Solar Sail Spacecraft

Solar Sail Concept Illustration

The Planetary Society received a big donation recently to develop a small solar sail spacecraft.  This new technology is being developed as a practical alternative for interstellar travel in the future.  Solar energy will provide the power to move the sail at high speeds.  More precisely, the spacecraft will sail on sunlight – the pressure from light itself!

Researchers and scientists are aiming to have a new solar sail complete for testing by the end of 2010.

Solar sail propulsion was explained by Louis Friedman, executive director of the Planetary Society:

A solar sail is a device that collects sunlight and transfers the energy of the sunlight to the momentum of the spacecraft. It uses pure light, reflecting off the sail, so you want a large area to collect a lot of photons and you want it highly reflective so you get a high efficiency of them bouncing off. We use aluminised mylar.

Solar sail spacecraft will be able to move without the use of fuel, propelled solely by light.  The technology will be useful for space missions over very long distances without having to carry heavy fuel.  However, it can also be used to analyze conditions here on Earth, including solar weather, the magnetosphere and environments at the poles.

Solar sailing to traverse the galaxies

Experts estimate that a solar sail can reach 20% of the speed of light.  The Planetary Society website explains:

Solar sail propulsion is simple in concept. Light photons bounce onto a mirror-like aluminized Mylar sail. As each photon hits, its momentum is transmitted to the spacecraft. Photons have no mass but lots of energy, so a solar sail space probe requires no onboard fuel. The force acts continuously, meaning a solar sail can eventually reach speeds five to ten times greater than any chemical rocket.

Despite its relatively large size (32 square meters), a solar sail only weighs 4.5 kilograms.  Of course, this means that interstellar solar sail missions will be unmanned.  The craft could not support human weight.

With a relatively low cost (several million dollars – instead of billions), the small spacecraft can be extremely valuable for future space missions.  The Light Sail mission is on its way, thanks to a million dollar anonymous donation.  If you would like to help the cause, or to learn more, click here.

Tags: insterstellar travel, light sail, planetary society, solar sail propulsion, solar sail spacecraft, solar sailing