The Dream Chaser, a reusable space plane currently under development by Sierra Nevada Corporation (SNC), is to undergo high altitude drop tests in 2012 following a 25.6 million US dollar boost from NASA to top-off the 80 million US dollar contract awarded earlier this year. But it won't be chasing just any dream. With the retirement of the Space Shuttle Program this year, the very tangible goal is to deliver a low-cost, safe alternative for transporting astronauts and cargo to the International Space Station and other low Earth orbit destinations.

The vertical-takeoff, horizontal landing (VTHL) space plane is designed to carry up to seven humans, but can fly autonomously if necessary. While the ability to carry people will reduce the United States' dependency on US$50 million per person flights to the International Space Station aboard Russia's Soyuz craft, it may be the space craft's ability to carry cargo that is of particular interest to NASA. As Mark Sirangelo, head of SNC Space Systems, pointed out in this BBC interview: "At the moment, there is no logical way to take things home from the space station. We can take three people home on a Soyuz but all the science work that's being done up there doesn't have a way to come back. Our vehicle has a particular use for that."

While a capsule landing subjects the cargo to severe G-forces, the Dream Chaser returns from space by gliding, experiences less than 1.5 g on re-entry and is capable of landing on almost any runway. Sirangelo also highlighted the fact that, unlike the Space Shuttle, the vehicle carries no hazardous materials and so can be approached immediately after landing.

The design is based on NASA's HL-20 Space Taxi concept developed by the Langley Research Center in Hampton, Virginia, in the 1980s and 1990s. The inspiration for HL-20 had in turn been drawn from photos of a mysterious spacecraft being recovered by a Soviet ship from the Indian Ocean in 1982 (the spacecraft was later identified as the Soviet BOR-4 and reverse-engineered up to a wind tunnel test stage). The most conspicuous aspect of this heritage is the lifting-body design, which can be thought of as the opposite of a flying wing design. While the latter does away with the fuselage in order to eliminate non-lifting surfaces, the former depreciates the importance of wings and uses the fuselage for lift generation in order to reduce drag on atmospheric re-entry.

The Dream Chaser is designed to be launched into space on the nose of a rocket. However, for the unmanned atmospheric drop-tests it is going to be carried into the skies by Virgin Galactic's WhiteKnightTwo carrier aircraft, originally built to launch SpaceShipTwo spacecraft.

So far the Dream Chaser project has been on schedule and all milestones have been completed. This includes testing the frame by mounting it on an earthquake simulator, as well as testing the hybrid rocket motors running on a peculiar combination of nitrous oxide and recycled rubber. If everything keeps going according to plan, the Dream Chaser will be sent to orbit in 2014, sitting on top of a powerful Atlas V rocket made by United Launch Alliance (see main image). After detachment from the rocket, the space plane will use the hybrid motors to adjust its orbit or dock to the ISS.

That said, the International Space Station is not the only destination SNC has in mind. The company has already invested tens of millions of US dollars on top of what it received from NASA, so it is only natural that it is also eyeing other potential income sources like space tourism. This is where a partnership with Virgin Galactic kicks in. Richard Branson's company is going to be responsible for marketing SNC's space tourism efforts, while SNC concentrates on designing hybrid motors for Virgin Galactic's SpaceShipOne and SpaceShipTwo.

Is space tourism going to guarantee a return on investment? Although the Dream Chaser is almost fully reusable, Mark Sirangelo estimates that in order to make a profit the company would have to be operating multiple Dream Chasers 50-100 times each. This is uncharted business territory.

This video shows an animation of how Dream Chaser would operate.

Source: SNC

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