For all you Orion fans out there

[james_davis_nicoll]

Seldon Ball's Orion page.

I'm a bit of an Orion sceptic (I think it would have been very expensive) and it seems to me that the idea of propelling a giant rocketship with a series of atomic explosions was wasted on the Americans.

nicked from Martha Adams on rasff

Comments

[derekl1963.livejournal.com]

Expensive compared to practically anything short of a steam powered rocket that used $10,000 bills to fire the boiler. Seriously. Orion depended above all else on the development of cheap, 'clean' pulse units - a development that has never come to pass. (I think it was once calculated that an Orion burned the cost of a Saturn V even before reaching the stratosphere.)

Also keep in mind that the current expense of chemical rockets is not a law a nature, but a consequence of how they are developed, produced, and operated.

[phanatic.livejournal.com]

Orion depended above all else on the development of cheap, 'clean' pulse units

Wait, which is it? James above said it was just fission bombs. That's my understanding of the actual program, and that scaled-up versions of the basic design could you fission-fusion pulse units.

[derekl1963.livejournal.com]

Some versions used fission, some fusion - as James correctly pointed out. But regardless of the type of pulse unit the whole scheme relied on them being cheap and clean.

[james-nicoll.livejournal.com]

Actually if some used fusion, then James was incorrect.

[montedavis.livejournal.com]

the current expense of chemical rockets is not a law [of] nature, but a consequence of how they are developed, produced, and operated.

Agreed with a qualification: the laws of nature (depth of gravity well, Isp of chemical propellants, heat limits of engine materials) do play a significant role in setting the economic boundary conditions. I.e., they impose poor payload mass fractions on expendable launch vehicles and even worse pmf's on reusables. It's not that the usual economic tricks for driving down cost (mass production, high flight rates, operational learning curve) aren't applicable -- but we start in a zone where it takes a whole lot of spending up front before they get much traction, and before we reach a scale of space activity where SPSats and other uses of space resources would begin to pay off.

Also, if not laws, "facts of nature" -- the uncongenial environment of space -- impose a requirement that people take along a lot more mass per person just to stay alive than any terrestrial explorers/settlers had to take. That exacerbates the problem above.

The conceptual charm of Orion was that in one brute-force step it would get over those stubborn quantitative humps.