After three-and-a-half years of sailing above Earth, the LightSail 2 spacecraft has burnt its shiny metallic wings as it reentered Earth’s atmosphere in a fiery blaze.
The Planetary Society announced the end of its solar sailing mission on Thursday. The spacecraft reentered Earth’s atmosphere sometime on November 17, burning up during its descent, but the mission successfully demonstrated the use of sunlight to propel satellites in orbit.
“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,” Bill Nye, CEO of The Planetary Society, said in a statement.
LightSail 2 launched in June 2019 and unfurled its giant 32-square-metre solar sail about a month after reaching orbit. Its solar sail ran on photons from the Sun, which propelled the spacecraft through small bursts of momentum as the photons hit its wings.
The spacecraft started off at an altitude of around 720 kilometres, where Earth’s atmosphere is still thick enough to slow it down by way of atmospheric drag. But LightSail 2 persevered, gaining 3.2 kilometres of altitude just two weeks into the mission.
Over time, atmospheric drag eventually got the best of LightSail 2. Particles from the atmosphere smashed into the spacecraft, slowing it down over time. The Sun, which is in an active period right now, also caused Earth’s upper atmosphere to heat up, causing it to become denser and harder to sail through.
After completing 18,000 orbits around Earth, covering 8 million kilometres of the skies, LightSail 2 reached lower altitudes and its eventual demise was anticipated. During reentry, the spacecraft was moving so quickly that it created an energetic pressure wave ahead of it, causing the air around it to heat up and turn the spacecraft into a disintegrating ball of fire.
Although LightSail 2’s time has come to an end, it has inspired a new generation of spacecraft, including NASA’s NEA Scout mission to a near-Earth asteroid (scheduled for launch in August), NASA’s Advanced Composite Solar Sail System to test out sail boom material in Earth orbit (scheduled for launch sometime mid-2022), and NASA’s Solar Cruiser (scheduled for a 2025 launch).
“We have braved the harbour of Earth and found that a small craft can sail and steer,” Bruce Betts, LightSail program manager and chief scientist for The Planetary Society, said in a statement. “Best wishes to those who sail similar craft into the vast ocean of space — we look forward to an exciting future of exploration, proud that we have played a role. Sail on!”
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