We all know that space exploration is one of the most impressive challenges of our time, evoking the mysteries of a universe without limits, something impossible for human beings to conceive of.
The hardest thing to imagine is the massive distance that a spaceship will have to travel to reach other planets such as Mars or asteroids even further afield. We can talk about hundreds of thousands kilometres, but numbers are not enough to convey the deep sense of isolation and loneliness that astronauts will have to face during interplanetary travel. People normally think about a journey in terms of time: How long will it take me to fly from Cologne to Houston? How long will this Soyuz take to reach the Space Station from the Baikonur launch pad? What is the furthest place on Earth that you can reach from your office chair?
Distance is probably the most relative concept in our fully connected world. The time needed to reach a place now depends only on the availability of means of transport and money…
Rome might be very close for a Japanese manager on an international flight, but unthinkably far for a property-less nomad living in the Sahara desert. For humans, space on Earth expands not through the laws of physics, but according to social status and the availability of technology.
Returning to the Universe, even if our astronauts travel at 28,000 km/h, it will take them over six months to reach Mars. Their communications from the red planet will take up to 20 minutes to reach Earth, even travelling at the speed of light. They will have to wait a further 20 minutes for our reply, and in the event of an emergency, nobody will be able to reach Mars and rescue them in a matter of hours.
This sense of immense distance is really unusual in our modern world. But surprisingly, some humans can claim to have experienced something similar: through exploring remote caves under the surface of the Earth.
Caving is a mixture of sport, science, and geographical exploration. Caves probably represent the last unexplored ‘Dark Continent’ of our planet, together with deep ocean abysses. The main characteristic of caving is that exploration is carried out by passionate people without expensive technologies, using only their bodies and minds. In the last thirty years, thousands of kilometres of caves have been explored under the Earth’s surface, surely just a fraction of what actually exists.
But what is really interesting is that there are no aeroplanes, space shuttles, submarines or robots able to reach the deepest and furthest parts of these caves. Only humans can do it, climbing with their own feet and hands, rappelling on ropes and crawling through tight squeezes for hours – sometimes days – in total darkness, impenetrable but for their lamps. People who in their ordinary lives are employees, sales staff or lawyers become geographic explorers in their free time. More often than not, they don’t know they are pushing back the boundaries of the known Earth, tracing its underground surfaces…
The most recent and extreme explorations have reached depths of over 2000 metres below the surface (e.g. the Voronya cave in Abkhazia) and travel many tens of kilometres from the entrance. For example, in the Sneznaya cave, Russian cavers need about five days of progression to reach the camp at the bottom of the cave and around seven to come back to the Sun with all their equipment. Their explorations inside this cave can mean spending more than one month underground, with no communication to the outside world.
Similar ventures are happening in many other places around the world, but no one knows about them because cavers are just ‘ordinary’ curious people who don’t need anything more than passion and courage to expand human knowledge.
So, where is the most distant place on Earth? I suspect most people would say “the Antipodes”. But this is not true, because the places that take the longest time to reach on Earth are the depths of caves. Inside caves, there are no fast means of transport and no one can help you in the event of an emergency: if an accident happens, the rescue team could take tens of hours or even days to reach you. Lost in these labyrinths, explorers feel a real sense of loneliness and isolation. You are thousands of miles further than in any other place you could be on the Earth’s surface.
That’s why the European Space Agency organized the CAVES course, which probably represents one of the most challenging experiences for an astronaut who may be sent on an interplanetary mission in the future. The exploration of the underground world is a great analogue of these long-distance, long-term space missions.
But just how far we can go? Maybe this is the question that both troubles and inspires astronauts and cavers alike.