Space-based solar power hardware ready for real-world testing in space

Enlarge / The frame needed to deploy the hardware worked on Earth, so it's time to test it in space. Caltech/Momentus

Solar energy has become the cheapest way to generate electricity on Earth. But building it on Earth places significant limits on the amount of power it can generate, with darkness and clouds often getting in the way. So there have always been a few people who liked the idea of ​​putting solar panels where they could generate electricity 24 hours a day: space.

While this gets you close to 24/7 power generation, it comes with a very obvious set of downsides: high start-up costs, inability to maintain hardware and difficulty getting power back to where it is needed. It's been difficult to determine how these trade-offs play out in the energy market, partly because the energy market is changing so rapidly, and partly because we don't really know what space solar hardware would look like. .

With funding from a private donor, however, researchers at the California Institute of Technology have been quietly working on developing the technology needed to make space solar power work. And they're apparently ready to put test material through the rigors of space, thanks to the successful launch of Falcon 9 this morning.

What do we need?

The Caltech team's planned design for a space-based power plant is shaped by simple economic considerations: the biggest cost will be the trip to orbit, where weight is the key factor. So getting the most out of a given weight is central to its planning. The design limits weight in part by minimizing support structure for functional hardware, including cabling. To do this, its "panels" are self-contained, with their own structural support and power transmitter. These individual panels will fit together like tiles to form a larger area but will function independently.

This design dictates what the Caltech team needs to test: a lightweight power transmitter, a thin membrane that can be deployed in space, and different photovoltaic materials that can be placed on the flexible membrane. And that's exactly what's now in space on their test hardware.

Hardware includes MAPLE (Microwave Array for Power-transfer Low-orbit Experiment), which is an array of lightweight, flexible microwave transmitters capable of the precise synchronization needed for a large collection of transmitters to all transmit to a single recipient. MAPLE has two different receivers on board so that direct transmission capability can be tested.

DOLCE is the orbit-deployable ultralight composite experiment, and it will expand once in orbit to cover an area of ​​about four square meters. It is intended to test the frame used to extend and support the solar panel in space.

DOLCE hardware in its compact form. Caltech/Momentus

Caltech does not say what ALBA stands for, but it will be a collection of 22 different photovoltaic materials and will be used to determine which of them holds up well in space.

All hardware is attached to a commercial orbital transfer vehicle, used to ferry smaller satellites to their intended orbit. DOLCE's testing, which largely consists of determining whether it runs successfully, should proceed relatively quickly, with results being captured by onboard video cameras and beamed back to Earth. By contrast, they expect testing of photovoltaic materials to take about six months in orbit to produce clear results.

First steps

It's not hard to see why this was done by a university team rather than a private company. Space is expensive and we don't even know what technologies would work to generate and transmit energy from orbit. It would be a very high-risk lawsuit for a private company, especially given how fast the cost of Earth-based renewable energy has fallen. Depending on the progress of the tests, it will probably take us a long time before we can deploy an operational space solar power plant.

But...