Volatiles on Rocky Planets

If we accept the mechanism I posted before is how the rocky planets formed, we still do not have the chemicals for life. So far, all we have is water and rocks with some planets having an iron core. The mechanism means that until the planet gets gravitationally big enough to attract gas it only accretes solids, together with the water that bonded to the silicates. There re two issues: how the carbon and nitrogen arrived, and if these arrived as solids, which is the only available mechanism, what happened next?

In the outer parts of the solar system the carbon occurs as carbon monoxide, methanol, some carbon dioxide, and “carbon”, which essentially many forms but looks like tar, is partially graphite, and there are even mini diamonds. There are also polyaromatic hydrocarbons, and even alkanes, and some other miscellaneous organic chemicals. Nitrogen occurs as nitrogen gas, ammonia, and some cyanide. As this comes closer to the star, and in the region of the carbonaceous chondrites, it starts getting hot enough for some of this to condense and react on the silicates, which is why these have the aminoacids, etc. However, as you get closer to the star, it gets too hot and seemingly the inner asteroids are mainly just silicates. At this point, the carbon is largely converted to carbon monoxide, and the nitrogenous compounds to nitrogen. However, on some metal oxides or metals, carbon forms carbides, nitrogen nitrides, and some other materials, such as cyanamides are also formed. These are solids, and accordingly these too will be accreted with the dust and be incorporated within the planet.

As the interior of the planet gets hotter, the water gets released from the silicates and they lose their amorphous structure and become rocks. The water reacts with these chemicals and to a first approximation initially produces carbon monoxide, methane and ammonia. Carbon monoxide reacts with water on certain metals and silicates to make hydrocarbons, formaldehyde, which in turn condenses to other aldehydes (on the path to making sugars) ammonia (on the path to make aminoacids) and so on. The chemistry is fairly involved, but basically given the initial mix, temperature and pressure, both in ready supply below the Earth’s surface, what we need for life emerges and will make its way to the surface. Assuming this mechanism is correct, then provided everything is present in an adequate mix, then life should evolve. That leaves open the question, how broad is the “right mix” zone?

Before considering that, it is obvious this mechanism relies on the temperature being correct on at least two times during the planetary evolution. Initially it has to get hot enough to make the cements, and the nitrides and carbides. Superficially, that applies to all rocky planets, but maybe not for the nitrides. The problem here is Mars has very little nitrogen, so either it has gone somewhere, or it was never there. If Mars had ammonia, since it dissolves in ice down to minus 80 degrees C, ammonia on Mars would solve the problem of how could water flow there when it is so cold. However, if that is the case, the nitrogen has to be in some solid form buried below the surface. In my opinion, it was carried there as urea dissolved in water, which is why I would love to see some deep digging there.

The second requirement is that later the temperature has to be cool enough that water can set the cements. The problem with Venus is argued that it was hotter and it only just managed to absorb some water, but not enough. One counter to that is that the hydrogen on Venus has an extremely high deuterium content. The usual explanation for this is that if water gets to the top of the atmosphere, it may be hit with UV which may knock off a hydrogen atom, which is lost to space, and solar wind may take the whole molecule, however water with deuterium is less likely to get there because the heavier molecules are enhanced in the lower atmosphere, or the oceans. If this were true, for Venus to have the deuterium levels it must have started with a huge amount of water, and the mechanism above would be wrong. An embarrassing problem is where is the oxygen from that massive amount of water.

However, the proposed mechanism also predicts a very large deuterium enhancement. The carbon and nitrogen in the atmosphere and in living things has to be liberated from rocks by reaction with water, and what happens is as the water transfers hydrogen to either carbon or nitrogen it also leaves a hydroxyl attached to any metal. Two hydroxyls liberate water and leave an oxide. At this point we recall that chemical bond to deuterium is stronger than that to hydrogen, the reason being that although in theory the two are identical from the electromagnetic interactions, quantum mechanics requires there to be a zero point energy, and somewhat oversimplifying, the amount of such energy is inversely proportional to the square root of the mass of the light atom. Since deuterium is twice the mass of hydrogen, the zero point energy is less, and being less, its bond is stronger. That means there is a preference for the hydrogen to be the one that transfers, and the deuterium eventually turns up in the water. This preferential retaining of deuterium is called the chemical isotope effect. The resultant gases, methane and ammonia as examples, break down with UV radiation and make molecular nitrogen and carbon dioxide, with the hydrogen going to space. The net result of this is the rocky planet’s hydrogen gradually becomes richer in deuterium.

The effects of the two mechanisms are different. For Venus, the first one requires huge oceans; the second one little more than enough water to liberate the gases. If we look at the rocky planets, Earth should have a modest deuterium enhancement with both mechanisms because we know it has retained a very large amount of water. Mars is more tricky, because it started with less water under the proposed accretion of water mechanism, and it has less gravity and we know that all gases there, including carbon dioxide and nitrogen have enhanced heavier isotopes. That its deuterium is enhanced is simply expected from the other enhancements. Venus has about half as much CO2 again as Earth, and three times the amount of nitrogen, little water, and a very high deuterium enhancement. In my mechanism, Venus never had much water in the first place because it was too hot. Most of what it had was used up forming the atmosphere, and then providing the oxygen for the CO2. There was never much on the surface. To start with Venus was only a bit warmer than Earth, but as the CO2 began to build, whereas on Earth much of this would be dissolved in the ocean, where it would react with calcium silicate and also begin weathering the rocks that were more susceptible to weathering, such as dunite and peridotite. (I have discussed this previously: https://wordpress.com/post/ianmillerblog.wordpress.com/833 ), on Venus there were no oceans, and liquid water is needed to form these carbonates.

So, where will life be found? The answer is around any star where rocky planets formed with the two favourable temperature profiles, and ended up in the habitable zone. If more details as found in my ebook “Planetary Formation and Biogenesis” are correct, then this is most likely to occur around a G type star, like our sun, or a heavy K type star. The star also has to be one of the few that ejects it accretion disk remains early. Accordingly life should be fairly well spaced out, which may be why we have yet to run into other life forms.

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Ross 128b a Habitable Planet?

Recently the news has been full of excitement that there may be a habitable planet around the red dwarf Ross 128. What we know about the star is that it has a mass of about 0.168 that of the sun, it has a surface temperature of about 3200 degrees K, it is about 9.4 billion years old (about twice as old as the sun) and consequently it is very short of heavy elements, because there had not been enough supernovae that long ago. The planet is about 1.38 the mass of Earth, and it is about 0.05 times as far from its star as Earth is. It also orbits its star every 9.9 days, so Christmas and birthdays would be a continual problem. Because it is so close to the star it gets almost 40% more irradiation than Earth does, so it is classified as being in the inner part of the so-called habitable zone. However, the “light” is mainly at the red end of the spectrum, and in the infrared. Even more bizarrely, in May this year the radio telescope at Arecibo appeared to pick up a radio signal from the star. Aliens? Er, not so fast. Everybody now seems to believe that the signal came from a geostationary satellite. Apparently here is yet another source of electromagnetic pollution. So could it have life?

The first question is, what sort of a planet is it? A lot of commentators have said that since it is about the size of Earth it will be a rocky planet. I don’t think so. In my ebook “Planetary Formation and Biogenesis” I argued that the composition of a planet depends on the temperature at which the object formed, because various things only stick together in a narrow temperature range, but there are many such zones, each giving planets of different composition. I gave a formula that very roughly argues at what distance from the star a given type of body starts forming, and if that is applied here, the planet would be a Saturn core. However, the formula was very approximate and made a number of assumptions, such as the gas all started at a uniform low temperature, and the loss of temperature as it migrated inwards was the same for every star. That is known to be wrong, but equally, we don’t know what causes the known variations, and once the star is formed, there is no way of knowing what happened so that was something that had to be ignored. What I did was to take the average of observed temperature distributions.

Another problem was that I modelled the centre of the accretion as a point. The size of the star is probably not that important for a G type star like the sun, but it will be very important for a red dwarf where everything happens so close to it. The forming star gives off radiation well before the thermonuclear reactions start through the heat of matter falling into it, and that radiation may move the snow point out. I discounted that largely because at the key time there would be a lot of dust between the planet and the star that would screen out most of the central heat, hence any effect from the star would be small. That is more questionable for a red dwarf. On the other hand, in the recently discovered TRAPPIST system, we have an estimate of the masses of the bodies, and a measurement of their size, and they have to have either a good water/ice content or they are very porous. So the planet could be a Jupiter core.

However, I think it is most unlikely to be a rocky planet because even apart from my mechanism, the rocky planets need silicates and iron to form (and other heavier elements) and Ross 128 is a very heavy metal deficient star, and it formed from a small gas cloud. It is hard to see how there would be enough material to form such a large planet from rocks. However, carbon, oxygen and nitrogen are the easiest elements to form, and are by far the most common elements other than hydrogen and helium. So in my theory, the most likely nature of Ross 128b is a very much larger and warmer version of Titan. It would be a water world because the ice would have melted. However, the planet is probably tidally locked, which means one side would be a large ocean and the other an ice world. What then should happen is that the water should evaporate, form clouds, go around the other side and snow out. That should lead to the planet eventually becoming metastable, and there might be climate crises there as the planet flips around.

So, could there be life? If it were a planet with a Saturn core composition, it should have many of the necessary chemicals from which life could start, although because of the water/ice live would be limited to aquatic life. Also, because of the age of the planet, it may well have been and gone. However, leaving that aside, the question is, could life form there? There is one restriction (Ranjan, Wordsworth and Sasselov, 2017. arXiv:1705.02350v2) and that is if life requires photochemistry to get started, then the intensity of the high energy photons required to get many photochemical processes started can be two to four orders of magnitude less than what occurred on Earth. At that point, it depends on how fast everything that follows happens, and how fast the reactions that degrade them happen. The authors of that paper suggest that the UV intensity is just too low to get life started. Since we do not know exactly how life started yet, that assessment might be premature, nevertheless it is a cautionary point.

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.

Bloghop: Red Gold

I have been introduced to the “Bloghop” concept, where an author posts answers to ten standard questions, so here goes. Needless to say, some of my answers will hardly be standard! (I have also cheated a little by including a touch of the greater concept behind my writing, but then again, it is my blog so why not!)

1   What is the title of your book?

My latest is called Red Gold, and is set in 2075-76.It forms part of a “future history”, which starts in 2030 with Puppeteer, proceeds to the early 2050s with Troubles.

 Where did the idea come from for the book?

I started writing a futuristic novel in the 1990s, but it had far too much backstory, so I cut out some bits, and part of those cuttings led to the idea for Red Gold. The cuttings have actually provided material for five further books.

 3   What genre does your book fall under?

Science Fiction and Thriller, although the series itself will include two that would qualify as historical. The series goes to the 24th century before progressing back to the 1st as a “reboot”, and apart from two chapters, one in each book, they would be straight historical, dealing with the life of the main protagonist under the end of the Imperium of Tiberius, through Gaius Caesar, and the invasion of Britain under Claudius.

 4   Which actors would you choose to play your characters in a movie rendition?

I have no idea, but I would love Peter Jackson to direct, and Weta Workshops to do the special effects. With a bit of luck, they might let the author in to see some of what is going on. Part of “Lord of the Rings” was filmed opposite where I was working at the time, and I really wanted to see what was going on behind the huge “fence”.

 5   What is the one-sentence synopsis of your book?

Red Gold is about one man’s need to expose a fraud committed by his business partner during the colonization of Mars.

 6   Will your book be self-published or represented by an agency?

 It is self-published as an ebook.

 7.   How long did it take you to write the first draft of your manuscript?

About 8 months, I think. It was some time ago, because I abandoned it for a number of years.

 8   What other books would you compare this story to within your genre?

Obviously, nothing is exactly similar, but Kim Stanley Robinson’s Red Mars has a certain similarity in terms of genre.

 9.   Who or What inspired you to write this book?

The first of the futuristic novels was written to “see if I could make it”. To explain that, my first attempt at writing a novel was as an undergraduate in the 1960s. I was with a few female students who were going for a BA, and I could not resist saying that at least science was aimed at creating something, while all they were doing was criticizing. They should be doing, like writing novels. Their response was, I could not come up with a plot so . . My response to that was, of course I could; it was them who could not. So they challenged me, and I came up with one. They challenged me to write it, so I did. I posted it off, got four rejections and gave up. About 15 years later, I looked at it again, and the first twenty pages were awful, and nobody got past them. So I tried rewriting, and sent out query letters, but got no response. Then I tried self-publishing, on the basis that (a) I had some sort of platform because I was on nationwide TV from time to time, and (b) I was getting involved with an industrial venture, and I needed to clear the decks, so to speak. I did, but the venture also took off, and financiers forbade me to seek any publicity for anything. With no advertizing, no publicity, sales were only modest, so in the 1990s I decided to try again and see if I could make it.

 10.    What else about your book might pique the reader’s interest?

I got an agent, the book went to a major publisher, but the editor died and his replacement cleared his desk. According to this editor, my plot was too ridiculous. The book is about a fraud during the colonization of Mars, and it is exposed by an unexpected discovery, which involved where the atmosphere of Mars went. The colonization of Mars is hardly too ridiculous for SciFi, fraud is never ridiculous, which meant my science was ridiculous, and that was the prime insult. I then devoted myself to going deeper into this topic, and this ended up as my ebook “Planetary formation and biogenesis”. If Mars rovers ever find a deposit of nitrogen-rich organic material, this will be the first book to have predicted it.

Finally, something about Bloghop. To see more, go to http://www.colleensayre.blogspot.com