In this article, we will be discussing Launch Escape Systems (LES). Also called Launch Abort System (LAS), it is a crew safety system connected to the space capsule.

In a situation of emergency, the Launch Escape System helps in quickly separate the space capsule from the main rocket/launch vehicle. The system can be activated either automatically upon detection of rocket failure or manually by the crew commander.

Types

There are primarily two types of LES —

  1. A rocket mounted on the top of the crew capsule that, once activated, the system produces a huge amount of thrust over a very short time interval carrying the space capsule up and sideways and thereby increasing the distance from the main rocket. These have been used in Mercury, Apollo, Soyuz, and Shenzhou capsules.
 Apollo LES pad abort test with boilerplate Command Module. Such systems often form the top most portion of the rocket.
Apollo LES pad abort test with boilerplate Command Module. Such systems often form the top most portion of the rocket.

2. Ejection Seats: Similar to the ones used in Military aircraft, the seats eject out the of the space capsule and the crew returns to earth with the assistance of individual parachute. These have been used in Vostok and Gemini Capsules

Ejection seat of the pilot of the Vostok-5 spacecraft are on display at the K. E. Tsiolkovsky Museum of the History of Cosmonautics. Credits: Stolbovsky

Tractor and Pusher Types

For the first type, it is further classified into — Tractor type and Pusher Type. The tractor type system has a rocket on the top of the capsule which “pulls” it away from the main rocket. While the pusher type has the system below the capsule which “pushes” it away from the main rocket. This “Pusher” type system is what is being used by SpaceX in Crew Dragon.

A Dragon 2 undergoing a Pad Abort test on May 6, 2015, demonstrating a pusher LAS.
A Dragon 2 undergoing a Pad Abort test on May 6, 2015, demonstrating a pusher LAS.

Conception
 

The idea of using a separate rocket to carry away the space capsule for crew safety was first envisioned by the legendary inventory Maxime Faget. (Faget was the designer of the Mercury spacecraft and also contributed to Apollo, Gemini and Space shuttle missions. 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.

 1. Retropack. 2. Heatshield. 3. Crew compartment. 4. Recovery compartment. 5. Antenna section. 6. Launch escape system.
1. Retropack. 2. Heatshield. 3. Crew compartment. 4. Recovery compartment. 5. Antenna section. 6. Launch escape system.

The Launch Escape System in Mercury Spacecraft. The same design was used in Apollo program.


The First Usage

The first usage with a crewed mission occurred during the attempt to launch Soyuz T-10-1 on September 26, 1983. The rocket caught fire, just before launch, and The launch escape system of the Soyuz spacecraft fired six seconds before the launch vehicle exploded, saving the crew.

In the complete process, the crew were subjected to an acceleration of 14 to 17 g for five seconds and were badly bruised. Reportedly, the capsule reached an altitude of 2,000 meters and landed 4 kilometers from the launch pad. As of 2022, it remains the only time a launch escape system has been fired before launch with a crew on board.

 A rare view of the rocket explosion of Soyuz 7K-ST No.16L.
A rare view of the rocket explosion of Soyuz 7K-ST No.16L.

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