Matt Edwards 🚴‍♂️

While the FCC has approved a test satellite from Reflect Orbital (which wants to illuminate solar farms at night), the basic physics here seems decisive — on the side of “No, this can’t possibly be a practical thing to do.” From the linked analysis by Michael Brown and Matthew Kenworthy: [Reflect Orbital’s plan is “simple satellites in the right constellation shining on existing solar farms”. And their goal is only 200 watts per square metre – 20% of the midday Sun. Can smaller satellites deliver? If a single 54 metre satellite is 15,000 times fainter than the midday Sun, you would need 3,000 of them to achieve 20% of the midday Sun. That’s a lot of satellites to illuminate one region. Another issue: satellites at a 625km altitude move at 7.5 kilometres per second. So a satellite will be within 1,000km of a given location for no more than 3.5 minutes. This means 3,000 satellites would give you a few minutes of illumination. To provide even an hour, you’d need thousands more. Reflect Orbital isn’t lacking ambition. In one interview, Nowack suggested 250,000 satellites in 600km high orbits. That’s more than all the currently catalogued satellites and large pieces of space junk put together. And yet, that vast constellation would deliver only 20% of the midday Sun to no more than 80 locations at once, based on our calculations above. In practice, even fewer locations would be illuminated due to cloudy weather.] https://theconversation.com/a-us-startup-plans-to-deliver-sunlight-on-demand-after-dark-can-it-work-and-would-we-want-it-to-264323 https://ca.pcmag.com/news/16760/fcc-approves-reflect-orbitals-giant-mirror-satellite-that-astronomers-hate