NOW IN SPACE: A microwave power-beaming experiment.

A secretive military space plane will soon test the idea of using microwave beams to send solar power to Earth from space. The U.S. Air Force’s X-37B space plane is expected to launch into orbit Saturday (May 16) with an experiment onboard that tests the possibility.

The Photovoltaic Radiofrequency Antenna Module Flight Experiment (PRAM-FX) represents the first orbital test of such a sci-fi technology since the 19th century — solar satellite power. Build a big solar array in orbit, the idea goes, and it could collect enough sunlight (unfiltered by atmospheric effects or clouds,) to generate a powerful beam of microwaves. A collection station on Earth would then convert that beam into useful power. Launch any satellite into a high enough orbit and it will receive a near-constant stream of sunlight, with only brief passes through the Earth’s shadow. A whole constellation of solar arrays might offer uninterrupted 24/7 power.

I like orbital solar. The power-beaming idea isn’t new — they did a proof-of-concept experiment at JPL Goldstone 50 years ago (with, if I recall correctly, around 50% efficiency), but now they’re doing actual engineering.