The LightSail 2 spacecraft will no longer travel in sunlight.
The Planetary Society’s crowdfunded solar sailing craft is back in earth’s atmosphere on Thursday morning (Nov. 17) after nearly 3.5 years in orbit, more than three times its designed mission life.
The LightSail 2 The team has not received any communication from the spacecraft since that date, leading them to conclude that the shoebox-sized craft had finally given up the ghost after completing 18,000 orbits and traveling about 5 million miles (8 million kilometers) around our planet.
“LightSail 2 is gone after more than three glorious years in the sky, blazing an elevator path with light and proving we could defy gravity by taking a sail into space,” said science communicator Bill Nye, CEO of The Planetary Society. in a statement (opens in a new tab). “The mission was funded by tens of thousands of members of the Planetary Society, who want to advance space technology.”
Related: LightSail 2 captures stunning photos of Earth from space
LightSail 2 was the first small spacecraft to demonstrate controlled solar navigation, harnessing photons from the sun to adjust its orbit. (LightSail 2 wasn’t the first craft of any kind to sail solar in space, though; Japan’s Icarus Probe it did in 2010).
Although light has no mass, its individual particles (photons) carry momentum that can be transferred to a reflecting surface to give it a small push.
LightSail 2 has demonstrated that solar navigation is an effective and viable propulsion method for small spacecraft, including small satellites known as dicedteam members said.
LightSail Program Manager and Chief Scientist Bruce Betts wrote in a planetary society statement (opens in a new tab) that deorbiting was always going to be LightSail 2’s destiny, even though the mission’s fiery end took longer to manifest than expected.
LightSail 2 captured this image of a nearly full moon on October 24, 2021. (Image credit: The Planetary Society)
The ending of LightSail 2 was a drag
LightSail 2 launched in June 2019 aboard a SpaceX Falcon Heavy rocket, tasked with a one-year mission to demonstrate controlled solar navigation in orbit. It began operations at an altitude of about 450 miles (720 kilometers) above Earth, slightly higher than the orbit of the International Space Station (ISS).
At this altitude, Earth’s atmosphere is still dense enough to exert little resistance on a spacecraft, and it is this effect that ultimately sealed LightSail 2’s fate.
Because of the large surface area of the spacecraft’s solar sail, which measured 244 square feet (32 square meters), about the size of a boxing ring, it experienced a greater drag effect than other spacecraft in the its mass
“Imagine throwing a rock versus throwing a piece of paper. Atmospheric drag will stop the paper much faster than the rock. In our case, LightSail 2 is the paper,” Betts wrote. “A spacecraft like the ISS is huge but also massive, more like rock. But even the ISS has to be boosted every few weeks using rockets to compensate for the drag.”
During its third year of operations, in which it demonstrated its most efficient solar navigation, LightSail 2 experienced an increase in atmospheric drag due to increased solar activity. This solar activity warmed the atmosphere, making the area LightSail 2 passed through denser.
“This marked the beginning of the end,” Betts wrote. “As solar activity increased further, solar sailing could not compete with the increased drag due to increased atmospheric density.”
LightSail 2 captured this image of Florida on December 24, 2021. (Image credit: The Planetary Society)
Over the past few weeks, LightSail 2 had been falling further and further into Earth’s atmosphere, experiencing more and more drag, which in turn dramatically increased the speed of its fall.
“The spacecraft was caught in an ever-increasing snowball effect: As the spacecraft descended, the density increased, causing the spacecraft to descend even faster,” Betts wrote.
While the LightSail 2 mission may be over, there is still scientific work to be done. The team behind the mission continues to analyze the data collected by the craft, which remained operational until the final moment.
That data will also be shared with future space missions that also make use of solar sails, such as NASA’s NEA Scout, which launched aboard the agency’s Artemis 1 mission on Nov. 16 and will take a trip powered by sunlight to travel to the Moon and beyond. towards a near-Earth asteroid.
“Despite the sadness of seeing this, everyone who worked on this project and the 50,000 individual donors who fully funded the LightSail program should reflect on this as a proud moment,” Betts wrote.
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