The spacecraft’s not much bigger than a loaf of bread and it has a boxing ring-sized solar sail propelling it through space.

LightSail 2, a project from The Planetary Society, a space advocacy group, successfully opened its solar sails earlier this week and is now floating through space. The project is meant to demonstrate the potential solar sails have for long distance space travel.

Via Science Alert:

If you’re not familiar with solar sail technology, the idea is relatively simple, at least in theory.

A solar sail utilizes the momentum of the photons coming from the Sun, much the same way that a sailboat captures the energy in the wind. The light sail doesn’t capture the photons. The photons bounce off of the reflective surface and propel the sail. It’s lightweight, simple technology that has great potential.

In the vacuum of space, it works. There’s no resistance to the spacecraft’s momentum, so over time, as more and more photons bounce off it, its speed increases. All without carrying any fuel or other propulsion system…

…They also gain more and more momentum as they travel. They can continue to accelerate as long as photons are hitting them. A solar sail spacecraft can reach speeds that a chemical rocket can never reach, even though, obviously, they can’t escape the gravitational pull of Earth on their own.

Here’s a look at the microthin sail.

And here’s a brief history of solar sailing. It starts all the way back in 1608.

Follow along at The Planetary Society.