Where to settle on Mars?

A few weeks ago I wrote an introductory post on Martian settlement issues (https://wordpress.com/post/ianmillerblog.wordpress.com/716 ). I am now going to ask, where should such a settlement be? Obviously, this is a matter of opinion, but there are some facts to consider. The first is seasons. The northern hemisphere spring and summer is about 75 Martian days longer than the autumn and winter (and opposite for the southern hemisphere. This is a consequence of the elliptical orbit, but it also means that the longer seasons mean the planet is further from the sun (which is why it is going slower) and because of the axial tilt that generates the seasons as well as the elliptical orbit, most likely places can get up to 40% less sunlight in winter than in summer. Add to that that by being so much further from the sun, Mars never gets more than about half the Earth’s solar energy. So the southern hemisphere has a shorter but warmer pair of seasons, and a longer colder other pair. Temperatures in summer can get up to 20 degrees C in the day and in winter, fall to minus 120 degrees C during the night. No plant can survive that, so besides providing air, heat is also required.

There is a reasonably easy way to get around the heat problem. Assuming you have a nearby power plant, and as I shall show in other posts, if a settlement is to be viable, it will have a heavy demand for high quality energy, then there will inevitably be waste heat. Space mirrors can also supplement the heat and light. Heating the planet is not on (you would need mirrors of area greater than the Martian cross-sectional area) but heating a settlement is plausible.

The location could be decided on the basis of nearness to raw materials, but that leaves open the question of which ones? The obvious one is metal ores, but here we do not know where they are, of even if they are. Again this can be left for another post.

The next question is air. Air pressure depends on altitude, and much of the exploration so far has been around the zero of altitude, where we get pressures of around 6 -8 millibar, depending on the season. In the southern hemisphere summer, the pole shrinks and vaporizes a lot of carbon dioxide, thus increasing atmospheric pressure. In my novel Red Gold I put the initial settlement at the bottom of Hellas Planitia. That is in the southern hemisphere, and is a giant impact crater, the bottom of which is about nine kilometres deep. That gives more atmospheric pressure, but at the cost of a cold winter. The important point of Hellas Planitia is that at the bottom of the impact crater the pressure, is high enough to be the only place on Mars for liquid water to exist, particularly in summer. The reason this was important, at least in my novel, is that unless you find water, you will probably have to pump it from the atmosphere and condense it. Also, while you are pumping up domes, you will want to get the dust out of the air. The dust is extremely fine. That means very fine filters, which easily clog; electrostatic dust precipitators, which may be too slow for many uses; or a form of water filtration. In Red Gold, I opted for a water-ring type pump. Of course here you need a certain amount of water to get started, and that will not be a small amount. The water will still evaporate fairly quickly, hence the need to have plenty of water, but the evaporite will go into the dome, so it is recoverable or usable. It could also be frozen out before going in; whatever else is in short supply on Mars, cold is not one of them, although with the low atmospheric pressure, the heat capacity of air is fairly low.

So strictly speaking, based on heat and air, both have to be heavily supplemented, it does not matter where you go. However, I think there is another good reason for selecting Hellas Planitia as the site. It is generally considered that water, or at least a fluid, flowed on Mars. The lower parts of Hellas have signs that there was water there once, and to the east two great channels, the Dao and the Harmarkis, seemingly emptied themselves into the Hellas basin. Water will flow downhill, so a lot of it would have resided in depressions, and either evaporated, or solidified, or both. So, there is a good chance that there is water there, or anything that got dissolved in the water. The higher air pressure will also help reduce sublimation by a little bit, so perhaps there will be more there than most places.

The next issue is, you wish to grow food and have plants make oxygen. Obviously you will need some fairly sophisticated equipment to get the oxygen from the plants to wherever you are going to live, assuming you don’t live with the plants, but the plants have to grow first. For that you need soil, water and fertilizer. The soil is the first problem. It is highly oxidised, and chlorides have been oxidised to perchlorates. That is fine for making a little oxygen, but it has to be treated or it will kill plants. Apparently it is something as good as bleaching powder. Again, you will have to take the treatment chemicals with you; forget something critical or do not bring enough, and you will be dead. Mars is not a forgiving place.

That leaves fertilizer. Most rock has some potassium and phosphate in it, and if these have been washed out, their residues will be where the water ended, so that should be no problem if you go to the right place. Nitrogen is slightly different. The atmosphere has very little nitrogen. On Earth, plants get their nitrogen from nitrates washed down in rain, from decayed biomass, and from farmers applying it. None of that works there immediately. Legumes can “fix” nitrogen from the air, but there isn’t much there to fix and partial pressure is important. You can, of course, pump it up and get rid of carbon dioxide. A lot of these issues were in the background of my ebook novel Red Gold, ad there, I proposed that Mars originally had somewhat more nitrogen, but it ended up underground. The reason is for another post, but the reason I had then ended up as being the start of my theory regarding planetary formation. However, the possibility of what was leached out or condensed out being at the bottom of the crater is why I think Hellas Planitia is as good a place as any to start a settlement.

Quick Commercial: Red Gold will be discounted to 99 c for six days starting the 13th. It is basically about fraud, late 1980s style, but much of the details of settling Mars are there.

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Science in fiction II

In my previous post, I tried to show that science is a way of thinking, but that left the main issue of the title, “Science in fiction” more or less free of comment. On television, at least, there has been a glut of programs showing forensic science, with various level of realism, but the general rules of cause and effect are generally followed, and given that most of the audience would know nothing of forensic science before these programs started, and given their apparent popularity, I think this shows that if properly done, there is no reason to suspect that readers would be put off by science. The important point of such forensic science programs is that there is usually someone present, like the policeman, who knows nothing about it, and hence can be told what is going to happen. I think the concept of “No surprises!” is important. If the reader is told in advance what is going to happen, and why, the reader accepts it, provided the explanations are reasonably clear.

However, you cannot do that with a surprising discovery, and sometimes the story needs just that to drive the plot along. Thus in my novel Red Gold, which was about fraud during the colonization of Mars, I needed a very big surprise of considerable economic significance to expose the fraud. Up until the critical point, it was believed that colonization of Mars might be very difficult because the soil, or more specifically, the regolith, is rather nitrogen deficient. At the same time, the atmosphere of Mars has very little nitrogen in it. These are standard facts and are correct, as far as we have been able to find out. Rather remarkably, we have found very few nitrates, which is something of a surprise since we have found perchlorates, and it would be something of a surprise if chloride in the regolith was oxidized to perchlorate, and nitrogen did not convert to nitrates. The obvious conclusion is that there has always been very little nitrogen in the Martian soil, although there is a reason why that reasoning might be superficial.

Accordingly, one question is, did Mars accrete with almost no nitrogen, or did it have some, and that nitrogen has disappeared. This is important, because unless nitrogen is plentiful in what is called a reduced form, life is very unlikely to evolve. Suppose the nitrogen was there in the reduced form: that means there was a lot of ammonia around. If it were, as the atmosphere oxidized and carbon species turned into carbon dioxide, the ammonia would be slowly turned into urea, which would then be carried more deeply below the surface by water. Any urea or ammonia left on the surface would be oxidised to nitrogen, and would contribute to the residue in the atmosphere. The surprise could therefore be simply the discovery of urea, which would act as he fertilizer and make the settlement viable. The important point of this, at least for me, was that the story could have the settlement declared viable at a point where the fraudsters were building up a case to cash in on compensation when the settlement failed.

A feature of a genuine scientific discovery is that once you make it, in most cases it also explains a number of other problems that had been a puzzle. In this case, the problem is, where did Martian rivers come from, Mars is too cold for water to flow now, and when these rivers did flow, the sun was only about 2/3 as strong as now. There is significant evidence that Mars has never been above – 60  for any reasonable length of time. Had there been ammonia around, water can flow down to -80,  so the story can be given more credibility. This, admittedly, is something of a special case, but I think there are other options if we do not need to know too many genuine facts. Thus, if something ‘amazing’ only applies to one thing, it looks suspiciously like the proverbial ‘magic wand’, designed to do nothing more than get the author out of a plot hole.

For interested readers, on December 13, Amazon.com and Amazon.co.uk will have promotional specials of both Red Gold and Planetary Formation and Biogenesis, the latter of which gives far more details of this theory.