Microsoft co-founder Paul Allen announced his next space venture with Burt Rutan today, called Stratolaunch Systems. The company follows up on the duo's SpaceShipOne project which won the $10 million Ansari X Prize in 2004 for being the first private craft to launch into space twice in two weeks, but this one will be run by NASA's former chief engineer Gary Wentz and is much bigger. Six 747 engines will power the carrier plane — developed by Rutan's company Scaled Composites — and it'll have the world's largest wingspan at 385 feet, beating out the Hughes H-4 Hercules's 319 feet. The multi-stage booster that detaches from the carrier to launch into space will be built by Elon Musk's SpaceX, rounding out this Avengers team for commercial space flight. The first unmanned payloads will launch in 2016 with manned flights expected after demonstrating safety and reliability.