Saturday, June 12, 2010

Space Exploration

Space Exploration

Three men were the first scientists to conceive pragmatically of spaceflight: the Russian Konstantin Tsiolkovsky, the American Robert Goddard, and the German Hermann Oberth. By the end of World War II, the German development of rocket propulsion for aircraft and guided missiles (notably the V-2) had reached a high level. After the war the US and its allies fell heir to the technical knowledge of rocket power developed by the Germans. The technical director of the German missile effort, Wernher von Braun, and some 150 of his top aides surrendered to US troops. Most immigrated to the US, where they assembled and launched V-2 missiles that had been captured and shipped there. The USSR carried out an unpublicized but extensive and likely similar program; Britain and France conducted smaller programs.

In both the US and the USSR the development of military missile technology was essential to the achievement of satellite flight. Preparations for the International Geophysical Year (IGY, 1957–58) stimulated discussion of the possibility of launching artificial Earth satellites for scientific investigations. Both the US and the USSR became determined to prepare scientific satellites for launching during the IGY. While the US was still developing a space launch vehicle, the USSR startled the world by placing Sputnik 1 in orbit on 4 Oct 1957. This was followed a month later by Sputnik 2, which carried a live dog. The failure by the US to launch its small payload on 6 Dec 1957 heightened that country’s political discomfiture in view of its supposed advanced status in science. Following debates on the necessity of achieving parity, the US government established the National Aeronautics and Space Administration (NASA) in 1958. Since that time, NASA has conducted virtually all major aspects of the US space program.

The first successful US satellite, Explorer 1, was launched about four months after Sputnik 1. During the next decades the two countries participated in a space race, conducting thousands of successful launches of spacecraft of all varieties including scientific- research, communications, meteorological, remote- sensing, military-reconnaissance, early-warning,and navigation satellites, lunar and planetary probes, and manned craft. The USSR launched the first human, (1) Yury Gagarin, into orbit around Earth on 12 Apr 1961. On 20 July 1969, the US landed two men, (2) Neil Armstrong and (3) Edwin (“Buzz”) Aldrin, on the surface of the Moon as part of the Apollo 11 mission. On 12 Apr 1981, the 20th anniversary of manned space flight, the US launched the first reusable manned space transportation system, the space shuttle. Since
the 1960s various European countries, Japan, India, China, and other countries have formed their own agencies for space exploration and development. The European Space Agency (ESA) consists of 18 member states. Private corporations, too, offer space launches for communications and remote-sensing satellites.

In the post-Apollo decades, while the US focused much of its manned space program on the shuttle, the USSR concentrated on launching a series of increasingly sophisticated Earth-orbiting space stations, beginning with the world’s first in 1971. Station crews, who were carried up in two- and three-person spacecraft, carried out mostly scientific missions while gaining experience in living and working for long periods in the space environment. After the USSR was dissolved in 1991, its space program was continued by Russia on a much smaller scale owing to economic constraints. The US launched a space station in 1973 using surplus Apollo hardware and conducted shuttle missions to a Russian station, Mir, in the 1990s. In 1998, at the head of a 16-country consortium and with Russia as a major partner, the US began in-orbit assembly of the International Space Station (ISS), using the shuttle and Russian expendable launch vehicles to ferry the facility’s modular components and crews into space. In addition to manned and unmanned lunar exploration, space exploration programs have included deep-space robotic missions to the planets, their moons, and smaller bodies such as comets and asteroids. Also important has been the development of unmanned spacebased astronomical observatories, which allow observation of near and distant cosmic objects above the filtering and distorting effects of Earth’s atmosphere.


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