Paul Allen, co-founder of Microsoft Corp., listens during a news conference for the launch of his new venture Stratolaunch Systems Inc. in Seattle, Washington, U.S., on Tuesday, Dec. 13, 2011. Allen said Stratolaunch Systems Inc. will bring "airport-like operations" to space flights, including eventual human missions. The first flight is planned within five years. Photographer: Kevin P. Casey/Bloomberg via Getty Images
