ESA astronaut Alexander Gerst has spent over 5700 sunrises and sunsets in space, yet he has never been more than a day in the total darkness of a cave on Earth.

“I have been to several caves for small trips, but I haven’t really spent a long time in them. One very special thing that I have seen are the ice caves of Mount Erebus in Antarctica,” Alexander says.

“Right at the top, the mountain is covered with thick glaciers, and it melts caves into the ice from below. There are massive cave systems with a very special biology under conditions to be found nowhere else in the world,” recalls the astronaut.

Geophysicist, volcanologist and more recently International Space Station commander, Alexander is looking forward to adding more skills and knowledge to his tool set for space exploration with CAVES.

Alexander at the top of Mount Erebus during an Antarctic expedition.
Credits: A. Gerst

“I find it fascinating to look for life and for answers to scientific questions not only in space, but also on – and inside – Earth,” he says.

Alexander sees the cave training as an excellent way to re-learn how to perform science and collect samples under difficult conditions. “We will definitely benefit from the experiences gained in courses like CAVES not only for doing science in the tight quarters of the Space Station, but also for later missions to Moon and Mars,” he adds.

One of the things he is looking forward to is going outside his comfort zone. Living in total darkness and constantly making sure the crew is safe, will be psychologically demanding.

“To me this is a very attractive setting because I will have to rely on all my senses, my intuition and my abilities to perform well. Whenever you leave your comfort zone, you learn something new,” he ponders.  

Follow his cave adventure and connect with Alexander.

Orbital sunrise from the International Space Station. Credits: ESA–A. Gerst