This company wants to reinvent the space rocket — as a space plane

In the 1990s, NASA developed the X-33, an experimental space plane aimed at reducing the cost of sending payloads into orbit. The X-33 was designed to be fully reusable and land like a plane instead of using rocket stages. However, the program was canceled in 2001 due to technical difficulties. Radian Aerospace, a Seattle-based company, is now working on the Radian One, a space plane that uses a rocket-powered sled for initial acceleration. Radian believes it can overcome the challenges of single stage to orbit (SSTO) vehicles with advancements in technology and the use of key technologies in their design.