Space

SSPP/Caltech

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Researchers at the California Institute of Technology (Caltech) have successfully demonstrated wireless transmission of power in space. The first-of-its-kind demonstration took place onboard the Space Solar Power Demonstrator (SSPD-1), which was launched earlier in January this year.

Space-based solar power is the next frontier of harnessing renewable energy. Research in the area has been ongoing for decades and promises to revolutionize the energy sector by making solar power available practically anywhere on the planet.

A research team led by Ali Hajimiri, a professor of Electrical Engineering at Caltech, initiated the Space Solar Power Project (SSPP) to harvest solar power in space and transmit it back to Earth. As part of the project, the 110-pound (50 kg) Space Solar Power Demonstrator (SSPD-1) was launched onboard a SpaceX rocket on January 3 this year, and it has reported back its first success.

For space-based solar power to be feasible, the researchers needed to first demonstrate that a solar array can be cost-effectively deployed in space. To do so, they developed Microwave Array for Power-transfer Low-orbit Experiment, or MAPLE for short, which is one of the three experiments on board the SSPD-1.

MAPLE consists of lightweight and flexible power transmitters controlled by custom electronic chips but built using low-cost silicon technologies. The flexibility of the array allows them to be folded up to be launched on a rocket, and their lightweight nature reduces the fuel needed to deploy them in space.

While the SSPD-1 was successful in deploying MAPLE in space, the real test of the experiment was the ability to harvest and transmit solar power.

MAPLE used interference between transmitters to shift the focus and direction of the energy, negating the need for moving parts. By using the coherent addition of electromagnetic waves, the researchers were able to dynamically focus the power from the transmitter array to a desired location.

MAPLE consists of two receiver arrays located about a foot (30 cm) away from the transmitter. The researchers successfully lit up a pair of LEDs connected to these receivers individually and switched between them to demonstrate the transmission of power in space. Since the experiment was not sealed, it also showed that it could function in the harsh environs of space, including temperature fluctuations and solar radiation, the press release said.

MAPLE also included a small window where it could beam the harvested solar energy back to Earth. This was detected by a receiver on the roof of Caltech's campus in Pasadena.

The researchers will now assess the performance of individual elements of the experiment to gain insights that will help them build the next generation of SSPD. The SSPD-1 has two more experiments that have not yet been completed, and results are expected in the coming months.