NASA's solar sail successfully spreads its wings in space
NASA's solar sail successfully spreads its wings in space
www.space.com
NASA's solar sail successfully spreads its wings in space
cross-posted from: https://lemmy.world/post/19354798
12 comments
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If photon hitting a surface can impart momentum, does generating photons also impart momentum? Like, if you put a solar powered laser pointer in space, would it move?
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Yes, it's called radiation pressure by emmision
The formula for it is Irradiance^1 of the emission/speed of light.
1: irradiance is basically how much power per unit area is emmited by the object, it's units are watt/m^2
As for the lasers thing, I'm not a 100% sure how effective that will be and TBH lasers are pretty complicated and I don't really get them
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Yes, but that would be a lot less efficient. With a dielectric mirror you can get easily 99.9% of the maximum momentum gain from the light, while with a solar powered laser you would get for the emission the compounded efficiency of the solar panel + storage + laser, so way below 10%. So you would gain around 10 times more impulse from your solar panel absorbing light than from the actual laser.
The final momentum gain is a bit different as the maximum you can gain from a photon is double its momentum (because you can reflect it back with opposite direction).
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aww so people are pushed away from me because of my brightness and not because I'm dumb??
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Sure, but it would be less efficient than a sail, and since the incoming radiation would impart inertia on the solar panels, you would still be limited on where you could steer.
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12 comments
"The location of the spacecraft in its orbit is roughly two times the altitude of the International Space Station. If you were looking at the sail from above..."
Gotta level with you nasa, for most of us we're going to be looking at things at that altitude from BELOW.
You can check heavens above (adjust your location) to check when it will be visible for you.
Wait a second, it’s going to pass over my house in 5 minutes!
Edit: Shit, clouds!
Edit2: I was able to see it through a few gaps in the cloud cover!
Fuck that's cool. You lucky bastard.
Wow. Suprised this is ground level visible. Cool that you saw it!
NASA needs to check their altitude privilege
/s