GARRETT REISMAN: There's a tremendous amount of science that comes out of space exploration.

One is the scientific benefit that we get from understanding our solar system, understanding the composition and the makeup of all the other planets and the other bodies in our solar system. Our sun. We learn a lot about the Earth. We look back at the Earth with space assets. We learn about how the earth is changing, what's happening with climate change, all that kind of stuff. Then there are all the spinoffs and your Velcro, which wasn't actually invented for the space program. I don't think Tang was either but there's plenty of other things like smoke alarms, MRIs, cordless drills, all kinds of those wonderful things that we like to brag about.

To me that's actually not a very good justification for space exploration, and I'll tell you why because we could do those things by having targeted R&D research for industrial and commercial applications probably more cost effectively.

So it is true that we get lots of spinoffs, but I think the science return that we get from space exploration is actually much more important than any kind of spinoff. But there's yet another reason I think trumps all those, which is the fact that, I'll put it to you very flippantly. There's an old joke about why did the dinosaurs go extinct, and it's because they didn't have a space program, okay. So if you take the very, very big picture view, the very, very long view of this kind of on geological time, it's about survival of the species. The earth is fantastic and we need to do a much better job of taking care of it because I could tell you there's no other place that we know of in the entire universe that is as well suited for human life as this planet. That's why we evolved here and we have been evolving for eons to get to this point. And we've evolved in this environment, so this is our home. This is what we are made for. We're not going to find something better for us out there. We need to take care this place. However, again if you look at the very, very big picture, this place as wonderful as it is is not going to last forever. I mean at a minimum eventually the Sun is going to basically explode and the solar system is going to change and it won't be a hospitable place for any of us.

Now if my kids are watching, do not be scared. Don't stay up all night and have nightmares about what I just said because we're talking about so far in the future that that's not something we have to worry about right now at all. There are other things. There have been many extinction events in the course of the earth's history. I think there have been about seven of them. The one everybody knows about is the extinction that took out all the dinosaurs. And there's a lot of different ways that can happen.

You can get hit by an asteroid. You can have a super volcano that could throw up so much stuff into the atmosphere that we can have the extinction of life on Earth. There's a lot of ways that can happen. And by the way the most probable way that we will have another mass extinction event on Earth is that if humans cause it ourselves. And we've been doing a pretty good job of that with climate change. Now for hundreds of years we've been putting all these greenhouse gases into the atmosphere, and if we keep doing that and don't do anything about it we will eventually make the earth uninhabitable and we will go extinct.

So there's all these reasons why this place, as perfect as it is, will not last forever. And so I look at space exploration as the ultimate Plan B. That if we have humans both on Earth and on Mars or other places inside our solar system, then if there is one of these extinction events, and that other colony is self-sustaining, that the species will survive. So if you look at it as a survival question, I think that might be the strongest justification for spreading human life beyond just Earth.