Female Astronauts Underground

What are female astronauts doing underground? They train for the unique conditions that await them on board the space station. Speleologist Sabrina Huber and her team joined astronauts in training Dr. Insa Thiele-Eich and Dr. Suzanna Randall on an underground mission to practice acclimatizing to extreme environments, constant darkness, and isolation. After all, Germany will soon be sending its 12th man into space, yet no German woman has had this opportunity so far. The initiative “Die Astronautin” (The Female Astronaut) is doing everything in its power to change this.

astronauts train underdground using jack wolfskin equipment

One warm day in May, we – a team of four women and two men in red waterproof dry suits – climb down into one of Germany’s largest cave systems, where we are to spend the next five days together. Some of us are strangers, and this particular group has never yet undertaken anything together.

JW adventure and scientific training in beautiful caves

Weighed down with heavy cave packs, we crawl backward on all fours through a narrow artificial passage secured with a thick iron door and metal structure, which continues almost 30 meters down into a fluvial cave system in Bavaria more than 10 kilometers in length. After passing through a small chamber, we soon reach the underground river and follow it upstream for the next two hours. On the way, we crawl and swim through what is known as a half-siphon, where there is still space for our heads between the water’s surface and the roof of the cave. Wading onward through water that comes up to between our knees and our hips, we reach a small waterfall which we could already hear roaring magnificently from quite a distance. Somehow we have to get up there, swimming downward on one side then climbing upward with straddled legs through the waterfall itself. The cave packs, which contain all our equipment sealed in waterproof screw-top containers, are handed up one by one. We made it!

We continue our expedition in inflatable dinghies, paddling hard against the current. This is the “Jules Verne Passage,” a section of the cave where the underground river has carved deep fissures in the rock and meanders in serpentine fashion through a tunnel. We disembark, tie up the boats, put our packs on our backs, pick up the rest of our equipment and continue just a few meters upstream up a loam slope: we have reached the “Icarus Bivouac.” Here we unpack all our materials and set everything up. The bivouac site is located in a niche close to the cave’s ceiling; it’s a safe place if the cave floods and offers plenty of space and an even surface on which to sleep. Here, we will be spending the next four nights in a dreamlike world that is usually pitch dark and is now only illuminated by the beams from our helmet lights. The temperature is just 9 degrees, it’s constantly wet, and all you hear is the rushing of the underground stream. Along with four experienced speleologists, the team on this underground mission consists of two aspiring female German astronauts, Dr. Insa Thiele-Eich and Dr. Suzanna Randall.

astronauts in training with head lamps making contact with their colleagues

Female German astronauts? Have you ever heard of any?

It’s difficult to believe in this day and age, but Germany has never yet sent a woman into space! Space engineer Claudia Kessler set up the initiative “Die Astronautin” in 2016 to change this state of affairs. Insa and Suzanna were chosen from among more than 400 applicants to begin training as astronauts. Their training is financed entirely by donations and grants. Unlike their male colleagues at the ESA, they don’t currently qualify for financial support from the government. Matthias Maurer (2014) and Alexander Gerst (2019) also completed a speleology training program. Matthias Maurer will soon become the 12th German man in space – but there still hasn’t been even one female Germ, an astronaut.

absailing and climbing through cave tunnels

So far, the two prospective astronauts have completed a course of basic training consisting of parabolic flights, diving training, and acquiring a pilot’s license. All this while holding down their primary jobs as scientists. Insa is a meteorologist and climate scientist at the University of Bonn, while Suzanna is an astrophysicist at the ESO, the European Southern Observatory in Garching close to Munich. They have also completed a course of theoretical training on the functioning and work methods of the International Space Station. They are now undergoing a course of special extreme training during which they will spend five days crawling, climbing, and swimming through this cave. Afterward, they will receive mission-specific training, which will prepare them for their unique deployment in the ISS research module. The foundation “Erste deutsche Astronautin gGmbH” has set itself a clear goal: to send the first female German astronaut into space! Other goals are to kindle enthusiasm for space travel, science, and technology in girls and young women and to support science and research on board the ISS. During the program, scientists also conduct research on the effects of zero gravity on the female body. In Europe, not even a handful of data records exist on this research topic. Especially in terms of eyesight, interesting differences between the male and female body have been found: about 30% of male astronauts suffer from significant damages to their eyesight. International records don’t show similar effects in female astronauts. It is not yet known why that is, in any case, Insa and Suzanna will conduct further research on board the ISS.

female astronauts exploring a cave system underground JW

Parallels between speleology and space research

After the first strange night in the bivouac, we set off to take a closer look at the fluvial cave and gradually penetrate some of its corners. We are in an unfamiliar environment, and at first, we find it hard to orient ourselves. But new experiences like these are exactly what we are looking for, 100 meters underground, far away from the outside world. The cave mission reproduces many of the unique conditions and specific aspects of a space flight, such as the extreme, alien environment, the constant darkness and need for artificial light, isolation, and remoteness. The human body’s rhythm can quickly change when there is no sunlight to show daytime or nighttime. Disordered sleep is the result – although in our case, this is mainly caused by snoring researchers. For this very reason, one team member is banished on the first night and made to sleep in a separate space on a loam slope some 30 meters away from the bivouac.

incredible hidden water system in beautiful green yellowish colors

We live absolutely autonomously. Everything we need has been sealed in watertight containers and transported to the bivouac in cave packs – 34 of them in all, some light, others very heavy. The screw-top containers are mostly filled with food, gas cookers, cooking utensils, clothing, insulating mats, sleeping bags, climbing equipment, and so on. For dinner, we choose sustainably produced vegan food. We have muesli with milk powder in the morning and an energy bar or two during the day. Once the mission is over, we will have to carry out all our leftovers and waste, even the camping toilet and its contents.

The team dynamic that develops during the mission is much like the one expected during a cooperative space mission. We don’t really know each other; neither do we know how we will react to each other or the cave environment in stressful situations. Moving inside the cave offers another parallel with space research. Movements underground are governed by safety rules similar to those on board the ISS. Even the slightest mistake could have fatal consequences down here. Since the astronauts will be spending a significant part of their time in space conducting scientific research, they have to undertake an authentic crew mission as “speleonauts,” which involves performing various experiments and activities during their explorations of the cave. After the team training, one of the missions’ goals is to conduct speleological scientific research. And perhaps we will discover previously unknown areas of the cave, virgin territory, while we are exploring and taking notes.

deep inside the earth a new world opens, two scientist discuss with head lamps their findings

The longest day

The third day is the hardest. We have to set off early, and we know that we won’t return to the bivouac until very late. Today’s destination is the “Giant’s Chamber,” where we will be taking samples from dripstones; these will later be investigated in the laboratory to find out how old they are and elicit statements about the climate in the past. It’s not unlike measuring tree rings. The growth rings inside a dripstone show when the stone grew more quickly, i.e., when the climate was wetter and when its growth slowed or stopped altogether, i.e., during drought periods or ice ages. Unlike trees or ice cores, dripstones allow us to look much further back into our planet’s climate history.

However, on the way to this enormous chamber, which could easily accommodate Cologne cathedral, we have to tackle an extremely arduous, narrow, and above all muddy path. Areas like “Fangoland” are marked on the cave map, which gives us some idea of what to expect. And we are not surprised: the brown slop drips from our red overalls, and everyone looks more than just muddy. After two hours of crawling, we finally reach our destination: a gigantic chamber with countless dripstones suspended from the ceiling and rising from the floor. Even our powerful helmet lamps are unable to illuminate the entire area. The beams of light simply disappear into the inky darkness. Here we extract various samples from dripstones and take photos. The way back with our heavy baggage seems long because the stone weighs a lot. The bags are handed on from person to person as we squeeze through narrow gaps. That’s precisely why we wear overalls since pants or jackets would quickly ride up or slip down. Men usually get stuck around the ribs, women at the hips, since these are the widest part of their skeletons – a round belly, on the other hand, can be squeezed through a small gap relatively easily. Late in the evening, we reach the main entrance of the cave and the underground stream, completely exhausted and plastered in mud, first to lie down and relax in the stream and clean our suits. Then it’s time for dinner in the bivouac, where we have set up a small kitchen with gas cookers and pots. There’s even a water-powered generator that provides enough electricity to illuminate our dining area with LED lights. This means we can conveniently recharge our batteries overnight. However, on the very first evening, we find that we have packed everything imaginable but only have four spoons for six people. This is a kind of psychological test for everyone involved; after all, only the early bird catches the worm.

man with a helmet and head light exploring and gathering data for science and training purposes

Goals of the underground mission

On the fourth day, we scale a tall shaft. We climb a rope with the help of ascenders then abseil back down using what’s known as the single-rope technique. Communication with the outside world is made possible through a special longwave telephone. We can use this to send daily status reports to our outside base from our location 100 meters underground. Emergency rescue operations for people who suffer caving accidents are often limited and usually highly complex. We just have to remember how a seriously injured speleologist was rescued from the “Riesending” cave in Untersberg, near Berchtesgaden, some 1,000 meters underground, or the difficulties encountered by the divers who rescued a children’s football team in Thailand. However, the food and equipment supplies and the logistics in the cave are just as limited and complex as on a space mission. Like in space, you have to be completely autonomous when undertaking a mission to accomplish scientific tasks underground.

Besides completing scientific tasks such as measuring various climate data in the cave, we are also interested in how humans behave and perform in an environment similar to that found in space. The theoretical and practical preparations for this cave mission alone took almost two weeks since we had to be sure that we could safely and efficiently carry out research in a subterranean environment. During this period, the two astronauts visited several caves to familiarize themselves with the conditions. The primary purpose of this is to improve their communication, decision-making, problem-solving, leadership, and team skills by taking part in team activities, undertaking an authentic crew mission, and bringing scientific results back to the surface. When you only have four spoons for six people, it means two people are waiting patiently in the bitter cold until a spoon becomes available while everyone else savors their hot food.

ancient stalactites within an underground cave in bright lights

Therefore, one of the expedition’s goals is to practice cooperating effectively in a challenging environment while continuing to study the cave. In doing so, we also have to cope with the psychological impact of the mission and deal with critical situations and hazards, which also requires an awareness of the safety requirements essential when entering a cave. At one point, for example, a rather large rock falls to the ground a few meters away from one of the researchers while his colleague is climbing the shaft so that they and the astronauts can record further details about the dinosaur bones located there. This is precisely the kind of situation that can be fatal. That’s why nobody is permitted to stand directly underneath the shaft while somebody is climbing up it.

Besides documenting dinosaur bones and recovering dripstones for science, the research program requires the scientists to analyze the chemical and physical properties of the water, measure the dripping velocity on stalagmites, monitor the inflow and outflow behavior of streams, and – still more important – make records of the cave climate. We spend time measuring parameters such as air temperature, relative humidity, wind patterns, air pressure, and concentrations of CO2 and radon.

Before leaving the cave, we turn our attention to the main task of speleologists, i.e., taking digital measurements of the cave and subsequently creating a plan, a kind of map of the cave. For this, we divide into two groups, each taking on a specific area of the cave. Equipped with laser range finders and small computers for storing measurements and drawing the outlines of each section of the cave, we move from one surveying point to the next. We take measurements upwards and downwards at each surveying point, to the right and the left, and calculate the distance to the next point. In this way, we gradually create a three-dimensional plan of the cave. The work is very time-consuming, and the day goes by in a flash.

inside a beautiful and mysterious cave system with blueish looking crystals


We spend the last evening sitting in the bivouac as always, but tonight we have more time than usual. Usually, we lie down exhausted in our warm sleeping bags soon after each strenuous day has ended. After all, they are the only places down here where you can get really warm and comfortable. The tension and stress of the last few days in this indescribable world that was never meant for human habitation melt away. Although we are rather sad that we will soon be going our separate ways, we are also glad to see the sun again. We sit together for a long time and tell stories far into the night.

The next morning, we have to pack and clean up the bivouac. Nothing, absolutely nothing, can be left behind. We leave the cave just the way we found it. Shouldering our many cave packs, we head back out into the daylight. After days spent in a gloomy, brownish environment, we reach the exit early in the afternoon and are welcomed by the sun.

And there’s a smell of forest, leaves, and ozone, a scent you only become aware of after spending days in the underworld, where all your senses become more acute.

Further information about speleology is available on the website of the Association of German Speleologists and Karst Researchers.

Join Insa and Suzanna on their adventures in space in the children’s books Unser Weg ins Weltall (Our Journey into Space) and Abenteuer Raketenstart (Adventure Rocket Launch).