page_title: LightSail
section_title: Design
hierarchical_section_title: LightSail / Design
caption_attribution_description: English: LightSail 2, a solar sail cubesat created by The Planetary Society, is shown "sailing" above the Earth in this artistic rendering. LightSail 2 launched on 25 June 2019 and deployed its sails to begin solar sailing on 23 July 2019.
context_page_description: LightSail is a project to demonstrate controlled solar sailing within low Earth orbit using a CubeSat. The project was developed by The Planetary Society, a global non-profit organization devoted to space exploration. It consists of two spacecraft—LightSail 1 and LightSail 2. LightSail 1 was an engineering demonstration mission designed to test its new sail deployment method in space, it did not perform solar sailing. LightSail 2 is a fully functional spacecraft intended to demonstrate true solar sailing and incorporates the lessons learned from LightSail 1. LightSail is a follow-on project to Cosmos 1—a solar-sail spacecraft designed by The Planetary Society in the early 2000s, which was destroyed during a launch failure in 2005.
  Both LightSail spacecraft measure 10 cm × 10 cm × 30 cm in their stowed configuration. After sail deployment, the total area of each spacecraft is 32 square meters.
context_section_description: As a solar sail, LightSail's propulsion relies on solar radiation and not the charged particles of the solar wind. Solar photons exert radiation pressure on the sail, which produces an acceleration on the spacecraft relative to the ratio of the sail's area to its mass. As such, the design challenge was to maximize the surface area of the sail while minimizing the mass of the spacecraft—all while adhering to the standard 3-unit CubeSat size limitation.
  LightSail's modular design is based on a modular 3-unit CubeSat, a small satellite format created for university-level space projects. One CubeSat-sized module carries the cameras, sensors and control systems, and the other two units contain and deploy the solar sails.
  The spacecraft contains four triangular sails, which combine to form a rectangular-shaped surface. The sails are made of Mylar, a reflective polyester film.
  LightSail has multiple configurations. It was launched in a stowed configuration with its sails folded within the spacecraft. After launch, it enters an intermediate phase by deploying a small antenna and flipping open its solar panels. This exposes the cameras and reveals the stowed solar sails. To achieve its final "solar sailing" configuration, LightSail extends four 4-meter cobalt alloy booms that slowly spread open the mylar sail material.
  Using an internal reaction wheel, LightSail 2 is able to orient itself against the Sun using Earth's magnetic field as a guide. By "tacking" in and out of the Sun, it can control the force on its sail and thus change its orbit.
caption: Artist's concept of LightSail orbiting the Earth
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