The fundraiser for the solar sail LightSail™ designed by The Planetary Society really started with a bang: in a few days $499.032 were pledged. The goal was to collect $200,000 so it was already possible to achieve the second stretch goal to support operations in orbit for four months. The Kickstarter campaign will continue until June 26, 2015.

The solar sail is a type of propulsion system that uses the pressure exerted by the solar radiation. When the sail reflects light, most of its momentum is transferred generating a thrust. The resulting acceleration is very small and decreases with the square of the distance from the Sun but the thrust is continues so over time can reach high speeds.

The idea of ​​the solar sail is very old but only in recent decades research began to develop it. Among the promoters there was the astronomer Carl Sagan, who was among the founders of the non-profi organization The Planetary Society. Today the organization’s CEO is Bill Nye, the famous science advocate.

This propulsion concept was used a few times to drive some space probes using their solar panels as sails but those are just small precision maneuvers. The first real experiments with solar sails as main thrusters began only a few years ago.

In 2010, JAXA, the Japanese space agency, launched the IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) spacecraft experimenting a successful solar sail. NASA tried experimenting with solar sail in its NanoSail-D missions but without success. There are other projects being developed and now The Planetary Society wants to try it as well with its LightSail™ project funded by donations from supporters.

A prototype of LightSail™ will be launched in the next few days but will only serve to test some onboard systems. It will be launched at an altitude too low to properly take advantage of a solar sail for propulsion. The fully operational LightSail™, also called LightSail-1, is supposed to be launched in 2016 in the launch of the test rocket Falcon Heavy SpaceX.

The LightSail™ will be based on the CubeSat architecture, which has become a standard for low-cost satellites. It’s composed of units with a 10 cm (4″) side, the LightSail™ will be composed of three units. After the launch, it’s expected to reach an altitude of 720 km (447 miles) and the other spacecraft launched with it, Prox-1 developed by CalTech, will eject it into space.

When the time comes, the LightSail™ will deploy its solar sail made in mylar only 4.5 microns thick. The total area of ​​the sail will be 32 square meters (345 square ft), enough to exploit the sunlight as its only form of propulsion. At that point, its mission can begin.

Now the fundraising approaches the next stretch goal, the organization of the mission data and their presentation to the scientists and engineers community. The people who pledged at least $35 will also receive a PDF file with the LightSail™ schematics. If things go on like this, the fundraising will exceed the million dollars, showing that there is an interest from the public for this kind of projects.

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