DW: What was the most difficult aspect of caving for you?

Matthias Maurer: There are different aspects. One is the technical aspect. You have to learn the different skills so that you can climb. Basically caving is climbing, but underground. It's also about teamwork because you have a task in a team and you can only be successful as a team. And you have to adapt to the environment which I have to say was also quite challenging.

What correlations are there between caving and exploration on the moon or drilling on Mars? What kind of practical things could you learn caving that would be potentially applicable on a planet or on a moon?

We did two different training exercises at ESA [the European Space Agency, the ed.]. One is the caving for team-work fostering so that you become a good team member and you learn to interact with your colleagues.

The other activity is the Pangaea training, which is geologically focused. There we practice going into caves and lava tubes because on the moon or on Mars, we expect to find such lava tubes and they could be a potential area of interest for explorers.

And not just an area of interest but also practice for potential habitation, if I remember correctly.

Yes, that is one of the concepts that we discuss because in a cave, you are protected from micrometeorites and from radiation. But there is also the challenge of bringing in all the gear. So maybe a lava cave is a good location, but maybe it's not.

When you heard about the Thai boys trapped in the cave, what was your first thought?

I first thought wow, it's so deep in the cave and isolated and they're not experienced — it's a group of boys. So I think there was for sure a lot of panic in this group. It's a completely different world to that which we know. Also being trapped like that on the other side of water and having to dive out — even for me with some cave training that would be challenging. It's really a risky situation.

What are some other dangers inside caves that people wouldn't necessarily think of?

So in the cave you also have to consider you need water, you need food. You have no equipment to filter the water, and you also need to go [to the restroom]. And so if you pee into the water that you drink, then you have the risk that you might get sick. So you need to keep the hygiene of the place. You need decent food and the boys were in there many days without food, so I guess they were already weak.

You also have a very humid environment. That means if you have a cut on your skin, it doesn't heal well. Very humid means you move a little bit and sweat. [If] you stand still, you freeze. You get chilly and cold. I don't know the exact temperatures in that Thai cave, but that was my impression in Italy. So it's a bizarre environment and you need training to be able to cope with it.

Matthias, would you say that you like caving now? Would you do it in your free time?

Yes I think it's a new world that I discovered. And I actually like it very much, discovering this unknown territory. But it's also challenging and I know that I wouldn't go there by myself without having trainers or trained personnel that helps me. Because I'm still a beginner.

Matthias Maurer is a German material science engineer and astronaut. He was selected for space training by ESA in 2015 and has yet to travel to space.