It comes under the New Frontiers program ( http://newfrontiers.msfc.nasa.gov/ ) - the program that covers things that are bigger than a Discovery Mission, not under the Mars Exploration program, but smaller than the keystone misisons like Cassini, Galileo etc. - approx $700m a go.

NH is the first mission in this program as I understand it, the second, some years away, will be Juno - a Jovian Orbiter.

How do you get a spacecraft to Jupiter in under a year? Easy. Make it very very light, and put it on a very very big rocket. The config of Atlas V rocket being used to launch NH (551 - 5m fairing, 5 solids, and one engine on the Centaur stage ) would typically put 8,670kg into GTO or 20,520 into LEO.

New Horizons is 478kg, and it's Star 48B 3rd stage is 2,137kg - so instead of hauling 20 tons, this vehicle is hauling about 2.5 tons thus you get a HUGE velocity out of it. AND, once it's done that, you have the final kick of the 48B, 591 thousand kgs-s (thus accelerating is all a further 3.5 - 4km/s ball park speed, if my maths is right)

At launch - the vehicle is 573,160kg. NH is 0.083% of it.

Imagine the Apollo entry capsule on top of a Saturn V...tiny tiny tiny... that was 5,800 kg on a 3,038,500kg rocket - 0.191% - more than double that percentage of NH. The cutaway's are almost comical, with this tiny gold-clad box on an enormous vehicle.

Basically - it's a LOT of rocket, and not a lot of payload.

For comparison, look how much fuss was made of Stardust that entered so quickly. It took >16 hrs to get from the distance of the moon to Utah. NH makes that journey in 9 hours :)

One thing the NH mission is not short of, is superlatives.

Doug