Come Sail Away With NASA's Latest Satellites, Which Will Travel Through Space Without Fuel


On Tuesday, NASA announced that 13 CubeSats — miniature satellites designed for scientific research — would tag along on its new rocket, the Space Launch System, when it ventures forth into the great unknown in 2018.

Before you assume that the CubeSats are all excessively futuristic and high-tech, however, you might want to take a look at the Near-Earth Asteroid Scout, a shoebox-sized satellite powered by a very unusual source — a sail.


That's right: The same idea that propelled explorers around the world centuries ago is now being adapted for space travel.

NEA Scout will use a solar sail to power itself toward its target. At the moment that planned target is a "mystery object" near Earth called 1991 VG, though NASA noted that "the target can change based on launch date." Broadly, NEA Scout's purpose is to gather and return data on near-Earth asteroids that may one day become targets for human travel.

Instead of fuel, however, the little satellite will use momentum from its 925-square-foot sail. Made of thin, shiny material capable of reflecting large amounts of light, the sail will use energy from the sun for power.

National Geographic has the rundown on how it works:

When a photon from the sun hits the mirror-like surface, it bounces off the sail and transfers its momentum to the spacecraft — the same way that a cue ball transfers its momentum when it smacks into another ball in a game of pool.

Though the idea of solar-powered travel has been around for quite some time, it didn't become feasible until very recently: In order for the system to work effectively, the satellite component needs to be small enough to properly accelerate.

"Back 25 or 30 years ago, electronics were not so lightweight," Les Johnson, the technical advisor for NASA's Advanced Concepts Office at the Marshall Space Flight Center, told National Geographic. "You couldn't imagine building a small enough spacecraft that didn't require a ginormous sail. With the advent of smartphones and the miniaturization of components, we're now able to make really lightweight, small spacecraft, which makes the size of the sail more reasonable."

Though NEA Scout will use gas for its "initial propulsive maneuvers," it will drink up sunlight for the rest of its journey to the near-Earth object, which is expected to last about two years

But it's not just a cool concept. Solar sails bring with them tantalizing possibilities for the future of space travel. Though the initial speed is much less than that of a traditional chemical rocket, the solar sail works the long game — it eventually outpaces fuel-powered rockets because its power supply is relatively constant. (It's also cheaper.)

"A sail wins the race in terms of final velocity because it's the tortoise and the hare," Johnson told National Geographic. "Since the sail doesn't use any fuel, we can keep thrusting as long as the sun is shining."

And when the satellite eventually moves too far away from the sun, Johnson posited that a laser could continue to provide the light power. 

"We could build a big laser," he said. "As the sail moves away from the sun and the sunlight gets dimmer, you could then shine the laser light on it to keep pushing it. The laser remains here in solar orbit, so it's continuing to push the sail faster and faster as it leaves the solar system." In this way, solar sailing could pave the way for visits to other solar systems. 


These theories, of course, are just pipe dreams at present, given the necessary size of the sail and power of the laser. But we're inching closer to testing them out: Aside from the NEA Scout, the nonprofit Planetary Society also has plans to launch a solar sail into space sometime this year.

The truth, as they say, is out there.

h/t National Geographic