When reading about how fast New Horizons will be going, I thought about our asteroid belt between Mars and Jupiter. Everyone practically held their breath as the Pioneers and even Voyagers passed through the asteroid belt.

[Pioneers 10 and 11 had preceded the Voyagers to Jupiter and the asteroid belt was a major concern for them. By the 1960's more than 3000 minor planets had been discovered and their orbits well determined. Even 50,000 minor bodies spread over the volume of space occupied by the asteroid belt would produce little direct danger, although a chance collision with an uncatalogued object was possible.

"While the largest of the asteroids were known and their orbits charted, many of the asteroids moved in unknown orbits. Although the risk of a spacecraft colliding with a charted asteroid was negligible, there was no way to estimate how many particles the size of a grain of sand might be present in the asteroid belt to collide with the spacecraft and seriously damage it". (From Pioneer, First to Jupiter, Saturn and Beyond, NASA SP-446, 1980) Only be going there could the danger be properly assessed - and Pioneer was first.]

http://voyager.jpl.nasa.gov/faq.html

Joy, now we have to worry about the vicinity of Pluto.

Thanks, Adam.

-Earth has her own ring as well man made and otherwise.

-Shields up, fingers crossed, it's going to be a long trip.