Space Shuttle Enterprise

Enterprise(OV-101) Background

         Enterprise, the first Space Shuttle Orbiter, was originally to be named Constitution (in honor of the U.S. Constitution's Bicentennial). However, viewers of the popular TV Science Fiction show Star Trek started a write-in campaign urging the White House to rename the vehicle to Enterprise. Designated, OV-101, the vehicle was rolled out of Rockwell's Air Force Plant 42, Site 1 Palmdale California assembly facility on Sept. 17, 1976. On Jan. 31, 1977, it was transported 36 miles overland from Rockwell's assembly facility to NASA's Dryden Flight Research Facility at Edwards Air Force Base for the approach and landing test program.

         The nine-month-long ALT program was conducted from February through November 1977 at the Dryden Flight Research Facility and demonstrated that the orbiter could fly in the atmosphere and land like an airplane, except without power-gliding flight.

         Two NASA astronaut crews-Fred Haise and Gordon Fullerton and Joe Engle and Dick Truly-took turns flying the 150,000-pound spacecraft to free-flight landings.

         The ALT program involved ground tests and flight tests. The ground tests included taxi tests of the 747 shuttle carrier aircraft with the Enterprise mated atop the SCA to determine structural loads and responses and assess the mated capability in ground handling and control characteristics up to flight takeoff speed. The taxi tests also validated 747 steering and braking with the orbiter attached. A ground test of orbiter systems followed the unmanned captive tests. All orbiter systems were activated as they would be in atmospheric flight. This was the final preparation for the manned captive flight phase.

         Five captive flights of the Enterprise mounted atop the SCA with the Enterprise unmanned and Enterprise's systems inert were conducted to assess the structural integrity and performance handling qualities of the mated craft.

         Three manned captive flights that followed the five captive flights included an astronaut crew aboard the orbiter operating its flight control systems while the orbiter remained perched atop the SCA. These flights were designed to exercise and evaluate all systems in the flight environment in preparation for the orbiter release (free) flights. They included flutter tests of the mated craft at low and high speed, a separation trajectory test and a dress rehearsal for the first orbiter free flight.

         In the five free flights the astronaut crew separated the spacecraft from the SCA and maneuvered to a landing at Edwards Air Force Base. In the first four such flights the landing was on a dry lake bed; in the fifth, the landing was on Edwards' main concrete runway under conditions simulating a return from space. The last two free flights were made without the tail cone, which is the spacecraft's configuration during an actual landing from Earth orbit. These flights verified the orbiter's pilot-guided approach and landing capability; demonstrated the orbiter's subsonic terminal area energy management autoland approach capability; and verified the orbiter's subsonic airworthiness, integrated system operation and selected subsystems in preparation for the first manned orbital flight. The flights demonstrated the orbiter's ability to approach and land safely with a minimum gross weight and using several center-of-gravity configurations.

         For all of the captive flights and the first three free flights, the orbiter was outfitted with a tail cone covering its aft section to reduce aerodynamic drag and turbulence. The final two free flights were without the tail cone, and the three simulated space shuttle main engines and two orbital maneuvering system engines were exposed aerodynamically.

         The final phase of the ALT program prepared the spacecraft for four ferry flights. Fluid systems were drained and purged, the tail cone was reinstalled, and elevon locks were installed. The forward attachment strut was replaced to lower the orbiter's cant from 6 to 3 degrees. This reduces drag to the mated vehicles during the ferry flights.

         After the ferry flight tests, OV-101 was returned to the NASA hangar at the Dryden Flight Research Facility and modified for vertical ground vibration tests at the Marshall Space Flight Center, Huntsville, Ala.

         On March 13, 1978, the Enterprise was ferried atop the SCA to NASA's Marshall Space Flight Center, where it was mated with the external tank and solid rocket boosters and subjected to a series of vertical ground vibration tests. These tested the mated configuration's critical structural dynamic response modes, which were assessed against analytical math models used to design the various element interfaces.

         These were completed in March 1979. On April 10, 1979, the Enterprise was ferried to the Kennedy Space Center. Mated with the external tank and solid rocket boosters and transported via the mobile launcher platform to Launch Complex 39-A. At Launch Complex 39-A, the Enterprise served as a practice and launch complex fit-check verification tool representing the flight vehicles.

         It was ferried back to NASA's Dryden Flight Research Facility on Aug. 16, 1979, and then returned overland to Rockwell's Palmdale final assembly facility on Oct. 30, 1979. Certain components were refurbished for use on flight vehicles being assembled at Palmdale. The Enterprise was then returned overland to the Dryden Flight Research Facility on Sept. 6, 1981.

         During May and June of 1983, Enterprise was ferried to the Paris, France, Air Show, as well as to Germany, Italy, England and Canada, and was returned to the Dryden Flight Research Facility.

         In the April-October 1984 time period, Enterprise was ferried to Vandenberg Air Force Base in California and to Mobile, Ala. From there it was taken by barge to New Orleans, La., for the United States 1984 World's Fair.

         In November 1984 it was ferried to Vandenberg Air Force Base and used as a practice and fit-check verification tool. On May 24, 1985, Enterprise was ferried from Vandenberg Air Force Base to NASA's Dryden Flight Research Facility.

         On Sept. 20, 1985, Enterprise was ferried from Dryden Flight Research Facility to the Kennedy Space Center in Florida. On Nov. 18, 1985, Enterprise was ferried from the Kennedy Space Center to Dulles Airport, Washington, D.C., and became the property of the Smithsonian Institution. The Enterprise was built as a test vehicle and is not equipped for space flight.

         Following in the Enterprise's, the orbiter Columbia was created and it became the first Space Shuttle to fly into Earth orbit in 1981. Four sister ships joined the fleet over the next 10 years: Challenger, arriving in 1982 but destroyed four years later; Discovery, 1983; Atlantis, 1985; and Endeavour, built as a replacement for Challenger, 1991.

         In the day-to-day world of Shuttle operations and processing, Space Shuttle orbiters go by a more prosaic designation. Enterprise is commonly refered to as OV-101, for Orbiter Vehicle-101.

Columbia (OV-102) Background

         Columbia, the oldest orbiter in the Shuttle fleet, is named after the Boston, Massachusetts based sloop captained by American Robert Gray. On May 11, 1792, Gray and his crew maneuvered the Columbia past the dangerous sandbar at the mouth of a river extending more than 1,000 miles through what is today south-eastern British Columbia, Canada, and the Washington-Oregon border. The river was later named after the ship. Gray also led Columbia and its crew on the first American circumnavigation of the globe, carrying a cargo of otter skins to Canton, China, and then returning to Boston.

         Other sailing ships have further enhanced the luster of the name Columbia. The first U.S. Navy ship to circle the globe bore that title, as did the command module for Apollo 11, the first lunar landing mission.

         On a more directly patriotic note, "Columbia" is considered to be the feminine personification of the United States. The name is derived from that of another famous explorer, Christopher Columbus.

         The spaceship Columbia has continued the pioneering legacy of its forebears, becoming the first Space Shuttle to fly into Earth orbit in 1981. Four sister ships joined the fleet over the next 10 years: Challenger, arriving in 1982 but destroyed four years later; Discovery, 1983; Atlantis, 1985; and Endeavour, built as a replacement for Challenger, 1991. A test vehicle, the Enterprise, was used for suborbital approach and landing tests and did not fly in space. The names of Columbia's sister ships each boast their own illustrious pedigree.

         In the day-to-day world of Shuttle operations and processing, Space Shuttle orbiters go by a more prosaic designation. Columbia is commonly refered to as OV-102, for Orbiter Vehicle-102. Empty Weight was 158,289 lbs at rollout and 178,000 lbs with main engines installed.

Upgrades and Features

         Columbia was the first on-line orbiter to undergo the scheduled inspection and retrofit program. It was transported August 10, 1991, after its completion of mission STS-40, to prime Shuttle contractor Rockwell International's Palmdale, California assembly plant. The oldest orbiter in the fleet underwent approximately 50 modifications, including the addition of carbon brakes, drag chute, improved nose wheel steering, removal of development flight instrumentation and an enhancement of its thermal protection system. The orbiter returned to KSC February 9, 1992 to begin processing for mission STS-50 in June of that year.

Discovery (OV-103) Background

         Discovery, the third orbiter to become operational at Kennedy Space Center, was named after one of two ships that were used by the British explorer James Cook in the 1770s during voyages in the South Pacific that led to the discovery of the Hawaiian Islands. Another of his ships was the Endeavour, the namesake of NASA's newest orbiter.

         Cook also used Discovery to explore the coasts of southern Alaska and northwestern Canada. During the American Revolutionary War, Benjamin Franklin made a safe conduct request for the British vessel because of the scientific importance of its research.

         Other famous ships have carried the name Discovery, including one used by Henry Hudson to explore Hudson Bay in Canada as well as search for what was hoped to be the northwest passage from the Atlantic to the Pacific in 1610 and 1611. Another, based on whaling ship design, was used by the British Royal Geographical Society for an expedition to the North Pole in 1875. This organization then built another Discovery in 1901 to conduct its Antartic expedition that concluded in 1904. This ship still exists and is being preserved by the Society.

         In the day-to-day world of Shuttle operations and processing, Space Shuttle orbiters go by a more prosaic designation. Discovery is commonly refered to as OV-103, for Orbiter Vehicle-103. Empty Weight was 151,419 lbs at rollout and 171,000 lbs with main engines installed.

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. Two orbiters, Challenger and Discovery, were modified at KSC to enable them to carry the Centaur upper stage in the payload bay. These modifications included extra plumbing to load and vent Centaur's cryogenic (L02/LH2) propellants (other IUS/PAM upper stages use solid propellants), and controls on the aft flight deck for loading and monitoring the Centaur stage. No Centaur flight was ever flown and after the loss of Challenger it was decided that the risk was too great to launch a shuttle with a fueled Centaur upper stage in the payload bay.

Space Shuttle Atlantis

Atlantis (OV-104) Background

         Atlantis, the fourth orbiter to become operational at Kennedy Space Center, was named after the primary research vessel for the Woods Hole Oceanographic Institute in Massachusetts from 1930 to 1966. The two-masted, 460-ton ketch was the first U.S. vessel to be used for oceanographic research. Such research was considered to be one of the last bastions of the sailing vessel as stream-and-diesel-powered vessels dominated the waterways.

         The steel-hulled ocean research ship was approximately 140 feet long and 29 feet wide to add to her stability. She featured a crew of 17 and room for five scientists. The research personnel worked in two onboard laboratories, examining water samples and marine life brought to the surface by two large winches from thousands of feet below the surface. The water samples taken at different depths varied in temperature, providing clues to the flow of ocean currents. The crew also used the first electronic sounding devices to map the ocean floor.

         The spaceship Atlantis has carried on the spirit of the sailing vessel with several important voyages of its own, including the Galileo planetary explorer mission in 1989 and the deployment of the Arthur Holley Compton Gamma Ray Observatory in 1991.

         In the day-to-day world of Shuttle operations and processing, Space Shuttle orbiters go by a more prosaic designation. Atlantis is commonly refered to as OV-104, for Orbiter Vehicle-104. Empty Weight was 151,315 lbs at rollout and 171,000 lbs with main engines installed.

Upgrades and Features

         Atlantis benefited from lessons learned in the construction and testing of Enterprise, Columbia and Challenger. At rollout, its weight was some 6,974 pounds less than Columbia. The Experience gained during the Orbiter assembly process also enabled Atlantis to be completed with a 49.5 percent reduction in man hours (compared to Columbia). Much of this decrease can be attributed to the greater use of thermal protection blankets on the upper orbiter body instead of tiles. During the construction of Discovery and Atlantis, NASA opted to have the various contractors manufacture a set of 'structural spares' to facilitate the repair of an Orbiter if one was damaged during an accident. This contract was valued at $389 million and consisted of a spare aft-fuselage, mid-fuselage, forward fuselage halves, vertical tail and rudder, wings, elevons and a body flap. These spares were later assembled into the orbiter Endeavour. Atlantis was shipped to California to undergo upgrades and modifications. These modifications include a drag chute, new plumbing lines that configure the orbiter for extended duration, more than 800 new heat protection tiles and blankets and new insulation for the main landing gear doors, structural mods to the Atlantis airframe. Altogether, 165 modifications were made to Atlantis over the 20 months it spent in Palmdale, California.

Challenger (STA-099, OV-99) Background

         Challenger, the second orbiter to become operational at Kennedy Space Center, was named after an American Naval research vessel that sailed the Atlantic and Pacific oceans during the 1870's. The Apollo 17 lunar module also carried the name of Challenger. Like her historic predecessors, Space Shuttle Challenger and her crews made significant contributions to America's scientific growth.

         Challenger joined NASA fleet of reusable winged spaceships in July 1982. It flew nine successful Space Shuttle missions. On January 28, 1986, the Challenger and its seven-member crew were lost 73 seconds after launch when a booster failure resulted in the breakup of the vehicle.

         Challenger started out as a high-fidelity structural test article (STA-099). The airframe was completed by Rockwell and delivered to Lockheed Plant 42 for structural testing on 02/04/78. The orbiter structure had evolved under such weight-saving pressure that virtually all components of the air frame were required to handle significant structural stress. With such an optimized design, it was difficult to acurately predict mechanical and thermal loading with the computer software available at the time. The only safe approach was to submit the structural test article to intensive testing and analysis. STA-099 underwent 11 months of intensive vibration testing in a 43 ton steel rig built especially for the Space Shuttle Test Program. The rig consisted of 256 hydraulic jacks, distributed over 836 load application points. Under computer control, it was possible to simulate the expected stress levels of launch, ascent, on-orbit, reentry and landing. Three 1 million pound-force hydraulic cylinders were used to simulate the thrust from the Space Shuttle Main Engines. Heating and thermal simulations were also done.

         Rockwell's original $2.6 billion contract had authorized the building of a pair of static-test articles (MPTA-098 and STS-099 and two initial flight-test vehicles (OV-101 and OV-102. A decision in 1978 not to modify Enterprise from her ALT configuration would have left Columbia as the only operational orbiter vehicle so on 1/29/79 NASA awarded Rockwell a supplemental contract to convert Challenger (STA-099) from a test vehicle into a space-rated Orbiter (OV-099).

         STA-099 was returned to Rockwell on 11/7/79 and it's conversion into a fully rated Orbiter Vehicle was started. This conversion, while easier than it would have been to convert Enterprise, still involved a major disassembly of the vehicle. Challenger had been built with a simulated crew module and the forward fuselage halves had to be separated to gain access to the crew module. Additionally, the wings were modified and reinforced to incorporate the results of structural testing and two heads-up displays (HUD's) were installed in the cockpit. Empty Weight was 155,400 lbs at rollout and 175,111 lbs with main engines installed. This was about 2,889 pounds lighter than Columbia Upgrades and Features

         Two orbiters, Challenger and Discovery, were modified at KSC to enable them to carry the Centaur upper stage in the payload bay. These modifications included extra plumbing to load and vent Centaur's cryogenic (L02/LH2) propellants (other IUS/PAM upper stages use solid propellants), and controls on the aft flight deck for loading and monitoring the Centaur stage. No Centaur flight was ever flown and after the loss of Challenger it was decided that the risk was too great to launch a shuttle with a fueled Centaur upper stage in the payload bay.