About it being cheaper to send them back than to resupply them, I mean. Think of the size of your average rocket. Fill a giant payload with supplies, and you could outfit a small team virtually forever with one shot. One shot in a rocket that requires no life support of any kind. A rocket that could, more or less, crash land on Mars (the cargo needs to stay basically intact, but you don't have to worry about people, or the vehicle itself).

Now think of the other scenario. You have to create and fuel a vehicle that could make the return trip from Mars. A vehicle that could take off from the undeveloped surface of Mars with none of the launch facilities available on Earth. I can only imagine how difficult that would be.

I read an article recently that said the cost of sending a robot to the moon vs sending an astronaut was something like $200 million, vs $150 billion. I understand that a supply ship is different from a robot (though maybe the ship would even be cheaper, since you don't have to design a robot that can roam around...), but that's still an astronomical (heh ) difference in cost. Seven-hundred and fifty times as much to send astronauts. To the moon.

Anyway, I'm not at all convinced that it wouldn't be cheaper to send a ship with 40 years worth of non-perishable food one way to Mars than it would to get the astronauts back. I'm not sure why I typed all that up either, but it was fun to think about.