In 2004 SpaceShipOne made a historic flight when it entered suborbital space, becoming the first manned, privately funded spacecraft to do so. The flight earned the $10 million Ansari X prize for Mojave Aerospace Ventures, an aerospace company run by Burt Rutan and owned by Microsoft co-founder Paul Allen.

Allen and Rutan are in the news again following an announcement (PDF) yesterday that their newest venture, Stratolaunch Systems, was planning to design and build full-scale private spacecraft. The goal of the project is to create a delivery system that would allow safer, more flexible, and less expensive missions to space.

The backbone of the project is a mobile launch system made up of three main parts. First is a carrier aircraft, expected to be the largest aircraft ever flown, which will carry the system’s payload to an in-air launch point. The second component is a multi-stage rocket booster, which will carry the payload from the launch point into space. Finally, there will be a sophisticated integration system allowing the carrier aircraft to haul the boosters, which will weigh nearly half a million pounds, safely to their launch point.

The project has the ambitious goal of completely revolutionizing human spaceflight. The company says they want to bring airport-like functionality to space travel, and to pave the way for both commercial and government missions, eventually including human spaceflight. The in-air launch system is meant to allow for a rapid turnaround between missions and offer greater flexibility at a lower cost than is currently available with ground-based operations.

In addition to Rutan, founder of aircraft manufacturer Scaled Composites, Allen has also brought a number of former NASA personnel into Stratolaunch. The CEO of Stratolaunch is former NASA chief engineer Gary Wentz, and former NASA Administrator Mike Griffin sits on the board.

The carrier aircraft will use six 747 engines, operate from a large airport or spaceport facility (it will require 12,000 feet of runway), and have a range of 1,300 nautical miles. The company is shooting for a first flight sometime in the next five years, and will move slowly up to unmanned missions, followed by manned operations, as the safety and reliability of the system become more certain.