June 8, 2015

LightSail, an experimental solar-powered spacecraft orbiting the Earth, has finally deployed its sail, Bill Nye proudly announced Sunday. The tiny solar sail — it’s only 11 pounds — is the work of a Science Guy-run NGO called The Planetary Society, a non-government organization that promotes space research. Its goal is to make space exploration affordable and efficient by building a spacecraft that sails entirely on beams of light.

Why haven’t I heard about this before?

LightSail is just on a test mission at this stage. Even though the sail has deployed, the spacecraft’s orbit is too low to allow the solar power to push it out of the atmospheric drag. For now, the LightSail is making sure that functions like sail deployment, communications and imaging are operational.

It hasn’t been smooth sailing, though: After the LightSail’s test mission launched on May 20, the spacecraft lost connection with on-the-ground controllers due to a software glitch. Nye’s team finally established a steady connection on Saturday.

So how does LightSail work?

It’s as simple as it sounds: LightSail moves through space by sailing on beams of light. Light is made up of tiny particles called photons, and when many photons are hitting the solar sail, they will theoretically push the spacecraft forward.

The design is simple, too, at least when compared to other spacecraft. LightSail consists of a CubeSat, a mini satellite roughly the size of a loaf of bread, and four triangular Mylar sails that form a square about 18.5 ft. by 18.5 ft in size. The estimated total cost is about $5.45 million.

Wait. Can you really sail on sunlight?

Yes. Since the 1990s, there have been many attempts to do exactly that — mostly unsuccessful — by space agencies around the world, including NASA. The first success came in 2010, when the Japanese Aerospace Exploration Agency announced that its spacecraft IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) had successfully deployed its sail and began being propelled by sunlight, according to the spacecraft’s data.

How fast can LightSail move if it’s powered by only light?

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We’ll know for sure once the primary mission scheduled for fall 2016 launches (and if it launches successfully). But data from Japan’s IKAROS showed that sunlight was providing an acceleration of 1.12 millinewtons, which is about 1/4,000th of a pound of force. That’s hardly anything, but since acceleration is constant up in space — there’s no friction for the most part — solar-powered spacecraft will continue to speed up, eventually reaching high speeds.

The biggest draw for this technology is that sunlight is absolutely free (and continuous, at least for the next several billion years). As a result, solar-powered space travel has the potential of reducing what are currently super-expensive, limited-lifetime space missions. Nye believes LightSail will promote “low-cost citizen projects” in space exploration, allowing students and faculty at universities to launch their own space missions.

That sounds great. But will I ever be able to do anything with LightSail?

Actually, yes. Though LightSail is nowhere near being capable of sailing a group of humans to Mars for the holidays, it is able to carry data and information, including your selfie. So even if you’re never going to launch your own solar-powered spacecraft, you can still get in on the fun by being part of the first collection of selfies to make it into space.

Read next: Watch Bill Nye Explain the Universe, Amy Schumer-Style

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