We're about to get our first demonstration of space-based solar power

A new demo from Caltech will test the viability of unlimited solar power beamed back to Earth from orbit
John Loeffler
An artists rendering of a space solar power demonstrator in orbit
An artists rendering of a space solar power demonstrator in orbit


A new demo from Caltech is set to launch in January 2023, and it could shake up the way we collect and harvest solar power in the future.

Caltech's Space Solar Power Project (SSPP) is getting ready to put its first Space Solar Power Demonstrator into space to test new technologies that could make the dream of space-based solar power harvesting — which could yield considerably more energy than ground-based solar arrays — closer to reality.

The 50-kilogram Demonstrator will be deployed from a Momentus Vigoride spacecraft carried into space by SpaceX in January and consists of three main components, the Deployable on-Orbit ultraLight Composit Experiment (DOLCE); the Microwave Array for Power-transfer Low-orbit Experiment (MAPLE), and a set of 22 varying types of photovoltaic cells called ALBA.

"For many years, I've dreamed about how space-based solar power could solve some of humanity's most urgent challenges," Donald Bren, a member of the Caltech Board of Trustees who first proposed a space-based solar power project to Caltech's then-president Jean-Lou Chameau in 2011 and helped provide the initial seed funding for the project in 2013, said in a Caltech statement. "Today, I'm thrilled to be supporting Caltech's brilliant scientists as they race to make that dream a reality."

Those scientists are going to be testing three major challenges to space-based solar power, namely deployment, efficiency, and wireless transmission back to Earth. The ALBA and MAPLE experiments will take time to get ready, but DOLCE, which will test the solar panel and Demonstrator's superstructure deployment, will take place first, and pretty quickly at that.

"We plan to command the deployment of DOLCE within days of getting access to [the Demonstrator] from Momentus. We should know right away if DOLCE works," said Sergio Pellegrino, co-director of SSPP and a professor of aerospace and professor of civil engineering at Caltech.

The unfolding of the superstructure for the Demonstrator is going to be a delicate maneuver, much like the deployment of the James Webb Space Telescope was in January 2022. DOLCE will also be testing new technologies for the first time in space, and a lot can go wrong.

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"Many times, we asked colleagues at [NASA and Caltech's Jet Propulsion Laboratory] and in the Southern California space industry for advice about the design and test procedures that are used to develop successful missions. We tried to reduce the risk of failure, even though the development of entirely new technologies is inherently a risky process," Pellegrino said.

Still, the payoff could be huge, and not just for space-based solar power.

"DOLCE demonstrates a new architecture for solar-powered spacecraft and phased antenna arrays. It exploits the latest generation of ultrathin composite materials to achieve unprecedented packaging efficiency and flexibility. With the further advances that we have already started to work on, we anticipate applications to a variety of future space missions," Pellegrino said.

What is space-based solar power?

Space-based solar power isn't a new idea, but it is an exciting one. Unlike ground-based solar power, space-based satellites would be able to avoid a lot of the drawbacks of a ground-based solar cell, like inclement weather, and prolonged day-night cycles.

The challenge, of course, is that space-based solar power is in space, and space is hard to get to and build in, no matter how easy SpaceX can make it look sometimes.

Lifting a 50-kilogram solar array hundreds of miles off the Earth's surface is an expensive proposition, which is one of the things that makes ALBA so important. These 22 solar cells are going to be testing for the most efficient form of solar collection so that Caltech researchers can see which technology holds the most promise for making space-based solar power economically practical given the cost of setting it up in the first place.

How do we get that power back to Earth?

Another major hurdle, which MAPLE will test, is how to get the power you do collect from a space-based satellite back to Earth where we can use it.

"The entire flexible MAPLE array, as well as its core wireless power transfer electronic chips and transmitting elements, have been designed from scratch," said Ali Hajimiri, also co-director of SSPP and a professor of electrical engineering and medical engineering at Caltech. "This wasn't made from items you can buy because they didn't even exist. This fundamental rethinking of the system from the ground up is essential to realize scalable solutions for [the Demonstrator]"

"No matter what happens, this prototype is a major step forward," Hajimiri added. "It works here on Earth and has passed the rigorous steps required of anything launched into space. There are still many risks, but having gone through the whole process has taught us valuable lessons. We believe the space experiments will provide us with plenty of additional useful information that will guide the project as we continue to move forward."