Where the sun always shines: putting the sun into space

Then he explained why his system didn't look like this in the end, even if it did.

Long Carry

In August, the California Institute of Technology announced that a board member had committed more than $100 million to space energy development. The timing was somewhat odd, given that the donor, Donald Burn, started the process over a decade ago. At the time, Bern expressed interest in the university's administration's space Force, which began identifying faculty with research interests related to the project.

“At first, I was very skeptical, because this is an idea that has been visited many times,” Atwater told Ars. "What new can be done?" But over the years, he gradually became convinced that a few different approaches might be possible. Atwater certainly had the relevant experience. He had previously established a subsidiary focused on ultra-lightweight PV devices. He was joined by Caltech specialists: Ali Hajimere (who has worked on energy conversion devices) and Sergio Pellegrino (described by Atwater as "one of the world's pioneers in developing usable lightweight space structures").

Group experiences were crucial to producing a design that represented a major change in thinking over previous ideas. “The key factor in space is not efficiency per se,” Atwater told Ars. “This is a special force — that is, the power per unit mass. What matters most to us is watts per kilogram,” because mass per unit area and the total mass of a charge were very large, respectively. In some important assumptions, most photovoltaic systems in space use highly efficient cells consisting of three layers of light capture, each modulated according to different wavelengths of light. They are used to achieve more efficiency per unit mass.

Efficiency loss per unit area by spreading photovoltaic cells over a large area. This is done using a flexible membrane that the Atwater can describe as "thinner than the thinnest plastic bag I've ever picked up". The structure is kept in place (AutoWater suggested thinking of a canopy or backpack tent.)

Another major source of weight is the copper wires used to transmit current to the c current that travels to the ground is used. So heavy wires must be eliminated, which limits the amount of current that can be transmitted to the transmitter. Therefore, the Solar space Project is focused on building small, independent units called tiles, each with its own transmitter. This limits the total power the wires have to carry and makes the wires much smaller possible. This also means that the energy conversion of the transmission can be done using a small chip of silicon. They are designed to be foldable into existing actuator hardware, and then expanded once in the circuit. While all structural tiles operate independently, the structure provides the small actuators needed to maintain useful orientation throughout the circuit.

"Plants" in space

A single structure alone does not provide much energy, so a potential power plant needs many structures to be formed. Thus, a complete plant consists of a hierarchy of components: tiles that work independently are installed on a single structure, with multiple structures to produce sufficient strength. The entire complex must be placed in a geostationary orbit in order to remain on top of a ground receiving station, enjoying sunlight around the clock.

Atwater told Ars the plan was to have the receiving station the size of a large solar farm. This group includes a large number of rectangles that convert microwaves sent from space into usable energy.

Early in the ground station discussion, Atwater interrupted our questions. "I want to get something off the table that you didn't ask me about," he said. The answer to his question lies in the physics that govern the focus of photons, which states that the combination of aperture and wavelength determines the smallest focus area. “The total flow of energy at microwave frequencies is what you get from walking under it,” Atwater says. It will be transmitted, and then large portions of that energy is lost during transmission.

How does it all balance out? It depends on your assumptions. , but Atwater gives a rough estimate of presentation.” Net energy generated is a little more than you can get in the sun 24 hours a day, noon.

Next Steps

Twelve years ago, we talked to the folks who founded a company that took a space energy approach indistinguishable from what Atwater was telling us. So, simply by challenging current thinking , the Caltech project could perform an important function.

But Atwater also said the project "aims to produce solar energy production infrastructure technology in space in a cost-effective and scalable manner." There are plans to submit a space demonstration in late 2022 or early 2023 (these dates may explain why Caltech decided to talk about the project.) They need to find business partners to really prove themselves. If they can attract one, it will be an assurance of achieving the "cost-effective" part of the goal .