An image of the interior of MAPLE,
An image of the interior of MAPLE, the instrument aboard the Space Solar Power Demonstrator that achieved the wireless transmission of energy through space.. Image Credit: Caltech


  • Through the MAPLE experiment, the Space Solar Power Demonstrator was able to wirelessly transmit solar electricity collected on Earth to receivers in orbit.
  • When fully realized, space solar power could tap into an unlimited supply of solar energy.
  • This could generate up to eight times more power than Earth-bound solar panels, say scientists.
  • This could "democratise" access to energy worldwide.

For the first time, a space solar power prototype has shown that it is capable of wirelessly beaming power through space and directing a detectable quantity of energy toward Earth.

The experiment shows that it is possible to access a virtually infinite supply of electricity in the form of solar energy from space.

Solar energy is constantly available in space since it is not affected by things like day and night, cloud cover, or weather on Earth. In fact, it is predicted that space-based harvesters might produce up to eight times as much energy as solar panels anywhere on Earth's surface.

The Microwave Array for Power-transfer Low-orbit Experiment (MAPLE), a collection of adaptable and lightweight microwave power devices, was responsible for the wireless power transmission.

It is one of the three experiments carried by the Space Solar Power Demonstrator (SSPD-1).

The California Institute of Technology's (Caltech) Space Solar Power Project (SSPP), whose main objective is to collect solar energy in space and send it to Earth's surface, launched SSPD-1 in January 2023.

"Through the experiments we have run so far, we received confirmation that MAPLE can transmit power successfully to receivers in space," Co-Director of the Space-Based Solar Power Project, Dr. Ali Hajimiri, said in a statement. "We have also been able to program the array to direct its energy toward Earth, which we detected here at Caltech. We had, of course, tested it on Earth, but now we know that it can survive the trip to space and operate there."

By delivering energy from a transmitter to two different receiver arrays about a foot apart, MAPLE was able to show how energy can be transmitted wirelessly through space and be converted into electricity. A pair of LEDs were lit using this.

On the Caltech campus in Pasadena, the equipment then directed energy from a tiny window into the unit to the roof of the Gordon and Betty Moore Laboratory of Engineering.

The experiment also showed that MAPLE, which is not sealed, is capable of operating in the hostile environment of space while being exposed to significant temperature changes and solar radiation. Large-scale SSPP units will soon be subject to the same circumstances as this prototype.

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

In a video from Caltech, Hajimiri, who was in charge of the Caltech team that created MAPLE, outlined how the wireless transmission of energy through space is based on a quantum phenomena known as "interference."

The fact that light is a wave causes interference. If two light waves overlap, they will align if they are in phase, creating a bigger peak with a height equal to the sum of the two original peaks when the waves meet. Constructive interference is what this is.

However, if the light waves are out of phase and cross over while out of alignment, a peak or trough in the wave may collide and cancel each other out, a phenomenon known as destructive interference.