Related by context. Frequent words. (Click for all words.) 66 XCOR Aerospace 62 Xcor 59 XCOR 53 Zero Gravity Corporation 52 reusable spacecraft 52 SpaceShipOne 51 Masten Space Systems 51 sub orbital 51 Rocketplane 51 spaceplane 51 Scaled Composites 50 Peter Diamandis 50 suborbital space 50 SpaceShipTwo 50 suborbital flights 50 SpaceX Falcon 9 50 designer Burt Rutan 50 suborbital 48 SpaceDev 48 VSS Enterprise 48 Burt Rutan 47 MOJAVE Calif. 47 ion propulsion 47 Mike Melvill 47 spaceflight 47 Rocketplane Kistler 46 Rutan 46 SpaceX 46 Virgin Galactic 46 UP Aerospace 46 agency Roskosmos 46 Perminov 46 spacecraft 46 Orion Crew 46 founder Elon Musk 45 VTOL 45 Dragon capsule 45 commander Dominic Gorie 45 robotic spacecraft 45 spaceship 45 spaceports 44 Ares rocket 44 unpiloted 44 Orbital Sciences Corporation 44 Orion capsule 44 NASTAR Center 44 suborbital flight 44 WhiteKnightTwo 44 remotely piloted 44 Taurus XL rocket 44 vertical takeoff 44 Sanswire 44 Aerion 44 hypersonic flight 44 Orbital Space 44 Ansari X 43 Will Whitehorn 43 Orion spacecraft 43 Regional Spaceport 43 Scaled Composites LLC 43 CEO Elon Musk 43 manned spacecraft 43 spaceport 43 scramjet engine 43 Dragon spacecraft 43 Sentient Flight Group 43 Launch Vehicle 43 ATK Launch Systems 43 Unmanned Aircraft System 43 Bigelow Aerospace 43 PlanetSpace 43 aircraft 43 Ares IX rocket 43 spaceflights 42 administrator Sean O'Keefe 42 General Atomics Aeronautical Systems 42 Dryden Flight Research 42 unmanned aerial 42 Luke Bucklin 42 Mojave Airport 42 spaceships 42 Commander Eileen 42 Kenneth Bowersox 42 Orbital Sciences Corp. 42 Space Adventures 42 NYSE ORB 41 spokeswoman Arlene Salac 41 hypersonic 41 Piper Seneca 41 P 8A Poseidon 41 scramjet 41 Shuttle commander 41 PSLV C# 41 unmanned aerial vehicle 41 EcoMotors 41 Geosynchronous Satellite Launch Vehicle 41 chief Anatoly Perminov 41 Orbital Sciences 41 agency Roscosmos 41 Beechcraft Baron 41 electric propulsion