NASA’s Advanced Composites Solar Sail System to be at the forefront of the testing of this innovative propulsion technology, to become sailors of the Solar System.
Have you ever imagined being a sailor with your ship and travelling in the Solar System? Well, NASA is testing revolutionary technology to allow spacecraft to literally sail in the Solar System using… Sunlight! The Advanced Composite Solar Sail System (ACS3) is a small spacecraft aimed to test new ways of exploring space. The mission is led by the Small Spacecraft Technology Program. After passing a crucial deployment test the past February, the spacecraft has just been launched on the 23rd of April 2024, aboard a Rocket Lab Electron rocket taking off from New Zealand.
On Earth, boats are propelled by wind, and, in a similar way, solar sails are propelled by the light coming from the Sun. How is that possible? Photons, the particles that make up radiation, have no mass but they can impart momentum: By bouncing off the sail, they provide a tiny push to the spacecraft which accelerates it away from the Sun. Naturally, the more the photons and the larger the size of the sail, the greater thrust it can provide. This means that the spacecraft does not need propellant, proving to be the ultimate green propulsion system. It is also long-lasting, at least as long as the Sun shines.
In ACS3, the sail is stored inside the spacecraft and is deployed in-flight about 950 kilometers above Earth thanks to innovative light-weight carbon fiber booms which unroll outside of the spacecraft and create support for the sail. The sail is extremely thin, made of a reflective polymer, and composed of four parts that create a square shape when deployed, as it is shown in the figure. Their size is around 10×10 meters. To maneuver the spacecraft, like changing its altitude and position, the sail is angled towards or away from the Sun.
The first test of the solar sailing concept happened in 1974, when the Mariner 10 spacecraft designed to fly past Venus and Mercury ran out of fuel. In that occasion, the solar panel of the spacecraft were angled to catch the Sun’s rays and be pushed by them. After other solar sailing tests and missions, new ambitious projects like the Breakthrough Starshot Initiative aim to send probes to our neighbor planetary system Alpha Centauri.
The results of ACS3 will guide the design of future, next-generation solar sail spacecraft, to explore and conduct low-cost science across the Solar System and, who knows, one day maybe beyond.