Alaunch escape system (LES) orlaunch abort system (LAS) is a crew-safety system connected to aspace capsule. It is used in the event of a critical emergency to quickly separate the capsule from itslaunch vehicle in case of an emergency requiring the abort of the launch, such as an impending explosion. The LES is typically controlled by a combination of automatic rocket failure detection, and a manual activation for the crew commander's use. The LES may be used while the launch vehicle is on thelaunch pad, or during its ascent. Such systems are usually of three types:
The idea of using a rocket to remove the capsule from a space vehicle was developed byMaxime Faget in 1958.[1] The system, using the tower on the top of the space capsule to house rockets, was first used on a test of the Project Mercury capsule in March 1959. Historically, LES were used on AmericanMercury andApollo spacecraft. Both designs used asolid-fuel rocket motor. The Mercury LES was built by the Grand Central Rocket Company inRedlands, California (which later became theLockheed Propulsion Company). Apollo useda design that had many similarities to the Mercury system. LES continue to be used on the RussianSoyuz and ChineseShenzhou spacecraft. TheSpaceXDragon 2 uses ahypergolicliquid-fueled launch abort system integrated to the capsule and theBoeing Starliner uses abort thrusters in its service module.
The Soviet Vostok and American Gemini spacecraft both made use ofejection seats. TheEuropean Space Agency'sHermes and the SovietBuran-classspaceplanes would also have made use of them if they had ever flown with crews. As shown bySoyuz T-10a, a LES must be able to carry a crew compartment from the launch pad to a height sufficient for its parachutes to open. Consequently, they must make use of large, powerful (and heavy)solid rockets. The Soyuz launch escape system is calledСАС orSAS, from the Russian/transliterated RussianСистема Аварийного Спасения orSistema Avariynogo Spaseniya, meaning emergency rescue system.[2]
The SovietProton launcher has flown dozens of times with an escape tower, under theZond program and theTKS program.[citation needed] All of its flights were uncrewed.
TheSpace Shuttle was fitted with ejection seats for the two pilots in the initial test flights, but these were removed once the vehicle was deemed operational and carried additional crew members,[3] which could not be provided with escape hatches. Following the 1986Challenger disaster, all surviving orbiters were fitted to allow for crew evacuation through the main ingress/egress hatch (using a specially developed parachute system that could be worn over a spacesuit),[3] although only when the shuttle was in a controlled glide.
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TheOrion spacecraft, which was developed to follow the Space Shuttle program, uses a Mercury and Apollo-style escape rocket system, while an alternative system, called theMax Launch Abort System (MLAS),[4] was investigated and would have used existing solid-rocket motors integrated into the bullet-shaped protective launch shroud.
Under NASA'sCommercial Crew Development (CCDev) programBlue Origin was awarded $3.7 million for development of an innovative 'pusher' LAS. It is used on theNew Shepard Crew Capsule.[5]
Also under NASA's CCDev program, SpaceX was awarded $75 million for the development of their own version of a "pusher" LAS.[6] Their Dragon 2 spacecraft uses itsSuperDraco engines during a launch abort scenario. Although often referred to as a "pusher" arrangement since it lacks a tower, theDragon 2 LAS removes both the capsule and its trunk together from the launch vehicle. The system is designed to abort with the SuperDraco engines at the top of the abort stack as occurs with a more traditional tractor LAS. The concept was first tested in a pad abort test conducted atSLC-40,Cape Canaveral Air Force Station, on May 6, 2015.[7] SpaceXtested the system on January 19, 2020, during a full-scale simulation of a Falcon 9 rocket malfunction atKennedy Space Center Launch Complex 39, where it has later launched crews to the International Space Station.[8]
The second crewed spacecraft selected by NASA for its CCDev program wasBoeing'sCST-100 Starliner, which, like SpaceX's Dragon 2 spacecraft, uses a "pusher" launch escape system, consisting of four launch abort engines mounted on the service module that can propel the spacecraft away from its Atlas V launch vehicle in an emergency on the pad or during ascent.[9] The engines, which use hypergolic propellants and generate 40,000 pounds-force (180 kN) of thrust each, are provided byAerojet Rocketdyne.[10] The abort system was tested successfully during theStarliner's pad abort test on November 4, 2019, atWhite Sands Missile Range.[11]
Orbital Sciences Corporation intends[when?] to sell the LAS it was building for the Orion spacecraft to future commercial crew vehicle providers in the wake of the cancellation of the Constellation project.[12]
During theMercury-Redstone 1 mission on November 21, 1960, the escape system unintentionally blasted off from the Mercury spacecraft after the Redstone booster engine shut down just after ignition on the pad. The spacecraft remained attached to the booster on the ground.[citation needed]
An accidental pad firing of a launch escape system occurred during the attempted launch of the uncrewedSoyuz 7K-OK No.1 spacecraft on December 14, 1966. The vehicle's strap-on boosters did not ignite, preventing the rocket from leaving the pad. About 30 minutes later, while the vehicle was being secured, the LES engine fired. Separation charges started a fire in the rocket's third stage, leading to an explosion that killed a pad worker. During the attempted launch, the booster switched from external to internal power as it normally would do, which then activated the abort sensing system. Originally it was thought that the LES firing was triggered by a gantry arm that tilted the rocket past seven degrees, meeting one of the defined in-flight abort conditions.[13]
The first usage with a crewed mission occurred during the attempt to launchSoyuz T-10-1 on September 26, 1983.[14] The rocket caught fire, just before launch, and the LES carried the crew capsule clear, seconds before the rocket exploded. The crew were subjected to an acceleration of 14 to 17g (140 to 170 m/s2) for five seconds and were badly bruised. Reportedly, the capsule reached an altitude of 2,000 meters (6,600 ft) and landed 4 kilometers (2.5 mi) from the launch pad.
On October 11, 2018 the crew ofSoyuz MS-10 separated from their launch vehicle after a booster rocket separation failure occurred at an altitude of 50 km during the ascent. However, at this point in the mission the LES had already been ejected and was not used to separate the crew capsule from the rest of the launch vehicle. Backup motors were used to separate the crew capsule resulting in the crew landing safely and uninjured approximately 19 minutes after launch.[citation needed]
On September 12, 2022 during Blue OriginNew Shepard flightNS-23, the booster'sBE-3 engine suffered a failure at about one minute into the flight. The launch escape system was triggered and the capsule successfully separated and landed nominally. The flight was carrying microgravity scientific payloads in the crew capsule, without crew on board.[15]
This article incorporatespublic domain material from websites or documents of theNational Aeronautics and Space Administration.
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