I hope that the volumes were (approximately) the same.

I am reminded of the comedian who claims to ask the checkout clerk at the supermarket -- "do you think this is the right amount of toilet paper for this much food?"

It may have been in our national grasp for _someone_ to get to Mars by now, but the absolute costs in energy to move you and your stuff (oxygen, food, clothes, other necessities for a vacation) back and forth from here to there seem awfully high for a random citizen to ever be be able to do that. Maybe you are a lot more wealthy than I realize, though . . . .

I can afford to go to the Alabama coast for a week every summer (order of magnitude 10^2 miles -- transportation is a minor part of the costs). I could even afford to go to Europe once (OoM 10^3 miles -- transportation is a significant part of the costs). But the costs would have to scale much less than linearly (and I don't see how they could) to ever get to Mars (OoM 10^7 miles -- transportation is more than I will ever earn in a lifetime, and while not a 1 per center, I am in the top quintile or decile of American wage earners). Vacations on Mars ain't gonna happen.

Einstein invented special relativity in his twenties, spent decades failing to disprove quantum mechanics, basing his ideas on a unified field theory that turned out to be fantasy, and ended his life unsuccessfully trying to change US policy on nuclear weapons. What a piker, eh?

Distance doesn't count. It's delta-V that matters.

And is rarely credited with anything else.

You can write a history of science backwards by assembling the pronouncements of elder scientists - Rutherford's dismissal of atomic power as "sheerest moonshine" ca. 1938 comes to mind. Einstein's rejection of quantum theory. Crooke or someone asserting that the atom was indivisible. Etc.

Which is my point: Tesla perfected AC theory and a few other things through sheer superhuman brilliance and insight, and then devolved into madness and mania by his thirties. Were it not for Cheney, he'd be remembered about as well as Steinmetz and other narrow figures of early 20th engineering. But the Teslaists see every dramatic finger gesture of his as calling into existence new worlds.

Not in our lifetimes and not likely in our childrens' either, not now.

But such things were within our grasp ca. 1960, and had we built a spacegoing infrastructure one layer at a time and with an eye on the really big picture, you and I could be waving at UFOs on our way to a once-in-a-lifetime visit to Syria Planum.

We squandered the time, the enthusiasm, the money and the opportunities on crippled, nearly meaningless efforts. Name one - just one - manned spaceflight that, all glory, gosh-wow and courage aside, accomplished anything an unmanned craft couldn't have - and probably cheaper. Even repairing and retrieving the Hubble could have been done with remotes.

So other than national feel-good (for a short time) and geekgasms for a minority, what has our showboating history of manned spaceflight gotten us?

When we could have had worlds?

I think it highly unlikely that funding for unmanned space missions would have materialized if there had been no manned ones to catch the imagination. How many people remember Surveyor 1 vs Apollo 11? Budgetary hand wringing aside, the manned missions had to happen. The biggest shame was that NASA needed a massive infrastructure to make the first ones and never had the imagination or incentive to make it any smaller. When the DC-X guys demonstrated that you could run a mission control with a handful of people, they got roundly stomped on. Still today virtually everyone thinks that you need a billion dollars and a large government institution to launch a rocket. No, that's just what the USA needs to do it at a high level of reliability (still far less reliably than NASA managers think, though).

You've either not answered or proven my point. Other than showboating, which did not engage the larger population very long nor with any lasting effect, the manned spaceflight program has had almost no reason to exist.

The bottom line is that we've spent 50 years doing it wrong, and persisting in doing it wrong, with no relief on the visible horizon other than the tech geeks in the southwest desert, who are about to run into the winnowing wall. The survivors, if any, will still be decades from manned launch capability as reliable as we had in the early 1960s.

You caught me -- my comparison is (obviously) not rigorous in an engineering sense. I was only trying to show that the differences between a trip to Europe (which is very near the high end of what I could afford) and a trip to Mars are so vastly different in kind that if the costs scale with distance in any way at all (and they do; more distance takes more time which takes more consumables), then even a moderately upper-middle-class (in an economic sense) citizen could never afford such a vacation.

But it's not all delta v, either. Delta V to LEO is something like 9-10 km/s, and the cost is often quoted at $10000 per pound. From LEO to Mars Surface is less than 10 km/s more, but no one thinks you can take the same payload from Earth surface to there for under $20000/pound.

We may be a long, long ways from "cheap" space travel, but there are many possibilities that would reduce the pound-to-orbit cost to industrially meaningful levels. (= meaningful levels for high-end tourism.) Cheaper fuels in 100% reusable booster craft, for one. Neither has been seriously explored and we keep returning to high-volatility fuels in disposable craft as the easier, short-term solution.

Except that the short term is now entering its seventh decade.