View original postArchimedes referenced a technology that was absolutely not possible for his time and civilization. The entire planet working together with every resource at their disposal could not have enacted his proposal. That, to me, says "technical" problem. Our civilization COULD get to Mars. We could do it for far less than the GDP of a single nation. Even if that's not a rational or sensible use of our resources, we could do it, without impacting the survival of our species whatsoever. That, to me, makes it a social / financial issue rather than a technical one. I agree with most of your points, though (even if I'm going to argue with some of them below, just because ) so I don't think we have vastly differing opinions. We just have different terminology is all.

Most nations in fact do not have GDP sufficient to the task, there are about 200 of them and only 60 have 100+ billion for GDP, and only 24 exceed 500 billion. As I said, it can be done, same as we can build a five mile high tower, but the 'technical issues' remain real, we certainly could do it but do address all those issues would require huge amounts of money. There's precious few things we can't actually so and I don't call those technical issues, I call them violation of known physics. My personal breakdown is:

Economically Viable
Technologically Viable
Technologically Impractical
Physically Impossible

Those obviously can get hazy and arbitrary, but to use pre-millenia examples a 20 inch TV is the first, a 20 foot TV is the second, a 20 mile TV is the third, and a 20 light year one is the fourth, it would undergo gravitational collapse. Those don't apply in the world of current LCD's so much, cost is almost strictly linear to area, such will likely be the case with space travel too..

Well that billion kilos, in perspective, is about two supertankers. And if we actually got to use even 10% of that for ship and payload, we'd be talking about the average long train. That's the kind of supplies I'd want to set up something akin to McMurdo in times of personnel. Sending 4 people or so is dumb.

Now as to Falcon Heavy, $2000 is the listed minimum LEO $/kg, and I won't take that seriously until its done multiple launches on that cost, as opposed to... none.

Around 900 kT of that is gonna end up being fuel, and yeah, I went very heavy, its a round number in the range where success is simple-easy and nearly guaranteed. As I said above, I see no reason to send 4 people there, they can't do jack, they can't form a core group at 16-40 minutes round trip conversation, and there's a decidedly non-zero chance of them having to deal with everything form severe depression to murder/suicide, etc. Unless you think several years of having no live communication to anyone but three people while being under huge stress, physically and physiologically and psychologically represents a healthy situation. Right now we don't need too much expertise, we send very smart and well-trained people who know they can literally perform any operation necessary with experts walking them through live, that's both a big technical advantage and a big psychological one. On a moon base we could literally have surgeons sitting there walking someone through complex surgery or techies saying 'no, the other green button' and so on.

Now look, I'm not disputing you can do it with a lot less mass, even with a high-success rate, if success is land live people on Mars and have them live for at least a few months, I'm just saying landing 4 people there is a fundamentally dumb idea unless you plan to bring them back, and that that is also a pretty dumb idea. Hence megaton range is what I'd want to ensure I could send at least a few dozen people there with lots of backups.