Paying a Visit to Pluto - Presented by Science at NASA.

At this very moment one of the fastest spacecraft ever

launched, NASA's New Horizons, is hurtling through the void

at nearly one million miles per day.

Launched in 2006, it has been in flight longer than some

missions last, and still has four more years of travel to go.

New Horizons is headed for the lonely world of Pluto on the

outer edge of the solar system.

Although astronomers now call Pluto a dwarf planet, "it's

actually a large place, about 5,000 miles around at the

equator," says Alan Stern, principal investigator for the mission.

"And it's never been explored."

Indeed, no spacecraft has ever visited Pluto or any dwarf

planet in the outer solar system.

"This is a whole new class of worlds," says Stern.

"To understand the solar system, we need to understand

worlds like Pluto."

Pluto is a resident of the Kuiper Belt, a vast region

beyond the orbit of Neptune.

Stern believes "the Kuiper Belt contains a thousand dwarf

planets or more - a whole zoo of them!

Dwarf planets are, in fact, the most numerous class of

planets in the solar system, and probably in the whole universe."

Pluto is a world of mysteries.

For one thing, Stern wonders, what are the molasses-colored

patches on Pluto's surface seen by the Hubble Space Telescope?

Some scientists think they could be deposits of primordial

organic matter.

"New Horizon's spectrometers will help us identify the

kinds of organic molecules on Pluto.

We expect to find something pretty interesting."

Hubble recently contributed more intrigue by spotting a new

moon circling Pluto - bringing the total to four.

Composite Hubble images of Pluto now resemble a miniature

planetary system.

New Horizons will hunt for even more moons as it approaches

the dwarf planet.

To aid in its investigations, New Horizons is carrying one

of the largest and highest resolution interplanetary

telescopes ever flown.

It's called LORRI, short for Long-Range Reconnaissance Imager.

"At closest approach to Pluto, LORRI can resolve details

almost as well as a spy camera.

The view will be incredible.

If we flew this instrument over Earth at the same altitude

as we plan to fly over Pluto, we would see individual

buildings and their shapes."

What will we see on Pluto?

Some researchers predict icy geysers.

Some say we could see those surface deposits of organic material.

Stern says simply, "There could be all kinds of surprises!

It's a first exploration of a new kind of planet."

New Horizons is scheduled to reach Pluto in 2015.

For mission updates, please visit science.nasa.gov.