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A hosted payload is a module attached to a commercial satellite with communications circuitry that operates independently of the main spacecraft but which shares the satellite’s power supply and transponders. The concept has been also been referred to as “piggybacking” or “hitchhiking.” ==Description== Hosted payloads are used most often by government agencies seeking to have communications capability in orbit without having to pay the cost of building and launching an entire government-owned satellite. Using a hosted payload on a commercial satellite can reduce both the expense and time required to get communications capacity into space. However, because some government agencies desire to own and control entire satellite platforms, hosted payloads have not been widely accepted by government space planners, despite the fact that a large proportion of government satellite communications is over commercially owned and operated satellites. For example, according to Space Commerce, over 80% of all U.S. government and military satellite communications goes through commercial services. Hosted payloads give government agencies the ability to own and control a portion of a satellite’s capacity. In 2007, the US Department of Defense projected that satellite demand for the next 10–13 years would increase much more rapidly than the government could build and launch its own satellite systems, making hosted payloads on commercial satellites an attractive alternative. Hosted payloads are perfect for a variety of missions. These include Space Situational Awareness (SSA) such as collision avoidance, debris monitoring, nuclear detection and still imagery; and data collection for hyper-spectral sounding, ocean color analysis, ozone mapping, earth staring, and weather tracking; as well as communications; and research and development. A hosted payload’s schedule usually takes from start date to launch around 30 months. This launch time is actually an advantage compared to the longer launch date of typical government satellite programs. Hosted Payload’s also allow the government a way to reduce and risks when it comes to program funding, launch delays and operational concerns. As of March 2010, eighteen commercial satellites that had the capability to carry U.S. government piggyback payloads have been placed into production, but only one is expected to host a payload because the government has yet to have a policy on the matter.〔http://www.spacenews.com/civil/100326-govt-missing-hosted-payload-opportunities.html〕 The role of hosted payloads in the government has been increasing over the years. In 2007, Department of Defense’s projected satellite demand for the next 10–13 years shows a rise in satellite demand but a gap in actual capability. Hosted Payloads is a potential answer to meet the demand of satellites through their ability to provide rapid and dependable access into space.〔http://www.intelsatgeneral.com/service-offerings/hosted-payloads〕 In December 2010, mobile satellite provider, Inmarsat, announced plans to construct three Ka-band satellites to provide bandwidth to commercial military customers. One of the Global Xpress satellites, to be built by Boeing Space and Intelligence Systems, will carry a hosted payload built by Inmarsat. It is expected to be leased by a customer of the U.S. Department of Defense.〔http://www.spacenews.com/satellite_telecom/101222-ex-im-financing-global-xpress.html〕 A particularly promising area of development for hosted payloads is in earth observation missions. There are countless environmental monitoring missions, both old and new, which should be launched in the coming years. 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「Hosted payload」の詳細全文を読む スポンサード リンク
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