Just as sea breezes propel sailboats across the sea on Earth, solar radiation may one day be able to propel spacecraft between stars. At least that’s the hope of the French startup Gama.
The aerospace company was founded in 2020 by Louis de Gouyon Matignon, Thibaud Elzière and Andrew Nutter, whose goal is to develop a low-cost solar sail that would use light as a means of propulsion for spacecraft. Gama raised $2 million in funding from the Public Investment Bank (BPI), the French Space Agency (CNES) and angel investors to demonstrate its technology in space in October. This mission will see a CubeSat launched on a SpaceX Falcon 9 rocket, after which a 789 square foot solar sail will unfurl to an altitude of 342 miles.
“We can test a lot of things on Earth, but deployment testing at these dimensions can only be done in the weightlessness of space,” Nutter told TechCrunch. (Dimensions suggest the sail should be around 10 meters wide.)
Sun sails aren’t exactly a new invention. They were first theorized by astronomer Johannes Kepler, who reflected on them in a letter to fellow astronomer Galileo Galilei in 1608. But the first successful deployment of a solar sail didn’t happen until 2010. : the “space yacht” IKAROS, a mission of the Japan Aerospace Exploration Agency (JAXA). That same year, NASA launched NanoSail-D, and in 2019 space advocacy group Planetary Society launched LightSail 2.
Now several organizations outside of Gama are developing new solar sail missions. NASA’s Advanced Composite Solar Sail System (ACS3) will have Illinois-based NanoAvionics design a spacecraft with an 800-square-foot solar sail. Breakthrough Initiatives’ Breakthrough Starshot mission, which received $100 million in funding, plans to send a fleet of hundreds of tiny, solar-powered sail spacecraft to the Alpha Centauri star system, located 4.7 light-years away.
Gama differs in two ways from previous and current missions. “First, the Gama team is working to iterate and move extremely quickly, launching the first of many solar sails in record time,” says Nutter. “Second, we deploy the sail by gently rotating the satellite and using the resulting centrifugal force to deploy the petals of our sail. This allows us to save on structural weight and deploy much larger areas in a timely manner.
Long before its first launch, the company is already designing its second mission – one that will deploy at a higher altitude and “demonstrate that we can steer sail and provide a reliable, low-cost alternative to traditional propulsion technologies,” according to Nutter.
Solar sails work almost the same as traditional sails, except they use photons for propulsion rather than the air molecules that make up the wind. Although photons have no mass, their momentum as they travel through space can be transferred to a reflective surface – a Mylar or polyamide solar sail – which can propel a spacecraft. The force is light, but in the vacuum of space it can add up quickly. It’s possible that a solar sail could propel a spacecraft at 20% of the speed of light, although it would take some time.
This would allow the spacecraft to eliminate (or at least reduce) the amount of propellant it must carry, freeing up onboard mass for other uses. The use of solar sails could also extend a spacecraft’s mission duration, since the vehicle could theoretically be propelled indefinitely. This would be crucial for long-duration deep space missions, which is why there is such interest in developing the technology further.