On May 20, a spacecraft roughly the size of a toaster will hitch a ride aboard an Atlas V rocket and soar to an altitude of 450 miles above Earth. Called the LightSail-1, the decades-in-the-making, privately funded $1.8 million mission from the Planetary Society will be the first step in testing a solar sail as a means of spacecraft propulsion.

"LightSail is technically wonderful, but it's also wonderfully romantic. We'll sail on sunbeams," Planetary Society CEO and "Science Guy" Bill Nye said in a statement earlier this year. "But wait, there’s more: this unique, remarkable spacecraft is funded entirely by private citizens, people who think spaceflight is cool." 

Bill Nye with LightSail-1 spacecraft

Bill Nye holding the toaster-sized LightSail-1 solar sail spacecraft. (Photo: Planetary Society/Scott Schafer) 

I previously wrote about this mission in late January, but solar sail technology is back in the news thanks to a video posted by the Planetary Society featuring its co-founder, the late great astronomer Carl Sagan, appearing nearly 40 years ago on "The Tonight Show with Johnny Carson." In it, Sagan talks about solar sails and their potential to revolutionize space travel. 

"There's a tremendously exciting prospect called solar sailing, which travels on the radiation and particles that come out of the sun — the wind from the sun," Sagan told Carson. "It works exactly as an ordinary sailboat does, so it can go out from the sun, it can tack inwards to the sun, and because it has a constant acceleration it can get you around the inner part of the solar system a lot faster and a lot more conveniently than the usual sorts of rocket propulsion." 

While LightSail-1 won't achieve an orbit high enough to take advantage of solar radiation, it will unfurl its 344 square feet of Mylar sails as a proof of concept. Should all go well, the Planetary Society will prep the launch of LightSail-2 for a full-fledged solar sail flight in 2016. 

"It's just an extraordinary idea," Sagan told Carson. "And there might be a time when we start doing it for planetary regattas. It's a whole new kind of idea." 

We can't wait to see Sagan's vision come to life. You can check out a live stream of the May 20 launch event here

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