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|family = Delta IV |derivatives = |comparable = |status = Active |sites = SLC-37B, Cape Canaveral SLC-6 Vandenberg AFB |launches = 8 |success = 7 |fail = |partial = 1 |other_outcome = |first = December 21, 2004 |last = |payloads = |stagedata = }} The Delta IV Heavy (Delta 9250H) is an expendable heavy lift launch vehicle, the largest type of the Delta IV family, and the world's highest capacity rocket currently in operation. It was first launched in 2004.〔("Boeing Delta IV Heavy Achieves Major Test Objectives in First Flight" ), Boeing, 2004, accessed March 22, 2012〕 The Delta IV Heavy uses two additional Common Booster Cores as liquid rocket boosters instead of the GEM-60 solid rocket motors used by the Delta IV Medium+ versions. At lift off, all three cores operate at full thrust, and 44 seconds later the center core throttles down to 55% to conserve fuel until booster separation. The boosters burn out at 242 seconds after launch, and are separated as the core booster throttles back up to full thrust. The core burns out 86 seconds later, and the second stage completes the ascent to orbit.〔 The first launch of the Delta IV Heavy in 2004 carried a boilerplate payload, and was a partial failure. Cavitation in the liquid oxygen propellant lines caused shutdown of both boosters 8 seconds early, and the core engine 9 seconds early; this resulted in a lower staging velocity for which the second stage was unable to compensate. The payload was left in a lower than intended orbit.〔(【引用サイトリンク】url=http://www.spaceflightnow.com/delta/d310/050316rootcause.html )〕 Its first operational payload was the DSP-23 satellite, successfully launched in 2007; it was then used to launch a further five visual and electronic reconnaissance satellites for the National Reconnaissance Office through 2013. In December 2014, the Delta IV Heavy was used to launch an uncrewed test flight of the Orion Multi-Purpose Crew Vehicle, designated EFT-1. After several delays on December 4, the mission was successfully launched at 12:05 UTC on December 5. Capacity of the Delta IV Heavy: *Low Earth orbit (LEO), 200 km × 28.7°: 〔 *Low Earth orbit (ISS), 407 km × 51.6°: 〔(【引用サイトリンク】url=http://www.spacelaunchreport.com/delta4.html )〕 *Geosynchronous transfer orbit (GTO): *Geosynchronous orbit (GEO): 〔 *Lunar transfer orbit (LTO) / Mars transfer orbit The Heavy's total mass at launch is approximately . ==Comparable vehicles== *Angara 5 *Long March 5 *Ariane 5 *Atlas V *Proton-M *Titan IV (retired) *Space Launch System (in development) *Falcon Heavy (in development) 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「Delta IV Heavy」の詳細全文を読む スポンサード リンク
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