The amount of water needed for a NASA base as planned may be extractable from all kinds of sources. However the amounts needed for a SpaceX architecture with MCT and a colony with many people is much higher. IMO it can only be effectively extracted from glaciers.
The regolith cover as determined by orbital radar is no more than 10m. That's not too much given there is a need for many thousands of tons of water. Removing a max amount of 10m of regolith may be a lot easier than mining the ice which is as hard as concrete at Mars temperatures. I don't see sublimation as a major problem as long as the ice is shaded from direct sunlight. Even sublimation needs the same energy as normal heating to liquid and then gaseous form. That's a lot of energy for much ice to sublimate and energy comes from sunlight.
My understanding of the findings is that they would not have any information about glaciers that have more than 10 meters of regolith coverage. I think there may be deeper ones, and that they could be drilled into directionally or horizontally to be harvested. However, there may also be boundaries between glacier and bedrock that could prove advantageous.
My understanding of the findings is that they would not have any information about glaciers that have more than 10 meters of regolith coverage. I think there may be deeper ones,
Trying to avoid this from becoming clogged with SpaceX fandom, but I knew it would be brought up sooner or later. My only statement for SpaceX along with Red Dragon, in regards to ISRU, is that it seems the obvious candidate for field testing ISRU; the trouble with standard probes is that you end up competing for payload space with scientists - MOXIE was lucky to get room on 2020. I suggest holding off on MCT talk until SpaceX declares what's needed in September.
10 meters is still over 32 feet deep...as in over five and a half times the height of an average man...as in hundreds and hundreds of pounds/kilos of material...some of which may also be as hard as concrete and in irregular chunks dropped by ancient Martian seas and glaciers. Moving all of that will drain batteries hard, more so if nuclear power is limited if allowed at all.
That's no idle work, and it is more conservative of energy to draw on easy-to-access regolith heavy in hydrogen, be it ice or gypsum.
That was a funny part of the NASA workshop about selecting landing sites. A glacier expert said, glacial ice is always very clean. Get a block of that ice into the habitat, let it melt and drink it.An expert on ECLSS was shocked. She said, get us a sample of that ice, give us 15 to 20 years development time and we will give you a space rated device that can make it drinkable.I guess the truth will be somewhere inbetween.
Of course, regarding ice, I'd hope for some testing before drinking it, but it sounds consistent with how I've heard frozen water can be surprisingly pure.
IMO, reading the M-WIP gave me the impression gypsum should be pursued. Aside from the mineral being water heavy, there is a very solid scientific motivation to seek it out: gypsum forms in seawater and hot springs. Wherever you find the stuff, odds are you will find many things related to the deep history of Mars prior to the dry Amazonian Era
A glacier expert said, glacial ice is always very clean.
Like glaciers on Earth, glaciers on Mars are not pure water ice. Many are thought to contain substantial proportions of debris, and a substantial number are probably better described as rock glaciers
Glaciers can contain rocks, true. The water is still very clean.It was said the glaciers on Mars they were talking about contain very little rocky material. It would show up as scatter in the signal. From lack of scatter they can safely assume very clean water.
The question is how did the glaciers form?
My understanding is that glaciers form by precipitation. So if they did not form from precipitation they are not glaciers. Given the discussion I assume they are glaciers and have been formed by precipitation. That would make it likely that they do include dust.Glaciers that contain rocky material have gathered it while flowing.Quite possible that my line of thought is too simplistic and wrong.
BTW, whenever there would be significant fuel production on Mars, there would be an excess of oxygen because rocket engines run fuel rich. CO2 extraction from the atmosphere would produce nitrogen, or rather a mix of nitrogen and argon, which is breathable. So a breathable atmosphere would be a welcome byproduct. Only CO2 removal should be necessary.
Quote from: guckyfan on 05/17/2016 04:53 amBTW, whenever there would be significant fuel production on Mars, there would be an excess of oxygen because rocket engines run fuel rich. CO2 extraction from the atmosphere would produce nitrogen, or rather a mix of nitrogen and argon, which is breathable. So a breathable atmosphere would be a welcome byproduct. Only CO2 removal should be necessary.Hmm... this is a semantics note, but I have a bit of a hiccup seeing the concept floated of just removing the CO2 from Mars' atmosphere and you have a useful atmosphere left.That's sort of like saying if you're looking to produce salt, all you need to do is remove the water from salt water, and you have useful salts. I would look at it a lot more as removing the salt from the water, not vice-versa.So, yeah -- what you describe, I would think of as purifying the CO2 in Mars' atmosphere by removing the less than 4% of trace gasses, which are almost entirely composed of nitrogen and argon. That tracks logically a lot better than looking at it as a "CO2 removal" operation...