Imagine a spacecraft propelled by nothing but light.
A massive aluminum-coated sail stretches wide, capturing the momentum from photons when they reflect off the surface. The photons' energy is transferred to the sail, slowly but surely propelling it forward. The continuous momentum allows it to soar through space, no rocket required.
Novelists, poets, and scientists have envisioned spacecraft powered by solar sails since the 1600s.
But now this fanciful concept is actually entering into reality.
NASA, the European Space Agency (ESA), the Japanese Aerospace Exploration Agency (JAXA), and The Planetary Society have all either deployed solar sail-powered spacecraft or are looking into it.
Here's how they could revolutionize space exploration.
Solar sails use light to move just like sailboats use wind.
Eliminating the need for rocket thrusters to position the satellite or spacecraft, solar sails can be much smaller and lighter. The Planetary Society's LightSail is about the size of a loaf of bread.
But its sail, which deploys once it's in space, stretches 344 square feet.
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