At Astronautix, it says that:

The propellant combinations WFNA/ JP-4 and later IRFNA/JP-4 were the first storable systems given serious consideration in the United States. Problems which caused the abandoning of these propellants were the absence of reliable hypergolic ignition and unstable combustion. IRFNA/UDMH and IRFNA/JP-X finally did prove satisfactory.

By the late 1950’s it was apparent that N2O4 by itself was a better oxidiser. Therefore nitric acid was almost entirely replaced by pure N2O4 in storable liquid fuel rocket engines developed after 1960.

Apparently it was so apparent that they have no need to explain why it was so apparent. What was the benefit of going from nitric acid to tetroxide for hypergolics? What was “better” about it? Anyone know?

I’m back in DC, and busy, so I don’t know how much posting there will be, but I did want to note on reconsideration one problem with the New York Times editorial advocating ending Shuttle and ISS. Jorge Frank, over at sci.space.policy, pointed out last night that they seem to want to eat their cake and have it too.

They call for an end to any more ISS missions, but want a Hubble repair. Well, if they do that, they should realize that a) they won’t get the forty billion in savings that their editorial states, and b) that Hubble repair mission will cost at least six billion or so (more than launching multiple replacement telescopes). This is because the soonest that a Hubble repair mission could be mounted is probably about a year and a half from now. That means that the infrastructure to support the Shuttle would have to be kept in place for another year and a half. It also means that, since there would be no ISS missions against which to charge these fixed costs, these would all be debited against the Hubble mission (the only reason that the system remained in place, accruing those costs).

So they can phase out Shuttle and ISS, but it’s hard to then make an argument for Hubble. And if they’re going to keep it alive for Hubble, then they might as well figure out some way to maximize the utility of it for getting station as far toward completion as possible while the system is still operating. In the latter scenario, it just means figuring out the minimum number of flights that should be done with Shuttle, and how to manage without it for the rest. Which (almost surely not coincidentally) is exactly what Mike Griffin’s NASA is planning to do.

[Update a few minutes later]

Mark Whittington disagrees with me. Well, actually, as he often does, he disagrees with a strawman argument he pretends is me:

…the fact of the matter is that the first people to return to the Moon and then go to Mars will be employees of some government (hopefully including the American one). The private sector will have a very big role, especially once people start living off the planet in significant numbers. But big bad government will also have a role in opening up the high frontier, just as it has with every other frontier. That’s the truth, supported by history and common sense, whether one wants to believe it or not.

their role would be, and I don’t think that it will be anywhere near as large as most conventional thinking about the space program would have it. The issue is not whether or not government will be involved, but which branches of it, and how. The monocultures that NASA’s manned space centers tend to produce will continue, I think, to be evolutionary dead ends (just as Shuttle and ISS have turned out to be). But because they generate so many jobs, they will continue until (like Shuttle and ISS) they become untenable in the face of clear private (and other government, such as the DoD) alternatives.

[Update again]

Now Mark trots out a new straw horse in response:

I must admit to a little confusion. What other government agency besides NASA would take the lead government role in space exploration?

I expect NASA (until costs come down quite a bit) to continue to lead “space exploration” (though much of that will be done out of Pasadena, and will be unmanned). But of course, until now, I said nothing about space exploration. I thought we were talking about humanity moving out into space, which is much less about space exploration than space development. And space development will occur with the help (and hindrance, and connivance) of a number of government agencies, including the FAA, the DoD (including DARPA), DoE, and perhaps even Commerce. NASA building small and expensive capsules launched on equally-expensive heavy-lift expendables from Cape Canaveral may provide some entertainment to the masses for a while, but it will have little to do, ultimately, with the development of space, any more than Shuttle and ISS have.