NASA is developing advanced technologies that will revolutionize America's space launch capabilities and unleash the commercial potential of space. The challenge is to develop advanced technologies for affordable reusble launch vehicles. NASA's goal is to reduce the payload cost of access to space by an order of magnitude, from $10,000 to $1,000 per pound, within 10 years, and by an additional order of magnitude, to $100's per pound within 25 years. This research is part of NASA's Aeronautics and Space Transportation Technology (ASTT) Enterprise's strategy to sustain U.S. leadership in aeronautics and space. The Enterprise has set bold goals that are grouped into Three Pillars: Global Civil Aviation, Revolutionary Technology Leaps and Access to Space.