24 Jun 2021

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, mission uses composite materials - or a combination of materials with different properties, in its novel, lightweight booms that deploy from a CubeSat. Data obtained from the ACS3 mission 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.

The primary objective of the ACS3 mission is to demonstrate the successful deployment of the composite boom solar sail in low-Earth orbit. After reaching space, the mission’s CubeSat 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 7 meters (about 23 feet) in length. After approximately 20 or 30 minutes when the solar sail is fully deployed, the square-shaped solar sail measures approximately 9 meters (about 30 feet) 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.

The ACS3 mission’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 space environment durability of the solar sail materials and spacecraft electronic systems. The ASC3 mission 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.

Mission Objectives:

• 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 orbit.
• These composite booms are 75% lighter and 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 23 centimeters x 23 centimeters x 34 centimeters, or slightly larger than a toaster oven. 
• The composite boom technology used for this ACS3 mission can 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).
• The ACS3 mission is scheduled to launch no earlier than mid-2022.

Partners:

• NASA’s Langley Research Center in Hampton, Virginia is designing the deployable composite booms and solar sail system for the ACS3 project.
• NanoAvionics of Columbia, Illinois is designing and building the 12U CubeSat for the ACS3 mission.
• NASA’s Ames Research Center in California’s Silicon Valley is managing the ACS3 project and will oversee final integration of the solar sail payload and CubeSat.
• The Santa Clara University’s Robotics Systems Lab in Santa Clara, California will provide CubeSat operations support for the ACS3 flight.
• NASA’s Small Spacecraft Technology program within the agency’s Space Technology Mission Directorate is sponsoring the ACS3 project.
• NASA’s Game Changing Development program within the agency’s Space Technology Mission Directorate is developing the mission’s deployable composite boom technology.

Learn More:

• Deployable Composite Boom Technology Advances In Space Construction

For Researchers:

• TechPort Project Summary for NASA’s ACS3 mission.
• Investigators interested in funding opportunities with the SST program should visit the program's website.

For News Media:

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

[Image]

(A) The three pictures above show the composite material’s light weight, flexibility, and rigidity – unique qualities that make them easily stowable and also less prone to bending when heated by the Sun.

(B) Illustration showing the solar sail beginning to unfurl after deployment of the spacecraft’s solar arrays.

(C) Since solar radiation pressure is small, the solar sail must be large to efficiently generate thrust.