The historic LightSail 2 mission finally burned up in Earth’s atmosphere

LightSail 2, The Planetary Society's solar sail proof-of-concept mission, finally reentered Earth's atmosphere almost three and a half years after it launched to orbit aboard a SpaceX Falcon Heavy rocket in July 2019.

The mission demonstrated that flight by light is possible when it used a 32-square-meter (244-square-foot) sail made out of mylar to raise a small CubeSat spacecraft’s orbit by 1.9 miles (3.2 km).

The Planetary Society announced in a press statement that LightSail 2 had reentered the atmosphere at some point on Nov.17.

LightSail 2 proved flight by light is possible

The LightSail 2 mission "showed that it could change its orbit using the gentle push of sunlight, a technique known as solar sailing," The Planetary Society's press statement revealed.

Though light, or photon particles, doesn’t have mass, its momentum can be transferred to a solar sail, which can very slowly lift a light CubeSat spacecraft and overcome the effects of atmospheric drag for a surprisingly long period of time.

“LightSail 2 is gone after more than three glorious years in the sky, blazing a trail of lift with light, and proving that we could defy gravity by tacking a sail in space,” said Bill Nye, CEO of The Planetary Society. “The mission was funded by tens of thousands of Planetary Society members, who want to advance space technology.”

This compilation of images taken by LightSail 2 from orbit captures some of the beauty of this remarkable mission. #ThankYouLightSail pic.twitter.com/h2BBbbNqj9

— Planetary Society (@exploreplanets) November 17, 2022

The Planetary Society says LightSail 2 came down after 18,000 orbits and five million miles (8 million kilometers) traveled, as the effects of atmospheric drag brought the spacecraft down over time until it could no longer keep itself in orbit. The spacecraft had used the solar sail technology to lower its decay rate throughout its almost three and a half years in orbit.

In an interview with IE, Bruce Betts, LightSail program manager and chief scientist for The Planetary Society, said "the LightSail 2 team has a lot to do over the coming months assembling and analyzing data from the entire mission and publishing and sharing the results.”

In February, Planetary Society CEO Bill Nye (of 'Bill Nye the Science Guy' fame) told IE the LightSail 2 mission had far exceeded his expectations. The Planetary Society team will now analyze all of their data before presenting it to the scientific community for peer review.

LightSail 2's legacy will live on as NASA sets sail

The historic LightSail 2 mission was inspired by famous science popularizer Carl Sagan, who was Bill Nye's astronomy professor at Cornell University. Sagan promoted the idea on ‘The Tonight Show’ with Johnny Carson in the 1970s, after Planetary Society co-founder Louis Friedman developed a solar sail concept for NASA.

Now, Sagan's and The Planetary Society's legacy lives on as the latter has collaborated with NASA on its upcoming solar sail missions that will push the envelope even further.

The Planetary Society has, for example, shared data with the NEA Scout team through a Space Act Agreement. NEA Scout was launched aboard NASA's Artemis I mission last week and it is currently on its way to catch up with asteroid 2020 GE using an 86-square-meter (926 square-feet) solar sail.

The space agency will also use solar sail technology for its Solar Cruiser and ACS3 missions, both of which will test larger solar sails.

The LightSail 2 mission was completely crowdfunded with more than 50,000 Planetary Society members, Kickstarter backers, private citizens, foundations, and corporate partners funding the mission.