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A spacecraft is a vehicle, or machine designed to fly in outer space. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, space colonization, planetary exploration, and transportation of humans and cargo. On a sub-orbital spaceflight, a spacecraft enters space and then returns to the surface, without having gone into an orbit. For orbital spaceflights, spacecraft enter closed orbits around the Earth or around other celestial bodies. Spacecraft used for human spaceflight carry people on board as crew or passengers from start or on orbit (space stations) only, whereas those used for robotic space missions operate either autonomously or telerobotically. Robotic spacecraft used to support scientific research are space probes. Robotic spacecraft that remain in orbit around a planetary body are artificial satellites. Only a handful of interstellar probes, such as ''Pioneer 10'' and ''11'', ''Voyager 1'' and ''2'', and ''New Horizons'', are currently on trajectories that leave the Solar System. Orbital spacecraft may be recoverable or not. By method of reentry to Earth they may be divided in non-winged space capsules and winged spaceplanes. Currently, humanity has achieved space flight but only a few nations have the technology for orbital launches, including, but not limited to: Russia (Roskosmos), the United States (NASA), the member states of the European Space Agency (ESA), Japan (JAXA) and China (CNSA). ==History== Sputnik was the first artificial satellite. It was launched into an elliptical low Earth orbit by the Soviet Union on 4 October 1957. The launch ushered in new political, military, technological, and scientific developments; while the Sputnik launch was a single event, it marked the start of the Space Age.〔(Walter A. McDougall ) "Shooting the duck," ''American Heritage'', Winter 2010.〕〔". . .On October 4, 1957 Sputnik I shot into orbit and forcibly opened the Space Age." Swenson, L, Jr, Grimwood, J. M. Alexander, C.C. ¶¶¶ 66-62424〕 Apart from its value as a technological first, ''Sputnik'' also helped to identify the upper atmospheric layer's density, through measuring the satellite's orbital changes. It also provided data on radio-signal distribution in the ionosphere. Pressurized nitrogen in the satellite's false body provided the first opportunity for meteoroid detection. If a meteoroid penetrated the satellite's outer hull, it would be detected by the temperature data sent back to Earth. ''Sputnik 1'' was launched during the International Geophysical Year from Site No.1/5, at the 5th Tyuratam range, in Kazakh SSR (now at the Baikonur Cosmodrome). The satellite travelled at 29,000 kilometers (18,000 mi) per hour, taking 96.2 minutes to complete an orbit, and emitted radio signals at 20.005 and 40.002 MHz While Sputnik 1 was the first spacecraft to orbit the Earth, other man-made objects had previously reached an altitude of 100 km, which is the height required by the international organization Fédération Aéronautique Internationale to count as a spaceflight. This altitude is called the Kármán line. In particular, in the 1940s there were several test launches of the V-2 rocket, some of which reached altitudes well over 100 km. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Spacecraft」の詳細全文を読む スポンサード リンク
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