The world is invited to help discover a potential new, icy follow-on destination for NASA's New Horizons spacecraft, using the IceHunters.org website. New Horizons is currently en route to make the first flyby of the Pluto system, and is then capable of making additional explorations of bodies still farther out in the Sun's Kuiper Belt.

Through this citizen science project, the public can help scientists search through specially-obtained deep telescopic images for currently unknown objects in the Kuiper Belt. Along the way, they will also discover variable stars and asteroids. IceHunters is a Zooniverse citizen science project.

"The New Horizons project is breaking new ground in many ways," says project Principal Investigator Alan Stern, of the Southwest Research Institute.

"We're flying by a new kind of planet," says Stern, "and we'll be making the most distant encounters with planetary bodies in the history of space exploration, and now we're employing citizen science to help find our potential extended mission flyby targets, perhaps a billion kilometers farther than even distant Pluto and its moons. We're very excited to be working with Zooniverse and breaking this new kind of ground. We hope the public will be excited to join in with us and with Zooniverse to make a little history of their own by discovering our next flyby target after Pluto."

Somewhere, on the outer edges of the solar system an icy body lurks undiscovered, orbiting on a path that will just happen to carry it toward a potential rendezvous with the New Horizons spacecraft. This mission is on course for a 2015 fly by of Pluto. This encounter begins New Horizons exploration of the Kuiper Belt.

After visiting Pluto, the spacecraft will have enough fuel remaining to change its course to fly toward at least one and possibly two Kuiper Belt objects in the distant outer solar system - an object the IceHunters website is designed to find. The expected date of the KBO flyby will be between 2016 and 2020, depending on the object chosen and its distance from Pluto.

The Kuiper Belt is a region of the outer solar system, extending past Neptune, which contains small planets ("dwarf planets"); icy objects of a variety of different sizes up to thousands of kilometers across.

The first KBO other than Pluto was only discovered in 1992, and the KBO population is still not well mapped. IceHunters will do its part to study one small slice of the Kuiper Belt as it looks for an object along New Horizon's trajectory after its Pluto flyby.

If that object can be found , it will become the most distant object ever visited by a spacecraft from Earth.

Using some of the largest telescopes in the world, scientists have imaged that region, producing millions of pictures for that could contain images of the rare objects that are orbiting toward just the right location, along with many other small worlds on different trajectories. Users of Ice Hunter's will be charged with marking these moving targets for follow-up.

The images contained in IceHunters.org are "difference" images, created by subtracting observations taken at two different times. By subtracting the two images, scientists can mostly (but not entirely) remove the light from constant sources like stars and galaxies.

Left behind are the things that move or vary in brightness: Kuiper Belt objects, asteroids, and variable stars. Since the stars never subtract off perfectly, the images appear messy, and computers can't be trained to find objects as effectively as a people can.

The search team will use the millions of mouse clicks made by IceHunters users to identify objects moving on orbits that New Horizons might reach.

"When you're looking for something special in masses of messy, real-world data, sometimes there's no substitute for the human eye, and Zooniverse IceHunters will put thousands of eyes to work on this important job," said John Spencer of Southwest Research Institute, a member of the New Horizons science team who is coordinating the search effort.