US successfully transmits solar power from space to Earth

A research team at the California Institute of Technology (Caltech) conducted the world's first experiment transmitting wireless power in space.

For the first time, detectable amounts of electricity have been transmitted back to Earth, New Atlas reported on June 5. The Space Solar Power Project (SSPP) aims to harness a virtually limitless source of clean energy in orbit.

The MAPLE module in the experiment transmitting electricity from space to Earth. (Photo: Caltech).

Space solar power could solve many of Earth's clean energy problems. Orbiting power plants could harvest sunlight 24/7, unaffected by the atmosphere or weather conditions. In theory, space solar panels could produce up to eight times more energy per square meter than solar panels on Earth.

So several teams are working to harness this energy, despite some major challenges. One is the size of the solar panels needed. Commercial solar panels would need to be as large as 9 square kilometers ^. The receivers on Earth would need to be equally large to collect the energy and send it back to the ground. That would require 39 launches, even with the ultralight, self-deploying smart module battery that the Caltech team is developing. Theirs consists of a series of modules, each about a cubic meter in volume ^when launched, but which can be stretched out into a giant flat square, 50 meters on each side, with a solar cell on one side and a wireless generator on the other.

The 50-kilogram Space Solar Power Test System (SSPD-1) was mounted on the Momentus Vigoride spacecraft and launched into low orbit by SpaceX rocket on January 3 this year. SSPD-1 is designed to test three small modules.

1. The DOLCE module tests the design and implementation of an ultra-lightweight folding structure.
2. The ALBA module tests a range of different solar cell designs to see which is most efficient in space.
3. The MAPLE (Low Orbit Microwave Power Experiment) module tests the technology for transmitting power wirelessly to Earth, towards a ground receiving station without any moving parts in the transmitter.

Part of MAPLE tested short-range power transmission, in which the transmitter sent power to two different receivers 30 centimeters away, to test the team's beam-steering technology. As a result, they were able to light up small LEDs at each receiver at will.

MAPLE also spent a short time using its transmitter to beam the energy beam straight back to Earth, to a receiver on the roof of an engineering laboratory at Caltech in Pasadena. The experiment was a success. The energy beam was detected by a ground station, at the intended time and frequency. This demonstrated the team's ability to precisely target the energy beam at long distances and confirmed that the associated instrumentation was functioning properly after the orbital journey.