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Space Infrastructure Servicing (SIS) is a spacecraft being developed by Canadian aerospace firm MacDonald, Dettwiler and Associates to operate as a small-scale in-space refueling depot for communication satellites in geosynchronous orbit. Intelsat is a requirements and funding partner for the initial demonstration satellite which, , was planned to be launched in approximately 2015.〔〔 MDA put the launch plans on hold in November 2011 pending finding a second launch partner, beyond Intelsat.〔 Such a customer was not found, and Intelsat dropped out of the collaboration in January 2012. 〔http://www.spacenews.com/satellite_telecom/120117-mda-intelsat-scrap-deal.html〕 In February 2012, MDA indicated that it was waiting on a possible DARPA contract before shelving the project. ==History== MDA Corporation announced in early 2010 that a small-scale geosynchronous-orbit refueling project was under development. The design point was to be a single spacecraft that would refuel other spacecraft in orbit as a satellite-servicing demonstration. The 2010 announcement indicated that MDA had already signed an option agreement "with an unidentified satellite fleet operator that has agreed to provide an aging telecommunications spacecraft for a refueling operation as the inaugural customer."〔 〕 Missions contemplated included not only satellite refueling but also space debris mitigation by including the vehicle capability to "push dead satellites into graveyard orbits."〔 The early technical design point included a fuel-depot vehicle that would maneuver to an operational communications satellite, dock at the target satellite’s apogee-kick motor, remove a small part of the target spacecraft’s thermal protection blanket, connect to a fuel-pressure line and deliver the propellant. In 2010, it was estimated that "the docking maneuver would take the communications satellite out of service for about 20 minutes."〔 A potential business model for the service, , would "ask customers to pay per kilogram of fuel successfully added to their satellite, with the per-kilogram price being a function of the additional revenue the operator can expect to generate from the spacecraft’s extended operational life."〔 In March 2011, MDA announced that Intelsat was to be their inaugural launch partner and that the SIS vehicle could be ready to launch as early as 2015, with Intelsat providing up to over the timeframe that the on-orbit services would be delivered to a portion of the Intelsat satellite fleet.〔 〕 , MDA suspended the satellite servicing mission while awaiting major decisions due soon on the scope and details on planned satellite servicing missions by US government civilian and defence agencies NASA and DARPA. MDA wants to "see the NASA and DARPA bid requests, see what’s in them, whether () can bid as a Canadian company, or as a U.S. company."〔 〕 MDA Chief Executive Officer Daniel E. Friedmann said "We can’t just go ahead. I know everybody says the government is not a competitor, and yes, literally they are not a competitor. But our whole business is about winning business from the government and then taking that dual-use technology into the commercial market."〔 In February 2012, MDA said it was awaiting "a decision on a contract bid to the U.S. Defense Advanced Research Projects Agency (DARPA) before deciding whether to shelve its work on a vehicle to service satellites and perform other chores in orbit."〔(Fate of Canadian Satellite Servicing Project Awaits DARPA Decision ), ''Space News'', 1 Mar 2012. ''〕 In a June 2012 article in ''The Space Review'', a number of approaches to satellite servicing were discussed and contrasted. The MDA Space Infrastructure Servicing concept is reported to be somewhat more complex than the competitive ViviSat Mission Extension Vehicle, and is considered to be similar to the concepts that NASA is investigating experimentally with a test platform called the Robotic Refueling Mission flying on the International Space Station during the Expedition 29–32 timeframe in 2011-2013. MDA's approach "would use its manipulators to refuel or repair the spacecraft. The original announcement of the SIS by MDA in March of 2011 envisioned using it to deploy stuck () arrays—like the case of () IS-19—or grapple debris. 'Direct refueling, robotically, of a satellite is not trivial, but it’s fully doable.'"〔 〕 By comparison, the DARPA Project Phoenix program has an even more complex mission concept: "cooperatively harvest and re-use valuable components from satellites in orbit that have been retired. DARPA envisions a servicing spacecraft that could remove a solar array, antenna, or other component from a defunct satellite and transport it to another satellite, either a newly constructed spacecraft or one in need or repairs. 'Phoenix is truly all about going up to retired, non-cooperative, non-controlled satellites that have been left for dead in the geosynchronous graveyard orbit, essentially, and see if we can resurrect capability out of those satellites or those satellite components.'"〔 , no customers have signed up for an MDA refueling mission.〔 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「Space Infrastructure Servicing」の詳細全文を読む スポンサード リンク
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