Being an astronaut seems like the coolest job in the world, but it's actually a whole lot harder than you might think.
The profession isn't hugely well-paid and it turns out that spending extended periods of time in space or low gravity can wreak havoc on your body.
One of the hardest parts of space missions can be staying in shape, as the zero-gravity environment means your muscles can easily start wasting away through lack of use.
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Now, some recent research has put forward an argument for a new way to help astronauts keep fit - with the ominously named 'wall of death'.
This is basically a hamster wheel-style circle of running track laid on its side, copied from amusement parks and circus acts that typically see motorcycles speeding around the walls in death-defying stunt acts.
Scientists at the University of Milan rented one of these 'walls of death' and then dropped people into it as part of their research, securing them from above with bungee cords to simulate a low level of gravity like that on the Moon.
The idea was to see if, using the bungee cord, people could run fast enough around the wall to stop themselves from falling to the ground, which wouldn't be possible under our normal gravity levels on Earth.
Those tested were typically able to make it around the wall a few times before falling.
Since the activity is really high-impact in fitness terms, the researchers estimate that doing this exercise "just twice a day, for three or four laps" could be enough to keep astronauts' muscles and bones healthy during long stays on the Moon.
Since lunar bases are very much back on the agenda for space agencies around the world, including NASA, these results could be really important in helping decide what facilities bases would need to include.
Rather than a gym that you might imagine in your mind's eye, then, a Moon base could instead include a sideways wall of death that everyone has to use twice a day - and while the name might make that seem terrible, it could actually be a major boost to any astronaut's physical health.
The effort is well worth it, too, since there's a long line of astronauts who've talked about the massive challenge of readjusting to live on Earth after the effects of low gravity on their bodies.
It can often take months and even years for them to get back to the full fitness levels they enjoyed before a long mission to the International Space Station - when all they needed was a wall of death up there!