[Andy Ross]

The trajectory of a craft on its way towards a planet is drastically different to the trajectory of the planet itself. To go from the one to the other takes a great deal of effort.

When we're sending things to Jupiter and other massive bodies, we can take advantage of their own gravitational forces to alter the energy state of the spacecraft. With Pluto being so tiny: it's really little more than a big asteroid; its puny gravitational strength is not conducive to a good transition. It's not impossible, but it is very impractical, to orbit Pluto.

Personally, I'm not convinced by the desire to send a craft to Pluto. Very little is to be gained by investigating the outer planets. I'd much prefer to see missions much closer to home (lunar missions and Mars).

Andrew

[traditionalist]

Thanks for the explanation. I've need to bone up on my physics.