Alan Stern said this quote

Pluto is still active four and a half billion years into its history. It was expected that small planets like Pluto would cool off long ago and not still be showing geological activity. Pluto is, in fact, showing numerous examples of geological activity on a massive scale across the planet.

~ Alan Stern

There are lots of really interesting little planets out there in the Kuiper Belt, but Pluto's the only one that's got all the cool attributes.

~ Alan Stern

I like the planets because they are real places that you can go to and send machines to. Faraway astronomy - galactic astronomy and extra-galactic astronomy - is really cool stuff, but to me, it's about destinations.

~ Alan Stern

It says something very deep about humans and our society, something very good about us, that we've invested our time and treasure in building a machine that can fly across three billion miles of space to explore the Pluto system.

~ Alan Stern