“SPS-Alpha incorporates the concept of the retrodirective phased array, which allows a large number of individual RF elements to be controlled and their transmissions made coherent through the use of a 'pilot signal' transmitted from the site of the planned receiver,” Mankins writes. “This technology (co-invented by Nobuyuki Kaya of Kobe University) allows the large microwave transmitter required for the concept to be assembled from modular elements via an RF version of adaptive optics.”

The SPS-Alpha study done for NASA aims to establish an analytical proof of concept for its “technical and economic viability” and a near-term road map for development like Sasaki's for the more conventional approach he studied. Either one could be interesting reading for today's energy companies as they look for ways to invest some of the record profits they are pulling down, along with mountaintops.