sail.planetary.orgLightSail, a Planetary Society solar sail… | The Planetary Society

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Support Our Mission Renew Membership Society Projects Travel Other Ways to Give Store The Planetary Fund Accelerate progress in our three core enterprises — Explore Worlds, Find Life, and Defend Earth. You can support the entire fund, or designate a core enterprise of your choice. Give Today Back To Overview Strategic Framework News & Press Careers Contact Us Our Story The Planetary Society Our Vision Know the cosmos and our place within it. Our Mission Empowering the world’s citizens to advance space science and exploration. Back ToMembership Become A Member Renew Membership Gift Membership Kids Membership Other Ways to Give Contact Us Our Work Explore Space Take Action About Membership Member Community Account Center Search Exploration is in our nature.” - Carl Sagan LightSail, a Planetary Society solar sail spacecraft Highlights The Planetary Society’s LightSail program demonstrated that solar sailing is a viable means of propulsion for small satellites. Solar sails use sunlight instead of rocket fuel for propulsion. They are one of the few technologies that could be used for interstellar travel. Our LightSail 2 spacecraft was in space from June 2019 to November 2022 and successfully used sunlight alone to change its orbit around Earth. LightSail® is a crowdfunded project from The Planetary Society to demonstrate that solar sailing is a viable means of propulsion for CubeSats — small, standardized spacecraft that are part of a global effort to lower the cost of space exploration. Our LightSail 2 spacecraft, which launched on June 25, 2019 and reentered Earth’s atmosphere on Nov. 17, 2022, used sunlight alone to change its orbit. LightSail 2 completes mission with atmospheric reentry The three-and-a-half-year solar sailing mission showed LightSail 2 could change its orbit with sunlight alone. LightSail 2 was named one of TIME’s 100 Best Inventions of 2019 , and won a Popular Science Best of What’s New award for 2019. The spacecraft carried a disk with names, selfies, and other messages from our members and supporters. Search for your participation certificate here . This content is hosted by a third party (youtube.com), which uses marketing cookies. Please accept marketing cookies to watch this video. LightSail 2’s views of Earth A compilation of images taken by The Planetary Society’s LightSail 2 spacecraft from orbit. It shows the solar sails’ deployment as well as many views of Earth. Video: The Planetary Society See images from LightSail 2 What is solar sailing? A solar sail, simply put, is a spacecraft propelled by sunlight. Whereas conventional rockets are propelled by the combustion of rocket fuel, a solar sail is pushed forward by light from the Sun. Learn more about the basics of flight by light here . Light is made of packets of energy called photons. While photons have no mass, they have momentum. Solar sails capture this momentum with sheets of large, reflective material such as Mylar. As photons bounce off the sail, most of their momentum is transferred, speeding up the sail in the direction opposite the bouncing light. Unlike chemical rockets that provide short, powerful bursts of thrust, solar sails provide continuous, slight thrust and can reach higher speeds over time. Sunlight is free and unlimited, whereas rocket propellant must be carried into orbit and be stored onboard a spacecraft. Solar sails are also one of the only known methods that could someday be used to travel to the stars. In 2016, the group Breakthrough Initiatives announced an initiative to send a fleet of laser-powered solar sails to our nearest star, Alpha Centauri. LightSail 2 solar sail specs The spacecraft’s sails measure 5.6 meters (18.4 feet) per side. Image: The Planetary Society LightSail 2 core spacecraft specs Image: The Planetary Society When did LightSail 2 launch? LightSail 2 launched on June 25, 2019. The spacecraft was enclosed within Prox-1 , a Georgia Tech student-built spacecraft the size of a large suitcase that was selected to fly as part of the Air Force’s University Nanosat Program. Both spacecraft were attached to the upper stage of SpaceX’s Falcon Heavy rocket, which launched 24 spacecraft to orbit for the U.S. Air Force’s Space Test Program 2 (STP-2) mission. Prox-1 and LightSail 2 were delivered into a circular, 720-kilometer (447-mile) orbit with an inclination of 24 degrees. Seven days after launch, Prox-1 ejected LightSail 2 . After a checkout period of a few days, LightSail 2 opened its hinged solar arrays . On July 23, 2019, it deployed its 32-square-meter solar sails. Each orbit, LightSail 2 swings its solar sail into and away from the Sun’s rays, giving the spacecraft a slight push. This content is hosted by a third party (youtube.com), which uses marketing cookies. Please accept marketing cookies to watch this video. When did LightSail 2 come down? The Planetary Society’s LightSail 2 spacecraft reentered Earth’s atmosphere on Nov. 17, 2022, successfully completing its mission to demonstrate flight by light for small spacecraft. Though the spacecraft orbited Earth higher than the International Space Station, the planet’s atmosphere was thick enough to counteract the thrust gained from solar sailing. Analyses of orbital data showed that LightSail 2’s rate of orbital decay was markedly slower in solar sailing mode, when the craft actively positioned itself to get a push from sunlight. During some time intervals, the spacecraft even gained enough thrust to briefly overcome atmospheric drag and raise its orbit. However, atmospheric drag eventually won out, bringing the spacecraft down low enough that it burned up. LightSail 2 images from space LightSail 2 regularly transmitted images from its onboard cameras. These images helped engineers track the condition of the sail while providing stunning public outreach images. See the full collection of images from the spacecraft here . LightSail 2 The Planetary Society’s LightSail 2 spacecraft during sail deployment testing in 2016. Image: Jason Davis / The Planetary Society How LightSail enabled future solar sail missions LightSail 2 was meant to enable and support future solar sailing missions. A big part of our extended mission involved sharing what we were learning. We published peer-reviewed journal articles , made conference presentations and conducted public outreach through social media and articles like the one you’re reading right now. We also interfaced directly with other solar sailing missions. NASA has three such missions planned or underway: NEA Scout , Solar Cruiser , and ACS3 . We continue share data and facilitate additional studies to help these mission teams learn from our experiences. Furthermore, we document and archive our LightSail 2 data so that it is available for analysis by future missions. The History of Solar Sailing Image: The Planetary Society Project history The Planetary Society’s history with solar sailing dates back to the mid-1970s, when co-founder Louis Friedman led a NASA effort to send...