SpaceX and Boeing emergency launch abandonment systems explained

If something goes wrong when a crew of astronauts launches into space, their spacecraft is still endowed with an integrated abandonment system that helps to return to Earth safely. But not all abandonment systems work the same way.

In October 2018, the Soyuz abandonment system After failing their rocket, two crew members linked to the International Space Station came back to Earth. In the same way, the new commercial crew vehicles built by SpaceX and Boeing are designed to safely separate their rockets and return to Earth in an emergency.

Neither company has yet fully tested the abandonment system on its new commercial crew vehicle. However, they both had problems with the first tests of the exhaust engines designed to propel the astronauts safely. Saturday, April 20 SpaceX crew crew suffers from a major anomaly during a test of the SuperDraco evacuation engines at the Kennedy Space Center in Florida, smoke could be seen miles away. Similarly, last July, Boeing reported an "anomaly" during a test of the company's engines that had halted the launch, although no case of a dramatic explosion or cloud of smoke has not been reported.

Watching something designed to save lives in smoke may not be very reassuring, especially for astronauts who plan to fly in these spacecraft. But these "anomalies" will ultimately make the spacecraft safer for astronauts, helping engineers find and solve any problem before it becomes a threat to life.

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A crew launch can be interrupted in two ways: the old "pull" method, tried and tested, and the new "push" method. In the older abandonment mechanism, a small set of thrusters is installed on the tip of the crew capsule, giving the nose of the rocket an elongated and pointed shape. When the mission is interrupted, these thrusters directed down "pull" the capsule safely after it has separated from the rocket.

NASA first used this type of evacuation system with Mercury Project, the first space program of the crew of the agency, as well as the Apollo program that places astronauts on the moon. It is also the kind of escape system of Russia Soyuz Rocket-capsule combination, on which NASA has relied to bring astronauts to and from the space station for almost a decade.

(Image: © SpaceX)

The idea for a new type of launching exhaust system was introduced by Boeing in 2010, but SpaceX was the first to realize this idea with the company's Crew Dragon spacecraft. Instead of mounting an emergency tower above the capsule, SpaceX built the thrusters into the outer walls of the capsule. Eight SuperDraco engines are built into the hull and "push" the capsule away from the rocket in case of emergency.

These SuperDracos were the engines that SpaceX was testing when the explosion occurred on April 20. In 2015, SpaceX completed the first test flight of the Crew Dragon drop system. The company has not yet given a reason for this recent accident, but this could be due to a change put in place since this first test.

Boeing CST-100 Starliner uses a system similar to the Crew Dragon, but instead of eight SuperDraco engines, it uses four RS-88 engines, built by Aerojet Rocketdyne. The Starliner also had problems with its launch-drop engines during a similar fire test in July 2018, when Boeing reported that the engine valves had a propellant leak. There was no dramatic explosion this time, but the first Starliner test flight was later delayed. Its launch is scheduled for August.

While the two commercial space flight companies use the new design of a launching exhaust system, NASA sticks to the old "pull" method with Orion's new crew capsule. NASA will use this spacecraft to send astronauts to the moon by 2024. The agency plans to test the Orion abandonment system for the second time on June 12th. The first test was successfully completed in 2010. Since then NASA has improved the design of the system using the data collected by the agency during this first test.

The three vehicles would use parachutes to safely bring the crews back to Earth, but SpaceX's Crew Dragon could rely on its propellers as an emergency landing ability, Elon Musk. tweeted in March. Although SpaceX appeared to be about to beat Boeing with his first crewed flight to the International Space Station, the recent SpaceX accident probably means that Boeing will arrive first. SpaceX has not yet said what caused Saturday's blast or how that will affect the Crew Dragon program. His first crewed flight, Crew Dragon Demo-2, is technically still scheduled for July 25, but that should change.

Email Hanneke Weitering at [email protected] or follow her. @hannekescience. Follow us on twitter @Spacedotcom and on Facebook.