Scientists demonstrate wireless power transmission from space to Earth for first time

Scientists have successfully demonstrated for the first time that solar power can be wirelessly transmitted in space and also beamed to Earth.

The space solar power prototype, dubbed Maple, is one of three key technologies being tested by the California Institute of Technology’s (Caltech) Space Solar Power Project (SSPP), which aims to harvest solar power in space and transmit it to the Earth’s surface.

Maple, short for Microwave Array for Power-transfer Low-orbit Experiment, consists of an array of flexible, lightweight microwave power transmitters, built using custom electronic chips, to beam the energy to desired locations.

For successfully achieving its outcome, scientists said such energy transmission arrays need to be lightweight to minimise the amount of fuel needed to send them to space, and flexible so they can be folded up and transported in a rocket.

“Through the experiments we have run so far, we received confirmation that Maple can transmit power successfully to receivers in space. We have also been able to program the array to direct its energy toward Earth, which we detected here at Caltech,” Ali Hajimiri, Electrical Engineering professor at Caltech, said in a statement.

“To the best of our knowledge, no one has ever demonstrated wireless energy transfer in space even with expensive rigid structures. We are doing it with flexible lightweight structures and with our own integrated circuits. This is a first,” Dr Hajimiri said.

Having previously tested on Earth, researchers now believe the prototype – made of materials optimised for space conditions – can survive a trip to space and operate there.

The results are yet to be published in a peer-reviewed journal.

The new technology consists of ultralight, high-efficiency materials that convert light into electricity which are also made to be compatible with an integrated power conversion and transmission system.

It converts direct current power from sunlight into radio frequency power, such as the type used to transmit cell phone signals, and send it to Earth as significantly harmless microwaves.

Maple also has a small window through which the array can beam the energy.

The transmitter array in the prototype uses timing-control elements to focus the power dynamically on the desired location.

A small fraction of this transmitted energy could be detected by a receiver on the roof of the Gordon and Betty Moore Laboratory of Engineering on Caltech’s campus in Pasadena, scientists said.

As expected, the energy directed towards Earth spread out most of its power over a very wide area, and only an extremely small fraction was detected by the receiver at Caltech’s campus.

Researchers are currently assessing the performance of individual elements within the system.

In further analysis that may take up to six months, they hope to sort out irregularities in the system and trace them back to individual units, providing insight for the next generation of the prototype.

Since solar energy in outer space is constantly available without being subjected to cycles of day and night, seasons and cloud cover, scientists said it can yield eight times more power than solar panels at any location on Earth.

In its full conception, SSPP would include a constellation of modular spacecraft deployed to space to collect sunlight, transform it into electricity and convert it to microwaves that will be beamed over long distances to wherever it is needed.

“The flexible power transmission arrays are essential to the current design of Caltech’s vision for a constellation of sail-like solar panels that unfurl once they reach orbit,” said Sergio Pellegrino, co-director of SSPP.

“In the same way that the internet democratized access to information, we hope that wireless energy transfer democratizes access to energy,” Dr Hajimiri said.