A team of researchers and engineers from the California Institute of Technology (Caltech) has made history by successfully transmitting energy from solar panels in space to Earth for the first time. The breakthrough could pave the way for a new era of clean, abundant and reliable energy generation.
The team, led by professors Ali Hajimiri, Harry Atwater and Sergio Pellegrino, is part of the Space Solar Power Project (SSPP), a visionary initiative funded by more than $100 million in donations from Donald Bren, chairman of Irvine Company and a Caltech trustee, and his wife, Brigitte.
The SSPP aims to deploy a constellation of modular spacecraft that collect sunlight in orbit, transform it into electricity, and then wirelessly beam it to receivers anywhere on the planet. Unlike terrestrial solar power, which is limited by weather and night conditions, space-based solar power could provide constant and uninterrupted energy to anyone, anywhere, anytime.
To test the feasibility of this concept, the SSPP launched a 50-kilogram demonstrator (SSPD-1) in January 2023 to orbit 550 kilometers above the Earth. The SSPD-1 consists of three key technologies: MAPLE, DOLCE and ALBA.
MAPLE is an array of flexible, lightweight microwave transmitters that can steer power to desired locations. DOLCE is a foldable, sail-like structure that opens to receive sunlight. ALBA is a set of different types of photovoltaic cells that convert sunlight into electricity.
On May 22, 2023, the SSPD-1 successfully transmitted a power signal from orbit to a receiver on the rooftop of a laboratory on Caltech’s Pasadena campus. The signal was detected by a custom-built device that lit up an array of LEDs in sequence.
“It took a few moments for it to sink in, then everybody got really excited,” said Hajimiri, who is the co-director of SSPP and the Bren Professor of Electrical Engineering and Medical Engineering. “This technology for wireless energy transfer can have a tremendous impact on lives, both on Earth and in space.”
Hajimiri added that the SSPD-1 is the lightest and most cost-effective system ever built for space-based solar power. He compared the potential of wireless energy transfer to that of the internet. “In the same way that the internet democratized access to information, we hope that wireless energy transfer democratizes access to energy,” he said.
Atwater, who is the co-director of SSPP and the Howard Hughes Professor of Applied Physics and Materials Science, said that the SSPD-1 is a proof-of-concept experiment that shows that space-based solar power is feasible. He said that the next steps for the SSPP are to scale up the system and demonstrate higher power levels and longer distances.
“The idea of collecting solar energy in space and beaming it down to Earth has been around for decades. But until now, no one has been able to demonstrate that it is feasible,” he said.
Pellegrino, who is also the co-director of SSPP and the Joyce and Kent Kresa Professor of Aeronautics and Civil Engineering, said that the SSPD-1 is a result of interdisciplinary collaboration among experts in electrical engineering, materials science, aerospace engineering and physics. He said that the SSPD-1 integrates ultralight and shape accurate structures with high efficiency photovoltaics and large scale phased array power transmission into a two dimensional scalable, deployable spacecraft.
“The SSPD-1 is a remarkable achievement that showcases the creativity and innovation of Caltech’s faculty and students,” he said.
Bren, who initiated the SSPP in 2011 after reading a Popular Science article about space-based solar power, said that he was impressed by the progress and results of the project. He said that he was intrigued by the potential for this technology to revolutionize how we generate and distribute energy on a global scale.
“I wanted to support Caltech’s vision and leadership in making this a reality,” he said. “Space-based solar power could be a game-changer for humanity. It could provide clean, abundant and affordable energy to anyone, anywhere, anytime.”
– Scientists Beam Solar Power From Space to Earth in World First, ScienceAlert, 06 June 2023
– Caltech prototype funded by O.C. donor beams solar power from space — a terrestrial first, Los Angeles Times, 01 June 2023
– Scientists claim they’re the first to transmit space-based solar power to Earth, Engadget, 03 June 2023
– Caltech researchers are bringing space-based solar power from sci-fi to reality, Caltech, 17 October 2022