"For fact 1: Real aerospace engineers have the actual densities of liquid hydrogen available and will undoubtedly have calculated the volume needed. NASA's conclusion is that in-situ utilization is an effective way to make an affordable Mars mission. Your reply is nothing but obfuscation."
Obfuscation? Let me get this straight; Mark Eby is accusing someone else of obfuscation? That's wonderful.
Did I say a real engineer wouldn't know hydrogen's density or in-situ utilization was not a means of achieving cost reduction in a Mars Mission?
No, I simply pointed that something the size of a school bus was not normally considered "a bit of hydrogen".

"For fact 2: The point was it takes more energy to land on the Moon than Mars even though it takes slightly less to reach it because of the lack of aerobraking. Your ramblings have nothing to do with that."

No, that wasn't the point of "fact 2". Fact 2 was regarding landing on the Moon to fuel up a mars spacecraft. And another "fact" about how a catapult would be required and this required some "advanced base" on the Moon. These were labeled "facts" but aren't facts, but rather were presuppositions.

"NASA is not a space business subsidy fund so your buying water suggestion makes no sense in its own right."

I didn't mention NASA buying water in my post, I said "NASA would simply buy rocket fuel which is delivered". Though I do think NASA should buy water, but it's different topic which I have explained in much detail in other posts- which you always seem to manage to avoid discussing directly.

"NASA's benefit to space business is far more likely to come from directly attempting to reduce launch costs and permanently reduce a real economic barrier than by providing an artifical boost over it."

The problem, Mark, is you seem to fail to understand how NASA could go about lowering launch costs. If you could buy a clue; you would understand why NASA should explore the Moon to determine if there is minable water. And you would also understand why NASA should buy water test payloads.

"For fact 3: Did you have a point?"

Just stating the facts....

"For Fact 4: The difference between artificial gravity on a space station and that suggested by Zubrin is the radius of rotation. Rotating a space station would leave noticable differences in rotation speed over short distances and diziness. Zubrin's tether approach was meant to reduce this coriolis effect to a negligible quantity, but there has been no work done to quantify at what level the effect becomes negligible."

Mark, get a clue. It's not that simple.
Do you actually think that other engineers hadn't thought of using a tether; AND IF they had Zubrin's idea of using a tether THEN they *might* have used this idea on the space station? Any type of truss would work as well or better than a cable. The Problem wasn't the radius of rotation.