Sat Oct 13, 2018, 12:22 AM

How Russia's Trusty Space Launch Escape System Saved 6 Lives After Initial Deadly Start

Published time: 12 Oct, 2018 18:53
Edited time: 12 Oct, 2018 18:56

Thursday's aborted launch of the Russian Soyuz spaceship may have sent the International Space Station's work into disarray, but it also highlighted how much effort Soviet space engineers put into their creations.

The apparent failure during booster separation of the Soyuz-FG launch vehicle rocket became the third time in history where crew lives were saved by a system called SAS, a Russian abbreviation for "system of emergency rescue." It's the Russian answer to the problem of how to save people during a manned rocket launch if something goes wrong.

In its entirety the SAS is basically a small solid-propellant rocket mounted above the payload fairing. If there is a need to abort the launch, the Soyuz spacecraft under the fairing sheds the lowest of its three modules while the fairing separates into upper and lower sections. Then the entire stack is towed up and away from the dangerous rocket by the SAS main thrusters, while four grid fins at the bottom make sure that the mini-rocket stays on a stable course. At a safe distance the space capsule separates from the frontal module and the fairing, and drops down to break speed and parachute to the ground.

Mounting the SAS atop the rocket is one of the more dangerous parts of the assembly process, because of its highly explosive propellant. During a launch the system is turned on about 15 minutes before liftoff. It can engage itself under some conditions, like if the rocket starts to tilt on one side, or can be engaged manually. Two operators on the ground must each press two buttons simultaneously to fire off the SAS – a measure meant to prevent false triggering.

Ironically, the first major incident when SAS was used resulted in a death. In December 1966, a Soyuz 7K-OK, a then experimental spaceship for manned missions, was supposed to be launched with a mannequin on board. The launch was aborted after one of the four first-stage boosters failed during the ignition phase.


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