NASA and 11 other research groups are testing two non-petroleum-based jet fuels in the pursuit of alternative fuels that can power commercial jets and address rising oil costs.

The Defense Advanced Research Projects Agency (DARPA) completed its Autonomous Airborne Refueling Demonstration program this month, showing that unmanned aircraft can autonomously perform in-flight refueling under operational conditions.

Hypersonic propulsion using supersonic combustion ramjet (scramjet) technology offers the possibility of very high speeds and fuel efficiencies. The technology has the potential to put numerous defense and civilian aerospace applications within reach during the next couple of decades.