3 ms·

Colour me stupid, but in a simple white vs. black comparison, wouldn't a VantaBlack-clad solar sail absorb more energy, so be more useful? - ed I'm misunderest

• twawaaay 4y ago
  For solar sail you don't want to absorb, you want to reflect. When you absorb you only get half of the push (assuming reflective surface reflecting directly back at 100% efficiency vs absorbed heat that gets radiated omnidirectionally).
• thehappypm 4y ago
  If you’re harvesting the energy from photons into heat, you’d want black. Any photon hitting your sail would be absorbed, and give you its momentum and energy. If you’re harvesting the momentum from a photon into momentum for your spaceship, you’re better off with white. A photon being reflected gives you its momentum twice. It’s first (briefly) caught like the black sail, imparting its momentum, but then it’s re emitted and hurled away, like a cannon, giving even more reactive momentum to the sail