This Space Solar Power presentation from April shows four companies actively pursuing space mirrors (Arthur D. Little, Reflect Orbital, Light Mirror, JX Crystals), though only Reflect has committed to launching 2 test satellites in 2025.Also found an interesting NASA study (Jan 2024) for two giant space-based solar power systems constructed by Starship (5.9 Mkg mass for design 1 and 10 Mkg for design 2).
Quote from: redneck on 09/25/2024 12:22 amI think this reflector concept appeals to people that aren't paying close attention to details. Thousand of reflectors to gain half an hour at dawn and dusk seems like it would lose out in trades to a system of coherent beaming. IOW, a dozen coherent beam sats vs thousands of reflectors.On the contrary, I think the vast majority of those dunking on it have only barely thought of the concept in detail.Sun synch orbit means the satellites are always in sunlight. They may only be in orbit over a site for a few minutes, but if solar farms are widely distributed, they should be able to beam sunlight roughly 10% of the time. That doesn't sound like a lot, but...A coherent beam satellite has to be super heavy. Solar panels are 100W/kg, plus the beam mechanism usually loses half the power in conversion to beam energy, so that has to be radiated and requires twice the input power. And the laser or microwave emitter itself is heavy and likely dominates the cost ($10/Watt for a cheap diode laser?). So you're at around 20W/kg, maybe less. And a coherent beam is going to require a large aperture.A solar sail can be insanely lightweight and doesn't need to convert, just reflect. The sail material itself can be just 1-3 microns thick. With booms and stuff, maybe 13 grams per square meter. Reflecting ~1300W/m^2 (98% efficiency), you're looking at 100,000W/kg.Solar sails typically don't optimize for high flatness. To do that you need more tension and/or a thicker material. So you may only get 65-130g/m^2 for early sails, but that's still an impressive 10,000-20,000W/kg. Still 1000 times better!I think people just aren't realizing how big of a difference there is between the weight of a mirror vs the weight of a solar panel, radiator, and radio transmitter (or laser) setup is. They're literally just not grasping this key aspect of the idea, just operating on vibes and then going straight for the dunk.
I think this reflector concept appeals to people that aren't paying close attention to details. Thousand of reflectors to gain half an hour at dawn and dusk seems like it would lose out in trades to a system of coherent beaming. IOW, a dozen coherent beam sats vs thousands of reflectors.
Quote[weird reflector idea that's probably a scam]If we could get an additional half-hour at dawn or dusk, could we call off daylights savings time?Because I would toss a very large number of satellites into the sky to do that.
[weird reflector idea that's probably a scam]
What kind of orbit would be needed to get reflectors to work during winter at really high latitudes (eg Alaska, northern Canada, Scandinavia, Iceland, northern Germany or Scotland)? Terrestrial solar + lots of batteries probably wins out over any space solution (and likely other high tech power solutions like fusion) in most places, but there's a huge difference between dealing with nighttime or a few cloudy days, vs an entire season with near zero insolation.
