Why ever would they stay there for 20-40 years? Are they seriously planning to make ships that would only go one way? If I were going to Mars, I'd want a round-trip ticket. I don't think anybody's talking about leaving people up there for that long. I don't remember who threw out the numbers of it taking 2-3 years to get to Mars, but that's not what Google is telling me. Here is how long it took for historic missions to reach Mars:
Mariner 4, the first spacecraft to go to Mars (1965 flyby): 228 days
Mariner 6 (1969 flyby): 155 days
Mariner 7 (1969 flyby): 128 days
Mariner 9, the first spacecraft to orbit Mars (1971): 168 days
Viking 1, the first U.S. craft to land on Mars (1975): 304 days
Viking 2 Orbiter/Lander (1975): 333 days
Mars Global Surveyor (1996): 308 days
Mars Pathfinder (1996): 212 days
Mars Odyssey (2001): 200 days
Mars Express Orbiter (2003): 201 days
Mars Reconnaissance Orbiter (2005): 210 days
Mars Science Laboratory (2011): 254 days
It doesn't look like it's even going to take a year. That seems much more bearable. So, you could actually go to Mars, do some work there and come back within a few years.
Mariner 4, the first spacecraft to go to Mars (1965 flyby): 228 days
Mariner 6 (1969 flyby): 155 days
Mariner 7 (1969 flyby): 128 days
Mariner 9, the first spacecraft to orbit Mars (1971): 168 days
Viking 1, the first U.S. craft to land on Mars (1975): 304 days
Viking 2 Orbiter/Lander (1975): 333 days
Mars Global Surveyor (1996): 308 days
Mars Pathfinder (1996): 212 days
Mars Odyssey (2001): 200 days
Mars Express Orbiter (2003): 201 days
Mars Reconnaissance Orbiter (2005): 210 days
Mars Science Laboratory (2011): 254 days
It doesn't look like it's even going to take a year. That seems much more bearable. So, you could actually go to Mars, do some work there and come back within a few years.
Now, think about what you just said.
Those "spacecraft" were unmanned. They cost $millions or $billions. They often barely made it. They never came back, and couldn't if we wanted them to.
Even if a manned vehicle made it in a year, there's a $ton $more $expense to going there manned, and if we try to do it too fast, there would have to be even $more $expense to set things up onboard so that people could withstand the rigors of acceleration/deceleration to do it in a year safely.
With war looming, there's no way to focus on a manned Mars mission with any idea of practicality, safety, and success.
Doesn't look like we will ever be going. Looks more like a drive to get people to give more money to Congress for something that will never happen. I mean, what did we spend on going to the moon? And what did it get us? $Lots and virtually nothing. And the guys that went, barely came back. If there had been great success in all areas of manned moon missions, we would have had bases on the moon long ago, with daily flights for the public a reality.
Mars shots are just a publicity campaign... to sucker more money out of the people.
I agree that the benefits of getting to the moon or Mars seem questionable, but it seems to me that it's possible. You are saying nobody will go to Mars, just as, I'm sure, people said nobody would ever go to the moon, before it happened.