A Private Space Shuttle Replacement

Once the space-shuttle program ends this year, the only way to get people into orbit and to the International Space Station will be to buy seats on Russia's three-person Soyuz capsules. So NASA, through its Commercial Crew Development program, has given 50 million in grants to companies developing new spacecraft capable of carrying people and supplies into orbit and to the space station.

The recipient of the biggest chunk of this money was the Sierra Nevada Corporation, which received 20 million to develop the Dream Chaser. This SPACECRAFT, the size of a business jet, will take cargo and up to eight people into low Earth orbit, where the space station is located, and then return and land on commercial airport runways.

The company reached all its development milestones for the Dream Chaser last year and is now finishing a battery of tests on the craft's carbon-composite frame. The shell of the spacecraft must be able to endure heavy loads and intense vibrations. So the Dream Chaser frame has been mounted on an earthquake simulator in a lab at the University of Colorado in Boulder. So far, the design has performed as expected, says Mark SIRANGELO, head of Sierra Nevada's Space Systems division. At facilities in San Diego, the company has been testing the craft's hybrid rocket motors. In the coming months, the company will put the two together to complete a full prototype, carry it into the air, and drop it to see how it flies.

Other orbital spacecraft under development by companies including SpaceX, Orbital Sciences, and Boeing are capsules that will use parachutes to descend on land or in the sea. The Dream Chaser has a lifting body design; it looks something like an airplane without the large wings on the side. Its shape, in combination with extensible wheels and motors, will enable it to make a controlled landing on a runway. SIRANGELO says that the craft will therefore be able to land on the ground in more places than other vehicles can, and that the gravitational forces to which it will expose passengers-and sensitive cargo and scientific instruments-will be less intense.

If the company continues to achieve its testing and development milestones, the Dream Chaser will be launched into orbit in 2014 on the nose of a powerful launch booster, the Atlas V, made by United Launch Alliance. After it reaches orbit, the craft will be dropped, and its hybrid motors will be used to adjust its orbit or dock it to a space station. These motors will also be used to guide it to its gentle landings.

Sierra Nevada, which also makes satellites, sensors, and other components, did not design the Dream Chaser from the ground up. In the 1970s, the Soviets tested a vehicle like it, known as the Bor-4. The crew of an Australian ship photographed it, and NASA used the image to reverse-engineer a similar craft. The resulting design, NASA's HL-20, underwent significant development and testing and was intended to be a lifeboat for astronauts aboard the space station. But the HL-20 program lapsed.

Reference: fromatlantistosphinx.blogspot.com