top of page

Caltech launches a potentially revolutionary solar harvesting prototype into space

A satellite is above Earth from space, facing the sun against a dark sky
Image credit: Wix

In the early hours of January 3, 2023, researchers at the California Institute of Technology, Caltech, launched the Space Solar Power Demonstrator (SSPD). The prototype will test key components of an ambitious plan to harvest solar power in space and beam the energy back to Earth in an effort to scale our renewable capacity.

The launch was a long time coming, as a team of roughly 35 researchers including principal investigators, graduate and postdoctoral students, and researchers have worked tirelessly for the last two years creating and testing SSPD’s parts to make this sci-fi dream a reality. However, the project dates back to 2011 when philanthropist Donald Bren learned about the potential for space-based solar energy manufacturing from a Popular Science article.

Bren, a Caltech Board of Trustees lifetime member, was fascinated by the possibility of space solar power and approached Caltech's then-president Jean-Lou Chameau to discuss the creation of a space-based solar power research project. Two years later, Bren and his wife Brigitte Bren made a donation to fund the project, and eventually, the fund for Caltech to send solar panels into space exceeded $100 million.

Now, over a decade later, the demonstration prototype is hitching a ride on SpaceX’s most recent Falcon 9 rocket launch in Cape Canaveral, Florida via the Momentus Vigoride spacecraft.

If the prototype’s initial experiments are successful, arrays similar to SSPD could one day beam essentially endless renewable energy back to Earth via microwave transmitters. The energy is endless because as Caltech says, the sunlight is not subjected to the cycles of the day, night, seasons, and cloud cover.

The roughly 110-pound prototype will test three different key technologies, including the architecture, a collection of 32 different types of photovoltaic (PV) cells in the punishing environment of space, and an array of flexible lightweight microwave power transmitters with precise timing control. These transmitters will beam the power back to Earth via wireless electricity.

Caltech isn't the only player in the space solar power game. Big aerospace and defense companies like Northrop Grumman appear to be leading the effort. The company completed ground-based tests for its space solar tech at the end of last year. Their tech is being developed through a $100 million partnership with the U.S. Air Force. Northrop Grumman is also a key financier of Caltech's program.

Additionally, there are also a handful of startups that could play a role in launching a space-based solar power farm in the next decade. One startup, Solestial, which spun out of Arizona State University, is currently in the promising prototype stage. It estimates that its space solar panels will cost a tenth of the cost of those stuck on planet Earth. The company raised $10 million in October to take its tech from the lab or orbit in a round led by venture capital groups for aviation giants Airbus and Boeing.

China's Longi Solar, the leading solar power maker on Earth, is also looking to dominate in space and began conducting experiments in September.

As of December, Washington-based company Gravitics is developing what it calls "dragon scales," solar panels intended to power modular space stations in low-Earth orbit.

Melbourne-based Solar Space Technologies has the ambitious goal of delivering a solar power satellite into geostationary orbit to supply baseload energy to the Australian grid by 2027. With their aspiration only four short years away, the startup plans to employ existing infrastructure to deliver solar energy from space, through its microwave transmitters, and to its ground station and homes and businesses.

With the device now in space, Caltech is leading the takeoff. The project's scientists will begin running their experiments over the next few weeks.

While significant challenges remain, such as the vast costs and unpredictability that come with any space engineering project, launching the prototype into space represents a significant achievement in the pursuit of space solar power.

"For many years, I've dreamed about how space-based solar power could solve some of humanity's most urgent challenges," Bren said via Caltech news. “Today, I'm thrilled to be supporting Caltech's brilliant scientists as they race to make that dream a reality."

bottom of page