332 lines
15 KiB
Plaintext
332 lines
15 KiB
Plaintext
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L A U N C H V E H I C L E S
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(Overview)
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Overcoming the pull of Earth's gravity is the first challenge of
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any space mission. Whether small and suborbital or large and
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traveling to another planet, every spacecraft must be carried into
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space before it can do its job. NASA has a family of launch
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vehicles--a graduated series of multistage rockets--to accomplish
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its space programs.
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A family of launch vehicles was developed because a number of
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different vehicles were required for missions that ranged from simple
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to complex. The vehicles are combinations of two or more stages,
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which burn one after the other, each being discarded when it is no
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longer needed, so only a small part of the whole vehicle is
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necessary to propel the spacecraft into the final orbit or space
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trajectory.
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When NASA was formed, its launch capability depended upon what
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was available and most of the vehicles were derived from the military
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missile program. In time, additional vehicles were developed, using
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both solid and liquid propellant rockets, specifically to acquire a
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variety of launch vehicle combinations suited to the expanded space
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exploration program.
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NASA owns launch sites at the Eastern and Western Space and
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Missile Centers (ESMC and WSMC) in Florida and California and the
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Wallops Flight Facility in Virginia, and has access to the San Marco
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launch complex off the east coast of Africa owned by Italy.
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R E D S T O N E
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STATUS: Inactive
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Adapted by NASA from an Army ballistic missile, the Redstone was used
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to launch Project Mercury suborbital flights from 1960-61. Redstone
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flew successfully five times after an initial failure. Two unmanned
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flights and one with the chimpanzee Ham preceded the first U.S.
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manned spaceflight by Alan B. Shephard, Jr. in May 1961, and Virgil
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I. Grissom's flight in July 1961.
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Redstone measured 25 meters (83 ft) in height with capsule and escape
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tower. It was a single stage launch vehicle using liquid propellant
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(alcohol and liquid oxygen) and developed 35,380 kg (78,000 lbs) of
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thrust.
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M E R C U R Y - A T L A S
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STATUS: Inactive
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Mercury-Atlas was a modified Air Force missile. It stood 29 meters
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(95.3 feet) high with capsule and escape tower. The vehicle was a
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stage-and-a-half rocket that produced 139,797 kg (308,000 lbs) of
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thrust, burning RP-1 (kerosene) and liquid oxygen.
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Mercury-Atlas was first used for John Glenn's orbital flight in 1962.
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It launched all succeeding Project Mercury orbital flights.
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G E M I N I - T I T A N
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STATUS: Inactive
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Titan, an Air Force ICBM, was modified by NASA as Titan II for
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Project Gemini (1965-66). Titan was a two-stage rocket, standing
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109 ft in height, burning Aerozine-50 and nitrogen tetroxide and
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produced 430,000 lbs of thrust in the first stage, 100,000 lbs of
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thrust in the second.
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A T L A S / A G E N A
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STATUS: Inactive
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The Atlas/Agena was a multipurpose two-stage liquid propellant
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rocket. It was used to place unmanned spacecraft in Earth orbit, or
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inject them into the proper trajectories for planetary or deep space
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probes.
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The programs in which the versatile Atlas/Agena was utilized included
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early Mariner probes to Mars and Venus, Ranger photographic missions
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to the Moon, the Orbiting Astronomical Observatory (OAO), and early
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Applications Technology Satellites (ATS). The Agena upper stage was
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used as the rendezvous target vehicle for the Gemini spacecraft
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during this series of two-man missions in 1965-1966. In preparation
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for the manned lunar landings, Atlas/Agena launched lunar orbiter
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spacecraft which went into orbit around the Moon and took photographs
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of possible landing sites.
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The Atlas/Agena stood 36.6 meters (120 ft) high, and developed a
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total thrust at liftoff of approximately 1,725,824 newtons (288,000
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lbs). It was the last used in 1968 to launch an Orbiting Geophysical
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Observatory (OGO).
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S A T U R N I B
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STATUS: Inactive
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The Saturn IB was originally used to launch Apollo lunar spacecraft
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into Earth orbit, to train for manned flights to the Moon. The first
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launch of a Saturn IB with an unmanned Apollo spacecraft took place
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in February 1966. A Saturn IB launched the first manned Apollo
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flight, Apollo 7, on October 11, 1968.
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After the completion of the Apollo program, the Saturn IB launched
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three missions to man the Skylab space station in 1973. In 1975 it
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launched the American crew for the joint U.S./U.S.S.R docking
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mission.
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Saturn IB was 69 meters (223 ft) tall with the Apollo Spacecraft and
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developed 7.1 million newtons (1.6 million lbs) of thrust at liftoff.
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S A T U R N V
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STATUS: Inactive
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The Saturn V, America's most powerful staged rocket, carried out the
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ambitious task of sending astronauts to the Moon. The first Saturn V
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vehicle, Apollo 4, was launched on November 9, 1967. Apollo 8, the
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first manned flight of the Saturn V, was also the first manned flight
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to the Moon; launched in December 1968, it orbited the Moon but did
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not land. Apollo 11, launched on a Saturn V on July 16, 1969,
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achieved the first lunar landing.
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Saturn V began its last manned mission on December 7, 1972, when it
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sent Apollo 17 on the final lunar exploration flight. It was last
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used on May 14, 1973, when it lifted the unmanned Skylab space
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station into Earth orbit, where it was occupied by three crews for
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171 days.
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All three stages of the Saturn V used liquid oxygen as the oxidizer.
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The first stage burned kerosene with the oxygen, while the fuel for
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the two upper stages was liquid hydrogen. Saturn V, with the Apollo
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spacecraft and its small emergency escape rocket on top, stood 111
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meters (363 ft) tall, and developed 34.5 million newtons (7.75
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million lbs) of thrust at liftoff.
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T I T A N I I I - E / C E N T A U R
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STATUS: Inactive
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The Titan III-E/Centaur, first launched in 1974, had an overall
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height of 48.8 meters (160 ft). Designed to use the best features of
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three proven rocket propulsion systems, this vehicle gave the U.S. an
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extremely powerful and versatile rocket for launching large
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spacecraft on planetary missions.
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The Titan III-E/Centaur was the launch vehicle for two Viking
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spacecraft to Mars, and two Voyager spacecraft to Jupiter, Saturn,
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Uranus and Neptune. It also launched two Helios spacecraft toward the
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Sun. All provided remarkable new information about our solar system.
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The Vikings and Voyagers produced spectacular color photographs of
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the planets they explored.
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The Titan III-E booster was a two-stage liquid-fueled rocket with two
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large solid-propellant rockets attached. At liftoff, the solid
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rockets provided 10.7 million newtons (2.4 million lbs) of thrust.
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The Centaur stage, still in use today, produces 133,440 newtons
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(30,000 lbs) of thrust from two main engines, and burns for up to
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seven and one-half minutes. The Centaur can be restarted several
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times which allows for more flexibility in launch times.
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D E L T A
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STATUS: Active
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Delta is called the workhorse of the space program. This vehicle has
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successfully transported over 160 scientific, weather, communications
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and applications satellites into space. These include the TIROS,
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Nimbus and ITOS satellites, and many Explorer scientific spacecraft.
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First launched in May, 1960, the Delta has been continuously upgraded
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over the years. Today it stands 35.4 meters (116 ft) tall. Its first
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stage is augmented by nine Caster IV strap-on solid propellant
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motors, six of which ignite at liftoff and three after the first six
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burn out 58 seconds into the flight. The average first-stage thrust
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with the main engines and six solid-propellant motors burning is
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3,196,333 newtons (718,000 lbs). Delta has liquid-fueled first and
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second stages and a solid-propellant third stage. For most launches
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today, this third stage has been replaced by a Payload Assist Module
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(PAM) stage attached to the satellite.
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The new PAM upper stage is also used on Space Shuttle launches. It
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boosts spacecraft from low Earth orbit achieved by the Shuttle
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orbiter into higher ones. Many spacecraft, especially communications
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satellites, operate in a geosynchronous (geostationary) orbit some
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35,792 kilometers (22,240 miles) above the equator. With the PAM and
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a recent change to a more powerful second stage, the Delta can lift
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some 1,270 kilograms (2,800 lbs) into a highly elliptical orbit, for
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transfer into geosynchronous orbit by a motor built into the
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spacecraft. This is almost double the 680 kilograms (1,500 lbs) a
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Delta could manage ten years ago.
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A T L A S / C E N T A U R
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STATUS: Active
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The Atlas/Centaur is NASA's standard launch vehicle for intermediate
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payloads. It is used for the launch of Earth orbital, geosynchronous,
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and interplanetary missions.
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Centaur was the nation's first high-energy, liquid-hydrogen
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liquid-oxygen launch vehicle stage. It became operational in 1966
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with the launch of Surveyor 1, the first U.S. spacecraft to soft-land
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on the Moon.
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Since 1966, both the Atlas booster and the Centaur second stage have
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undergone many improvements. At present, the combined stages can
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place over 4,530 kilograms (10,000 lbs) in low-Earth orbit, about
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2,020 kilograms (4,453 lbs) in geosynchronous transfer orbit, and
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over 1,000 kilograms (2,205 lbs) on an interplanetary trajectory.
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An Atlas Centaur stands 41.9 meters (137.6 ft) tall. At liftoff, the
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Atlas booster develops over 1.9 million newtons (438,400 lbs) of
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thrust. The Centaur second stage develops 146,784 newtons (33,000
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lbs) of thrust in a vacuum.
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Spacecraft launched by Atlas/Centaurs include Orbiting Astronomical
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Observatories; Applications Technology Satellites; Intelsat IV, IV-A
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and V communications satellites; Mariner Mars orbiters; a Mariner
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spacecraft which made a fly-by of Venus and three of Mercury; Pioneer
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spacecraft which accomplished fly-bys of Jupiter and Saturn, and
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Pioneers that orbited Venus and plunged through its atmosphere to the
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surface.
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S C O U T
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STATUS: Active
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The Scout launch vehicle, which became operational in 1960, has been
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undergoing systematic upgrading since 1976. The standard Scout
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vehicle is a solid-propellant, four stage booster system
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approximately 23 meters (75 ft) in length with a launch weight of
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21,600 kilograms (46,620 lbs) and liftoff thrust of 588,240 newtons
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(132,240 lbs).
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Recent improvements include an uprated third-stage motor which
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increases the Scout's payload capability. It can now place up to 211
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kilograms (465 lbs) in low-Earth orbit. The third stage also has been
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provided with an improved guidance system.
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Over 100 scouts have been launched to date. They have been used to
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place a variety of U.S. and international payloads into inclined,
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equatorial and polar orbits for orbital, probe and reentry missions.
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S P A C E S H U T T L E
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STATUS: Active
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The Space Shuttle consists of a reusable delta-winged spaceplane
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called the orbiter; two solid-propellant rocket boosters, which are
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recovered and also reused; and an expendable external tank containing
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liquid propellants for the orbiter's three main engines.
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The assembled Space Shuttle is approximately 56 meters (184 ft) long,
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23.3 meters (76 ft) high (to tip of orbiter's vertical tail), and 24
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meters (78 ft) wide, measured across the orbiter's wingtips. Liftoff
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weight of the Shuttle vehicle is approximately 2,041,168 kilograms
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(4,500,000 lbs).
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At launch, the orbiter's three liquid-fueled engines--drawing
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propellants from the external tank--and the two solid propellant
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rocket boosters burn simultaneously. Together, they generate about
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28,650,000 newtons (6,400,000 lbs) of thrust at liftoff. As the Space
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Shuttle reaches an altitude of about 50 kilometers (31 mi), the spent
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solids are detached and parachuted into the ocean where they are
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recovered by waiting ships for eventual refurbishment and reuse on
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later missions. The orbiter and external tank, still attached to each
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other, continue toward Earth orbit. When the orbiter's main engines
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cut off, just before orbit is achieved, the external tank is
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jettisoned, to impact in a remote ocean area. Using onboard orbital
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maneuvering engines, the orbiter with its crew and payload
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accelerates into orbit to carry out an operational mission, normally
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lasting from two to seven days.
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When the mission is completed, the orbiter reenters the atmosphere,
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and returns to Earth, gliding to an unpowered landing. Touchdown
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speed is above 335 kilometers (210 mi) per hour.
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E X P E N D A B L E L A U N C H V E H I C L E S
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For the decade of the 1990s and beyond, NASA plans to employ a mixed
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fleet of launch vehicles in which the Space Shuttle will be
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complemented by expendable launch vehicles (ELVs). The latter
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vehicles will not be purchased for NASA operation; NASA will
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contract for launch services with aerospace companies or procure
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such services through the Department of Defense.
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The intent of the plan is to reduce dependence on the Space Shuttle,
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add flexibility to the space program, and free the Shuttle for manned
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scientific, Shuttle-unique and important national security missions.
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A major objective is to accelerate deployment of space science
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missions backlogged by the Shuttle's temporary removal from service.
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The number of ELV launches required annually cannot be fixed
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precisely since it is dependent upon future program approvals.
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Generally, NASA foresees possible annual need for three to five
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medium ELVs, one or two each in the intermediate and large classes,
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and an undetermined number in the small vehicle category. The
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vehciles available or being developed in these categories are the
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medium ELV Delta II, built by McDonnell Douglas Corporation; the
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intermediate Atlas Centaur (General Dynamics Corporation) and Titan
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III (Martin Marietta Corporation); and the large Titan IV (also
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Martin Marietta). LTV Aerospace Corporation manufactures the standard
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small launch vehicle, the Scout.
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---
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NASA Information Summaries, Countdown! NASA Launch Vehicles and
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Facilities, PMS 018 (KSC), Nov 1986
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NASA, The First 25 Years 1958-1983, A Resource For Teachers, EP-182
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NASA FACT SHEET, Space Launch Vehicles , KSC 49-80
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SPINOFF 1987, Washington Headquarters, 1987-190-760
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