SPACE SHUTTLE

SPACE SHUTTLE. The space shuttle is a reusable orbital vehicle that transports aerospace travelers. Officially titled the Space Transportation System(STS), the space shuttle expands space exploration possibilities and contributes to better comprehension of Earth. The orbiting shuttle enables astronauts to conduct experiments in a weightless environment, deploy or repair satellites, and photographically survey the planet. The shuttle aids building, equipping, and transporting of personnel to and from the International Space Station (ISS). Only selected passengers, based on scientific, engineering, professional, or piloting qualifications, can ride in the shuttle. Americans benefit from the shuttle because of zero-gravity pharmaceutical developments and satellite maintenance.

Throughout the twentieth century, engineers envisioned creating a reusable spacecraft. Military and industrial representatives suggested spacecraft resembling gliders such as the late-1950s Dyna Soar design. By the 1970s, the National Aeronautics and Space Administration (NASA) focused on developing the STS. Engineers and scientists at NASA centers, universities, industries, and research institutions cooperated to build this unique spacecraft, contributing expertise in specific fields to design components and propulsion, guidance, control, and communication systems. Shuttle orbiters were constructed and tested in California with additional testing at the Marshall Space Flight Center in Huntsville, Alabama.

The winged space shuttle structurally resembles airplanes. Interior areas are designed for crews to live and work safely and comfortably while in space. Externally, the space shuttle is coated with ceramic tiles to protect it from burning up during reentry in Earth's atmosphere. Special bays and robotic arms are created for extravehicular activity (EVA) and satellite interaction.

In 1977, a trial space shuttle orbiter named Enterprise was carried on a 747 jet to high altitudes and then released to determine that the shuttle could maneuver through the atmosphere before landing. On 12 April 1981, the shuttle Columbia, with Robert L. Crippen and John W. Young aboard, was launched from Kennedy Space Center, Florida. After completing thirty-six orbits in two days, the Columbia landed at Edwards Air Force Base, California. NASA built four additional shuttles: Challenger, Discovery, Atlantis, and Endeavour.

The shuttle enabled the accomplishment of significant aerospace milestones. On the June 1983 STS-7 flight,

Sally K. Ride became the first American woman astronaut. The next year, Bruce Mc Candless II and Robert Stewart utilized Manned Maneuvering Units to become the first astronauts to walk in space without being tethered to a spacecraft.

The 28 January 1986 Challenger explosion paralyzed the space shuttle program. When O-ring seals on a solid rocket booster failed, the shuttle disintegrated, and the entire crew was killed. A presidential commission determined that NASA was accountable due to ineffective engineering control and communication. After redesigning the O-ring seals, NASA launched the shuttle Discovery on 29 September 1988. Shuttle flights became routine again.

Post-Challenger achievements included deployment of the Hubble Space Telescope in 1990. Beginning in 1995, the space shuttle occasionally docked with the Russian space station Mir. In late 1998, the shuttle Endeavour transported Unity, the ISS core, into orbit. The February 2000 Shuttle Radar Topography Mission (SRTM) aboard the space shuttle Endeavour collected information about 80 percent of Earth's surface.

The original space shuttles are scheduled for retirement in 2012. In May 2002, NASA announced that future shuttles would physically resemble their predecessors but would be smaller, safer, more affordable, and not require pilots.

BIBLIOGRAPHY

Harland, David M. The Space Shuttle: Roles, Missions, and Accomplishments. New York: Wiley, 1998.

Jenkins, Dennis R. Space Shuttle: The History of the National Space Transportation System: The First 100 Missions. 3d ed. Cape Canaveral, Fla.: D.R. Jenkins, 2001. The most thorough compendium of the space shuttle.

NASA. Home page at http://www.nasa.gov

Rumerman, Judy A., and Stephen J. Garber, comps. Chronology of Space Shuttle Flights, 1981–2000. Washington, D.C.: NASA History Division, Office of Policy and Plans, NASA Headquarters, 2000.

Elizabeth D.Schafer

space shuttle Re-usable rocket-powered US spacecraft. The main part of the shuttle, the orbiter (of which four have been built, Columbia, Challenger, Discovery, and Atlantis), looks like a bulky jet aircraft with swept-back wings. It ferries people and equipment between the ground and Earth orbit. It takes off attached to a large fuel tank, using its own three rocket engines, assisted by two booster rockets. The boosters are jettisoned about two minutes after launch and are later recovered for re-use. Six minutes later, the orbiter's main engines cut off and the external fuel tank is dumped. Manoeuvring engines then put the craft into the required orbit. When returning to Earth, these engines provide reverse thrust to slow the craft down for descent into the atmosphere. It glides down and lands on a runway. The first space shuttle, Columbia, was launched into orbit on April 12, 1981. The orbiter has a large payload bay in which it carries satellites for release into orbit. On mission 25 in January 1986, the shuttle Challenger exploded soon after launch, killing all seven people on board. A leak enabled burning gases from a booster rocket to ignite the fuel in the main tank.

space shut·tle • n. a rocket-launched spacecraft, able to land like an unpowered aircraft, used to make repeated journeys between the earth and earth orbit.