Oases in Space Earlier space stations The International Space Station (ISS) is the most complicated international scientific project ever undertaken. First proposed in 1984, it involved the effort of sixteen nations: the United States, Canada, Japan, Russia, eleven nations of the European Space Agency, and Brazil. The first component of the ISS, Zahra ('sunshine' in Russian), was launched into orbit in 1998. A few weeks later, the crew of a U.S. space shuttle brought the second piece, Unity, and connected the two. The launch of the third major component, the Russian Avezda ('star'), was postponed by financial problems until July 2000, and the station's first crew arrived in November. Eventually, the ISS will contain more than 100 parts and will require forty-four spaceflights to deliver them. A total of 160 spacewalks will be needed to assemble the components. The ISS was originally scheduled to be completed in 2006, although unexpected events such as the Columbia space shuttle tragedy of 2003 may delay the date. When work is finished, the station will house a full-time crew of seven astronauts and scientists and contain six scientific laboratories. With an anticipated lifetime of 10 years after completion, the ISS is not only the most complicated scientific project ever undertaken but also, at a projected cost of $ 35 billion, one of the most expensive. The ISS is not the first space station~ That distinction belongs to the Soviet Union's Salyut 1. Salyut 1 was sent into orbit in 1971 but suffered setbacks. The first crew to arrive was unable to get in: There was something wrong with the hatch(舱口)! The second crew, equipped with special tools, got in and spent 24 days there. However, on the way back to Earth, a tragedy occurred. A valve(气阀)had opened by mistake and let all the air out of the capsule, and the three cosmonauts, who were not wearing space suits, died during the descent. In all, there were six successful Salyut stations. The first -- and only American space station, Skylab, was launched in 1973. To save money, the Americans used the third stage of a Saturn V booster rocket left over from the Apollo moon missions, and so Skylab was much roomier than the Soviet stations. Three crews spent time on Skylab, but the station had to be abandoned in 1975 because there was simply no way to get to it. The United States had used up its Apollo rockets and the first space shuttle wouldn't be launched until 1981. Eventually, Skylab's orbit decayed, and the station fell to Earth in 1979. At the time, some people feared that the debris(碎片)might land in an inhabited area, and a few people even built 'Skylab shelters.' However, there was no reason to panic Skylab burned up harmlessly over Australia. In 1986, the Soviet Union launched another station, Mir ('peace'). Although damaged by an on-board fire and a collision with a supply rocket, Mir stayed in orbit for 15 years, and both U.S. and Russian crewmen, who would later serve on the ISS, trained on Mir. New designs for space stations The ISS and earlier space stations are a far cry from the space stations described by science fiction writers and dreamers, and even by scientists earlier in the century. After World War Ⅱ, many German rocket scientists who had worked on weapons programs immigrated to the United States and the Soviet Union. Werner yon Braun, the most famous of these scientists, played a vital role in the early days of the U.S. space program. It was Von Braun who decided that a large space station was essential to the exploration of space, a first step that would provide a stopping place on the way to the moon and the planets. In the March 1952 edition of Collier's Magazine, Von Braun contributed an article about the proposed station and introduced the idea of a wheel-shaped design. Illustrated by the artist Charles Bonestell, this issue popularized the 'spinning wheel' or 'donut in the sky' d