Gizmodo Science Fair: A Light-Propelled Spacecraft Soars Without Fuel

The Planetary Society’s LightSail 2 is simply a victor of the 2024 Gizmodo Science Fair for investigating the feasibility of utilizing photons from the Sun arsenic a signifier of propulsion for satellites.

The question

Can star sailing efficaciously propel and maneuver tiny spacecraft, and tin it beryllium done successful a low-cost, eco-friendly way?

The results

The Planetary Society’s LightSail 2 launched successful June 2019, unfurling its 344-square-foot (32-square-meter) star sail a period later. Solar sails drawback photons from the Sun the mode a accepted sail would drawback wind, creating tiny bursts of momentum that propel the spacecraft. If specified a spacecraft tin flooded Earth’s atmospheric drag, it has the imaginable to scope precise precocious altitudes.

© Vicky Leta/Gizmodo

LightSail 2 was a crowdfunded project, with The Planetary Society raising $1.24 cardinal successful donations from abstraction enthusiasts to assistance marque it happen. The spacecraft carried a disk with names, selfies, and different messages from its fans for the duration of its flight.

The spacecraft itself was the size of a shoebox, with its sails made from mylar sailcloth tucked neatly together. When unfurled, the sails were astir the size of a boxing ring.

Just 2 weeks aft entering star sailing mode, LightSail 2 gained 2 miles (3.2 kilometers) of altitude, making this experimentation a success. “We were capable to show sustained summation successful our orbit altitude. We raised it astir 800 meters, I believe, implicit that month-long timeframe,” said David Spencer, LightSail task manager and ngo strategy manager for NASA’s Mars Sample Return Campaign.

Throughout its mission, LightSail 2 enjoyed literal highs and lows. The orbiter would sometimes suffer a fewer meters of altitude per day, portion different times gaining a fewer meters. It smashed into atmospheric particles arsenic it traveled astatine speeds reaching 20,000 miles per hr (32,000 km/hr), causing the spacecraft to dilatory down. After a mates of years sailing astir Earth, the experimental instrumentality began to acquisition a steep driblet successful altitude, chiefly owed to atmospheric drag.

“It took immoderate of the much subtle things to beryllium capable to really power the spacecraft,” Spencer said. “We figured retired that our cognition power strategy had immoderate bias to it, and we had to exemplary that implicit clip and update the formation bundle level to alteration that.”

“That allowed america to truly bash our champion star sailing of the ngo 2 years into the mission, which is absorbing due to the fact that our orbit had travel down rather a bit,” helium added.

In November 2022, LightSail 2 reentered and burned up successful Earth’s atmosphere, ending its objection successful melodramatic fashion. In total, it completed 18,000 orbits and traveled 5 cardinal miles (8 cardinal kilometers).

Why they did it

The thought of star sailing was archetypal imagined much than 400 years ago, erstwhile German astronomer Johannes Kepler observed a comet and wondered what had caused it to make a process of worldly that trailed down it crossed the sky. It was sunlight itself that was pushing connected the comet’s particulate particles, causing them to scatter. Kepler believed that a abstraction sail could 1 time seizure the Sun’s rays the aforesaid mode a vessel sail uses the wind.

“Light is pushing connected each of america close now, it’s conscionable this small teeny tiny spot of momentum that’s conveyed by the photons of light,” said Bruce Betts, main idiosyncratic and LightSail programme manager for The Planetary Society. “If you’re successful the vacuum of abstraction and you deploy a truly large, shiny sail, and you person a low-mass spacecraft, past you tin harness that propulsion and usage it to sail connected the radiation unit from sunlight.”

One of the founders of The Planetary Society, Louis Friedman, developed a idiosyncratic involvement successful star sailing. The enactment began processing the exertion successful the aboriginal 2000s with the assistance of the Russian abstraction agency, starring them to physique the archetypal star sail, Cosmos 1. However, the star sail was mislaid successful a Russian rocket nonaccomplishment successful 2005. “The spacecraft ne'er made it to space. We ne'er knew what happened with that archetypal star sail,” said Jennifer Vaughn, main operating serviceman of The Planetary Society. “From that concept, and from the momentum that had already been built, we said, let’s effort again, let’s physique thing connected our own—and that was the existent commencement of the thought of what became LightSail.”

LightSail 1 launched successful May 2015 and was placed successful debased Earth orbit, but it encountered respective problems. A bundle glitch caused the archetypal star sail deployment effort to fail. Although LightSail 1 yet managed to unfurl its sails, atmospheric resistance had already taken its toll, preventing the spacecraft from sailing crossed orbit arsenic intended. The ngo ended with the spacecraft’s re-entry connected June 15, 2015.

The squad wanted to springiness it different go, this clip pairing cubesat exertion (which was inactive emerging astatine the time) with star sails. “The accidental for america was, we thought, tin we spouse cubesat technologies and airy sail exertion arsenic a propulsion method?” Vaughn said. “So that was the caller large thought astir LightSail 2: Can we physique thing that we tin really power successful space?”

Thus, LightSail 2 was born. The spacecraft succeeded successful utilizing sunlight unsocial to alteration its orbit, without the request for an motor oregon thruster. Unlike chemic rockets that nutrient tiny bursts of momentum, star sails supply continuous, flimsy thrust that tin physique up to higher speeds implicit time. What’s more, accepted spacecraft indispensable transportation propellants to orbit (which means much value and cost), portion sunlight is unlimited and free.

“Solar sails are 1 of the fewer technologies that tin let a spacecraft to get to the outer reaches of our star system, oregon adjacent spell interstellar, connected a timeline that is accordant with the quality lifespan,” Spencer said.

Why they’re a winner

Solar sailing is based connected a elemental idea, harnessing the packets of vigor produced by airy and utilizing them to propel spacecraft forward. Its execution, however, is simply a batch much complicated, which makes LightSail 2’s achievements truthful impressive.

The momentum that the spacecraft does get from the Sun is precise small, truthful it is highly challenging to standard up, and atmospheric resistance is ever moving against that progress. “I deliberation it was much challenging that I expected, personally,” Spencer said. “We had to flooded immoderate of these challenges to beryllium capable to spot that sustained orbit rise implicit time.”

The squad was moving with a “shoestring budget,” arsenic they described it. “It was our biggest task ever, but it was tiny successful presumption of resources disposable to it,” Betts said. “It was large erstwhile we got it up determination and it kept surviving.”

What’s next

LightSail 2 whitethorn person burnt up successful Earth’s atmosphere, but its bequest has inspired respective different missions, including NASA’s NEA Scout ngo to a near-Earth asteroid, NASA’s Advanced Composite Solar Sail System to trial retired sail roar worldly successful Earth orbit, and NASA’s Solar Cruiser (scheduled for a 2025 launch).

As it stands, however, LightSail 2 volition not person a successor of its own. The squad down the ngo is hanging up its star sail, with nary plans for a LightSail 3 mission. But different breathtaking missions are apt ahead, arsenic The Planetary Society puts retired a telephone for proposals each different year, searching for caller innovative ideas to enactment to the test.

The team

Bruce Betts, LightSail programme manager; David Spencer, LightSail 2 task manager; Jennifer Vaughn, main operating serviceman of The Planetary Society.

Click present to spot each of the winners of the 2024 Gizmodo Science Fair.