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Our Work Explore Space Take Action About Account Center Search “Exploration is in our nature.” - Carl Sagan LightSail Flight by Light for CubeSats 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, launched 25 June 2019 , uses sunlight alone to change its orbit, and is currently operating under an extended mission to further advance solar sailing technology. 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 a solar sail spacecraft to visit Halley’s Comet . Fellow co-founder Carl Sagan promoted the concept on The Tonight Show with Johnny Carson in 1976 . The Planetary Society’s first crowdfunded solar sail mission, Cosmos 1, failed to reach orbit after launching aboard a Russian rocket in 2005. That effort led to the dual-spacecraft LightSail program . LightSail 1, identical to LightSail 2 with a few key differences , completed a successful deployment test in 2015. 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 carries a disk with names, selfies, and other messages from our members and supporters. Search for your participation certificate here . LightSail 2 over India LightSail 2 regularly transmits images from its onboard cameras. These images help engineers track the condition of the sail while providing stunning public outreach images. The Planetary Society More images from LightSail 2 Track the spacecraft How LightSail 2 works For launch , LightSail 2 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 orbit with an inclination of 24 degrees. LightSail 2 launch video from SpaceX The Planetary Society's LightSail 2 spacecraft launched aboard a SpaceX Falcon Heavy rocket on 25 June 2019. SpaceX Please accept marketing-cookies to watch this video. 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 23 July 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. 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. 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. LightSail 2 sails deployed The Planetary Society LightSail 2 panels open The Planetary Society Though the spacecraft orbits Earth higher than the International Space Station, the planet’s atmosphere is still thick enough to counteract the thrust gained from solar sailing. Analyses of orbital data show that LightSail 2’s rate of orbital decay is markedly slower in solar sailing mode, when the craft actively positions itself to get a push from sunlight. During some time intervals, the spacecraft even gains enough thrust to briefly overcome atmospheric drag and raise its orbit. The LightSail 2 extended mission is expected to continue as long as the spacecraft remains healthy, or until its orbit decays and the spacecraft reenters Earth’s atmosphere many months from now. LightSail Academic Resources Our LightSail academic resources include schematics, links to peer-reviewed papers, parts lists, and more. How to see and track LightSail 2 Naked-eye observing LightSail 2 is visible to the naked eye for some observers at dusk and dawn. Our mission control dashboard shows upcoming passes based on user location, and includes a link to a page that highlights passes when the sail is more likely to be visible . The spacecraft has an orbital inclination of 24 degrees, which will keep it much closer to the equator than LightSail 1. We estimate this will restrict viewing to latitudes within 42 degrees of the equator. You can see a location’s latitude and longitude in Google Maps by right-clicking the map and selecting “What’s Here?” The first number in the resulting information box is your latitude, and must be between 42 and -42 to see LightSail 2. Radio tracking Radio trackers can download LightSail 2's beacon structure for help with decoding packets. Here are some additional useful parameters: WM9XPA | 437.025 MHz | AX.25 | FSK | 9600 bps Every 45 seconds, the spacecraft transmits its call sign, WM9XPA, in morse code: .-- -- ----. -..- .--. .- You can download audio files of the morse code beacon below, and even use them as a ringtone for your phone! LightSail 2 Morse code beacon, sample (WAV format) LightSail 2 Morse code beacon, sample (M4R format) LightSail 2 Morse code beacon, actual as recorded by Justin Foley (WAV format) LightSail 2 Morse code beacon, actual as recorded by Justin Foley (M4R format) Other solar sails Japan’s IKAROS spacecraft, launched to interplanetary space with Venus-bound Akatsuki in 2010, was the first and only spacecraft to have demonstrated controlled solar sailing as a sole method of propulsion. LightSail 2, which began development in 2009, will demonstrate the technology for CubeSats. CubeSats have revolutionized the space industry thanks t...