Spacelab - astronomy.

Spacelab - astronomy. I INTRODUCTION Spacelab, science laboratory designed to fly into orbit inside the cargo bay of a space shuttle. The European Space Agency (ESA) designed and built Spacelab to fly aboard the United States National Aeronautics and Space Administration (NASA) space shuttle. In the early 1970s the ESA was deciding on its strategy for space at the same time that NASA was beginning its space shuttle program. The ESA proposed a joint scientific program and in 1973 NASA accepted the ESA's offer to build Spacelab. The first Spacelab flew in 1983. Spacelab permitted the type of research that would occur aboard a space station while NASA was still working on plans to build a permanent space station in orbit. Using Spacelab, space shuttle astronauts studied the effects of weightlessness on materials and living things and observed stars, the Sun, and Earth's atmosphere. Spacelab missions lasting up to 17 days helped prepare NASA for planned research aboard the International Space Station, scheduled for completion in 2006. The last Spacelab mission occurred in 1998. II EQUIPMENT Spacelab was modular, meaning it consisted of standardized parts that could be bolted into the space shuttle's payload bay in different combinations. The core module was a cylindrical, sealed, pressurized room in which astronauts in ordinary clothing could perform experiments. The core module was 2.7 m (9 ft) long, with an outside diameter of 4.1 m (13.5) ft. The experiment module was the same size as and similar to the core module; it could be attached to the core module to double the available workspace for the astronauts. Both the experiment module and core module were outfitted with racks that held the scientific instruments and equipment that the astronauts needed. Equipment could also be bolted to the center aisle or floor of the core module. Hand rails and foot restraints helped astronauts move about and work in space. The modules could include airlocks to allow the astronauts to expose materials to space and viewports for observing Earth or astronomical objects from the module. A Spacelab configuration could also include several pallets, U-shaped platforms open to the cargo bay and exposed to space if the cargo bay doors were open. Up to five of the pallets, which were 4.1 m (13.5 ft) wide and 3 m (10 ft) long, could be bolted to the cargo bay floor during one mission. Some Spacelab missions used only pallets and left the core and experiment modules on Earth. Each pallet could support up to five tons of scientific equipment, such as telescopes and sensors. The core and experiment modules held the electronic controls for the pallet instruments on missions that included one or both of the pressurized modules, but on pallet-only missions a small module called the Igloo held the instrument controls in a pressurized and temperature-controlled environment. Some of the instruments needed more precise positioning than the space shuttle itself could provide, so the ESA developed the Instrument Pointing System (IPS). The IPS was mounted on a pallet and could point instruments precisely by keeping track of certain stars to determine its position. The Spacelab modules, no matter what their configuration, were attached to the back end of the cargo bay of the space shuttle to properly balance the shuttle's weight. If pressurized modules were part of the mission, they were placed forward of the pallets. Astronauts exited the mid-deck of the space shuttle through an airlock and used a tunnel to get to the pressurized Spacelab modules. Even though the tunnel and the Spacelab modules were pressurized like the space shuttle cabin, astronauts usually kept the airlocks between the cabin and the tunnel and between the tunnel and module closed for safety. The tunnel was only 1 m (3.3 ft) wide, so astronauts navigated through the tunnel horizontally, usually head first. III MISSIONS Twenty-five Spacelab missions flew aboard the space shuttle between 1983 and 1997. All five of the space shuttle orbiters (Columbia, Challenger, Discovery, Atlantis, and Endeavour) carried Spacelab modules. Columbia carried the most, 15 in all, including the first and last Spacelab missions. Columbia carried Spacelab 1 in 1983 aboard the ninth space shuttle flight. On Spacelab 1, astronauts performed more than 70 experiments in seven areas of science. Subsequent Spacelab missions included research in materials science, life science, astronomy, and microgravity science. In 1985 Spacelab 2 astronauts aboard Challenger used telescopes on three Spacelab pallets to study stars and the Sun. Similar astronomy studies occurred during the two Spacelab ASTRO missions, in 1990 and 1995. Spacelab D-1 (1985) and D-2 (1993) carried primarily German experiments, while Spacelab-J (1992) carried mostly Japanese experiments. Three Atmospheric Laboratory for Applications and Science (ATLAS) Spacelab missions studied Earth's atmosphere in 1992, 1993, and 1995. In 1995 the first space shuttle mission to dock with Russia's Mir space station used a Spacelab module as a laboratory and a cargo carrier for delivering supplies to Mir. In 1998 doctors aboard a Spacelab mission called Neurolab studied the effects of space on behavior and the nervous system of humans and animals. NASA phased out Spacelab missions as the International Space Station laboratories became available. IV SCIENTIFIC RESULTS During its 15-year career, Spacelab carried into space more than 400 experiments designed by about 500 scientists from 17 countries. Research involving humans, animals, and plants helped scientists learn more about the effects of space travel on living things. This research also brought new understanding of diseases such as cancer and osteoporosis, the gradual weakening of bones. Astronauts studied the behavior of fluids and flame in weightlessness to help engineers design future spacecraft, and also to help researchers better understand these phenomena on Earth. Astronomical missions charted ultraviolet, X-ray, and infrared radiation from the stars. Solar instruments mounted on Spacelab pallets collected some of the best photographs of the Sun ever taken, while atmospheric sensors gathered important data on ozone depletion and global warming on Earth. Contributed By: David S. F. Portree Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. 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