Cool!

Gary 7

I wonder why anyone would have ever doubted there was subterranean water on MArs? Earth has lots of hydrogen locked up in minerals such as hydrides and oxygen in oxides. Both elements are highly reactive and readily bond with a wide range of metals. They are thus conserved and protected from solar wind dispersal.
Of course, it’s a LOT easier to retrieve water from underground reservoirs than to extract it from oxides/hydrides, so this discovery is really exciting, from a utilization point of view.

I expect we’ll find a lot of subterranean Lunar water, when we finally have geo(Luna?)physicists poking around on the moon.

We just need to go and stay there,,,

GAry 7

Yes indeed. In fact “Red Mars” is a favourite: Kim Stanley Robinson’s awesome descriptions of the unmanned rover routing past navigation beacons to ferry water to the camp, and the automated water extraction station are very atmospheric for me. They mine ice blocks and the plant refines the water until it’s pure. Think I’m going to have to read it again.
Bob(Big)

As mentioned by Ivan3, for particle radiation (cosmic rays) you want something with lots of hydrogen in it – water, plastics, etc. However – hydrogen materials are fairly useless against EM radiation (gamma and X-rays). This is where you need the dense materials – lead, tungsten, etc.

There is a basic overview and some basic equations at ‘Atomic Rocket’.

http://www.projectrho.com/rocket/rocket3ah.html – Radiation and Shielding
http://www.projectrho.com/rocket/rocket3ah.html#stormcellar – Storm Cellars (aka Biowells)

A song comes to mind:

“There’s a great, hot desert
South of Mexicali.
If you don’t have the water
Boy you better not go.

I can see that you love her
By the look in your eye, boy.
She’s the rose of the desert,
In old Mexico.”

I think that we should establish a working relationship with a close celestial body (read: Moon) before casting off for more distant shores. In the same way that we learn to creep before we learn how to brace ourselves against a wall and pretend to walk. Just because we perceive Mars as more seductive than the Moon does not implicate that the Moon could not be an instructive and reliable mistress.

We are now learning lessons on the ISS. Lessons that are a direct result of all our previous experience in space. Mercury, Gemini, Apollo and on to our present understanding. In order to go far, we must know how; not hypothetically, but by virtue of experience. The Moon is the most obvious training ground. Not to mention that it is not only very close, but it is also just far enough away. Let us test ourselves.

Thanks.

In an earlier post you said this:

…going back to the Moon can benefit all of space exploration and science if done properly.

Could you please explain what “done properly” means in this instance?

The atoms of liquid hydrogen are particularly good as a screen for galactic cosmic rays because they don’t fragment into secondary particles as much as heavier elements — like lead — do when bombarded by high-energy radiation. Those secondary particles could be just as harmful as space radiation itself. Generally high-mass density materials, usually of high atomic number, are not good choices for shielding the spacecraft because, when struck by the primary positive ions, the nuclei of these materials fragment and produce a shower of secondary radiation that includes more charged particles, photons, and neutrons, and the thicknesses of heavy shielding material necessary to stop these becomes excessive from a weight standpoint.

Polyethylene is a good shielding material because it has high hydrogen content, and hydrogen atoms are good at absorbing and dispersing radiation. In fact, researchers have been studying the use of polyethylene as a shielding material for some time.

Click on my name for the link to the NASA article on Shields to Protect Future Space Crews.

Hydrogen does a good job of absorbing various kinds of ionizing radiation (which is the kind that destroys living tissues). What happens, in a vastly simplified explanation, is that the high speed charged particles that make up ionizing radiation impact the hydrogen atoms in water – which slows down the particles. Slower particles mean less energy, less energy means less damage to living tissues – hence we consider water to make a decent shield against various kinds of ionizing radiation.

If you want to learn more you can start here http://en.wikipedia.org/wiki/ALARA
That’s actually not a great laymans introduction though, sorry.

(you just wait – the aquifer outflows of the ’61 revolution will be BRUTAL…)

the hydrogen in water makes a pretty good radiation shield

Huh? I don’t understand.