SpaceX and NASA today announced no-earlier-than (NET) Tuesday, May 5, for conducting the company’s highly-anticipated, and critically important, Dragon Pad Abort Test (PAT) at the company’s primary launch site on Cape Canaveral Air Force Station in Florida. SpaceX is already well into the development of their crewed space systems for low-Earth orbit transport, having secured a multi-billion dollar NASA contract last year to fly astronauts to and from the International Space Station (ISS) starting in the next couple years, but before any astronaut straps themselves inside a Dragon capsule, SpaceX must successfully demonstrate the spacecraft’s ability to abort from a launch or pad emergency and safely carry crew members out of harm’s way.
On May 5 the company will conduct their first pad abort test of a prototype Crew Dragon (also known as the Dragon 2) to demonstrate precisely that, simulating an emergency abort from a test stand at SpaceX’s Space Launch Complex-40 (SLC-40). The test is currently scheduled to take place at around 9:30 a.m. EDT, with a four-hour window available to conduct the PAT. Should the May 5 attempt be scrubbed, SpaceX does have May 6 secured on the range to try again.
“The whole test is less than two minutes from pad to splashdown,” said SpaceX in comments to AmericaSpace, “and most of that distance is covered in the first 25-30 seconds of the test.”
For the test the Dragon PAT vehicle will be mounted atop a custom-made truss to simulate the spacecraft atop a Falcon-9 rocket, and will be outfitted with hundreds of instruments and sensors for data collection. An instrumented mannequin will be the sole passenger, providing SpaceX with important information regarding the stresses put on the mannequin, information that will be be critical in ensuring development an abort system that prevents serious injury to the crew.
A series of eight SpaceX-designed “SuperDraco” engines, an advanced version of the Draco engines currently used by SpaceX’s un-crewed “cargo only” Dragon to maneuver on orbit and during reentry, will ignite to begin the PAT—just as they would in a real emergency scenario either on the pad or in flight. The eight SuperDraco engines are built into the side walls of the Crew Dragon, and will produce up to 120,000 pounds of axial thrust to carry astronauts to safety (16,000 pounds of thrust each, compared to 100 pounds of thrust each with the original Draco thrusters on Dragon 1)
After ascending thousands of feet the PAT Dragon will deploy three parachutes, splashing down offshore of Cape Canaveral.
The engines can also be restarted multiple times if necessary, and the engines will have the ability to deep throttle, providing astronauts with precise control and enormous power. In addition, as a part of a recoverable Dragon spacecraft, the engines can be used repeatedly, helping to advance SpaceX’s long-term goal of making spacecraft more like airplanes, which can be flown again and again with minimal maintenance between flights.
This gives SpaceX’s launch escape system many advantages over past systems. It is inherently safer because it is not jettisoned like all other escape systems. This distinction provides astronauts with the unprecedented ability to escape from danger at any point during the launch, not just in the first few minutes. The eight SuperDracos also provide redundancy, coming in pairs, so if one engine fails the other can increase its thrust to compensate for the engine that is not firing.
The SuperDraco engines on the Dragon-2 are also the first fully 3-D printed engines intended for space. The chamber is regeneratively cooled and printed in Inconel, a high-performance superalloy that offers both high strength and toughness for increased reliability; they will become the first printed rocket engines ever used in spaceflight. SpaceX has completed qualification testing for the SuperDraco thruster at the company’s Rocket Development Facility in McGregor, Texas, which included testing across a variety of conditions including multiple starts, extended firing durations, and extreme off-nominal propellant flow and temperatures.
The initial crewed flights on Dragon will parachute safely into the waters of the Pacific Ocean off the coast of Southern California, but future missions will land on terra firma by also employing the SuperDraco engines; so the engines have been designed to serve multiple roles since the beginning.
A second abort test is expected to be conducted later this year to put the Dragon’s in-flight abort capability into action, demonstrating that it can carry a crew safely away from an exploding or out of control Falcon-9 rocket. If the PAT Dragon survives its test next month in good condition, SpaceX may use the same vehicle for the in-flight abort test as well.
The first orbital space flight for the Crew Dragon is expected to fly in 2016, without a crew, to validate the system as a whole before carrying out the first crewed test flight in early 2017.
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