Another great crowdfunding project has been launched, this time to produce an experimental light sail for use in space exploration. The planetary society wants to raise $1.2million to build a light sail and test it for thirty days sometime next year. If successful, it could be a more efficient method of launching probes to other planets and interesting objects within our solar system.

Traditional rockets work by burning fuel - essentially creating a controlled explosion. The high speed gas particles that are thrown out of the rocket cause an 'equal and opposite' reaction that pushes the rocket forward through space. Such methods are proven to work in numerous space missions by this time, but they are not efficient. The rocket must carry a lot of fuel, and that fuel needs to be propelled with the ship causing it to need yet more fuel. And with the currently available chemical fuels, they are not very fast either.

One alternative is to build a light sail. The ship would still need chemical fuel to reach space, but once there it can rely instead on solar power. The sun is constantly emitting radiation and light radially outward from itself, and this creates pressure on any large surface it encounters.

And so if you attach a spaceship of some form to a very large, very light sail, then this light pressure would cause it to accelerate away from the sun.  (Proposals have also been made to build large pulsed lasers on Earth or in orbit that could add to this pressure on a sail, and to provide some directional variation to the system). And although it would start slow, since the solar pressure is not a large quantity, it would keep accelerating as it moved and would eventually reach much higher speeds.

The Planetary Society believes that they can get one built and tested over the next year, and they just need the funding to make it happen.