DARPA continues with its ambitious projects and now is working on its Vulture program, which will be an unmanned aircraft. As they say, it will be capable of flying without stopping for five years and will also carry up to 1,000 pounds and will have an onboard power of 5kW.

The Vulture will be able to keep its speed even at powerful winds that will encounter at altitudes of 60,000 to 90,000 feet. It should improve communication capabilities working as a pseudo-satellite flying in the stratosphere and not low Earth orbit, as usual satellites.

Daniel Newman, manager of the Vulture program stated that they “want to completely change the paradigm of how we think of aircraft” and to demonstrate aircraft capabilities. “Aviation has a perfect record - we’ve never left one up there. We will attempt to break that record.”

Yet they are only at the project phase, because they aren’t sure what energy cycle to use, having three possibilities. The first one, nuclear power, has been excluded due to risks. Another possible one is in-flight refueling and the aircraft would use fuel-cells, being more reliable than gas-turbine and internal-combustion engines. The third one is solar thermal or solar energy, along with the most possible one - solar electric - which is a tested and proven technology.