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The SpaceX reusable launch system development program is a privately funded program to develop a set of new technologies for an orbital launch system that may be reused many times in a manner similar to the reusability of aircraft. The company SpaceX is developing the technologies over a number of years to facilitate full and rapid reusability of space launch vehicles. The project's long-term objectives include returning a launch vehicle first stage to the launch site in minutes and to return a second stage to the launch pad following orbital realignment with the launch site and atmospheric reentry in up to 24 hours. Both stages will be designed to allow reuse a few hours after return. The program was publicly announced in 2011 and the design for returning the rocket to its launchpad using only its own propulsion systems was completed in February 2012.〔 SpaceX's active test program began in late 2012 with testing low-altitude, low-speed aspects of the landing technology. High-velocity, high-altitude aspects of the booster atmospheric return technology began testing in late 2013. The reusable launch system technology is under development for the first stages of the Falcon family of rockets.〔 It is particularly well-suited to the Falcon Heavy where the two outer cores separate from the rocket earlier in the flight, and are therefore moving more slowly at stage separation. If the technology is used on a reusable Falcon 9 rocket, the first-stage separation would occur at a velocity of approximately rather than the for an expendable Falcon 9, to provide the residual fuel necessary for the deceleration and turnaround maneuver and the controlled descent and landing.〔 The reusable technology will also be extended to both the first and upper stages of the future launch vehicle for the Mars Colonial Transporter.〔 〕〔 The first successful controlled landing of an orbital rocket stage on the ocean surface was achieved in April 2014. Two of the controlled-descent tests have also attempted to land the returning first stage on a floating landing platform—one each in January and April 2015. But although the booster was guided to the floating platform in both cases, neither test was successful in achieving a vertical landing on the platform.〔 (【引用サイトリンク】title=Elon Musk Explains SpaceX Falcon 9 Recovery Attempt )〕〔 (【引用サイトリンク】title=SpaceX Checks Throttle Valve After Flawed Falcon 9 Recovery Attempt )〕 == History == The broad outline of the reusable launch system was first publicly described on September 29, 2011. SpaceX said it would attempt to develop powered descent and recovery of both Falcon 9 stagesa fully vertical takeoff, vertical landing (VTVL) rocket. The company produced a computer-animated video depicting a notional view of the first stage returning tail-first for a powered descent and the second stage with a heat shield, reentering head first before rotating for a powered descent. In September 2012, SpaceX began flight tests on a prototype reusable first stage with the suborbital Grasshopper rocket.〔 Those tests continued into 2014, including testing of a second and larger prototype vehicle, F9R Dev1. News of the Grasshopper test rocket become public earlier in September 2011, when the US Federal Aviation Administration released a draft Environmental Impact Assessment for the SpaceX Test Site in Texas, and the space media had reported it by September 26.〔 In May 2012, SpaceX obtained a set of atmospheric test data for the recovery of the Falcon 9 first stage based on 176 test runs in the NASA Marshall Space Flight Center wind tunnel test facility. The work was contracted for by SpaceX under a reimburseable Space Act Agreement with NASA. In November 2012, CEO Elon Musk announced SpaceX's plans to build a second, much larger, reusable rocket system, this one to be powered by LOX/methane rather than LOX/RP-1 used on Falcon 9 and Falcon Heavy. The new system will be "an evolution of SpaceX's Falcon 9 booster", and SpaceX reiterated their commitment to develop a breakthrough in vertical landing technology. By the end of 2012, the demonstration test vehicle, Grasshopper, had made three VTVL test flightsincluding a 29-second hover flight to on December 17, 2012. In early March 2013, SpaceX successfully tested Grasshopper for a fourth time when it flew to an altitude of over . In March 2013, SpaceX announced that it would instrument and equip subsequent Falcon 9 first-stages as controlled descent test vehicles, with plans for over-water propulsively-decelerated simulated landings beginning in 2013, with the intent to return the vehicle to the launch site for a powered landingpossibly as early as mid-2014. The April 2013 draft Environmental Impact Statement for the proposed SpaceX private launch site in south Texas includes specific accommodations for return of the Falcon 9 first-stage boosters to the launch site. Elon Musk first publicly referred to the reusable Falcon 9 as the Falcon 9-R in April 2013.〔 In September 2013, SpaceX successfully relit three engines of a spent booster on an orbital launch, and the booster re-entered the atmosphere at hypersonic speed without burning up. With the data collected from the first flight test of a booster-controlled descent from high altitude, coupled with the technological advancements made on the Grasshopper low-altitude landing demonstrator, SpaceX announced it believed it was ready to test a full land-recovery of a booster stage.〔 Based on the positive results from the first high-altitude flight test, SpaceX advanced the expected date of a test from mid-2014 to early 2015, with the intention of doing so on the next Space Station cargo resupply flight pending regulatory approvals.〔〔 That flight took place on April 18, 2014. Musk stated in May 2013 that the goal of the program is to achieve full and rapid reusability of the first stage by 2015, and to develop full launch vehicle reusability following that as "part of a future design architecture". In February 2014, SpaceX made explicit that the newly defined super-heavy launch vehicle for the Mars Colonial Transporter would also make use of the reusable technology. This is consistent with Musk's strategic statement in 2012 that "The revolutionary breakthrough will come with rockets that are fully and rapidly reusable. We will never conquer Mars unless we do that. It'll be too expensive. The American colonies would never have been pioneered if the ships that crossed the ocean hadn't been reusable." Also in May 2014, SpaceX publicly announced an extensive test program for a related reusable technology: a propulsively-landed space capsule called ''DragonFly''. The tests will be run in Texas at the McGregor Rocket Test Facility in 2014–2015. In June 2014, COO Gwynne Shotwell clarified that all funding for development and testing of the reusable launch system technology development program is private funding from SpaceX, with no contribution by the US government.〔 〕 SpaceX has not publicly disclosed the cost of the development program.〔 〕 For the first time, SpaceX stated in July 2014 that they are "highly confident of being able to land successfully on a floating launch pad or back at the launch site and refly the rocket with no required refurbishment."〔 〕 By late 2014, SpaceX suspended or abandoned the plan to recover and reuse the Falcon 9 second stage;〔https://www.youtube.com/watch?v=y13jbl7ASxY&feature=youtu.be&t=14m20s〕 the additional mass of the required heat shield, landing gear, and low-powered landing engines would incur too great a performance penalty. Blue Origin's New Shepard suborbital rocket, following the first landing attempts of test boosters by SpaceX, completed its first successful controlled descent and landing from space on 23 November 2015. 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「SpaceX reusable launch system development program」の詳細全文を読む スポンサード リンク
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