NASA is sending a solar sail spacecraft after an asteroid

When NASA launches its uncrewed Artemis I mission to the moon, it will have a small companion along for the ride. At the same time as it carries the Orion capsule (which will orbit the moon), the Space Launch System rocket will also carry a tiny shoebox-sized smallsat called the Near-Earth Asteroid Scout (NEA Scout) which will visit an asteroid. This particularly tiny satellite is quite unusual.


What makes NEA Scout unusual is its method of propulsion. The tiny craft will use a solar sail to move through the solar system, marking NASA's first use of this technology for a deep space mission.

Solar sails sound like something out of science fiction, but they are indeed real – and they work. They consist of very thin, very light sails which are highly reflective. Photons of light from the sun hit the sails and propel the craft forward. 

The process involved in moving with solar sails is a lot slower to get started than other methods of propulsion, but it is extremely efficient, and allows craft to sail out into space without needing to carry fuel with them. Solar sails have already been used by spacecraft in practice in real-life missions such as LightSail 2!

The NEA Scout mission will deploy a solar sail the size of a racquetball court to visit an asteroid called 2020 GE, a smaller asteroid which is under 60 feet (18 meters) across. This asteroid is classified as a near-Earth asteroid, meaning it will come close to our planet, and the NEA Scout mission will be equipped with a camera to collect data on its size, shape, rotation, and surface properties.

It's important to learn more about mid-sized asteroids like 2020 GE as most asteroid research has focused on larger asteroids.

"Thanks to the discoveries of NEAs by Earth-based observatories, several targets had been identified for NEA Scout, all within the 16-to-100-foot [5-to-30-meter] size range," said Julie Castillo-Rogez, the mission's principal science investigator at NASA's Jet Propulsion Laboratory in Southern California (via JPL). "2020 GE represents a class of asteroid that we currently know very little about."

Studying this size asteroid can help researchers understand more about how to protect Earth from potential asteroid impacts. "Although large asteroids are of most concern from a planetary defense perspective, objects like 2020 GE are far more common and can pose a hazard to our planet, despite their smaller size," said Castillo-Rogez.

As well as investigating the asteroid, this mission will also demonstrate how solar sails could be used for future missions. One advantage of the mission's slower speed is that it will pass the asteroid slowly, allowing researchers more time to gather data. And NASA has plans for more solar sail missions in the future, including the Solar Cruiser mission which plans to start a journey toward the sun in 2025.

NEA Scout will be launched along with the Artemis I mission, currently expected to launch later this year.