The water machine

Let's talk about the water machine.
As in the beginning, we see and hear him saying that he squeezes water out of a rock.
He extracts H and O and recombines them.

But the reason of the failing machine is because it can't squeeze any further.
It has already went to the limit of extracting the water out, that's why the extract becomes contaminated.

Not only him, but also the whole cabin is living on the water, cabin condensed, the plants, the electronics.
So he needs to find other ways to squeeze out water and finds them in the above, but also in himself.
That's the hard part of his journey.
It's a metaphor for going at the edge of your limits to achieve your goals.

So my ending is a very positive one.
Once he set foot on Mars, he'll find the recourses they already sent over there.
He also has a new source now for his machine...