Without a connection to existing civilization, and without a source of easily accessible water provided by nature? No, we have never done that.
You aren't going to be sending only one ship at a time. You will be staggering shipments, with 3-4 ships in transit at a time. You could make the time between resupplies as short as you want.
I assume you're talking about the Hohmann transfer [0], which is the most efficient path a ship could take. We're not optimizing for efficiency here, we're optimizing for delivery. You should also realize that while there is a specific moment of peak efficiency in launch times, you have a window on the order of months before a Hohmann transfer becomes less efficient than other methods. Once every 2 years sounds less drastic when it's 6 months out of those 2 years.
All that being said, the Hohmann transfer is a lot sketchier in practice than one would think. Neither Mars nor Earth has a perfectly circular orbit. It's often easier just to take the old-fashioned route.
Take a look at this chart [1] for an idea of the spread of trip length vs launch time.
[0] http://www.planetary.org/multimedia/space-images/charts/hohm...
[1] https://mars.jpl.nasa.gov/spotlight/images/porkchop_lg.gif
Then you don't understand the economics. Or maybe it's something else you don't understand, but you are clearly missing something. The orbital mechanics of getting to any target in the solar system are unique to that target. Designing orbital trajectories is a profession unto itself.
Yes, it is theoretically possible to have staggered deliveries so that spacecraft arrive at Mars on a schedule other than every two years. But think about it: how would this help? The schedule on which the supply craft arrive doesn't matter. What matters is the latency between when a need manifests itself and when it can be fulfilled. Fundamental physics lets you get to Mars in a matter of days if you could accelerate and decelerate the entire time at 1-G. But you can't, not because orbital mechanics forbids it, but because technology and economics and the rocket equation forbids it.
The one thing you're going to need to optimize for more than anything else is kilogram delivered per dollar spent. That means being as efficient as you possibly can because launch costs are ridiculously high even with reusable boosters. That means using Hohmann orbits, and that means eight month transfer times with launch windows every two years. Yes, those windows are fairly broad, but that doesn't matter. You're still going to have to wait for periods of time measured in months and years for your Amazon order to be fulfilled on Mars.
> But think about it: how would this help? The schedule on which the supply craft arrive doesn't matter. What matters is the latency between when a need manifests itself and when it can be fulfilled.
Think about this: You're no longer disagreeing with my premise, and are now moving goalposts. My premise remains true, so your accusation that I don't understand the orbital mechanics involved here is unfounded and unwarranted. A little deconstructive to meaningful conversation, which you seem keen on having with people.
> Fundamental physics lets you get to Mars in a matter of days if you could accelerate and decelerate the entire time at 1-G
It's also a bit deconstructive to talk about extremities. Keeping the discussion within rational limits helps us tackle this realistically and collaboratively.
Now this discussion has shifted to latency vs regularity and yeah, it will take some planning ahead to smooth things out, and everything must come in triplicate in case the replacement breaks while you'r installing it. But that's entirely feasible and the only barrier is money. So what we need to focus on with regards to the great Nevada desert is things like terraforming. Sustainability is no problem if you have a water source and a climate something can grow in.
That depends on what you consider "the math." In principle, it's all F=ma. In practice it's a good deal more complicated than that. There's a reason people make careers out of designing orbital trajectories.
> the only barrier is money
Well, yeah, the only barrier was only ever money. But that's a pretty big barrier right now.
> what we need to focus on with regards to the great Nevada desert is things like terraforming
Yes, terraforming is one way to solve the problem of sustainability. But I don't think we're any closer to being able to have a serious discussion of terraforming than we are about having a self-sustaining settlement without terraforming first.
You can most definitely stagger supply ships and launch them at any time, it's just that some will take a bit longer than others to arrive and their various transit times can be taken into account to have them arrive in a staggered fashion.
It enables a continuous supply, without having to try to plan everything to happen all at once during a short launch window/timeframe
> You can launch as many ships as you like during those windows, but you can't stagger them.
Well, you don't have to only launch "during those windows". I'm no logistic genius, but it seems like it would be easier/more cost effective to loft resources towards Mars at intervals that don't depend on a relatively short event that occurs every ~18 months. Try collecting all of the things you need to go camping 30 minutes beforehand, vs over the period of a week/month before you go. Yea, not very effective.. ?
Your comment I replied to above seems to be overly aggressive (that doesn't belong here):
> You don't understand the orbital mechanics of getting to Mars.
I'm quite sure there are lots of things you (or I) don't understand. Try being more constructive next time.
Civilization had to start somewhere. At some point humans started a civilization without any connection to an existing civilization. In all likelihood, several times in different places on Earth. And on Mars that would not be "without a connection to an existing civilization" They would absolutely be bringing equipment and supplies from Earth and have a communication link.
Easily accessible water is a different story, but that's just a technological problem.
If you go to mars, you're going to be living in a bubble and it hardly even matters whether you're on Mars at that point (aside from being close enough to study it.) You could just as well colonize the bottom of the ocean or Antarctica, and there's plenty of value in doing those things because the rewards from the efforts could easily be transported back to normal society. And if you get sick or injured, you can still survive rather than casting your valuable experience into the void.
If the advances you speak of can't help you survive in Earth's mildly hostile uninhabited environments, then you can't expect them to work on Mars.