I agree, but I think it's still interesting from the point of view of food. As it takes months to get there, and months to get back, you probably want astronaut

I agree, but I think it's still interesting from the point of view of food. As it takes months to get there, and months to get back, you probably want astronauts to be staying there for at least a few months. Resupply from Earth is slow and expensive - especially when Mars is at the far end of its orbit. And as far as I know, we can't synthesise food artificially. Even if we could make some simple sugars, that will hardly keep the astronauts healthy. So I think growing plants would start to look quite inviting. But I think the bigger challenge is getting anyone there in the first place. They'd need life support for months. I suspect you'd have to assemble something about the size of the ISS in Earth orbit, then send it across to Mars, and deploy landers to reach the surface.