Dream ChaserNow that the U.S. space shuttle program has ended, NASA is turning to the private sector for the next generation of reusable manned spacecraft—including the Sierra Nevada Corporation's Dream Chaser (illustrated above). (Related: "After Space Shuttle, Does U.S. Have a Future in Space?")The brainchild of the Colorado-based Sierra Nevada Corporation, the Dream Chaser is one of five private-spacecraft proposals that won U.S. $50 million in federal grants under the 2009 American Recovery and Reinvestment Act.The proposed new shuttle's primary mission is to transport cargo and up to seven astronauts to the International Space Station, and to return crews safely to Earth, according to Sierra Nevada's website.Among Dream Chaser's advantages: It's designed to launch on top of Atlas rockets, which have been reliably used by NASA since 1957.Last month Sierra Nevada was awarded an additional $213 million grant—along with $440 million to SpaceX and $460 million to Boeing Corporation—to continue plans that, NASA said, would set the stage for "demonstration missions to low-Earth orbit by the middle of the decade."—Richard A. Lovett

Illustration courtesy SNC Space Systems