This year, The Planetary Society celebrates its 45th anniversary. Since 1980, the Society has been empowering members to advance space science and exploration through public education, political advocacy, innovative science and technology projects, and international collaborations. One particular effort has been ongoing for much of the organization’s history: solar sailing. In 2019, LightSail 2 succeeded at using sunlight alone to change its orbit around Earth, achieving a goal that The Planetary Society had been working toward since its very beginnings.

The concept of sailing on sunlight stretches back much farther than our organization. After observing Halley’s Comet in 1607, Johannes Kepler mused that people might one day surf on the same force that causes a comet’s tail to spread: “Provide ships or sails adapted to the heavenly breezes, and there will be some who will brave even that void.”

It would take centuries for Kepler’s romantic idea to get serious consideration. In the 1970s, engineer Jerome Wright discovered that a spacecraft propelled by the gentle push of sunlight might be able to rendezvous with Halley’s Comet in 1986, marking a full-circle moment for the concept.

NASA was interested and funded a Halley solar sail spacecraft study. One of the engineers on the project was Louis Friedman, who would later become a co-founder of The Planetary Society. The spacecraft’s eventual design resembled two spinning ceiling fans stacked on top of one another, each with six blades measuring more than 6 kilometers (4 miles) long. Ultimately, the design was deemed too ambitious, and the U.S. did not send a mission to Halley’s Comet.

In 1980, Friedman, Carl Sagan, and Bruce Murray founded The Planetary Society. All three were solar sail enthusiasts, with Murray having supported the Halley sail study when he was the director of NASA’s Jet Propulsion Laboratory and Sagan having written a popular article about the concept for Parade magazine.

Source: The Planetary Society.