What do Organic Compounds Found on Mars Mean?

Last week, NASA announced that organic compounds had been found on Mars. The question then is, what does this mean? First, organic compounds are essentially chemicals formed that involve carbon, which means Mars has carbon besides the carbon dioxide in the atmosphere. The name “organic” comes from the fact that such compounds found by early chemists, with the exception of a very few such as carbon dioxide, came from organisms, hence there is the question, do these materials indicate that Mars had life? The short answer is, the issue remains unresolved. One argument is that if there were no organic compounds on Mars, it obviously did not have life. That it has taken so long to find organic compounds does not say anything about the probability, though, because the surface of Mars is strongly oxidizing, and had any been there, they would have been turned into carbon dioxide. The atmosphere already has a lot of that. The reason none has been found, therefore, is because most of the rovers have not been able to dig very deeply.

I shall try to summarise the results that were reported [Eigenbrode et al., Science 360, 1096–1101 (2018)]. One important point is that the volatiles analysed were obtained by pyrolysing the mudstone the rover dug up, so what was detected may not be the same that was in the rock. The first compounds were identified as aliphatic hydrocarbons, from C1 (methane) to C5, and these were stated to be typical of that obtained from Kerogen or coal on Earth. One problem I had with these data was there were odd-numbered masses, BUT they all indicated that the cause was a fractured hydrocarbon, i.e. the pyrolysis had chopped that bit off something else and produced a radical.

One big problem was they could not say whether nitrogen or oxygen was present ” because mass spectra are not resolvable in EGA and other molecules share the diagnostic m/z values. ” I really don’t understand that. First, the identification of aliphatic hydrocarbons was almost certainly correct, because they form series of signals that are very recognizable to anyone who has done a bit of this work before. They stick out like an organ stop, so to speak. However, the presence of nitrogen species in any reasonable amount should be just as easily identified because while hydrocarbons, and their like with oxygen, basically give even mass signals, nitrogen, because of its valency of 3, gives odd numbered mass signals that is 1 bigger than a hydrocarbon. Now, a few of the fragmentation patterns of hydrocarbons give odd numbered mass signals, but if you cannot tell where the molecular ion is, you do not know what the mass of your molecule is. If all you have are fragmentation ions, then the instrument was somewhat poorly designed to go to Mars. With any experience, you can also tell whether you have oxygenated materials because hydrocarbons go up by adding 14 to the basic ion, and the atomic weight of oxygen is 16. If it has oxygen, it abd the fragments containing oxygen have an entirely different mass.

Of course the authors did note the presence of CO2 and CO. These could arise from the pyrolysis of carboxylic acids and ketones, but that does not mean life. Carboxylic acids would pyrolyse at about 400 – 550 degrees C and ketones a bit higher. They also found aromatic hydrocarbons, thiophenes and some other sulphur containing species. These were explained in terms of sulphur –bearing gases coming in contact, and further chemical reactions then taking place, in other words, these sulphur containing species such as hydrogen sulphide do not necessarily provide any information regarding what formed the original deposit. The sulphurization, however, was claimed to provide a preservative function by protecting against mild oxidation. If it carried out that function, it would be oxidized, and none of the observed materials were.

Unfortunately, the material is not directly associated with anything related to life. The remains of life can give rise to these sort of chemicals, as noted by our crude oil, which is basically hydrocarbon, and formed from life, but then altered by tens of millions of years change. These Martian deposits are believed to be in rocks 3.5 billion years old. However, the materials were also obtained by pyrolysis at temperatures exceeding 500 degrees C. The original molecules could have rearranged, and what we saw was the sort of compounds that organic compounds might rearrange to. Nevertheless, the absence of nitrogen is not encouraging. Nitrogen is present in all protein and nucleic acids, and there tends to be high levels of these in primitive life. Pyrolysis would be expected to produce pyrazines and pyridines, and these should be detectable. Pyrazines, having two nitrogen atoms, tend to give even numbered ions, and give the same mass as a ketone, but since neither was seen, that is irrelevant. Had there been such signals, the fragmentation patterns are quite distinctive if you have done this sort of work before.

Other possible sources of organic compounds, besides carbon, are from chondrites that have landed, and geochemically. It is hard to assess chondrites, because we do not have other information. It is possible to tell the difference between oxygen from chondrites from oxygen from other places (because of the different ratios of isotopes of mass 17 and 18 compared with 16), but they never found oxygen. The materials could be geochemical as well. The same reaction used by Germany to make synthetic petrol during WW2 can occur underground, and make hydrocarbons. So overall, while this is certainly interesting, as is often the case it raises more questions than it answers.

Advertisements

A Response to Climate Change, But Will it Work?

By now, if you have not heard that climate change is regarded as a problem, you must have been living under a flat rock. At least some of the politicians have recognized that this is a serious problem and they do what politicians do best: ban something. The current craze is to ban the manufacture of vehicles powered by liquid fuels in favour of electric vehicles, the electricity to be made from renewable resources. That sounds virtuous, but have they thought out the consequences?

The world consumption of petroleum for motor vehicles is in the order of 23,000 bbl/day. By my calculation, given some various conversion factors from the web, that requires approximately 1.6 GW of continuous extra electric consumption. In fact much more would be needed because the assumptions include 100% efficiency throughout. Note if you are relying on solar power, as many environmentalists want, you would need more than three times that amount because the sun does not shine at night, and worse, since this is to charge electric vehicles, which tend to be running in daytime, such electric energy would have to be stored for use at night. How do you store it?

The next problem is whether the grid could take that additional power. This is hardly an insurmountable problem, but I most definitely needs serious attention, and it would be more comforting if we thought the politicians had thought of this and were going to do something about it. Another argument is, since most cars would be charged at night, the normal grid could be used because there is significantly less consumption then. I think the peaks would still be a problem, and then we are back to where the power is coming from. Of course nuclear power, or even better, fusion power, would make production targets easily. But suppose, like New Zealand, you use hydro power? That is great for generating on demand, but each kWhr still requires the same amount of water availability. If the water is fully used now, and if you use this to charge at night, then you need some other source during the day.

The next problem for the politicians are the batteries, and this problem doubles if you use batteries to store electricity from solar to use at night. Currently, electric vehicles have ranges that are ideal for going to and from work each day, but not so ideal for long distance travel. The answer here is said to be “fast-charging” stops. The problem here is how do you get fast charging? The batteries have a fixed internal resistance, and you cannot do much about that. From Ohm’s law, given the resistance, the current flow, which is effectively the charge, can only be increased by increasing the voltage. At first sight you may think that is hardly a problem, but in fact there are two problems, both of which affect battery life. The first is, in general an overvoltage permits fresh electrochemistry to happen. Thus for the lithium ion battery you run the risk of what is called lithium plating. The lithium ions are supposed to go between what are called intercalation layers on the carbon anode, but if the current is too high, the ions cannot get in there quickly enough and they deposit outside, and cause irreversible damage. The second problem is too fast of charging causes heat to be generated, and that partially destroys the structural integrity of the electrodes.

The next problem is that batteries can be up to half the cost of the purely electric vehicle. Everybody claims battery prices are coming down, and they are. The lithium ion battery is about seven times cheaper than it was, but it will not necessarily get much cheaper because at present ingredients make up 70% of the cost. Ingredient prices are more likely to increase. Lithium is not particularly common, and a massive increase in production may be difficult. There are large deposits in Bolivia but as might be expected, there are other salts present in addition to the lithium salts. There is probably enough lithium but it has to be concentrated from brines and there are the salts you do not want that have to be disposed of, which reduces the “green-ness” of the exercise. Lithium prices can be assumed to go up significantly.

But the real elephant in the room is cobalt. Cobalt is not part of the chemistry of the battery, but it is necessary for the cathode. The battery works by shuttling lithium ions backwards and forwards between the cathode and anode. The cathode material needs to have the right structure to accommodate the ions, be stable so the ions can move in and out, have valence orbitals to accommodate the electron transfer, and the capacity to store as many lithium ions as possible. There are other materials that could replace cobalt, but cobalt is the only one where, when the lithium moves out, something does not move in to fill the spaces. Cobalt is essential for top performance. There are alternatives to use in current technology, but the cost is in poorer lifetimes, and there are alternative technologies, but nobody is sure they work. At present, a car needs somewhere between 7 – 20 kg of cobalt in its batteries, and as you reduce the cobalt content, you appear to reduce the life of the battery.

Cobalt is a problem because the current usage of cobalt in batteries is 48,000 t/a, while world production is about 100,000 t/a. The price is increasing rapidly as electric vehicles become more popular. At the beginning of 2017, a tonne of cobalt would cost $US 32,500; now it is at least $US 80,000. Over half the world’s production comes from the Democratic Republic of Congo, which may not be the most stable country, and worse, most of that 100,000 t/a comes as a byproduct from copper or nickel production. If there were to be a recession and the demand for stainless steel fell, then the production of cobalt would drop. The lithium ion batteries that would not be affected are the laptops and phones; they only need about 10 – 20 g of cobalt. Even worse, there are a lot of these batteries that currently are not being recycled.

In a previous post I noted there was not a single magic bullet to solve this problem. I stick to that opinion. We need a much broader approach than most of the politicians are considering. By broader, I do not mean the approach of denying we even have a problem.

This post is later than my usual, thanks to time demands approaching Easter, and I hope all my readers have a relaxing and pleasant Easter.

A personal scientific low point.

When I started my PhD research, I was fairly enthusiastic about the future, but I soon got disillusioned. Before my supervisor went on summer holidays, he gave me a choice of two projects. Neither were any good, and when the Head of Department saw me, he suggested (probably to keep me quiet) that I find my own project. Accordingly, I elected to enter a major controversy, namely were the wave functions of a cyclopropane ring localized (i.e., each chemical bond could be described by wave interference between a given pair of atoms, but there was no further wave interference) or were they delocalized, (i.e. the wave function representing a pair of electrons spread over more than one pair of atoms) and in particular, did they delocalize into substituents? Now, without getting too technical, I knew my supervisor had done quite a bit of work on something called the Hammett equation, which measures the effect or substituents on reactive sites, and in which, certain substituents that had different values when such delocalization was involved. If I could make the right sort of compounds, this equation would actually solve a problem.

This was not to be a fortunate project. First, my reserve synthetic method took 13 steps to get to the desired product, and while no organic synthesis gives a yield much better than 95%, one of these struggled to get over 35%, and another was not as good as desirable, which meant that I had to start with a lot of material. I did explore some shorter routes. One involved a reaction that was published in a Letter by someone who would go on to win a Nobel prize. The very key requirement to get the reaction to work was omitted in the Letter. I got a second reaction to work, but I had to order special chemicals. They turned up after I had submitted my thesis. They travelled via Hong Kong, where they got put aside and forgotten. After discovering that my supervisor was not going to provide any useful advice on chemical synthesis, he went on sabbatical, and I was on my own. After a lot of travail, I did what I had set out to do, but an unexpected problem arose. The standard compounds worked well and I got the required straight line set with minimum deviation, but for the key compound at one extreme of the line, the substituent at one end reacted quickly with the other end in the amine form. No clear result.

My supervisor made a cameo appearance before heading back to North America, where he was looking for a better paying job, and he made a suggestion, which involved reacting carboxylic acids that I already had in toluene. These had already been reported in water and aqueous alcohol, but the slope of the line was too shallow to be conclusive. What the toluene did was to greatly amplify the effect. The results were clear: there was no delocalization.

The next problem was the controversy was settling down, and the general consensus that there was such delocalization. This was based on one main observational fact, namely adjacent positive charge was stabilized, and there were many papers stating that it must on theoretical grounds. The theory used was exactly the same type of programs that “proved” the existence of polywater. Now the interesting thing was that soon everybody admitted there was no polywater, but the theory was “obviously” right in this case. Of course I still had to explain the stabilization of positive charge, and I found a way, namely strain involved mechanical polarization.

So, where did this get me? Largely, nowhere. My supervisor did not want to stick his head above the parapet, so he never published the work on the acids that was my key finding. I published a sequence of papers based on the polarization hypothesis, but in my first one I made an error: I left out what I thought was too obvious to waste the time of the scientific community, and in any case, I badly needed the space to keep within page limits. Being brief is NOT always a virtue.

The big gain was that while both explanations explained why positive charge was stabilized, (and my theory got the energy of stabilization of the gas phase carbenium ion right, at least as measured by another PhD student in America) the two theories differed on adjacent negative charge. The theory involving quantum delocalization required it to be stabilized too, while mine required it to be destabilized. As it happens, negative charge adjacent to a cyclopropane ring is so unstable it is almost impossible to make it, but that may not be convincing. However, there is one UV transition where the excited state has more negative charge adjacent to the cyclopropane ring, and my calculations gave the exact spectral shift, to within 1 nm. The delocalization theory cannot even get the direction of the shift right. That was published.

So, what did I learn from this? First, my supervisor did not have the nerve to go against the flow. (Neither, seemingly, did the supervisor of the student who measured the energy of the carbenium ion, and all I could do was to rely on the published thesis.) My spectral shifts were dismissed by one reviewer as “not important” and they were subsequently ignored. Something that falsifies the standard theory is unimportant? I later met a chemist who rose to the top of the academic tree, and he had started with a paper that falsified the standard theory, but when it too was ignored, he moved on. I asked him about this, and he seemed a little embarrassed as he said it was far better to ignore that and get a reputation doing something more in accord with a standard paradigm.

Much later (I had a living to earn) I had the time to make a review. I found over 60 different types of experiment that falsified the standard theory that was now in textbooks. That could not get published. There are few review journals that deal with chemistry, and one rejected the proposal on the grounds the matter was settled. (No interest in finding out why that might be wrong.) For another, it exceeded their page limit. For another, not enough diagrams and too many equations. For others, they did not publish logic analyses. So there is what I have discovered about modern science: in practice it may not live up to its ideals.

Scientific low points: (2)

The second major low point from recent times is polywater. The history of polywater is brief and not particularly distinguished. Nikolai Fedyakin condensed water in, or repeatedly forced water through, quartz capillaries, and found that tiny traces of such water could be obtained that had an elevated boiling point, a depressed freezing point, and a viscosity approaching that of a syrup. Boris Deryagin improved production techniques (although he never produced more than very small amounts) and determined a freezing point of – 40 oC, a boiling point of » 150 oC, and a density of 1.1-1.2. Deryagin decided there were only two possible reasons for this anomalous behaviour: (a) the water had dissolved quartz, (b) the water had polymerized. Everybody “knew” water did not dissolve quartz, therefore it must have polymerized. From the vibrational spectrum of polywater, two new bands were observed at 1600 and 1400 cm-1. From force constant considerations this was explained in terms of each OH bond being of approximately 2/3 bond order. The spectrum was consistent with the water occurring in hexagonal planar units, and if so, the stabilization per water molecule was calculated to be in the order of 250-420 kJ/mol. For the benefit of the non-chemist, this is a massive change in energy, and it meant the water molecules were joined together with a strength comparable to the carbon – carbon bonds in diamonds. The fact that it had a reported boiling point of » 150 oC should have warned them that this had to be wrong, but when a bandwagon starts rolling, everyone wants to jump aboard without stopping to think. An NMR spectrum of polywater gave a broad, low intensity signal approximately 300 Hz from the main proton signal, which meant that either a new species had formed, or there was a significant impurity present. (This would have been a good time to check for impurities.) The first calculation employing “reliable” methodology involved ab initio SCF LCAO methodology, and water polymers were found to be stabilized by polymer size. The cyclic tetramer was stabilized by 177 kJ/mol, the cyclic pentamer by 244 kJ/mol, and the hexamer by 301.5 kJ/mol. One of the authors of this paper was John Pople, who went on to get a Nobel prize, although not for this little effort.

All of this drew incredible attention. It was even predicted that an escape of polywater into the environment could catalytically convert the Earth’s oceans into polywater, thus extinguishing life, and that this had happened on Venus. We had to be careful! Much funding was devoted to polywater, even from the US navy, who apparently saw significant defence applications. (One can only imagine the trapping of enemy submarines in a polymeric syrup, prior to extinguishing all life on Earth!)

It took a while for this to fall over. Pity one poor PhD candidate who had to prepare polywater, and all he could prepare was solutions of silica. His supervisor told him to try harder. Then, suddenly, polywater died. Someone notice the infrared spectrum quoted above bore a striking resemblance to that of sweat. Oops.

However if the experimentalists did not shine, theory was extraordinarily dim. First, the same methods in different hands produced a very wide range of results with no explanation of why the results differed, although of course none of them concluded there was no polywater. If there were no differences in the implied physics between methods that gave such differing results, then the calculation method was not physical. If there were differences in the physics, then these should have been clearly explained. One problem was, as with only too many calculations in chemical theory, the inherent physical relationships are never defined in the papers. It was almost amusing to see, when it was clear there was no polywater, a paper was published in which ab initio LCAO SCF calculations with Slater-type orbitals provide evidence against previous calculations supporting polywater. The planar symmetrical structure was found to be not stable. A tetrahedral structure made by four water molecules results in instability because of excessive deformation of bond angles. What does that mean, apart from face-covering for the methodology? If you cannot have roing structures when the bond angles are tetrahedral, sugar is therefore an impossible molecule. While there are health issues with sugar, impossibility of its existence is not in debate.

One problem with the theory was that molecular orbital theory was used to verify large delocalization of electron motion over the polymers. The problem is, MO theory assumes it in the first place. Verifying what you assume is one of the big naughties pointed out by Aristotle, and you would thing that after 2,400 years, something might have stuck. Part of the problem was that nobody could question any of these computations because nobody had any idea of what the assumed inputs and code were. We might also note that the more extreme of these claims tended to end up in what many would claim to be the most reputable of journals.

There were two major fall-outs from this. Anything that could be vaguely related to polywater was avoided. This has almost certainly done much to retard examination of close ordering on surfaces, or on very thin sections, which, of course, are of extreme importance to biochemistry. There is no doubt whatsoever that reproducible effects were produced in small capillaries. Water at normal temperatures and pressures does not dissolve quartz (try boiling a lump of quartz in water for however long) so why did it do so in small capillaries? The second was that suddenly journals became far more conservative. The referees now felt it was their God-given duty to ensure that another polywater did not see the light of day. This is not to say that the referee does not have a role, but it should not be to decide arbitrarily what is true and what is false, particularly on no better grounds than, “I don’t think this is right”. A new theory may not be true, but it may still add something.

Perhaps the most unfortunate fallout was to the career of Deryagin. Here was a scientist who was more capable than many of his detractors, but who made an unfortunate mistake. The price he paid in the eyes of his detractors seems out of all proportion to the failing. His detractors may well point out that they never made such a mistake. That might be true, but what did they make? Meanwhile, Pople, whose mistake was far worse, went on to win a Nobel Prize for developing molecular orbital theory and developing a cult following about it. Then there is the question, why avoid studying water in monolayers or bilayers? If it can dissolve quartz, it has some very weird properties, and understanding these monolayers and bilayers is surely critical if we want to understand enzymes and many biochemical and medical problems. In my opinion, the real failures here come from the crowd, who merely want to be comfortable. Understanding takes effort, and effort is often uncomfortable.

Scientific low points: (1)

A question that should be asked more often is, do scientists make mistakes? Of course they do. The good news, however, is that when it comes to measuring something, they tend to be meticulous, and published measurements are usually correct, or, if they matter, they are soon found out if they are wrong. There are a number of papers, of course, where the findings are complicated and not very important, and these could well go for a long time, be wrong, and nobody would know. The point is also, nobody would care.

On the other hand, are the interpretations of experimental work correct? History is littered with examples of where the interpretations that were popular at the time are now considered a little laughable. Once upon a time, and it really was a long time ago, I did a post doctoral fellowship at The University, Southampton, and towards the end of the year I was informed that I was required to write a light-hearted or amusing article for a journal that would come out next year. (I may have had one put over me in this respect because I did not see the other post docs doing much.) Anyway, I elected to comply, and wrote an article called Famous Fatuous Failures.

As it happened, this article hardly became famous, but it was something of a fatuous failure. The problem was, I finished writing it a little before I left the country, and an editor got hold of it. In those days you wrote with pen on paper, unless you owned a typewriter, but when you are travelling from country to country, you tend to travel light, and a typewriter is not light. Anyway, the editor decided my spelling of a two French scientists’ names (Berthollet and Berthelot) was terrible and it was “obviously” one scientist. The net result was there was a section where there was a bitter argument, with one of them arguing with himself. But leaving that aside, I had found that science was continually “correcting” itself, but not always correctly.

An example that many will have heard of is phlogiston. This was a weightless substance that metals and carbon gave off to air, and in one version, such phlogisticated air was attracted to and stuck to metals to form a calx. This theory got rubbished by Lavoisier, who showed that the so-called calxes were combinations of the metal with oxygen, which was part of the air. A great advance? That is debatable. The main contribution of Lavoisier was he invented the analytical balance, and he decided this was so accurate there would be nothing that was “weightless”. There was no weight for phlogiston therefore it did not exist. If you think of this, if you replace the word “phlogiston” with “electron” you have an essential description of the chemical ionic bond, and how do you weigh an electron? Of course there were other versions of the phlogiston theory, but getting rid of that version may we’ll have held chemistry back for quite some time.

Have we improved? I should add that many of my cited failures were in not recognizing, or even worse, not accepting truth when shown. There are numerous examples where past scientists almost got there, but then somehow found a reason to get it wrong. Does that happen now? Since 1970, apart from cosmic inflation, as far as I can tell there have been no substantially new theoretical advances, although of course there have been many extensions of previous work. However, that may merely mean that some new truths have been uncovered, but nobody believes them so we know nothing of them. However, there have been two serious bloopers.

The first was “cold fusion”. Martin Fleischmann, a world-leading electrochemist, and Stanley Pons decided that if deuterium was electrolyzed under appropriate conditions you could get nuclear fusion. They did a range of experiments with palladium electrodes, which would strongly adsorb the deuterium, and sometimes they got unexplained but significant temperature rises. Thus they claimed they got nuclear fusion at room temperature. They also claimed to get helium and neutrons. The problem with this experiment was that they themselves admitted that whatever it was only worked occasionally; at other times, the only heat generated corresponded to the electrical power input. Worse, even when it worked, it would be for only so long, and that electrode would never do it again, which is perhaps a sign that there was some sort of impurity in their palladium that gave the heat from some additional chemical reaction.

What happened next was nobody could repeat their results. The problem then was that being unable to repeat a result when it is erratic at best may mean very little, other than, perhaps, better electrodes did not have the impurity. Also, the heat they got raised the temperature of their solutions from thirty to fifty degrees Centigrade. That would mean that at best, very few actual nuclei fused. Eventually, it was decided that while something might have happened, it was not nuclear fusion because nobody could get the required neutrons. That in turn is not entirely logical. The problem is that fusion should not occur because there was no obvious way to overcome the Coulomb repulsion between nuclei, and it required palladium to do “something magic”. If in fact palladium could do that, it follows that the repulsion energy is not overcome by impact force. If there were some other way to overcome the repulsive force, there is no reason why the nuclei would not form 4He, because that is far more stable than 3He, and if so, there would be no neutrons. Of course I do not believe palladium would overcome that electrical repulsion, so there would be no fusion possible.

Interestingly, the chemists who did this experiment and believed it would work protected themselves with a safety shield of Perspex. The physicists decided it had no show, but they protected themselves with massive lead shielding. They knew what neutrons were. All in all, a rather sad ending to the career of a genuinely skillful electrochemist.

More to follow.

A Further Example of Theory Development.

In the previous post I discussed some of what is required to form a theory, and I proposed a theory at odds with everyone else as to how the Martian rivers flowed. One advantage of that theory is that provided the conditions hold, it at least explains what it set out to do. However, the real test of a theory is that it then either predicts something, or at least explains something else it was not designed to do.

Currently there is no real theory that explains Martian river flow if you accept the standard assumption that the initial atmosphere was full of carbon dioxide. To explore possible explanations, the obvious next step is to discard that assumption. The concept is that whenever forming theories, you should look at the premises and ask, if not, what?

The reason everyone thinks that the original gases were mainly carbon dioxide appears to be because volcanoes on Earth largely give off carbon dioxide. There can be two reasons for that. The first is that most volcanoes actually reprocess subducted material, which includes carbonates such as lime. The few that do not may be as they are because the crust has used up its ability to turn CO2 into hydrocarbons. That reaction depends on Fe (II) also converting to Fe (III), and it can only do that once. Further, there are many silicates with Fe (II) that cannot do it because the structure is too tightly bound, and the water and CO2 cannot get at the iron atoms. Then, if that did not happen, would methane be detected? Any methane present mixed with the red hot lava would burn on contact with air. Samples are never taken that close to the origin. (As an aside, hydrocarbon have been found, especially where the eruptions are under water.)

Also, on the early planet, iron dust will have accreted, as will other reducing agents, but the point of such agents is, they can also only be used once. What happens now will be very different from what happened then. Finally, according to my theory, the materials were already reduced. In this context we know that there are samples of meteorites that have serious reduced matter, such as phosphides, nitrides and carbides (both of which I argue should have been present), and even silicides.

There is also a practical point. We have one sample of Earth’s sea/ocean from over three billion years ago. There were quite high levels of ammonia in it. Interestingly, when that was found, the information ended up as an aside in a scientific paper. Because it was inexplicable to the authors, it appears they said the least they could.

Now if this seems too much, bear with me, because I am shortly going to get to the point of this. But first, a little chemistry, where I look at the mechanism of making these reduced gases. For simplicity, consider the single bond between a metal M and, say, a nitrogen atom N in a nitride. Call that M – N. Now, let it be attacked by water. (The diagram I tried to include refused to cooperate. Sorry) Anyway, the water attacks the metal and because the number of bonds around the metal stays the same, a hydrogen atom has to get attached to N, thus we get M-OH  + NH. Do this three times and we have ammonia, and three hydroxide groups on a metal ion. Eventually, two hydroxides will convert to one oxide and one molecule of water will be regenerated. The hydroxides do not have to be on the same metal to form water.

Now, the important thing is, only one hydrogen gets transferred per water molecule attack. Now suppose we have one hydrogen atom and one deuterium atom. Now, the one that is preferentially transferred is the one that it is easier to transfer, in which case the deuterium will preferentially stay on the oxygen because the ease of transfer depends on the bond strength. While the strength of a chemical bond starts out depending only on the electromagnetic forces, which will be the same for hydrogen and deuterium, that strength is reduced by the zero point vibrational energy, which is required by quantum mechanics. There is something called the Uncertainty Principle that says that two objects at the quantum level cannot be an exact distance from each other, because then they would have exact position, and exact momentum (zero). Accordingly, the bonds have to vibrate, and the energy of the vibration happens to depend on the mass of the atoms. The bond to hydrogen vibrates the fastest, so less energy is subtracted for deuterium. That means that deuterium is more likely to remain on the regenerated water molecule. This is an example of the chemical isotope effect.

There are other ways of enriching deuterium from water. The one usually considered for planetary bodies is that as water vapour rises, solar winds will blow off some water or UV radiation will break a oxygen – hydrogen bond, and knock the hydroden atom to space. Since deuterium is heavier, it is slightly less likely to get to the top. The problem with this is that the evidence does not back up the solar wind concept (it does happen, but not enough) and if the UV splitting of water is the reason, then there should be an excess of oxygen on the planet. That could work for Earth, but Earth has the least deuterium enrichment of the rocky planets. If it were the way Venus got its huge deuterium enhancement, there had to be a huge ocean initially, and if that is used to explain why there is so much deuterium, then where is the oxygen?

Suppose the deuterium levels in a planet’s hydrogen supply is primarily due to the chemical isotope effect, what would you expect? If the model of atmospheric formation noted in the previous post is correct, the enrichment would depend on the gas to water ratio. The planet with the lowest ratio, i.e. minimal gas/water would have the least enrichment, and vice versa. Earth has the least enrichment. The planet with the highest ratio, i.e. the least water to make gas, would have the greatest enrichment, and here we see that Venus has a huge deuterium enrichment, and very little water (that little is bound up in sulphuric acid in the atmosphere). It is quite comforting when a theory predicts something that was not intended. If this is correct, Venus never had much water on the surface because what it accreted in this hotter zone was used to make the greater atmosphere.

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.