A solar sail in orbit at low cost – Le Figaro

The LightSail demonstrator of the Planetary Society has successfully deployed its solar sail last weekend after two agonizing weeks since its launch into orbit in May.

After many adventures, the LightSail demonstrator of the Planetary Society, a private American association for the promotion of planetary exploration, has successfully raised its solar sail. Its engine has fired Sunday, allowing four triangles 8m2 Mylar, a polymer film reflective of 4.5 microns thick (two to four times thinner than plastic wrap) to deploy. Released Tuesday, a shot taken by cameras mounted on the satellite evidenced (although it is not yet certain whether the deployment is perfect).

This is a great relief for officials project. After take-off on May 20 aboard an Atlas V rocket (especially that carried into orbit the mysterious military automatic shuttle X-37), the contact was lost twice with the nano-satellite about the size of a loaf Bread (it is formed from three CubeSat, a small standard structure nano-satellite 10 cm square invented by American universities).

The onboard computer had particularly stuck in day following the launch, idling without reaching restart, plunging the probe for 8 days in an eerie silence. It would be a cosmic ray (an atom or a charged particle from high-speed interstellar void) that would have unlocked the satellite, allowing it to restart. The president of the Planetary Society, Bill Nye, science journalist featured in the United States, acknowledged having experienced “emotional roller coaster” in recent weeks.

But the main thing is this: the sail is deployed. The satellite is still too low and too small-scale to achieve break away from Earth’s gravity. It was not in any event not the goal of this first mission. “The radiation pressure exerted by photons coming bounce off the reflective sail is equivalent to the force of a coin on a football field,” says Olivier Boisard, president of the Union for the Advancement of photonic propulsion (U3P) founded in 1981.

In 2016, the Planetary Society should conduct a second launch solar sail, to 720 km altitude. This one should be able to make a first small space cruise, as well as the Nano-Sail-D NASA in 2008 or the most ambitious Japanese IKAROS, the first solar sail to have made an interplanetary voyage in 2010. The latter is also still in flight between the orbits of Venus and Earth. He wakes every 7 months to give some news.

The LightSail project is less ambitious. Even in its second version, it should not fly for years, nor reach Venus. But it also costs much less: just 5.5 million in total, of which 4.2 have already been harvested, including through a crowdfunding campaign on Kickstarter. If it is more modest in its ambitions, its future seems more promising.

“The idea of ​​using sails for small payloads of a few kilos as CubeSat is no future for large exploration missions for which it would sail to several thousand square meters to take the hundreds of kilos of scientific instruments necessary, “notes Jean-Yves Prado, head of solar physics program at CNES, the French Space Agency

We can imagine that mere universities may be able to send their own probe equipped with cameras to meet asteroid in a decade for a limited cost with this technology. NASA plans to send itself two CubeSat propelled by solar sails in 2018 for micro-missions, one to a nearby asteroid, the other to the Moon.

“With a sail 30 meters in diameter, it might be possible to reach Jupiter with a small probe a few kilos in a few months against for years now, “enthuses Olivier Boisard.