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Sierra Nevada Corp.'s Dream Chaser mini-shuttle space plane may have lost out in NASA's space taxi competition, but the company is still keeping the dream alive.

On Friday, Sierra Nevada challenged NASA's $6.8 billion award to its rivals, Boeing and SpaceX, on the grounds that Boeing put in a significantly higher bid "for a space program equivalent to the program that SNC proposed." On Monday, the company announced that it would offer the Dream Chaser as a winged spaceship for customers around the world.

Now Sierra Nevada says it has designed a launch system for low Earth orbit, or LEO, that combines a scale version of the Dream Chaser with the Stratolaunch super-airplane that's bankrolled by software billionaire Paul Allen.

The combination "could provide a highly responsive capability with the potential to reach a variety of LEO destinations and return astronauts or payloads to a U.S. runway within 24 hours," Chuck Beames, president of Allen's Vulcan Aerospace Corp. and executive director for Stratolaunch Systems, said Tuesday in a Sierra Nevada news release.

Stratolaunch is currently building the world's biggest airplane at California's Mojave Air and Space Port — a twin-fuselage behemoth that's designed to launch rockets in midflight. The plane is due to start flight tests in 2016, and the first space mission may come in 2017 or 2018. Stratolaunch's industrial partners include Orbital Sciences Corp. and ATK, two prominent aerospace companies that are in the process of merging.

Sierra Nevada said the Dream Chaser-Stratolaunch system could carry a crew of three astronauts to LEO destinations (such as the International Space Station). The air-launch system could also be used for uncrewed space missions or suborbital point-to-point transportation, Sierra Nevada said.

The idea of Sierra Nevada teaming up with a venture backed by Allen, the man who funded the SpaceShipOne rocket plane, is already stirring up a buzz among spaceflight mavens like SpaceKSC.com blogger Stephen C. Smith: