If you're thinking, "This sounds like a teambuilding day taken to extremes", you'd be bang on the money.
Just like your work-sanctioned day trip to a local escape room, CAVES aims to teach participants how to cooperate and solve problems. The difference is that these astronauts aren't learning how to work with Barry from finance – they're building vital skills that they'll eventually use on a real spaceflight.
But, you may be wondering, why a cave?
Caves and the cosmos
It's difficult to recreate cosmic conditions on Earth.
Plenty have tried. You might have heard of
human centrifuges – those gigantic spinning tops that simulate the intense G-force of atmospheric reentry. Or
reduced gravity aircraft , which take death-defying nosedives to create brief moments of weightlessness for those onboard.
The problem is that this kind of equipment is bulky, expensive and only really deals with one aspect of spaceflight: gravitational conditions.
To really get to grips with space, you have to go back to basics and start poking around in a cave.
Here's the thing. Space is a dark, cold and lonely place. You can ride the human centrifuge until Tuesday afternoon, but it won't prepare you for the sheer isolation of spaceflight.
Caves are pretty dark and lonely too. In fact, they're pretty much the closest thing to space that we have here on Earth.
And unlike zero-G aircraft, they're cheap and abundant. We know of thousands of caves around the world – and there are probably many, many more yet to be discovered. A multi-million pound rocket launch this is not.
The scientists say it best. Here's ESA's
explanation as to why they use caves for training:
"The cave environment provides many space-relevant conditions, including isolation from the outside world, lack of diurnal cycles, confinement, minimal privacy, technical challenges, limited equipment and supplies for hygiene and comfort, and the constant presence of risk."
This isn't the only reason that ESA sends space trainees underground. It's also a great excuse for them to practice their spacewalking skills.
While they're underground, the fledgling astronauts undertake a simulated spacewalk – or "cavewalk" – along the limestone walls. Aided by cables and tethers, they navigate across tricky obstacles in near darkness.
As ESA says, "'cavewalks' are similar to spacewalks because they require safety tethering, 3D orientation, staying clear of dangerous areas and careful planning and teamwork".
After all that, we bet a real spacewalk feels like a tea break.
The Stump-space connection
Stump Cross Caverns has not – as yet – welcomed any astronauts for space training.
But we came very close in 1963. That summer, a local caver called Geoff Workman
spent an astonishing 105 days underground at Stump Cross .
