A solar-sailing mission is now marking three years of spaceflight, but is unlikely to celebrate a fourth anniversary.
The Planetary Society's LightSail 2 is a crowdfunded solar sail that launched June 25, 2019. It was expected to last a year in an assessment of how well a spacecraft could perform using only the power of the sun.
Now tripling that expectation, the spacecraft continues to work well but is in a fight with atmospheric drag. Molecules of the Earth's atmosphere are slowly pulling the spacecraft back to our planet, with re-entry expected in perhaps a few months, according to a Planetary Society update.
"We have continued to work to learn more and sail more efficiently as part of its extended mission including its second year in orbit as well as this last year, its third year," Bruce Betts, the mission's project manager, wrote Friday (June 24) on the Planetary Society's website.
Like any long-running mission, the spacecraft has met a few challenges. Last summer, engineers recalibrated the gyroscopes on the spacecraft to account for drift, but the gyros "began returning data that measured incorrect spin rates," Betts wrote.
"We developed techniques to calibrate the gyros on orbit, and updated the onboard flight software to enable corrections to the gyro bias parameters. The update improved our sail control, thus improving our solar sailing."
The change allowed the altitude to rise by 328 feet (100 meters) per day for a few months, but as of today the average altitude is about 390 miles (627 kilometers). That's compared with 446 miles (718 km) at mission start.
The altitude fell for a few reasons, Betts explained, including communications trouble with the spacecraft due to ground station components breaking (and requiring replacement), ongoing atmospheric drag, and increased activity in the 11-year solar cycle puffing up Earth's atmosphere and moving more molecules higher.
That said, the Mylar sail material remains in good condition and the spacecraft has no major component failures, which Betts said is "an amazing testament to the many tens of people over the years who’ve worked on it."
He added the team plans to "make the most out of the next several months" before LightSail 2's eventual re-entry, but the data collected will remain useful essentially forever after the mission. The team plans numerous mission analyses, paper publications and conference publications for LightSail, as well as continuing their connections with other space missions planning on using solar sails themselves.
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Elizabeth Howell (she/her), Ph.D., is a staff writer in the spaceflight channel since 2022 covering diversity, education and gaming as well. She was contributing writer for Space.com for 10 years before joining full-time. Elizabeth's reporting includes multiple exclusives with the White House and Office of the Vice-President of the United States, an exclusive conversation with aspiring space tourist (and NSYNC bassist) Lance Bass, speaking several times with the International Space Station, witnessing five human spaceflight launches on two continents, flying parabolic, working inside a spacesuit, and participating in a simulated Mars mission. Her latest book, "Why Am I Taller?", is co-written with astronaut Dave Williams. Elizabeth holds a Ph.D. and M.Sc. in Space Studies from the University of North Dakota, a Bachelor of Journalism from Canada's Carleton University and a Bachelor of History from Canada's Athabasca University. Elizabeth is also a post-secondary instructor in communications and science at several institutions since 2015; her experience includes developing and teaching an astronomy course at Canada's Algonquin College (with Indigenous content as well) to more than 1,000 students since 2020. Elizabeth first got interested in space after watching the movie Apollo 13 in 1996, and still wants to be an astronaut someday. Mastodon: https://qoto.org/@howellspace