© LIGHTSAIL - Deployed solar sails in earth orbit.

LightSail, the solar sailing spacecraft

Posted on 10 September 2015.

A new era for spacecraft has begun - the small experimental spacecraft developed by The Planetary Society managed to deploy its reflective sails while in space.

On May 20, 2015, a new type of spacecraft went into space: an experimental solar sail CubeSat called "LightSail".

When science fiction becomes reality

LightSail, for which its designers have high hopes, is a tiny triple CubeSat type satellite (30 x 10 x 10 cm) that weighs no more than 5 kg! Once in space, it can deploy a large solar sail made from Mylar - a very thin light and robust polymer – to make a square with a total area of 32 m2.

The LightSail project is the baby of The Planetary Society, a nonprofit organization that promotes space exploration and the search for extraterrestrial life forms. Founded in 1980 by astronomy and astronautics enthusiasts - including the eminent Carl Sagan - it now has a membership that includes influential figures such as Bill Nye, Neil deGrasse Tyson, Elon Musk and Steven Spielberg. In the early 2000s the organization began investing in solar sail research - a dream cherished as far back as the seventeenth century by Johannes Kepler which resurfaced in science fiction in the 1950s. In June 2005, The Planetary Society launched the first solar sailing spacecraft into space, Cosmos 1. However, a rocket failure unfortunately prevented the spacecraft from reaching its intended orbit. The LightSail mission has revived a NASA project, NanoSail-D2 to demonstrate that sunlight can be used as an energy source for spacecraft.

As its name suggests, LightSail-1 is only the first stage in the project, which is intended to test the deployment of the solar sail in space. Although the tiny satellite encountered some difficulties when it first went into orbit, it completed its mission on June 8. And science fiction became (almost) reality!

Solar sails mean spacecraft will eventually have a longer range for exploring space... and without using a single drop of fuel.

To infinity and beyond!

The real flight will take place in 2016. This time LightSail-2 will be launched into orbit to test the solar sail and its ability to move by means of photon propulsion under real conditions. Today, most spacecraft use chemical propulsion systems (and, more often, electric) produced by the reaction between a fuel and an oxidizer, as their propellant. The main disadvantage of this system is that it requires a very amount of fuel. Photonic propulsion uses sunlight.

The sun emits photons - elementary particles of light. When these photons collide with the surface of the solar sail, they exert a weak but continuous pressure which will propel the spacecraft. Like sailing ships that moves thanks to the momentum of water and wind, a solar sailing spacecraft will be able to sail through space, eventually reaching higher speeds – it is flight by light.

Eventually, solar sails, could be fitted on increasingly heavy spacecraft, giving them a longer range for visiting space or Mars (and beyond!)… without consuming a single drop fuel.