But of course this is never ever mentioned in this Augustine Committee.

What is it a space fashion show ?

Please people… the problem with the space agency is NASA it has lost focus with human flight it refuses to look at the space nuke issue ’cause it just too scary for the public so it bans nuclear space propulsion.

In fact Chernobyl wildlife like horses and bears thrive in hot rad zones that astronauts would endure without the hollywood mutation fear campaigns that are so pervasive in film documentaries.

http://www.nsrl.ttu.edu/chornobyl/conclusions.htm

Why should anyone be banned from further space travel because of radiation exposure? Simple. Because we’ve got a lot more who would like to go. It’s easier to tell someone to move over than it is to surround them with lead.

Permanent space stations in deep space? As in, people living at Lagrange points for many years? I don’t think there are any plans for such things. As to a space station in Mars orbit, we’ve got it already. It’s called Phobos, and it comes with its own free rocks for shielding. Why would one blast rocks off of the Moon to make a base on Phobos?

No, the primary focus of the manned component of our space program is not to “enhance the health and survival of humans”. It’s to get people to new places reasonably in one piece.

I’m aware of at least one ISS astronaut that has already been banned from further space travel because of too much radiation exposure. Why should anyone be banned? Why not properly protect astronauts from over exposure to radiation in the first place.

The primary focus of the manned component of our space program should be to enhance the health and survival of humans in the New Frontier so that private industry, tourist and colonies can follow.

“TO MATCH THE PROTECTION offered by Earth’s atmosphere takes the same one kilogram of shielding material per square centimeter, although astronauts could comfortably make do with 500 grams, which is equivalent to the air mass above an altitude of 5,500 meters. Any less would begin to be counterproductive, because the shielding material would fail to absorb the shrapnel.

If the material is water, it has to be five meters deep. So a spherical water tank encasing a small capsule would have a mass of about 500 tons.

So where did the NRC come up with a factor of 25 less shielding needed for interplanetary travel? Well, it comes down to acceptable risk. If there is a substantial chance that a person will die on a Mars trip, it’s a little absurd to be worried about a fractional percent chance that they will die from radiation exposure equivalent to what they’d get on the surface of the Earth. So the 20 g/c number takes that into account. Yes, I agree, if you want the shielding we enjoy on the surface of the Earth for the 1-year travel duration to Mars, we’d probably never go! The per-year radiation dose from LEO astronauts assessed from badges is about factor of 100 larger than the maximum recommended dose for the U.S. public. Their life expectancy may well be shortened as a result. Should Mars travelers be better protected than our ISS travelers?

I completely agree that solar and cosmic radiation is a serious issue for interplanetary travel by humans, and mitigating that exposure will call for serious design efforts. But we’re not at the point where we desperately need to be building rock walls in space.

Go look at the NRC report.

“Aside from the fact that shielding can be devised from all parts of a mission, those numbers are disputable. Where do you get those?”

Shielding Space Travelers; March 2006; Scientific American Magazine; by Eugene N. Parker

http://www.sciamdigital.com/index.cfm?fa=Products.ViewIssuePreview&ARTICLEID_CHAR=50103539-2B35-221B-658E15D66059B5F5

Rand Simberg did a fairly good article about why Apollo was unique and that article coupled with Oberg’s missive about how the technology of Apollo just barely did it (my phrase but pretty accurate description) should illustrate to all who are rushing to Mars or back to the Moon the perils of such efforts without the space industrial base (not to mention the commercial base) to support such activities.

Oberg’s current article is unique in my view in that it nits (in some timeline which I think is long) some projects which can spur development of items which would be useful with the time comes to knit all those things together and go exploring.

The problem with current human exploration of space is that when we decide to do it almost everything has to be developed from scratch…or atleast the mentality is there at NASA to do just that.

happy Sunday

Robert G. Oler

Aside from the fact that shielding can be devised from all parts of a mission, those numbers are disputable. Where do you get those? I believe the NRC study on managing space radiation risk last year came up with a solar minimum shielding requirement, for tolerable risk of exposure induced death in a one year free space mission, of something like 20 g/cm2 of H-rich material. One Ares V can loft 300 m2 of such material. That’s doesn’t exactly make for a palatial hab, but it is enough wall area to contain a goodly volume that astronauts can spend most of their time in. This doesn’t even consider other mitigation options such as reduced travel time, active shielding, and radiobiological strategies. In principle, this hab could be used for successive trips.

No question that radiation mitigation is a crucial problem for deep space efforts, but when there are other more elegant technical solutions possible, building rock walls in space does suffer somewhat in “style points”. This isn’t the venue to argue about this, as it is getting decidedly OT, and I would refer you to the recent NRC study.

But much of the trouble here is about going to Mars, and it’s clear in the flexible path scenario that any way you look at it, Mars is a long way off. There are many deep space goals that would keep us busy before we go to Mars, and a lot of radiation mitigation engineering and research that can be done.

How would the perilune be raised? Or do the regolith bags get caught by something before completing the first orbit?

To shield a tiny interplanetary habitat module is going to require at least 500 tonnes of water or 400 tonnes of polyethylene. So your talking about at least 8 Ares V launches for the shielding alone. A solar or nuclear electric powered mass driver would require about about three Ares V launches to deposit the mass driver and nuclear power plant on the lunar surface. Once the mass driver is set up, it could continuously deliver thousands of tonnes of regolith into lunar orbit annually. And electricity is a lot cheaper than chemical fuels and regolith bags are a lot cheaper than rockets.

Lunar regolith from mass drivers makes sense if you want to protect astronauts living is space stations or interplanetary vehicles beyond LEO and you want to lower the cost of transport between the Earth and the Moon with cheap fuels of lunar origin.

In the words of Dick Cheney, “Whaa…whaa…whaa!”