Launch Escape System Saves Lives in Space Flight

Blue Origin rocket explodes, but the spacecraft survives.

Spaceflight is hard, and dangerous. From the beginnings of crewed spaceflight in the early 1960s, ejection seats and launch escape rockets were designed to carry astronauts and cosmonauts away from the fireball of an exploding booster. Launch escape rockets can be carried on top of the spacecraft and lift it off tractor-style or be mounted under the capsule and push it free of the upper stages. Ejection seats have fallen out of favour after the second Space Shuttle flight, but both tractor and pusher type launch escape rockets are human rated today. Blue Origin and SpaceX use the pusher type, while NASA prefers the traditional tractor type. Which is better? 

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For the 60 years of human crewed spaceflight, a single factor has remained constant throughout: it’s dangerous. Nineteen people have died in spaceflight over that time, ten during the re-entry phase, and nine during boost.

Launch is generally understood to be the most dangerous part of crewed spaceflight. A fully fuelled spacecraft and booster is essentially a gigantic explosive charge, and the combination of vibration, air loads, G forces and the need for precise trajectory control put a premium on structures, testing and simulation.

Astronauts and cosmonauts have been protected during the boost phase in two ways: by using a launch escape rocket motor to lift the crew capsule away from the exploding booster, and in Gemini and developmental Space Shuttle flights with crew ejection seats. The capability for crew escape has always been there, but in U.S. missions it has not been used in flight since Mercury Atlas 3 in April of 1961.

Until this year. Blue Origin’s September 12th New Shepard 23 mission suffered a booster explosion during climb, with the capsule separating and parachuting to safety. Like the NASA flight 60 years ago, sensors detected the breakup of the booster and ignited rockets to propel the crew capsule away from the fireball.

The original NASA system, similar to the one used today in the Space Launch System with the Orion capsule, used a tractor rocket assembly to pull the spacecraft free in an emergency. Launch escape systems used by Blue Origin and SpaceX use pusher engines with no tower. While both the Mercury and New Shepard capsules were not crewed, the launch escape system has saved lives from an exploding booster once: on September 26th, 1983.

The Soyuz T-10-1 mission, carrying two cosmonauts intended to link with the Salyut 7 space station, suffered a booster fire on the launch pad. Flight controllers activated the launch escape system, and two cosmonauts endured over 14G’s of acceleration for five seconds, landing bruised but safely away from the explosion.

So what’s the better way to protect crews? Is it ejection seats, to push them off the booster? Or to pull them away?

Ejection seats are heavy and require the installation of pyrotechnics inside the crew compartment, which is a safety issue. Tractor-type escape towers are heavy but can be jettisoned as soon as a ballistic free fall escape trajectory is possible, lightening the spacecraft for orbit insertion. Pusher-type rockets are lighter, but the weight must be carried to orbit. 

Pusher and tractor rockets are in use today, and both are crew rated. Ejection seats appear to have fallen out of favor—at least until crewed orbital space planes are developed again, where they can offer protection during the approach and landing phases of flight as well as launch. 

But if you’re planning to buy a ride on a SpaceX or Blue Origin capsule soon, the good news is, two types of escape systems are well tested, and they work.

Written by

James Anderton

Jim Anderton is the Director of Content for Mr. Anderton was formerly editor of Canadian Metalworking Magazine and has contributed to a wide range of print and on-line publications, including Design Engineering, Canadian Plastics, Service Station and Garage Management, Autovision, and the National Post. He also brings prior industry experience in quality and part design for a Tier One automotive supplier.