NASA'S ORBITER FLEET COLUMBIA Columbia (OV 102), the first of NASA's orbiter fleet, was delivered to Kennedy Space Center in March l979. Columbia initiated the Space Shuttle flight program when it lifted off from Launch Complex 39's Pad A on April 12, 981. It proved the operational concept of a winged, eusable spaceship by successfully completing the Orbital light Test Program -- missions STS-1 through 4. Other achievements for Columbia include the first launch of satellites from a Space Shuttle (STS-5) and the first flight of the European-built scientific workshop -- Spacelab -- on mission STS-9. Columbia is named after a small sailing vessel that operated out of Boston in l792 and explored the mouth of the Columbia River. One of the first U.S. Navy ships to circum- navigate the globe was named Columbia. The command module for the Apollo 11 lunar mission was also named Columbia. DISCOVERY Discovery (OV 103), the third of NASA's fleet of reusable, winged spaceships, arrived at Kennedy Space Center in November 1983. (Challenger was the second orbiter to ar- rive at KSC. See "Challenger" for its history.) It was launched on its first mission, flight 41-D, on August 30, 1984, from Pad A. It carried aloft three communications satellites for deployment by its astronaut crew. Other Dis- covery milestones include the first dedicated Department of Defense mission, the first flight to retrieve and return disabled satellites to Earth for repair and the first Space Shuttle mission of the post-Challenger era. Discovery is named for two famous sailing ships; one sailed by Henry Hudson in 1610-11 to search for a northwest passage between the Atlantic and Pacific Oceans, and the other by James Cook on a voyage during which he discovered the Hawaiian Islands. ATLANTIS Atlantis (OV 104) was delivered to Kennedy Space Center in April 1985, as the fourth spaceship of NASA's orbiter fleet. Atlantis lifted off from Pad A on its maiden voyage on Oct. 3, 1985, on mission 51-J, the second dedicated Depart- ment of Defense flight. On its second mission, 61-B, Nov. 26, 1985, its astronaut crew conducted the first experiments for assembling erectable structures in space. Atlantis is named after a two-masted sailing ship that was operated for the Woods Hole Oceanographic Institute from 1930 to 1966. ENDEAVOUR Endeavour was the first ship commanded by James Cook, the 18th century British explorer, navigator and astronomer. In August 1768, on Endeavour's maiden voyage, Cook sailed to the South Pacific, around Tahiti, on a mission to observe and record the important and seldom occurring event when the planet Venus passes between Earth and the sun. Determining the transit of Venus allowed early astronomers to determine the distance of the sun from Earth. This distance then could be used as a unit of measurement essential in calculating the parameters of the universe. On June 3, 1769, Cook completed this mission and continued his voyage to explore the southern hemisphere. He discovered and charted New Zealand and surveyed the eastern coast of Australia and navigated the Great Barrier Reef. In addition, Cook's voyage on the Endeavour set a precedent of establishing the usefulness of sending scientists on voyages of exploration. Joseph Banks and Carl Solander, who sailed with Cook, became the first naturalists to examine plants and animals in an organized manner. The wealth of scientifically collected material was unique. They collected specimens from more than 100 new plant families with 800 to 1,000 new species. They also encountered hundreds of new species of animals. Cook also had astronomers and artists onboard. Endeavour and her crew made the first long-distance voyage on which no crewmen died from scurvy, the dietary disease caused by the lack of ascorbic acids. Cook is credited with being the first to use diet as a cure for scurvy, making his crew follow a strict diet that included cress, sauerkraut and an orange extract. He also ensured cleanliness and ventilation in the crew's quarters. The Endeavour was small, 368 tons, about 100-feet long and 20-feet wide. She had a round bluff bow and a flat bottom that provided uncommon spaciousness and helped prevent her from being torn apart by coral. However, in 1795, Endeavour ended her career on a reef along Rhode Island. Endeavour (OV 105) was delivered to Kennedy Space Center in May, 1991, as the fifth spaceship of NASA's orbiter fleet. Endeavour lifted off from Kennedy Space Center for the first time on May 7, 1992, on mission STS-49. MISSION The delta-winged orbiter resembles an airplane and is about the size of a DC-9 jetliner. It is launched into space like a conventional rocket while bolted to an external propellant tank and two solid rocket boosters. After liftoff, the boosters burn for a little over two minutes before being jettisoned and carried by parachutes to a watery landing. After splashdown, they are retrieved and returned to Kennedy Space Center for refurbishment. The orbiter's main engines continue to burn until about 8 1/2 minutes into the flight. After shutdown, the exter- nal tank is jettisoned, breaks up in the atmosphere, and falls into the Indian Ocean. It is the only piece of Shuttle flight hardware that is not reused. The orbiter then carries out its mission in space and returns to Earth like a glider. LAUNCH PROCESSING After completing a space mission, the orbiter is returned to Kennedy Space Center to undergo preparations for its next flight in a sophisticated aircraft-like hanger called the Orbiter Processing Facility (OPF). Here, the vehicle is safed, residual propellants are drained and any returning payloads are removed. Any problems that may have occurred with orbiter sys- tems and equipment on the previous mission are checked out and corrected. Equipment is repaired or replaced and extensively tested. Any modifications to the orbiter that are required for the next mission are also made in the OPF. Orbiter refurbishment operations and processing for the next mission also begin in the OPF. Large horizontal payloads, such as Spacelab, are installed in the orbiter cargo bay. Vertical payloads are installed at the launch pad. Following extensive testing and verification of all electrical and mechanical interfaces, the orbiter is trans- ferred to the nearby Vehicle Assembly Building where it is mated to the external tank and solid rocket boosters. Then, the assembled Space Shuttle vehicle is carried to the launch pad by a large tracked vehicle called the crawler- transporter. At the launch pad, final preflight and interface checks of the orbiter, its cargo and associated ground support equipment are conducted. After a positive Flight Readiness Review, the decision to launch is given and the final countdown begins. ORBITER MODIFICATIONS More than 200 significant modifications are being made to the orbiter fleet. These modifications involve orbiter main engines, brakes and landing gear, thermal protection system and propellant supply systems, as well as a new crew escape system. Main engine modifications include changes to the high- pressure turbomachinery, hydraulic actuators, and main combustion chamber. The orbiter braking system will be upgraded to increase braking capacity, improve steering, and reduce the effects of tire damage and failure. Additions to the system also in- clude tire pressure monitoring. Some of the tiles that make up the orbiter thermal protection system have been replaced with thermal blankets to make the system lighter, stronger and more durable. Also, a reinforced carbon-carbon panel will be added to the or- biter chin between the nose cap and the nose wheel door to provide improved insulation against the searing heat of reentry. Improvements to the orbiter propellant supply system in- clude a redesigned 17-inch quick disconnect valve between the orbiter and the external tank. Additional modifications will be made to the propellant systems of the orbiter reac- tion control system, orbital maneuvering system, and the auxiliary power units. A new crew escape system has been added that allows the Space Shuttle crew to bail out if the orbiter has to make an emergency return descent and a safe runway cannot be reached. This system consists of an escape pole that would be extended from the opened crew hatch. The crew would then fasten a lanyard hook assembly that is a part of the pole to their parachute harnesses. Once attached to this hook, the crew would slide down the deployed pole, away from the orbiter. Once free of the pole, they would parachute to safety. SPACE SHUTTLE Height: 184.2 feet Gross liftoff weight: 4,500,000 pounds Total liftoff thrust: 7,700,000 pounds ORBITER Length: 122.17 feet Wingspan: 78.06 feet Dry Weight: Columbia (OV 102) 178,000 pounds Discovery (OV-103) 171,000 pounds Atlantis (OV-104) 171,000 pounds Main Engines: (3) 375,000 pounds of thrust each (sea level) Cargo Bay: length - 60 feet diameter - 15 feet SOLID ROCKET BOOSTERS (2) Length: 149.16 feet Diameter: 12.17 feet Liftoff Weight: (each) 1,300,000 pounds Recovery weight: (each) 192,000 pounds Thrust: (each) 3,300,000 pounds (sea level) EXTERNAL TANK Length: 153.8 feet Diameter: 27.6 feet Weight: Liftoff: 1,655,600 pounds (535,000 gallons) Empty : 66,000 pounds Propellants Liquid Oxygen: Capacity: 143,351 gallons Volume: 19,600 cubic feet Liquid Hydrogen: Capacity: 385,265 gallons Volume: 53,500 cubic feet