When you think of planets and the solar system, sailing is not normally the first thing that launches to mind.

But solar sails are no longer science fiction and the small spacecraft could soon potentially travel to the outer reaches of the universe.

The Planetary Society, based in the United States, is ready to trial its latest version, the LightSail 2.

Its chief executive and science guru, Bill Nye, has told the International Astronautical Congress in Adelaide that LightSail 2 will be on Elon Musk's next rocket to shoot for the stars.

Sorry, this video has expired Bill Nye says solar sails have been tested and are 'ready to go'

"We're ready to go," he said.

"The spacecraft has been built, it's been tested, the batteries are running, the clock is running.

"We're waiting for a ride, as we say, on the second SpaceX Falcon Heavy rocket."

What exactly is a solar sail?

For the space community, the concept has been around for decades and many different organisations are building different kinds — including electric ones.

In a nutshell, it is a small spacecraft which can be pushed along by the energy of the sun, or particles of light, with the help of fine sails made out of super-thin reflective film.

The concept initially might sound strange, as sunlight has no mass.

"But sunlight or light, even though it has no mass, it has momentum, it's pure energy," Mr Nye said.

"So, if you have a spacecraft [with sails] in the vacuum of space that is big enough and with low enough mass, it will get a push from sunlight."

The LightSail 2 is light enough for the trial to be a success, according to Mr Nye.

"This is a spacecraft that comes out of a box no longer than a loaf of bread," he said.

"It extends almost five metres on each side [where the sails are released] and gets a push from sunlight."

Mr Nye said solar sails are the future of space travel and a cheaper form of exploration, as they also have cameras that can send photos back to earth.

The craft could also be attached to satellites, helping them to sail through space.

"People have talked about using this system to de-orbit … satellites when they're worn out," Mr Nye said.

"But [a use that is] cooler and more interesting is to use these things in situations where you've run out of rocket fuel.

"So the strange and surprising thing about a solar sail is it's never out of fuel."

Can solar sails carry humans?



While technology is constantly improving, Mr Nye said it is not likely we will see a spacecraft with sails big enough to carry humans through the solar system.

"The technology is limited in materials," he said.

"We've built these spacecraft to demonstrate this technology and that's what's ready to go."

The Planetary Foundation's first craft, LightSail 1, was launched into orbit in May 2015 and transmitted signals back to earth.

The test mission went for three-and-a-half weeks.

Mr Nye is also known in America as 'The Science Guy' and is one of more than 4,000 delegates at the world's biggest science conference, which is being held in Adelaide this week.