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February 02, 2011

Spacex proposes integrated rocket powered launch abort

Unlike traditional emergency systems, called a tractor design by engineers, SpaceX wants to build an integrated launch abort rocket to provide escape capability throughout the rocket's flight to orbit. Tractor designs used by the U.S. Mercury and Apollo programs were thrown away a few minutes after liftoff, as soon as their boosters cleared the atmosphere.

The integrated system would be part of the Dragon capsule, staying with the spacecraft during months at the International Space Station and returning to Earth at the end of a normal flight. It could even be fired for a rocket-assisted touchdown on land, bringing astronauts home to a soft landing closer to recovery teams.

After the Space Shuttle retires next year, NASA will be totally dependent on the Russian Soyuz to carry astronauts to and from the International Space Station for a price of over $50 million per seat. Spacex is proposing to do it for about $20 million per seat.



SpaceX has proposed an integrated launch abort system design, which has several advantages over the tractor tower approaches used by all prior vehicles:

* Provides escape capability all the way to orbit versus a tractor system, which is so heavy it must be dumped about four minutes after liftoff.
* Improves crew safety, as it does not require a separation event, whereas any non-integral system (tractor or pusher), must be dumped on every mission for the astronauts to survive.
* Reduces cost since the escape system returns with the spacecraft.
* Enables superior landing capabilities since the escape engines can potentially be used for a precise land landing of Dragon under rocket power. (An emergency chute will always be retained as a backup system for maximum safety.)

An emergency parachute would always be carried as a backup, according to SpaceX.

SpaceX claims the concept improves crew safety and reduces Dragon operating costs.

According to Musk, it will likely cost $1 billion and take three years to have a flight-ready Dragon ready for crew duty. That includes test flights.

SpaceX is calling for a three-step design, development and test schedule, beginning with the initial concept of the abort engines and crew accommodations, progressing to static fire testing of the escape engines, then prototype evaluations by NASA crews of seats, control panels and cabin layout.

"If a reasonable number of test articles and abort flights are assumed, then the total development cost to get crew to station and meet all the NASA requirements is probably around $1 billion and three years from initial contract award," Musk told Spaceflight Now Monday. "To put that figure into perspective, that’s roughly how much NASA will spend on Soyuz seats over the same period of time."

SpaceX’s competitors will not discuss how much it will cost to develop their designs.

Musk acknowledged his estimates are "a bit fuzzy" and will depend on the safety requirements levied by NASA. He has long publicly disclosed it would cost roughly $500 million for the hardware modifications themselves, but a "huge variable is what level of testing is required, how many tons of paperwork and how many qualification articles need to be built," Musk said, emphasizing extras could push the cost closer to $1 billion.

The company says the Dragon spacecraft is scheduled to fly at least 11 more times, and the Falcon 9 rocket 17 more times, before humans strap inside.

SpaceX is sticking to its figure of $20 million per seat for Dragon, adjusted for inflation. That price is contingent upon NASA using the Dragon's full capacity of seven seats and purchasing at least four flights per year, enough to cover SpaceX's fixed costs.

"Over time, we'd like to make that a lot lower, but it is still a huge savings over Soyuz," Musk said.

Until a U.S. commercial operator is ready for crew rotation, space station residents will continue flying to and from the complex on Russian Soyuz spacecraft. In its last agreement with NASA, which provides for seats through 2013, Russia charged the space agency more than $50 million for each roundtrip seat. NASA and Russia are expected to soon begin negotiating for more Soyuz services stretching into 2015.

SpaceX's competitors are Boeing Co., Orbital Sciences and Sierra Nevada Corp. None of the companies have disclosed the price of a seat aboard their spacecraft, but Boeing has stated their cost projects compare favorable with Soyuz.

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