One of the current questions for the future of space exploration is whether to return to the moon, or just head to Mars.

Should we return somewhere we’ve been before? Or just strike out toward someplace totally new? Is there any benefit to going back to the moon? Can we make it to Mars without building up our endurance and scientific knowledge on the moon first?

There are intelligent, well-connected, even famous, proponents on both sides.

Going to the moon is a much shorter trip, obviously. It will not require new technology, though an update of Apollo-era tech would definitely be in order. Much knowledge and ability has actually been lost since Apollo, due to the dismantling of the Apollo rockets, the retirement of most of the Apollo-era scientists and engineers, and the lack of good documentation in many areas. Returning to the moon would allow us to regain that prior level of capability. It’s also cheaper than going to Mars, and money is always a large factor in any NASA project.

Humans have only spent a few days on the moon, at most. Long-duration stays on space stations have taught us some things, but a long-duration surface stay will likely provide even more of an education. Having a permanent outpost in space is a great thing to have. We have that in the space station right now, but we could have an additional outpost on the moon, still close enough for minimal communication lag.

The moon could be a testbed for trying out long-duration infrastructures and technologies. In-situ resource utilization (ISRU) can be evaluated on the moon, such as turning ice into breathable air, drinkable water, or burnable rocket fuel (assuming there really is water ice on the moon). Actually finding out if there is water ice on the moon is another reason to return. There are things we haven’t learned about the moon, despite all the studies, probes, and visits we’ve made to our nearest neighbor.

And as a personal note, the only humans who have been to the moon have been men. It’s about time we send a woman to the moon!

But what about Mars? We’ve never sent any humans to Mars, men or women. It’s a real planet, not just a moon, and it is a new frontier. Instead of revisiting an old place, doing things already accomplished, we could be doing something new. Mars has more science for us to learn, more secrets for us to uncover. Instead of spending our time and money on something we don’t need to do, we could be focused on a new adventure. And speaking of money, a plan to return to Mars is more exciting for the public - hence, more alluring to politicians, more acceptable to taxpayers, and more likely to garner the needed funds.

Mars might also harbor life. Life in a totally different ecosystem than Earth’s. Life that might have developed totally separately from Earth’s. Life that robots are trying to find (and as a roboticist, I am a huge supporter of robot exploration), but that humans might find much easier.

Now, of course, those who want to return to the moon also want to go on to Mars as a second step. But which should we do first? Personally, I have always wanted us to go back to the moon first, but that’s primarily due to my involvement in moon-focused research in the past. I don’t think this question has been answered yet, so that is one reason I wrote this article - to generate discussion.

When I first worked for NASA, we were (unofficially) told to not mention or talk about going to the moon or Mars in our conference presentations or research proposals. All our research was for generic planetary surfaces. Speaking in specific terms could potentially get our funding cancelled, if we focused on a destination that was not in current favor. Then, it changed. Then we could wear those little lapel pins that said "Mars or bust!" Later, we had to switch to the "Moon or bust!" pins.

The most unfortunate part of NASA is that its research projects are so closely linked to political winds. So we need to decide, to choose a destination.

And then go there.