It comes as quite a shock when the ground beneath your feet, your house or your field suddenly disappears leaving a hole. This hole may be tens of meters or more deep, and it will eventually lead into a cavity which may extend downwards for hundreds of meters below the ground.
After the historic Apollo Missions, which saw humans set foot on another celestial body for the first time in history, NASA and the Russian Space Agency (Roscosmos) began to shift their priorities away from pioneering space exploration and began to focus on developing long-term capabilities in space. In the ensuing decades (from the 1970s to 1990s), both agencies began to build and deploy space stations, each one bigger and more complex than the last.
In the film The Martian, Matt Damon’s character survives being stranded on another planet by growing potatoes in his own faeces. And if we want to visit or maybe even settle on other planets for real, we’ll have to find a way to grow plants outside the safe environment of the Earth. On long space voyages in particular, plants will provide a vital source of food and oxygen.