This mission marks a pivotal moment as it will be the first time composite booms are utilized in Earth orbit, testing their capability to deploy the sail successfully.
NASA is gearing up for an exciting venture into space with its experimental solar sail, set to revolutionize propulsion methods beyond Earth’s atmosphere. The project, known as the Advanced Composite Solar Sail System (ACS3), is poised for launch on Tuesday, April 23, aboard Rocket Lab’s Electron rocket from New Zealand. This mission marks a pivotal moment as it will be the first time composite booms are utilized in Earth orbit, testing their capability to deploy the sail successfully.
The deployment process will take place approximately 600 miles above Earth’s surface, more than twice the altitude of the International Space Station. Here, the solar sail will begin to unfurl, stretching across 30 feet per side. NASA has equipped the mission with onboard digital cameras to capture images of the sail during and after deployment, enabling assessment of its shape and alignment.
Once fully deployed, the solar sail system will be about the size of a tiny studio apartment in Bushwick, crucial for efficiently generating thrust. The sail’s size and high orbit are essential for overcoming atmospheric drag using the gentle force of sunlight. In fact, the pressure exerted by sunlight on the sail is roughly equivalent to the weight of a paperclip resting on your palm.
The solar sail will be deployed using four composite booms spanning the diagonals of the square, each reaching 23 feet in length. These booms, made from a lightweight yet stiff polymer material, function similarly to a sailboat’s boom, capturing the propulsive power of sunlight instead of wind. They are designed to resist bending and warping when exposed to varying temperatures.
During the mission’s initial flight phase, lasting approximately two months, a series of pointing manoeuvres will demonstrate the ability to raise and lower the orbit solely using sunlight pressure on the sail. Solar sails harness photons from the Sun, generating small bursts of momentum that propel the spacecraft away from the star. If successful in surpassing Earth’s atmospheric drag, the spacecraft could potentially reach very high altitudes.
The concept of solar sails offers the promise of indefinite operation, although limitations exist due to the durability of sail materials and spacecraft electronic systems. A notable example is the Planetary Society’s LightSail 2, which launched in June 2019 and gained 2 miles of altitude just two weeks after unfurling its 344-square-foot solar sail. However, in November 2022, the mission concluded as it began losing altitude and reentered Earth’s atmosphere.
Despite this setback, LightSail 2’s legacy inspired subsequent missions, including ACS3, NASA’s NEA Scout mission to a near-Earth asteroid, and NASA’s Solar Cruiser scheduled for launch in 2025. The composite boom technology employed in the ACS3 demo mission holds the potential to deploy solar sails up to 500 square meters, equivalent to the size of a basketball court.
