Energy from space…

Maple (Microwave Array for Power-transfer Low-orbit Experiment) is the latest achievement of Caltech’s Space Solar Power Project, a research program aimed at enabling space-based solar energy production to address humanity’s current energy challenges. It is one of the three experiments launched into space in January as part of the Space Solar Power Demonstrator, a prototype developed to field-test technologies developed by researchers over the past 10 years. Maple consists of a group of space-specific microwave emitters controlled by special chips that allow precise modification of the electromagnetic radiation produced by each emitter.

Maple has no moving parts but utilizes constructive and destructive interference between the electromagnetic waves generated by each emitter to precisely direct the resulting microwave beam. During the test, Maple transmitted its microwave beam to two receivers located about 30 centimeters away from the emitters. The receivers converted the electromagnetic waves into direct current, which was used to power two LEDs, demonstrating the functionality of the entire system. The experiment proved successful as the LEDs lit up as expected, and by adjusting the emitted microwave beams, researchers were able to turn them on and off at will, demonstrating precise control over their direction. Additionally, the prototype had a small side window through which the microwaves were directed outside the device towards Earth, where they were detected by a receiver placed on the roof of the Caltech campus in Pasadena.

“As far as we know, no one had successfully tested wireless energy transfer in space, even using rigid and expensive structures,” explains Ali Hajimiri, professor of electrical engineering and medical engineering at Caltech and co-director of the Space Solar Power Project. “We are doing it using flexible and lightweight structures, and with a custom-built integrated circuit, so I believe it is definitely the first time it has happened.”