US-based scientists have launched a spacecraft in order to test an innovative technology they say could change the way some craft are propelled through space.
Lightsail1, which was launched from Cape Canaveral Air Force Station in Florida, will test the idea that the energy and momentum that exists in the photons in sunlight can pass on to an object. In this case a 32-square-metre ultra-thin Mylar sail.
"The light from the sun and the radiation from the Sun produces some kind of pressure on that sail," said Francisco Diego, a Senior Research Fellow at the Department of Physics and Astronomy at University College, London.
"That pushes it very gently, only a few grams per square kilometre, but enough to propel a space craft."
The team say this tiny but continual force could gradually accelerate a craft to high speeds.
"A chemical rocket will burn for a few minutes. 10 minutes then you are done and that's it," says Bill Nye, from the Planetary Society, the non-profit space advocacy group behind the mission.
"A solar sail is getting a push all the time."
Lightsail1 is about the size of a loaf of bread.
Its sails are made of polyester a quarter the thickness of a normal plastic bag and fully deployed, they measure 5.5 metres along each side.
By making the spacecraft very small in terms of mass, but with a very large sail, the researchers say it could propel spacecraft much more efficiently.
"They don't need any fuel. They don't need all the handling," says Nye. "You could go to the moon, you could go to Mars, you can catch-up with comets and asteroids."
Similar solar sails have been tested before by the Japanese Space Agency and NASA.
The US space agency cancelled its Sunjammer mission last year, citing technical problems with the design.
This is the first time solar sailing has been done by a private organisation.
The Planetary Society has raised more than $4m for the project from its 46,000 members.
"By doing this with citizen-funded stuff we believe that other organisations, universities, other organisations that want to explore comets and asteroids can use this technology," says Nye.
Not all experts are sold on the idea, saying the force of the sunlight is simply not strong enough to be useful.
"I think the lightsails have a short-term future as something that is interesting to see how it works," says Diego.
"In the future I doubt it will have very strong applications. There will be other technologies based on magnetic fields and other kinds of forces that may be more efficient."
LightSail will be visible for the next month as it orbits 720km above the Earth.
If the craft's systems and sail perform as planned, the Planetary Society is hoping to launch a second test vehicle next year.
Source: Al Jazeera