How do you feel about sustainable space travel? Awesomely? The Japanese space program has successfully unfurled the first solar sail, which means Big Things for us humans ranging about the galactic neighborhood.
A solar sail uses the pressure from photons striking its surface to push the spacecraft through space. Materially, the 650 square-foot sail is made of incredibly thin, aluminized plastic that’s only 0.0003 inches thick, a little thicker than spider silk, or about the diameter of a red blood cell. When a photon strikes its surface, it bounces off, imparting its momentum to the sail. Each photon might not deliver much thrust, but over time, all that light adds up.
“It’s the only way we know — that anybody knows — to ultimately do practical interstellar flight because you don’t have to carry your propellant along with you,” exploration guru Louis Friedman said. “Anything else you do, whether it’s nuclear or advanced engines, you’re always carrying propellant and the mass becomes too great.”
The propellant problem is with us down here on earth, too.
via Wired Science.
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