The LightSail 2 spacecraft will no longer roll in the sun.
The Planetary Society’s crowdfunded solar sailboat is back earth’s atmosphere Thursday morning (November 17) after nearly 3.5 years in orbit – more than three times longer than its expected lifespan.
The Dinghy Sailing 2 The team has received no communication from the spacecraft since that date, leading them to conclude that the shoebox-sized craft had finally passed away after completing 18,000 orbits and traveling approximately 5 million miles (8 million kilometers) around our planet.
“LightSail 2 is gone after more than three glorious years in the sky, charting a course of lift with light and proving that we can defy gravity by turning a sail in space,” said science communicator Bill Nye, CEO. from 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.”
LightSail 2 was the first small spacecraft to demonstrate controlled solar navigation, harnessing photons from the sun to adjust its orbit. (LightSail 2, however, was not the first craft of any type to navigate space on solar power; Japan Ikaros probe did it in 2010.)
While light lacks mass, its individual particles – photons – carry momentum that can be transferred to a reflective surface to give it a small amount of thrust.
LightSail 2 has shown that solar navigation is an efficient and viable method of propulsion for small spacecraft, including the tiny satellites known as cubesatsthe team members said.
Bruce Betts, LightSail program manager and chief scientist, wrote in Planetary Society statement (opens in a new tab) that deorbiting was always going to be LightSail 2’s fate, though the fiery end of the mission took longer to manifest than expected.
The end of LightSail 2 was a drag
LightSail 2 launched in June 2019 aboard a SpaceX Heavy Falcon rocket, tasked with a one-year mission to demonstrate solar-controlled navigation in orbit. It began operations at an altitude of approximately 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 a slight drag on a spacecraft, and it was this effect that ultimately sealed the fate of LightSail 2.
Due to the large surface area of the craft’s solar sail, which measured 244 square feet (32 square meters) – about the size of a boxing ring – it experienced greater drag than other spacecraft. of its mass.
“Imagine throwing a stone versus throwing a piece of paper. Atmospheric drag will stop the paper much faster than the stone. 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 propelled higher every few weeks using rockets to compensate for the drag.”
In its third year of operation, in which it demonstrated its most efficient solar navigation, LightSail 2 experienced increased atmospheric drag due to increased solar activity. This solar activity has warmed the atmosphere, making the area LightSail 2 passes through denser.
“It marked the beginning of the end,” Betts wrote. “As solar activity increased even more, solar navigation was unable to compete with the increase in drag due to increased atmospheric density.”
Over the past few weeks, LightSail 2 has been sinking deeper and deeper into Earth’s atmosphere, experiencing more and more drag, which, in turn, has dramatically increased the rate of its fall.
“The spacecraft was caught in a growing snowball effect: as the spacecraft descended, the density increased, causing the spacecraft to descend even faster,” Betts wrote.
Although LightSail 2’s mission may be over, there is still more science to be done. The team behind the mission continues to analyze the data collected by the machine, which remained operational until its last moments.
This data will also be shared with future space missions that also use solar sails, such as NASA’s NEA Scout, which launched on the Artemis 1 mission on Nov. 16 and will hitchhike on sunlight to the moon and then to a near-Earth asteroid.
“Despite the sadness of seeing it go, everyone who worked on this project and the 50,000 individual donors who fully funded the LightSail program should reflect on it as a proud moment,” Betts wrote.