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The Titan 34D was a U.S. expendable launch vehicle, used to launch a number of satellites for mostly military applications. After its retirement from military service, a small number were converted to the Commercial Titan III configuration, which included a stretched second stage, and a larger fairing. Several communications satellites, and the NASA Mars Observer spacecraft were launched by commercial Titan 34Ds. Derived from the Titan III, the Titan 34D featured stretched first and second stages with more powerful solid boosters. A variety of upper stages were available, including the Inertial Upper Stage, the Transfer Orbit Stage, and the Transtage. The Titan 34D made its maiden flight on 30 October 1982 with two DSCS defense communications satellites for the United States Department of Defense (DOD). All launches were conducted from either LC-40 at Cape Canaveral Air Force Station or SLC-4E at Vandenberg Air Force Base. 15 launches were carried out, of which three failed. The first of failure was a launch of a KH-11 photoreconnaissance satellite on August 28, 1985 when the core stage suffered a turbopump malfunction and was destroyed by Range Safety. The flight proceeded normally until core engine start at T+102 seconds. Engine 1 experienced below-normal performance and after SRM separation at T+117 seconds, the engine completely shut down, followed by loss of vehicle attitude control. The onboard computer then shut off Engine 2 and began a premature separation and ignition of the second stage. With the Titan now tumbling and headed back towards land, the destruct command was issued at T+272 seconds and the KH-11 crashed into the Pacific Ocean. In addition, during Stage 1's powered flight, the oxidizer tank began leaking N2O2 which was thought to have resulted in loss of lubrication to the Engine 1 turbopump and breakdown of the pinion gear. A piece of cork insulation also broke off of the right SRM at liftoff, however this was not believed to be a factor in the accident. In the end, the exact reason for the loss of lubrication to the turbopump could not be determined. The second proved to be one of the worst space launch disasters in US history when on April 18, 1986, an attempted launch of a KH-9 photo reconnaissance satellite ended catastrophically as the right solid rocket booster exploded only eight seconds into the flight, destroying the entire vehicle and showering SLC4E with debris and toxic propellant. The right solid rocket motor ruptured and the resulting torque on the launch vehicle caused the left SRM to break away, triggering its automatic destruct system, blowing the first stage to pieces and rupturing the second stage N2O2 tank. The upper stages were ejected and launched through the air until a manual destruct command was sent by the range safety officer around T+20 seconds. Debris rained onto SLC-4E, badly damaging the launch complex in the process and starting numerous small fires, some of which burned for up to two days. The disaster drew unfortunate comparisons to the Challenger shuttle accident three months earlier, which was also the victim of a solid rocket motor malfunction. However, the Titan incident was found to have a rather different cause as it had not suffered O-ring burn through, but instead the culprit was a small air pocket between the SRM propellant and its metal motor casing. This allowed hot exhaust gases to burn through the casing and eventually rupture the SRM. The event also caused serious reappraisals of safety for launch personnel as smoke leaked into the blockhouse. In addition, the left SRM, which had merely had its casing ruptured by the destruct charges and was mostly still in one piece, fell onto a building near the pad and crushed it flat. While the structure was empty at the time of the launch, the rocket could just as easily have landed on the crowded blockhouse. SLC4E was out of commission until October 1987, after which it hosted the remaining two Titan 34D launches without incident. == Use with Vortex satellites == Three Vortex satellites were launched using Titan 34D vehicles between 1984 and 1989. 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「Titan 34D」の詳細全文を読む スポンサード リンク
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