Bill Nye the Science Guy is counting down to a launch almost 40 years in the making.

In 1976, Carl Sagan went on The Tonight Show to talk to Johnny Carson about a new technology he and his Planetary Society cofounders, Louis Friedman and Bruce Murray, were hoping to put to work: solar sailing. Their dream is finally about to become a reality. This week, Nye—who is the current CEO of The Planetary Society—launched a Kickstarter devoted to raising money for LightSail, the world’s first solar-sailing spacecraft.

“LightSail is a huge contribution to space science and exploration,” Nye explains on the campaign’s page. “Through this proof-concept mission, we will … open new paths beyond Earth, and, one day, potentially to other planets with an inexpensive, inexhaustible means of propulsion: photons, solar energy in its purest form.”

How, exactly, does solar sailing work? The sun emits light, which is comprised of units of energy called photons. When these traveling photons come into contact with the LightSail’s mirrored surfaces—its sails—their momentum is transferred to the spacecraft, which pushes each sail. Because these tiny accelerations are continuous, the craft is able to reach greater speeds than fuel-powered vehicles, which are driven by short bursts.

The spacecraft itself is tiny—“no bigger than a breadbox,” Nye notes—but its success would pave the way for future voyages to further locations using bigger spacecraft. 

The LightSail is scheduled for a test flight on May 20 so its creators can check its sail deployment. If all goes well, it will take part in a 30-day, low-orbit test flight in 2016. That's where the Kickstarter comes in.

Though The Planetary Society was able to raise most of the $5.45 million required for the 2016 flight, the group still needs an additional $1.2 million. The Kickstarter has already surpassed its initial $200,000 goal and is now in “stretch goal” territory, having brought in nearly $335,000 to date.

For updates on the LightSail project, check out the group’s Kickstarter page, or visit sail.planetary.org.