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The Progress ((ロシア語:Прогресс)) is a Russian expendable cargo spacecraft. Its purpose is to deliver supplies needed to sustain human presence in orbit. While it does not carry a crew it can be boarded by astronauts when docked with a space station, hence it being classified as ''manned'' by its manufacturer.〔(【引用サイトリンク】title=Progress )〕〔(【引用サイトリンク】title=Return to selections: 1 )〕〔(【引用サイトリンク】title=Russian Designations )〕 Progress is derived from the manned Soyuz spacecraft and launches on the same vehicle, a Soyuz rocket. Progress has supported space stations as early as Salyut 6 and as recently as the International Space Station. Each year there are between three and four Progress flights to the ISS. A Progress remains docked until shortly before being replaced with a new one or a Soyuz (which will use the same docking port). Then it is filled with waste, disconnected, and de-orbited, at which point it burns up in the atmosphere. Due to the variation in Progress vehicles flown to the ISS, NASA uses its own nomenclature where "ISS 1P" means the first Progress spacecraft to ISS. Progress was developed because of the need for a constant source of supplies to make long duration space missions possible. It was determined that cosmonauts needed an inflow of consumables (food, water, air, etc.), plus there was a need for maintenance items and scientific payloads that necessitated a dedicated cargo carrier. Such payloads were impractical to launch with passengers in the restricted space of a Soyuz. As of April 28, 2015 there have been 140 flights with three failures. == Design == Progress is of much the same size and shape as Soyuz. It consists of three modules: * A pressurized forward module. This carries the supplies for the crew such as scientific equipment, clothes, prepackaged and fresh food, and letters from home. The docking drogue is similar to that of the Soyuz but features ducting for the UDMH fuel and N2O4 oxidiser. * A fuel compartment. The reentry module of the Soyuz was replaced with an unpressurized propellant and refueling compartment with ducting along the outside of the spacecraft. This meant that if a leak occurred, the poisonous gas would not enter the station's atmosphere. The fuel is carried in two tanks. * A propulsion module. The propulsion module, at the rear of the spacecraft, remained unchanged and contains the orientation engines used for the automatic docking. It may be used to boost the orbit of the station once docked. Reduction in mass was possible because the Progress was designed to be unmanned and disposable. This means that there is no need for bulky life support systems and heat shields. A small amount of weight is saved due to the lack of automatic rescue crews system and lack of parachutes. The spacecraft also has no ability to split into separate modules. After undocking, the spacecraft performs a retrofiring and burns up in the atmosphere. 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「progress spacecraft」の詳細全文を読む スポンサード リンク
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