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What is the Advanced Composite Solar Sail System?

A small spacecraft in Earth orbit deploys solar sail

Using Sunlight to Power Deep Space Exploration

NASA is developing new deployable structures and materials technologies for solar sail propulsion systems destined for future low-cost deep space missions. Just as a sailboat is powered by wind in a sail, solar sails employ the pressure of sunlight for propulsion, eliminating the need for conventional rocket propellant. NASA’s Advanced Composite Solar Sail System, or ACS3, technology demonstration uses composite materials – or a combination of materials with different properties – in its novel, lightweight booms that deploy from a CubeSat. Data obtained from ACS3 will guide the design of future larger-scale composite solar sail systems that could be used for space weather early warning satellites, near-Earth asteroid reconnaissance missions, or communications relays for crewed exploration missions.

ACS3 Solar Sail
Engineers at NASA’s Langley Research Center test deployment of the Advanced Composite Solar Sail System’s solar sail. The unfurled solar sail is approximately 30 feet (about 9 meters) on a side. Since solar radiation pressure is small, the solar sail must be large to efficiently generate thrust.

The primary objective of the ACS3 technology demonstration is the successful deployment of the composite boom solar sail in low-Earth orbit. After reaching space, the ACS3 spacecraft will deploy its solar power arrays and then begin unfurling its solar sail via four booms that span the diagonals of the square and unspool to reach 23 feet (about 7 meters) in length. After approximately 25 minutes, the solar sail is fully deployed, and the square-shaped solar sail measures approximately 30 feet (about 9 meters) per side, or about the size of a small apartment. A suite of onboard digital cameras will obtain images of the sail during and after deployment in order to assess its shape and alignment.

ACS3’s sails are supported and connected to the spacecraft by booms, which function much like a sailboat’s boom that connects to its mast and keeps the sail taut. The composite booms are made from a polymer material that is flexible and reinforced with carbon fiber. This composite material can be rolled for compact stowage, but remains strong and lightweight when unrolled. It is also very stiff and resistant to bending and warping due to changes in temperature. Solar sails can operate indefinitely, limited only by the durability of the solar sail materials and spacecraft electronic systems in the space environment. The ACS3 technology demonstration will also test an innovative tape-spool boom extraction system designed to minimize jamming of the coiled booms during deployment.

Interest in solar sailing as an alternative to chemical and electric propulsion systems continues to increase. Using sunlight to propel small spacecraft in lieu of consumable propellants will be advantageous for many mission profiles and offers flexibility in spacecraft design to help NASA meet its missions’ objectives most efficiently.

ACS3’s 12U CubeSat
Advanced Composite Solar Sail System’s, or ACS3’s, 12-unit (12U) CubeSat spacecraft bus undergoing assembly and testing. The complete ACS3 spacecraft measures approximately 9 inches x 9 inches x 13 inches (23 centimeters x 23 centimeters x 34 centimeters), or about the size of a small microwave oven.
AST&Defense LLC


  • Demonstrate successful deployment of the composite boom as well as sail packing and deployment systems in low Earth orbit
  • Evaluate the efficacy of the shape and design of the solar sail
  • Characterize the thrust functionality of the sail as the spacecraft gradually changes orbit
  • Collect data on the sail’s performance to inform the design of larger, more complex systems

Fast Facts:

  • This is the first use of composite booms as well as sail packing and deployment systems for a solar sail in space.
  • ACS3’s composite booms are 75% lighter and designed to experience 100 times less in-space thermal distortion – change of shape under heat – than previously flown metallic deployable booms.
  • The solar sail is designed to fit inside a 12-unit (12U) CubeSat, which measures approximately 9 inches by 9 inches by 13 inches  (23 centimeters by 23 centimeters by 34 centimeters), or about the size of a small microwave oven. 
  • The composite boom technology used for this ACS3 technology demonstration could be used in future missions for solar sails up to 500 square meters (5,400 square feet), about the size of a basketball court. Follow-on composite boom technologies now in development will enable solar sails as large as 2,000 square meters (21,500 square feet).
  • ACS3 launched on April 23, 2024, aboard a Rocket Lab Electron rocket from the company’s Launch Complex 1 in Māhia, New Zealand.


  • NASA’s Langley Research Center in Hampton, Virginia, designed and built the ACS3 deployable composite booms and solar sail system.
  • AST&Defense LLC of College Park, Maryland, designed and built the 12U CubeSat spacecraft bus for the ACS3 technology demonstration.
  • NASA’s Ames Research Center in California’s Silicon Valley manages the ACS3 project and designed and built the ACS3 on-board camera diagnostic system.
  • Santa Clara University’s Robotics Systems Lab in Santa Clara, California, is providing CubeSat operations support for the ACS3 technology demonstration.
  • NASA’s Small Spacecraft Technology program within the agency’s Space Technology Mission Directorate is sponsoring the ACS3 project and is providing the funding for the launch.
  • NASA’s Game Changing Development program within the agency’s Space Technology Mission Directorate developed ACS3’s deployable composite boom technology.

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Members of the news media interested in covering this topic should reach out to the NASA Ames newsroom.

Banner image: A sped up animation of the solar sail unfurling to its final size. The process of unfurling takes about 25 minutes to complete. Credits: NASA/Aero Animation/Ben Schweighart