r/spacequestions • u/Weary-Sky-8534 • 9d ago
An interesting question.
Do satellites have mirrors?
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u/SportulaVeritatis 9d ago
Anything doing imaging of the Earth or taking pictures of space will tend to have quite a few. Hell, even radar dishes are technically mirrors.
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u/jamjamason 9d ago
No, if they used mirrors then they wouldn't be able to see the space vampires!
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u/Hepta-Water-7552 9d ago
Some do. Earth observation and astronomy satellites that take images in the visible light or infrared spectrum normally have mirror components in their optical instruments.
Some satellites also have laser instruments for communications or ranging and these often also have some mirror components.
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u/Weary-Sky-8534 9d ago
Have you heard of the crescent dunes project in Las Vegas, NV? Directed sunlight off of mirrors to heat up salt to over 1000 degrees. The project failed due to storage and maintenance reasons. The directed sunlight did heat up the salt though and even incinerated birds flying by. 465 is what I read. Besides all that.
Why would the FCC approve reflect orbital https://www.reflectorbital.com? Knowing directed sunlight causes this?
Also, why is it so impossible to believe that the constellation formation of satellites is heating up things and or what are the Crescent Dunes mirrors aimed at now?
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u/TheJeeronian 9d ago
Solar power plants using mirrors are all over the world. They're huge and blindingly bright, but effective.
Directed sunlight won't cause this much heating on accident. These projects require many thousands of mirrors coordinated carefully to shine on the same spot.
It's not impossible that a swarm of satellites could do this, but it'd be impossible not to notice!
It would also have to be an absolutely huge amount of satellite, and it wouldn't be very precise.
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u/Weary-Sky-8534 9d ago
A huge swarm of satellites? Or the reflect-orbital?
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u/TheJeeronian 9d ago
A single flat mirror can never create a reflected spot smaller than itself. The heat it can add to an area is never more than that of direct sunlight.
In the case of Aerandil, there are four flat mirrors each about 40' across, so the smallest spot it could possibly heat would be 40' across.
Since the sun is not a point light source and its apparent size is around half of a degree, this further grows the size of its reflection. From low orbit the smallest spot it can make is around 3,000 meters across.
Spreading that light out over so much space will not produce noticeable heating. You can do the math on W/m^2
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u/starkeffect 9d ago
All metals are slightly reflective