ACS3 Engineering Breakdown

NASA's Advanced Composite Solar Sail System, commonly called ACS3, is a small-spacecraft technology demonstration built to test lightweight composite booms that unfold a reflective solar sail. The CubeSat launched in April 2024 and later deployed a sail approximately 9 meters (30 feet) on each side, covering about 80 square meters (860 square feet). The mission explores a form of propulsion that uses the pressure of sunlight instead of carrying conventional propellant for continuous thrust after launch.

Light carries momentum. When photons strike and reflect from a shiny sail, they transfer a tiny amount of momentum to the spacecraft. The force is extremely small, but it acts continuously while sunlight reaches the sail. Solar sailing does not push against air and is not powered by solar wind. It uses radiation pressure from light. By changing the sail's angle relative to the Sun, operators can change the direction of the force and gradually alter the orbit. ACS3's primary technology is its deployable composite-boom system. Flexible polymer and carbon-fiber booms can be flattened and rolled compactly for launch, then extend to support a structure far larger than the CubeSat that carried it.

ACS3 launched on 23 April 2024 aboard Rocket Lab's Electron from Launch Complex 1 in Māhia, New Zealand, as part of the Beginning of the Swarm mission. After spacecraft checkout, mission controllers commanded the composite booms to extend and unfurl the sail. NASA announced successful deployment in August 2024 and began evaluating the boom and sail performance for future missions.