Science is really about individual experts reaching a consensus.

Typically in science, individual scientists make up their minds about scientific fact or theory one at a time. We don't take votes. We just don't vote on quantum mechanics, the theory of relativity, why the sky is blue, or anything else.

I'm hopeful that commercial space exploration will takeoff. To really fuel the spaceflight revolution will require an investment of hundreds of billions of dollars a year, and I think that's only going to happen in the commercial sector - if there are large profits to be made.

I think if you were between maybe 6 and 16, there was nothing like Apollo, and I wonder if there can be something like that again. We'll just have to see.

At the time of Apollo 11, I was a grade-schooler, and I remember every time an Apollo mission would take place that, like a lot of little boys, I'd gather in front of the TV for hours and hours and hours with my little brother.

As a researcher, I look forward to being able to do space science in a space environment.

Absence of evidence is not evidence of absence.

During one of the Apollo missions, I saw Walter Cronkite showing off the flight plan. It just mesmerized me. All this detail! That's what I wanted.

The Kuiper belt region, which I call the third zone because it lies beyond the rocky terrestrial planets and beyond the giant planets, is a bizarre frontier.

By going to Pluto, we have a chance to anchor, with real data, models of the early evolution of Earth's atmosphere.

The New Horizons Pluto mission will be the first mission to a binary object and will help us understand everything from the origin of Earth's moon to the physics of mass transfer between binary stars.

Just because Pluto or comets aren't as big as Jupiter doesn't mean they are not scientifically important - indeed, just the reverse is often true. Sometimes, great things come in small packages.

Discovering that our solar system has many more planets than we ever expected, and that most of them are ice dwarfs rather than like Earth and the other rocky terrestrials, is just another step in the revolution in viewpoint that removed the Earth from the center of the physical universe and makes Earth all the more special.

Of course Pluto is a planet: It's massive enough to have its shape controlled by gravity rather than material strength, which is the hallmark of planethood.

Just speaking for myself, I think the return of people to the Moon has a lot to offer for understanding the formation and evolution of terrestrial worlds; so would the exploration of near-Earth asteroids by people.

My field is called planetary science.

In science, we take large numbers of disparate facts and reduce them to see patterns. We use the patterns to reduce the amount of information. It's the reason we name species and genera and families in biology. It's also the reason we have names for certain types of geological features and so on in other fields.

A river is a river, independent of whether there are other rivers nearby. In science, we call things what they are based on their attributes, not what they're next to.

It shouldn't be so difficult to determine what a planet is. When you're watching a science fiction show like 'Star Trek' and they show up at some object in space and turn on the viewfinder, the audience and the people in the show know immediately whether it's a planet or a star or a comet or an asteroid.

No one predicted Mercury would be a planetary core with the mantle stripped off. No one predicted volcanoes on the Jovian moons, or oceans on the inside of them. I can tell you, for every single planet, huge 'we never guessed that' things.

I've been on 26 space missions; they range from suborbital to orbital to shuttle experiments to planetary missions.

Every mission has life-or-death moments.

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.

The big lesson of planetary science is when you do a first reconnaissance of a new kind of object, you should expect the unexpected.