There is a fiction I've read years ago that mentioned satellites becoming makeshift weapons by overheating exposed objects (think reactors, gas trucks, oil refineries) by acting as a solar furnace [1] via mirrors.
Not sure/don't recall how it deals with practical issues such as clouds and distance/intensity, but good enough for a story I guess.
I thought this was interesting because it doesn’t really seem like an applicable top level claim, surely this is referring to a specific furnace, not all solar furnaces?
Then this got me thinking if there is some universal upper bound constraint to these temperatures. E.g. if I recall a telescope can’t make a source object brighter than it actually is, and this just seems like a thermal telescope, so I wonder if that principle applies here or not.
It applies, but also in practice the maximum temperature is lower than the theoretical upper bound.
> "In general, there's no way to "overlay" light beams on each other, because the whole system has to be reversible".
Behold, my two torches.
Masers are not useful as powerful transmitters, but only as amplifiers with a very low noise or as generators with a very stable frequency.
Edit: and also don't forget that the Sun is not a point source and has an appreciable angular size, further making it impossible to focus it with a reasonably-sized lens or mirror.
Obviously this satellite isn't viable, but all things start small. Large tracts of land could be illuminated.
But of course, I question the logic of redirecting more sunlight, especially such large amounts, onto a world already warming uncontrollably.
Still, it could be useful for the polar caps on Mars?
These seem like unlikely things though.
What might be more useful is to illuminate just the areas where a human currently needs to see well. It would hypothetically be both more useful - you can concentrate more light in just the areas you need it - and less expensive.
What would be particularly cool about this hypothetical technology is that it could work equally well under foliage and indoors.
That said, I'm (armchair) confident it'll be good for moonlight-level illumination on a local area at best. They'll need to scale up to thousands / tens of thousands to make any measurable impact - which is their objective by the looks of it, but it'll take a while yet. If this one creates enough backlash, a fleet won't make it. Assuming they get the money and customers to justify a fleet in the first place.
(For reference, I think all of these are likely to be somewhere between moderately and incredibly bad ideas...)
The energy has to go somewhere. If you're not reflecting it you're absorbing it and you eventually have to do something else with it.
My guess is it's probably easier to make a bunch of greenhouses on the surface? But the scale is so huge that which is best will be affected by technology invented after you start.
In my book, that would have been a "Fortunately," entry.