SCM: Can you explain forwards and backwards contamination?
BG: There is no way to put humans on Mars without taking a lot of Earth microbes with us, which would contaminate Mars. And we may become contaminated with something on Mars that is pathogenic. Could those people (who first go to Mars) return to Earth, or would it be a one-way trip? What are the costs and benefits? There’s a tension there.
Some people say this isn’t a big issue; we’re already trading meteorites back and forth from Mars and if there’s any life, that would have been shared already. I’m not convinced about that. We have the ability to do science on Mars, and I think we should do science first. But good science will probably take longer than Elon Musk wants it to.
SCM: But in their race to be the first, the spirit of many innovators is to move fast and take risks. It’s what drives their success.
BG: If you’re going to be a visionary, you have to be a dreamer, and he’s absolutely fantastic in that regard. But at the same time, people who get their hearts set very strongly on things sometimes get so focused on achieving the thing they want that they don’t fully consider the negative consequences. It’s what I call “the Jurassic Park question”: the scientists were so preoccupied with whether they could, they didn’t stop to think whether they should.
SCM: Instead of trying to settle Mars right away, you recommend settling the moon first. What would be the advantages?
BG: A moon settlement can do everything a Mars settlement can do, including serving as a “back-up Earth,” for much less cost and risk. It has lots of resources—not quite everything, but almost (NASA has detected water molecules on the moon)—and what it lacks can be imported from Earth or from asteroids. We know the moon doesn’t have any life, so we know there is not going to be a forwards/backwards contamination issue. No one has returned to the moon since 1972. Let’s go there first; it’s a lot closer and it’s a lot easier. It’s still super difficult, but not as difficult as Mars.