Skip to Content

LightSail2 has just unfurled its sails and is now powered by the sun

LightSail2Planetary Society

The spacecraft is now  harnessing sunlight to power itself on low Earth orbit.

The news: Engineers pushed a button yesterday to unfurl LightSail2’s sails, which have a surface area of 340 square feet (32 square meters) and are thinner than a human hair. 

How it works: Rather than using wind to move, solar sails harness the energy of photons from the sun as they strike its sails. This doesn’t provide much power initially, but momentum builds up over time, letting LightSail2 accelerate. Engineers on the ground can steer it by adjusting the angle of the sails, much the way you would a boat. The craft sent back its first photos of Earth earlier this month. 

Background: LightSail2 was part of the cargo on board SpaceX’s Falcon Heavy rocket, which launched four weeks ago on June 25. The Planetary Society had waited for a decade to launch the solar sail, which it paid for by crowdfunding. LightSail1, its predecessor, unfurled its sails in 2015 but fell back to Earth after just a few days. The Japanese space agency, JAXA, has also successfully flown a solar sail in the past.

But the idea for solar sails is much older. Although it was first proposed by the astronomer and science writer Carl Sagan in the 1970s, it was imagined way back in the 1600s by German astronomer Johannes Kepler, after he observed comet tails being blown by what he thought to be a solar “breeze.”

Want to stay up to date with space tech news? Sign up for our newsletter, The Airlock.

Deep Dive


How the James Webb Space Telescope broke the universe

Scientists were in awe of the flood of data that arrived when the new space observatory booted up.

NASA’s return to the moon is off to a rocky start

Artemis aims to deliver astronauts back to the lunar surface by 2025, but it’s riding on an old congressional pet project.

James Webb Space Telescope: 10 Breakthrough Technologies 2023

A marvel of precision engineering, JWST could revolutionize our view of the early universe.

What’s next in space

The moon, private space travel, and the wider solar system will all have major missions over the next 12 months.

Stay connected

Illustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at with a list of newsletters you’d like to receive.