Most of the time when I wear my Occupy Mars t-shirt (available from Space X), I get a thumbs up from people I meet. But awhile back a woman took a look and said, “No, no. Don’t occupy Mars.”

She was just passing by, so I didn’t get a chance to ask her what her objection was. Did she think humans would mess up Mars? Or did she think exploring space was a luxury we can’t afford? I’d disagree either way, though I’d be willing to have a thoughtful conversation on whether we humans, with all our flaws, might be a destructive force in the rest of the universe.

But when it comes to the “we can’t afford it” argument, my response is “we can’t afford not to do it.”

I got to thinking about this reading Steven Popkes’s post last Sunday and visiting the Evergreen Aviation and Space Museum over Thanksgiving. Just looking at the history of aviation — which went from the Wright Brothers to jet planes in about 40 years and now is so routine that most of us think nothing of flying across the country for a holiday weekend — is enough to get me started on what human beings are capable of inventing and discovering once they’re given half a chance.

Visiting the part of the museum devoted to the history of space exploration reminded me that I grew up with the US space program. What’s now called the Johnson Space Center was plunked down in a cow pasture about five miles from where I grew up. Our fledgling Episcopal Church in Friendswood got a boost from scientists and engineers who came from all over to work at Mission Control. We didn’t get any astronauts, but we did get a lot of the powerful people who made things happen.

We landed human beings on the Moon in 1969 — finally getting ahead of the Russians at something in space — and then started scaling back. Of course, as I’ve mentioned before, the space program was a Cold War program — war by other means. But it was also a prime example of what people can do when there’s money and support for a program.

And if you want to talk about the economy, you can just look at the growth of the area where I grew up in the post-NASA days. I can’t say I liked all that growth — some of it was environmentally irresponsible — but there were plenty of jobs.

Had we kept up the pace from the 1960s, we could be mining the Asteroid Belt by now. We could have some settlements on the Moon and maybe even on Mars. The kind of work the rovers are now doing on Mars could be happening on other planets in our Solar System.

xkcd had a good comic this week showing all habitable planets within 60 light years of Earth:

Other countries — Steven mentioned India and China — are now working on space exploration, and private businesses have begun some projects. Imagine what we could do if there was real, widespread, economic support for such projects.

We can’t reach those habitable planets yet, but what if we were focused on finding a way to do that? What else might we discover?

I’m not advocating doing this at the expense of dealing with poverty, by the way. We can afford to do both. It’s a matter of how we set our priorities as a society. Me, I think space programs, health care, education, and infrastructure are a lot more important than making it easy for the rich to get even richer.