With the retirement of the shuttle program in 2011, astronauts now only have one way to ride to the International Space Station -- Russia’s Soyuz spacecraft. To return crewed launches to U.S. soil, NASA has partnered with two commercial companies, Boeing and SpaceX. Both companies were evaluated and awarded contracts by NASA with an outline of required milestones for Boeing and SpaceX to meet to fully receive crew certification.
SpaceX’s Dragon spacecraft is one of two vehicles that NASA hopes will ferry astronauts to and from the International Space Station in 2017. But before that can happen, SpaceX has to show that the crewed Dragon vehicle meets all the safety requirements set by NASA. One such requirement is the implementation of a launch abort system (LAS). This system will allow the astronauts and the Dragon spacecraft to separate from the rocket as quickly as possible in case something goes wrong during launch -- sort of like an ejector seat for a fighter pilot.
Image credit: SpaceX. Dragon test vehicle.
“One thing we learned from the shuttle program was the importance of the LAS. We thought we could build a machine that didn’t need one, and physics taught us different,” Jon Cowart, NASA’s Partner Manager for SpaceX stated during a pre-test press conference.
Today, SpaceX aims to complete another milestone on their way to a crewed launch with the first flight test of their innovative new launch abort system. During the demonstration, the Dragon test vehicle will sit atop a trunk. Instead of a Falcon 9 rocket, it will rely on eight SuperDraco engines to liftoff the pad. Each one has been designed and constructed on a 3D printer.
What makes the SpaceX launch abort system unique is the use of an integrated system. Traditional systems rely on a rocket tower on top of the spacecraft to ignite and pull the spacecraft to safety. This works well on the pad and up to a certain altitude; yet once the spacecraft reaches a certain point, the LAS would have to be discarded. SpaceX’s system features eight SuperDracos built into the spacecraft and will allow crews to abort all the way to orbit. This is the first time this type of design has been used.
Image credit: SpaceX. Pad abort test flight path.
Firing for only six seconds, the Dragon's eight SuperDraco engines will produce 120,000 pounds of thrust (roughly equivalent to two 747 GEnx engines). Dragon will be accelerated to 100 mph after only one second, and will reach its highest altitude of 4910 feet (1500 meters) 15 seconds after firing.
The entire test will last about two minutes and during that time, SpaceX will collect data from 270 different sensors. There is even a passenger on board in the form of a dummy equipped with sensors to measure the g-forces astronaut crews will be subjected to.
Image credit: SpaceX. Dummy astronaut, preparing for test flight.
Vice President of Mission Assurance for SpaceX Hans Koenigsmann said, “The goal of SpaceX has always been to transport people. This test will show that we've developed a revolutionary system for the safety of the astronauts. It's our first big test of the crewed Dragon.”
After the spacecraft reaches its highest point, the trunk will jettison and small drogue parachutes will deploy approximately five seconds later. Once the vehicle has been stabilized, three main parachutes will deploy and the spacecraft will splash down in the Atlantic Ocean, approximately 1.4 miles (2200 meters) downrange. Transported to shore via barge, the vehicle will be then shipped to Texas for evaluation. Once refurbished, the capsule will be used for an in-flight abort test later this year.