Private spacecraft will sail on streams of photons from the sun

Bill Nye and The Planetary Society want to propel a spacecraft by bouncing the sun's photons off it. The first test of such a craft will take place this May.

Michael Franco
Freelancer Michael Franco writes about the serious and silly sides of science and technology for CNET and other pixel and paper pubs. He's kept his fingers on the keyboard while owning a B&B in Amish country, managing an eco-resort in the Caribbean, sweating in Singapore, and rehydrating (with beer, of course) in Prague. E-mail Michael.
Michael Franco
2 min read

You can see the mylar sails folded up inside the LightSail as team members prepare it for its test flight. The Planetary Society

Solar sailing might sound like a sport played in a galaxy far, far away, but it's actually a legitimate means of propulsion around our very own solar system. The concept is that the photons in beams of light, like those from the sun, actually have a force and speed to them that can be bounced off sails to move a spacecraft along.

Now a small spacecraft, commissioned by The Planetary Society, which is led by CEO Bill Nye, will take the first step to using the power of photons to move around when it is launched on an Atlas V rocket in May.

The craft, known as LightSail, consists of three small satellites known as CubeSats all linked together to form a machine that's about the size of a loaf of bread, according to The Planetary Society. (See video below for more.)

When the LightSail is launched, it won't actually be high enough to put the principles of solar sailing to work, but it will be extending four thin sails to ensure the process works smoothly. "Each sail is just 4.5 microns thick--one-fourth the thickness of an average trash bag," says the project's website. The idea is that these sails would get bombarded by photons from the sun that would move it slowly but steadily forward. Because space is a vacuum, slow and steady forward momentum could eventually cause a craft to pick up some serious speed.

The sails deploy on "tape measure" like metallic booms, and The Planetary Society says that they'll be visible from Earth when LightSail finally goes into orbit. They say they'll help amateur astronomers know where to look to see it. The LightSat also has three electromagnetic rods that will help orient the craft using the Earth's magnetic field.

After the test flight in May, The Planetary Society will send another LightSail up on one of SpaceX's Falcon Heavy rockets -- and this time it will go into orbit to test its solar sailing ability. Another satellite known as Prox-1, designed to inspect other spacecraft by the Georgia Institute of Technology, will be along for the ride and will rendezvous with LightSail to report back on its condition. Prox-1 will also film the moment that LightSail unfurls its sails for the first time in space.

"We strongly believe this could be a big part of the future of interplanetary missions," Bill Nye told The New York Times about LightSail. "It will ultimately eventually take a lot of missions a long, long way."

Nye is the CEO of the Planetary Society, a nonprofit space-advocacy and exploration group. The LightSail project has been completely funded by private citizens and cost under $4 million, according to The Times.