 Rollout from Palmdale May 7, 1991 Delivery to Kennedy Space Center April 6, 1992 Flight Readiness Firing May 7, 1992 First Flight (STS-49)
Upgrades and Features

Spare parts from the construction of Discovery (OV-103) and Atlantis (OV-104), manufactured to facilitate the repair of an orbiter if needed, were eventually used to build OV-105.

Endeavour also featured new hardware, designed to improve and expand orbiter capabilities. Most of this equipment was later incorporated into the other three orbiters during out-of-service major inspection and modification programs.

Endeavour's upgrades include:
A 40-foot-diameter drag chute that reduces the orbiter's rollout distance by 1,000 to 2,000 feet. An updated avionics system that include advanced general purpose computers, improved inertial measurement units and tactical air navigation systems, enhanced master events controllers and multiplexer-demultiplexers, a solid-state star tracker. Improved nose wheel steering mechanisms. An improved version of the Auxiliary Power Units that provide power to operate the Space Shuttle's hydraulic systems. Installation of an external airlock, making Endeavour capable of docking with the International Space Station. Originally equipped as the first extended duration orbiter, later removed during OMDP to save weight for ISS missions. Installation of a ground cooling hookup to allow payload bay to cool the mini-pressurized logistics module (MPLM). General weight-reduction program to maximize the payload capability to the ISS. Doublers added to several wing spars to allow heavier payloads and two wing glove truss tubes were replaced with units having increased wall thickness. Approximately 100 modifications made to Endeavour during its first Orbiter Major Modification period (OMDP). Space Shuttle Endeavour's OMDP began in December 2003. Engineers and technicians spent 900,000 hours performing 124 modifications to the vehicle. These included recommended return to flight safety modifications, bonding more than 1,000 thermal protection system tiles and inspecting more than 150 miles of wiring. Eighty five of the modifications are complete and 39 are still underway.

Two of the more extensive modifications included the addition of the multi-functional electronic display system (glass cockpit), and the three-string global positioning system.

The glass cockpit is a new, full-color, flat-panel display system that improves interaction between the crew and orbiter. It provides easy-to-read graphics portraying key flight indicators like attitude display and mach speed. Endeavour was the last vehicle in the fleet to receive this system.

The three-string global positioning system will improve the shuttle's landing capability. It will allow Endeavour to make a landing at any runway long enough to handle the shuttle. The previous system only allowed for landings at military bases. Shuttle major modification periods are scheduled at regular intervals to enhance safety and performance, infuse new technology and allow thorough inspections of the airframe and wiring. This was the second of modification period performed entirely at Kennedy. Endeavour's previous modification was completed in March 1997.

Endeavour has undergone extensive modifications, including the addition of all of the return-to-flight safety upgrades added to both Discovery and Atlantis.

Endeavour's flight on mission STS-118 was the first launch for the orbiter in more than four years.