LightSail 2 Spacecraft Uses Sunlight to Push Forward

Source: Image: Josh Spradling / The Planetary Society

The Planetary Society's LightSail 2, which captures sunbeams in a solar sail, takes off from Earth aboard a SpaceX Falcon Heavy Rocket on June 22.

June 22 will mark a major milestone for SpaceX as it launches the Falcon Heavy Rocket from the Kennedy Space Center. The rocket, which measures 230 feet tall and weighs over 3 million pounds, will be carrying a bread loaf-sized device that could shape the future of spaceflight. It’s spacecraft equipped with a thin sail designed to capture the pressure of sunlight.

Dubbed LightSail 2, the tiny spacecraft will be a test for future space missions that might use a solar sail. The Falcon Heavy Rocket will travel to a medium orbit around Earth, 450 miles (725 kilometers) from the surface, which is about double the International Space Station’s orbit. After several days in space, LightSail 2 will deploy from its container by extending four long booms carrying sheets of highly reflective Mylar plastic in the shape of a kite.

The solar sail uses the gentle push from the sun’s photons for propulsion and is about the size of a boxing ring (340-square-feet) when fully open. If the test is successful, the greatest benefit from this technology is that the spacecraft won’t need to carry any fuel, which is critical on small satellites, where every gram counts.

Although sunlight exerts a tiny amount of force, barely more than a paperclip resting in your hand, the situation changes in space where there no air or atmosphere to compete with. There, solar pressure is a slight but persist wind that’s strong enough to push a craft along.

"If successful, LightSail 2 will become the first spacecraft to raise its orbit around the Earth using sunlight," said Planetary Society representatives in a statement (via

LightSail 2 isn’t the first attempt at testing a solar sail. The Planetary Society launched the Cosmos-1 in 2005, but it was lost when the rocket carrying it failed 82 seconds into flight. LightSail 1 managed to reach orbit and deployed its sail in 2015, but it was placed too low in orbit. Drag from Earth’s upper atmosphere overwhelmed the sun’s gentle push. Other attempts failed in similar ways for various reasons.

However, LightSail 2 isn’t making the trip to space alone. The spacecraft is on board the Falcon Heavy Rocket as part of the Department of Defense's Space Test Program-2, which includes 24 spacecraft to three different orbits. LightSail 2 itself is traveling inside the Prox-1 spacecraft, designed by the Georgia Institute of Technology to demonstrate operations performed close to other orbiting spacecraft.

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Steven is a pop culture junkie who regularly binges on sci-fi TV shows, movies, books, and video games before completely overthinking them.