Space Exploration Technologies (SpaceX) has announced it has successfully completed the preliminary design review of its revolutionary launch abort system, a system designed for manned missions using its Dragon spacecraft. This represents a major step toward creating an American-made successor to the Space Shuttle.

NASA's approval of the latest design review marks the fourth successfully completed milestone under the agency's Commercial Crew Development (CCDev) program and demonstrates the innovation that's possible when NASA partners with the private sector.

"Each milestone we complete brings the United States one step closer to once again having domestic human spaceflight capability," said former astronaut Garrett Reisman, one of the two program leads of SpaceX's DragonRider, which is adding capabilities to the Dragon spacecraft for astronaut carriage.

Now that the Space Shuttle program has ended, the United States relies on the Russian Soyuz spacecraft for astronaut transport, costing American taxpayers as much as $62 million a seat. By comparison, Dragon is designed to carry seven astronauts at a time for an unparalleled $20 million per seat.

As with all SpaceX designs, increased safety and reliability are paramount. "Dragon's integrated launch abort system provides astronauts with the ability to safely escape from the beginning of the launch until the rocket reaches orbit," explained David Giger, co-lead of the DragonRider program. "This level of protection is unprecedented in manned spaceflight history."

With the latest design review approved by NASA, SpaceX can now start building the hardware at the heart of its innovative launch abort system.

The SpaceX design incorporates the escape engines into the side walls of Dragon, eliminating a failure mode of more traditional rocket escape towers, which must be successfully jettisoned during every launch. The integrated abort system also returns with the spacecraft, allowing for easy reuse and radical reductions in the cost of space transport.

Over time, the same escape thrusters will also provide Dragon with the ability to land with pinpoint accuracy on Earth or another planet.

In its first flights, on June 4 and December 8, 2010, SpaceX's Falcon 9 launch vehicle achieved consecutive mission successes. The December mission, which was the first demonstration flight under NASA's Commercial Orbital Transportation Services (COTS) program, marked Dragon's historic debut and established SpaceX as the first private company to launch and recover a spacecraft from orbit.

As a result, many Falcon 9 and Dragon components required for transporting humans to Earth orbit have already been demonstrated in flight.