when there has been no leadership anything can seem exciting.

but to the point I have talked about privatizing space lift, human tended stations around the Moon and aerobraking in terms of return for a long time.

but who knows what will happen

Robert G. Oler

you obviously are well versed in the subject far more then my “semi engineer” knowledge….I agree with what you said.

I should have been more careful in my comments I dont think aerobraking/capture is a front up technology, but I do see it as something that we “technology” up…we are going to use it if we ever do the planet thing in my view

Robert G. Oler

How would the radiation dose with the schemes others have proposed compare to, say, the 260 mGy/year that residents of Ramsar, Iran, get throughout their entire lifetime? It appears that the effects of radiation are quite nonlinear.

http://www.sciencemag.org/cgi/content/full/309/5736/883

Atlas derivatives would make more sense if one insists on an ‘HLV’ (dual RD-180 core)

I suggest reading http://en.wikipedia.org/wiki/Aerobraking and http://en.wikipedia.org/wiki/Aerocapture and of course there is “direct” entry and “skip” entry. The problem with aerobraking is the time it takes. The reason mainly is aerodynamic heating, rates and loads.

Trying to make it simple: When you come back at lunar-like return velocity (or faster) you have to account for i) convective heating and ii) shock radiation (radiative) heating. One way to decrease convective heating on your heat shield is to increase the radius of your heat shield which unfortunately results in higher radiative heating which are very, very significant at such velocities. And this does not make your life simple. The heat rates will tell you what kind of material you need (typically the only known choice is to go with ablative materials, a la Apollo) and the heat loads (rates integrated in time) the thickness of said materials. BTW this is a painfully complex thing to do for ablative materials (some Apollo re-entry(ies?) were hmm reallly hot). Today the best CEV/Orion came up with was to re-create AVCOAT the same as the Apollo TPS (thermal protection system – heat shield), developed 40 years ago. So it is far from trivial.

When you blend all this above and more, shake, not stirr, you end up with a very very complex process.

Basically the development of such an aerobraking vehicle is years if not decades away. It’ll probably be an aerocapture vehicle though. And then there are a lot of questions about its mode of operation (e.g. abort in space, abort during the braking period, etc) that are far from trivial. And more.

Hope this helps a little.

Robert G. Oler

Absurd but not surprising given the mental blinders present under the current “Economics” game.