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.

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The Fermi Paradox and Are We Alone in the Universe?

The Fermi paradox is something like this. The Universe is enormous, and there are an astronomical number of planets. Accordingly, the potential for intelligent life somewhere should be enormous, but we find no evidence of anything. The Seti program has been searching for decades and has found nothing. So where are these aliens?

What is fascinating about this is an argument from Daniel Whitmire, who teaches mathematics at the University of Arkansas and has published a paper in the International Journal of Astrobiology (doi:10.1017/S1473550417000271 ). In it, he concludes that technological societies rapidly exterminate themselves. So, how does he come to this conclusion. The argument is fascinating relating to the power of mathematics, and particularly statistics, to show or mislead.

He first resorts to a statistical concept called the Principle of Mediocrity, which states that, in the absence of any evidence to the contrary, any observation should be regarded as typical. If so, we observe our own presence. If we assume we are typical, and we have been technological for 100 years (he defines being technological as using electricity, but you can change this) then it follows that our being average means that after a further 200 years we are no longer technological. We can extend this to about 500 years on the basis that in terms of age a Bell curve is skewed (you cannot have negative age). To be non-technological we have to exterminate ourselves, therefore he concludes that technological societies exterminate themselves rather quickly. We may scoff at that, but then again, watching the antics over North Korea can we be sure?

He makes a further conclusion: since we are the first on our planet, other civilizations should also be the first. I really don’t follow this because he has also calculated that there could be up to 23 opportunities for further species to develop technologies once we are gone, so surely that follows elsewhere. It seems to me to be a rather mediocre use of this principle of mediocrity.

Now, at this point, I shall diverge and consider the German tank problem, because this shows what you can do with statistics. The allies wanted to know the production rate of German tanks, and they got this from a simple formula, and from taking down the serial numbers of captured or destroyed tanks. The formula is

N = m + m/n – 1

Where N is the number you are seeking, m is the highest sampled serial number and n is the sample size (the number of tanks). Apparently this was highly successful, and their estimations were far superior to intelligence gathering, which always seriously overestimated.

That leaves the question of whether that success means anything for the current problem. The first thing we note is the Germans conveniently numbered their tanks, and in sequence, the sample size was a tolerable fraction of the required answer (it was about 5%), and finally it was known that the Germans were making tanks and sending them to the front as regularly as they could manage. There were no causative aspects that would modify the results. With Whitmire’s analysis, there is a very bad aspect of the reasoning: this question of whether we are alone is raised as soon as we have some capability to answer it. Thus we ask it within fifty years of having reasonable electronics; for all we know they may still be asking it a million years in the future, so the age of technological society, which is used to base the lifetime reasoning, is put into the equation as soon as it is asked. That means it is not a random sample, but causative sample. Then on top of that, we have a sample of one, which is not exactly a good statistical sample. Of course if there were more samples than one, the question would answer itself and there would be no need for statistics. In this case, statistics are only used when they should not be used.

So what do I make of that? For me, there is a lack of logic. By definition, to publish original work, you have to be the first to do it. So, any statistical conclusion from asking the question is ridiculous because by definition it is not a random sample; it is the first. It is like trying to estimate German tank production from a sample of 1 and when that tank had the serial number 1. So, is there anything we can take from this?

In my opinion, the first thing we could argue from this Principle of Mediocrity is that the odds of finding aliens are strongest on earth-sized planets around G type stars about this far from the star, simply because we know it is at least possible. Further, we can argue the star should be at least about 4.5 billion years old, to give evolution time to generate such technological life. We are reasonably sure it could not have happened much earlier on Earth. One of my science fiction novels is based on the concept that Cretaceous raptors could have managed it, given time, but that still only buys a few tens of millions of years, and we don’t know how long they would have taken, had they been able. They had to evolve considerably larger brains, and who knows how long that would take? Possibly almost as long as mammals took.

Since there are older stars out there, why haven’t we found evidence? That question should be rephrased into, how would we? The Seti program assumes that aliens would try to send us messages, but why would they? Unless they were directed, to send meaningful signals over such huge distances would require immense energy expenditures. And why would they direct signals here? They could have tried 2,000 years ago, persisted for a few hundred years, and given us up. Alternatively, it is cheaper to listen. As I noted in a different novel, the concept falls down on economic grounds because everyone is listening and nobody is sending. And, of course, for strategic reasons, why tell more powerful aliens where you live? For me, the so-called Fermi paradox is no paradox at all; if there are aliens out there, they will be following their own logical best interests, and they don’t include us. Another thing it tells me is this is evidence you can indeed “prove” anything with statistics, if nobody is thinking.

Trappist-1, and Problems for a Theoretician

In my previous post, I outlined the recently discovered planets around Trappist-1. One interesting question is, how did such planets form? My guess is, the standard theory will have a lot of trouble explaining this, because what we have is a very large number of earth-sized rocky planets around a rather insubstantial star. How did that happen? However, the alternative theory outlined in my ebook, Planetary Formation and Biogenesis, also has a problem. I gave an equation that very approximately predicts what you will get based on the size of the star, and this equation was based on the premise that chemical or physical chemical interactions that lead to accretion of planets while the star is accreting follow the temperatures in various parts of the accretion disk. In turn, the accretion disk around Trappist-1 should not have got hot enough where any of the rocky planets are, and more importantly, it should not have happened over such a wide radial distance. Worse still, the theory predicts different types of planets in different places, and while we cannot eliminate this possibility for trappist-1, it seems highly likely that all the planets located so far are rocky planets. So what went wrong?

This illustrates an interesting aspect of scientific theory. The theory was developed in part to account for our solar system, and solar systems around similar stars. The temperature in the initial accretion disk where the planets form around G type stars is dependent on two major factors. The first is the loss of potential energy as the gas falls towards the star. The temperature at a specific distance due to this is due to the gravitational potential at that point, which in turn is dependent on the mass of the star, and the rate of gas flowing through that point, which in turn, from observation, is very approximately dependent on the square of the mass of the star. So overall, that part is very approximately proportional to the cube of the stellar mass. The second dependency is on the amount of heat radiated to space, which in turn depends on the amount of dust, the disk thickness, and the turbulence in the disk. Overall, that is approximately the same for similar stars, but it is difficult to know how the Trappist-1 disk would cool. So, while the relationship is too unreliable for predicting where a planet will be, it should be somewhat better for predicting where the others will be, and what sort of planets they will be, if you can clearly identify what one of them is. Trappist-1 has far too many rocky planets. So again, what went wrong?

The answer is that in any scientific theory, very frequently we have to make approximations. In this case, because of the dust, and because of the distance, I assumed that for G type stars the heat from the star was irrelevant. For example, in the theory Earth formed from material that had been processed to at least 1550 degrees Centigrade. That is consistent with the heat relationship where Jupiter forms where water ice is beginning to think about subliming, which is also part of the standard theory. Since the dust should block much of the star’s light, the star might be adding at most a few tens of degrees to Earth’s temperature while the dust was still there at its initial concentration, and given the uncertainties elsewhere, I ignored that.

For Trappist -1 it is clear that such an omission is not valid. The planets would have accreted from material that was essentially near the outer envelope of the actual star during accretion, the star would appear large, the distance involving dust would be small, the flow through would be much more modest, and so the accreting star would now be a major source of heat.

Does this make sense? First, there are no rocky bodies of any size closer to our sun than Mercury. The reason for that, in this theory, is that by this point the dust started to get so hot it vaporized and joined the gas that flowed into the star. It never got that hot at Trappist-1. And that in turn is why Trappist-1 has so many rocky planets. The general coolness due to the small amount of mass falling inwards (relatively speaking) meant that the necessary heat for rocky planets only occurred very close to the star, but because of the relative size of the stellar envelope that temperature was further out than mass flow would predict, and furthermore the fact that the star could not be even vaguely considered as a point source meant that the zone for the rocky planets was sufficiently extended that a larger number of rocky planets was possible.

There are planets close to other stars, and they are usually giants. These almost certainly did not form there, and the usual explanation for them is that when very large planets get too close together, their orbits become unstable, and in a form of gravitational billiards, they start throwing each other around, some even being thrown from the solar system, and some end up very close to the star.

So, what does that mean for the planets of Trappist-1? From the densities quoted in the Nature paper, if they are right, and the authors give a wide range of uncertainty, the fact that the sixth one out has a density approaching that of Earth means they have surprisingly large iron cores, which may mean there is a possibility most of them accreted more or less the same way Mercury or Venus did, i.e. they accreted at relatively high temperatures, in which case they will have very little water on them. Furthermore, it has also been determined that these planets will be experiencing a rather uncomfortable amount of Xrays and extreme ultraviolet radiation. Do not book a ticket to go to them.

Trappist-1

By now, I suspect everybody has heard of Trappist-1, a totally non-spectacular star about 39 light years from Earth, and in terms of astronomy, a really close neighbour. I have seen a number of people on the web speculating about going there some time in the not too distant future. Suppose you could average a speed of 50,000 kilometers per hr, by my calculation (hopefully not hopelessly wrong) it would take about 850,000 years to get there. Since chemical rockets cannot get significantly more velocity, don’t book your ticket. Is it possible for a person to get to such stars? It would be if you could get to a speed sufficiently close to light speed. Relativity tells us that as you approach light speed your aging process slows down, and if you went at light speed (theoretically impossible if you have mass) you would not age, even though it would take 39 years as seen by an observer on earth. (Of course, assuming an observer could see your craft, it would seem to take 78 years at light speed because the signal has to get back.) It is not just aging; everything you do slows down the same way, so if you were travelling at light speed you would think the star was surprisingly close.

The chances are you will also have seen the comment that Trappist-1 is only a little bit bigger than Jupiter. In terms of mass, Trappist-1 is about 8% the mass of the sun, and that certainly makes it a small star as stars go, but it is about 84 times the mass of Jupiter. In my book, 84 times as big is not exactly “a little bit bigger”. Trappist-1 is certainly not as hot as the sun; its surface temperature is about 40% that of the sun. The power output of the star is also much lower, because power radiated per unit area is proportional to the fourth power of the temperature, and of course the area is much less. In this context, there are a lot of planets bigger than Jupiter, many of them about 18 times as big, but they are also too small to ignite thermonuclear reactions.

Nevertheless the system has three “earth-sized” planets in the “habitable” zone, and one that would be too hot for water to be in the liquid state, with a surface temperature predicted to be about 127 degree Centigrade provided it is simply in equilibrium with incoming stellar radiation. Of course, polar temperatures could be significantly cooler. The next three out would have surface temperatures of about 68 degrees C, 15 degrees C (which is rather earth-like) and minus 22 degrees C. Such temperatures do not take into account any greenhouse effect from any atmosphere, and it may be that the planet with a temperature of 68 degrees could equally end up something like a Venus. Interestingly, in the Nature paper describing them, it is argued that it is the planets e, f and g that could have water oceans, despite having temperatures without any greenhouse effect of minus 22, minus 54, and minus 74 degrees C. This arises from certain modeling, which I find unexpected. The planets are likely to be tidally locked, i.e. like the moon, the same face will always be directed towards the star.

So, there is excitement: here we have potential habitable planets. Or do we?

In terms of size, yes we do. The planetary radii for many are quite close to Earth’s, although d, the one with the most earth-like temperatures has a radius of about 0.77 Earth’s. Most of the others are a shade larger than earth, at least in terms of radius.

Another interesting thing is there are estimates of the planetary masses. How they get these is interesting, given the complexity of the system. The planets were detected by their transiting over the face of the star, and such transits have a periodic time, or what we would call a year, i.e how long it takes to get the next transit. Thus the closest, b, has a periodic time of 1.51087081 days. The furthest out has a period of 20 days. Now, the masses can be determined by mutual gravitational effects. Thus since the planets are close, suppose one is being chased by the other around transit time. The one behind will be pulled along a bit and the one in front retarded a bit, and that will lead to the transits being not quite on time. Unfortunately, the data set meant that because of the rather significant uncertainties in just about every variable, the masses are somewhat uncertain, thus the mass of the inner one is 0.85 + 0.72 earth masses. The second one is calculated to have a density of 1.17 times that of earth, which means it has a huge iron core. However, with the exception of the outer one, they all have densities that strongly suggest rocky planets, most with iron cores.

Suppose we went there. On our most “earth-like” planet we might have trouble growing plants. The reason is the light intensity is very low, and is more like on earth just after sunset. The reason the temperatures are adequate is that the star puts out much of its energy in the form of infrared radiation, and in general that is not adequate to power any obvious photochemistry, although it is good for warming things. The web informs us that astronomers are excited by this discovery because they give us the best chance of analyzing the atmospheres of an alien planet.

The reason is the planets orbit in a plane that means they pass in front of the star from our observation point, and that gives us an excellent chance to measure their size, but eventually also to analyse their atmospheres if they have certain sorts of gases. The reason for this is that as infrared radiation passes through material, the energies corresponding to the energies of molecular vibrations get absorbed. So, if we record the spectrum of the stellar radiation, when a planet passes in front of it, besides the main part of the planet lowering the intensity of all the radiation, where there is an energy corresponding to a molecular vibration, there would be a further absorption, so there would be little spikes on the overall dip. Such absorption spectra are often used by chemists to help identify what they have. It only identifies the class of compounds, because all compounds with the same functional group will absorb the same sort of radiation, but as far as gases go, there are not very many of them and we should be able to identify the with quite a degree of confidence, with one exception. Gases such as nitrogen and oxygen do not absorb in the infrared.

So, where does that leave us? We have a system that in principle lets us analyze things in greater detail than for most other planetary systems. However, I suspect this might also be misleading. This system is quite unlike others we have seen, mainly because it is around a much smaller star, and the planets may also be different due to the different conditions around a smaller star during planetary formation.

Evidence that the Standard Theory of Planetary Formation is Wrong.

Every now and again, something happens that makes you feel both good and depressed at the same time. For me it was last week, when I looked up the then latest edition of Nature. There were two papers (Nature, vol 541 (Dauphas, pp 521 – 524; Fischer-Gödde and Kleine, pp 525 – 527) that falsified two of the most important propositions in the standard theory of planetary formation. What we actually know is that stars accrete from a disk of gas and dust, the disk lingers on for between a million years and 30 million years, depending on the star, then the star’s solar winds clear out the dust and gas. Somewhere in there, planets form. We can see evidence of gas giants growing, where the gas is falling into the giant planet, but the process by which smaller planets or the cores of giants form is unobservable because the bodies are too small, and the dust too opaque. Accordingly, we can only form theories to fill in the intermediate process. The standard theory, also called oligarchic growth, explains planetary formation in terms of dust accreting to planetesimals by some unknown mechanism, then these collide to form embryos, which in turn formed oligarchs or protoplanets (Mars sized objects) and these collided to form planets. If this happened, they would do a lot of bouncing around and everything would get well-mixed. Standard computer simulations argue that Earth would have formed from a distribution of matter from further out than Mars to inside Mercury’s orbit. Earth the gets its water from a “late veneer” from carbonaceous chondrites from the far side of the asteroid belt.

It is also well known that certain elements in bodies in the solar system have isotopes that vary their ratio depending on the distance from the star. Thus meteorites from Mars have different isotope ratios from meteorites from the asteroid belt, and again both are different from rocks from Earth and Moon. The cause of this isotope difference is unclear, but it is an established fact. This is where those two papers come in.

Dauphas showed that Earth accreted from a reasonably narrow zone throughout its entire accretion time. Furthermore, that zone was the same as that which formed enstatite chondrites, which appear to have originated from a region that was much hotter than the material that, say, formed Mars. Thus enstatite chondrites are reduced. What that means is that their chemistry was such that there was less oxygen. Mars has only a small iron core, and most of its iron is as iron oxide. Enstatite chondrites have free iron as iron, and, of course, Earth has a very large iron core. Enstatite chondrites also contain silicates with less magnesium, which will occur when the temperatures were too hot to crystallize out forsterite. (Forsterite melts at 1890 degrees C, but it will also dissolve to some extent in silica melts at lower temperatures.) Enstatite chondrites also are amongst the driest, so they did not provide Earth’s water.

Fischer-Gödde and Kleine showed that most of Earth’s water did not come from carbonaceous chondrites, the reason being, if it did, the non-water part would have added about 5% to the mass of Earth, and the last 5% is supposed to be from where the bulk of elements that dissolve in hot iron would have come from. The amounts arriving earlier would have dissolved in the iron and gone to the core. One of those elements is ruthenium, and the isotope ratios of Earth’s ruthenium rule out an origin from the asteroid belt.

Accordingly, this evidence rules out oligarchic growth. There used to be an alternative theory of planetary accretion called monarchic growth, but this was soon abandoned because it cannot explain first why we have the number of planets we have where they are, and second where our water came from. Calculations show it is possible to have three to five planets in stable orbit between Earth and Mars, assuming none are larger than Earth, and more out to the asteroid belt. But they are not there, so the question is, if planets only grow from a narrow zone, why are these zones empty?

This is where I felt good. A few years ago I published an ebook called “Planetary Formation and Biogenesis” and it required monarchic growth. It also required the planets in our solar system to be roughly where they are, at least until they get big enough to play gravitational billiards. The mechanism is that the planets accreted in zones where the chemistry of the matter permitted accretion, and that in turn was temperature dependent, so specific sorts of planets form in zones at specific distances from the star. Earth formed by accretion of rocks formed during the hot stage, and being in a zone near that which formed enstatite chondrites, the iron was present as a metal, which is why Earth has an iron core. The reason Earth has so much water is that accretion occurred from rocks that had been heat treated to about 1550 degrees Centigrade, in which case certain aluminosilicates phase separated out. These, when they take up water, form cement that binds other rocks to form a concrete. As far as I am aware, my theory is the only current one that requires these results.

So, why do I feel depressed? My ebook contained a review of over 600 references from journals until a few months before the ebook was published. The problem is, these references, if properly analysed, provided papers with plenty of evidence that these two standard theories were wrong, but each of the papers’ conclusions were ignored. In particular, there was a more convincing paper back in 2002 (Drake and Righter, Nature 416: 39-44) that came to exactly the same conclusions. As an example, to eliminate carbonaceous chondrites as the source of water, instead of ruthenium isotopes, it used osmium isotopes and other compositional data, but you see the point. So why was this earlier work ignored? I firmly believe that scientists prefer to ignore evidence that falsifies their cherished beliefs rather than change their minds. What I find worse is that neither of these papers cited the Drake and Righter paper. Either they did not want to admit they were confirming a previous conclusion, or they were not interested in looking thoroughly at past work other than that which supported their procedures.

So, I doubt these two papers will change much either. I might be wrong, but I am not holding my breath waiting for someone with enough prestige to come out and say enough to change the paradigm.

Proxima b

The news this week is that a planet has been found around Proxima Centauri, the nearest star to our solar system. Near, of course is relative. It would take over four years for a radio message to get there, or 40 years if you travel at 0.1 times light speed. Since we can never get anywhere near that speed with our current technology, it is not exactly a find critical to our current society. The planet is apparently a little larger than Earth, and it is in the so-called habitable zone, where the star gives off enough heat to permit liquid water to flow, assuming it has sufficient atmospheric pressure of a suitable composition. That last part is important. Thus Mars and Venus might permit water to flow if their atmospheres were different. In Venus’ case, far too much carbon dioxide; in Mars’ case, insufficient atmosphere, although it too might need something with a better greenhouse effect than carbon dioxide.

Proxima Centauri is what is called a red dwarf. Its mass is about 1/8 of the sun’s, so it gives off a lot less energy, however, Proxima b is only 0.0485 times as far from the star as Earth is, so being closer, it gets more of what little heat is available. The question then is, how like Earth is it?

Being so close to the star, standard wisdom argues that it will be tidally locked to the star, i.e. it always keeps the same face towards the star. So half of the planet is unaware of the star’s presence; one side is warm, the other very cold and dark. However, maybe here standard theory does not give the correct outcome. That it should be tidally locked is valid as long as gravitational interactions are the only ones applicable, but are they? According to Leconte et al. (Science 346: 632 – 635) there is another effect that over-rides that. Assuming the planet does not start tidally locked, and if it has an atmosphere, then there is asymmetric heating through the day, and because the highest temperature is at about 1500 hrs, the heat causes the air there to rise, and air from the cold side to replace it, which leads to retrograde rotation through conservation of angular m omentum. (Prograde rotation is as if the planet went around its orbit as if rolling on something.) Venus is the only planet in our system that rotates retrogradely, and Leconte argues it is for this reason. The effect on Venus is small because it is quite far away from the star, and it has a very thick atmosphere.

Currently, everyone seems to believe that because the planet is in the habitable zone then it will be a rocky planet like Earth. This raises the question, how do planets form? In previous posts I have outlined how I believe rocky planets form, (https://wordpress.com/post/ianmillerblog.wordpress.com/568 and https://wordpress.com/post/ianmillerblog.wordpress.com/576 ). These posts omit the cores of the giants, which in my theory accrete like snowballs. There are four cores leading to giants (Jupiter, Saturn, Uranus and Neptune) and there are four sets of ices to form them. (There are actually potentially more that would lead to bodies much further out.) The spacing of those four planets is very close to the projected ice points, assuming Jupiter formed where water ice would snowball.

Standard theory has it that we start with a distribution of planetesimals about the star, and these attract each other gravitationally, and larger bodies accrete until we get protoplanets, then there are massive collisions. The core of Jupiter, for example, would take about 10 My to form, then it would rapidly accrete gas.

There are, in my opinion, several things wrong with this picture. The first is, nobody has any idea how the planetesimals form. These are bodies as large as a major asteroid. The models assume a distribution of them, and this is based on the assumption all mass is evenly distributed throughout the accretion disk, except that the density drops off inversely proportional to rx. The index x is a variable that has to be assumed, which is fine, and it is then assumed that apart from particle density, all regions of space have equal probability of forming planetesimals. It is the particle density that is the problem. Once beyond the distance of Saturn, collision probability becomes too low to form planets, although the distribution of planetesimals permits Uranus and Neptune to migrate out of the planet-forming zone. Now, for me a major problem comes from the system LkCa 15, where there is a planet about five times bigger than Jupiter about three times further away from a star slightly smaller than our sun that is only 3 My old. There has simply been insufficient time to form that. In my ebook Planetary Formation and Biogenesis I proposed that bodies start accreting in the outer regions similar to snowballs. As the ices are swept towards the star, when they reach a certain temperature the ices start sticking together, and such a body can grow very quickly because as it grows, it starts orbiting faster than the gas. Accordingly, what you get depends on the temperatures in the accretion disk. Unfortunately, for any star we have no idea of that distribution because the disk is long gone. However, to a first approximation, the temperature is dependent on the heat generated less the heat lost. The heat generated at a point would depend on the gravitational potential at that point, which is dependent on stellar mass M, and the rate of flow past that point, which to a very rough approximation, depends on M2. That is by observation, and is + over 100%. So if we assume that all disks radiate equally (they don’t) and we neglect accretion rate variability, the position of a planet depends on M3. That gives a rough prediction of where planets might be, within a factor of about 3, which is arguably not very good.

However, if we use that relationship on a red dwarf of Proxima’s mass, the Jupiter core would be about 0.01 A.U. from the star. In short, Proxima b is at the very centre of where the Saturn equivalent should be, although I think it is far more likely to be the Jupiter core. The relationship is very rough, as the rate of accretion varies considerably from that relationship, and also, as the distances collapse, the size of the star now becomes significant, and back-heating will push the ice point further out. However, what is important here is that this “ice point” is relevant to any accretion theory. If ice is a solid at a given distance, then the ice should be accreted alongside any other solid.

So my opinion is that Proxima b would be a water world, with no land on the surface at all. Further, if it is the Jovian equivalent, it probably will not have an atmosphere, or if it does, it will be mainly oxygen from photolysed water. So I am very interested in seeing the future James Webb telescope aimed at that planet, as water gives a very clear infrared spectrum.

Martian water

To have life, a planet needs water. Mars, being cold, has ice. There is a water ice-cap at the North Pole, and presumably at the South Pole. Yet there are huge valleys consistent with once having had huge flows through them. A recent scientific paper in Science (vol 348, pp218 – 221) shows evidence that Mars once had enough water to cover an area equal to that of the whole planet to a depth of 137 meters. Since Mars is now a desert, where did it go? Some would be lost to space, but a lot probably sunk into the ground, and apparently there are large areas in the northern hemisphere where underground ice sheets have been located by radar.

Having said that, there has been a recent news item of water on Mars at Gale Crater. This might be misleading. What they appear to have found is damper soil, and this has arisen because the salt calcium perchlorate sucks water from almost anywhere and dissolves, and does so at very much lower temperatures. If you mix salt (sodium chloride) with ice, it dissolves in water from the ice and takes heat from the ice, and settles as a liquid at minus 20 oC. Calcium chloride takes the temperature much lower, and apparently, so does calcium perchlorate. Yes, water can be present on Mars, even at the lower temperatures if there is something dissolved in it that lowers the freezing point enough.

Now, one of the puzzles of Mars is that there is evidence of quite significant fluid flows, in the form of great valleys carved out of the land, and which sometimes meander, but always go downhill. There should have been plenty of water, but the average temperature of Mars is currently about minus 80 oC, and back in time when these valleys formed, the sun would have been only 2/3 as bright. Unless the temperatures can be over 0 oC water freezes, so what created these valleys? Carbon dioxide as a greenhouse gas would not have sufficed, because if there were the necessary amounts available, the pressure and temperature would lead it to raining out, then as the temperature dropped with lower pressure, the carbon dioxide would frost out as a solid (dry ice). There was simply not enough heat to keep enough carbon dioxide in the atmosphere. Finally, the evidence available is that Martian temperatures never got above minus 60 oC for any significant length of time over a significant area.

The other alternative would be to dissolve something in the water to lower its freezing point. That something would not be calcium chloride or calcium perchlorate, because there simply is not enough of it around, and if there were, there would be massive deposits of lime or gypsum now. So, what could it be? When I was writing my fictional book Red Gold, which was about fraud during the colonization of Mars, I needed something unexpected to expose the fraud, and I thought that whatever caused these fluid flows could be the answer. The problem is simple: something was needed to lower the temperature of the melting point of ice by at least sixty Centigrade degrees, and not many things do that. But, there is another problem. Some of the longest fluid flows start in the southern highlands, which will be amongst the coldest parts of Mars. The reason they start there is simple in some ways: that will be where snow falls, or even where ice that has sublimed elsewhere will frost out. So, why does it melt? It cannot be something like calcium chloride because even leaving aside the point that it may not take the temperatures low enough and there was not enough of it, there most certainly was not enough in one place to keep going, and solids do not move.

My answer was ammonia. Ammonia is a gas, and hence it can get to the highlands, and furthermore, it dissolves in ice, then melts it, as long as the temperatures are at least minus eighty degrees Centigrade. Thus ammonia is one of the very few agents that could conceivably have done what was required. Given that, why is ammonia never cited by standard science? The reason is that ammonia in the air would be destroyed by solar UV, and studies have shown that ammonia would only last a matter of decades.

I argue that reasoning is wrong. On Earth, after 1.4 billion years, samples of sea water were trapped in rock at Barberton, in South Africa, and this water had almost as much ammonia in it as there was potassium. The salt levels were very high, presumably because water got boiled off when the volcanic melt solidified and sealed the water inside, and if that were the case, ammonia would have been lost too, so my estimate that ten percent of the Earth’s nitrogen remained in the form of ammonia may have been an underestimate. Why would the ammonia not be degraded? There are two reasons. The first is that most of the ammonia would be dissolved in water and not be in the air. The second is, ammonia degraded in the upper atmosphere would react with other degradation products and form a haze that would act as a sunscreen that would seriously slow down the degradation. That is the chemistry that causes the haze on Titan.

So what happened to the ammonia on Mars? My answer was, ammonia reacts with carbon dioxide to form first, ammonium carbonate, and subsequently, urea amongst other things. Such solids would dissolve in water, and in my opinion, then sink into the soil and lie below the Martian surface. This would account for why the Martian atmosphere has only about 2% nitrogen in it, and it is only 1% as thick as Earth’s atmosphere. (Nitrogen would not freeze out.) The alternative, of course, is that Mars never had any more nitrogen, in which case my argument fails because there is nothing to make the ammonia with. Does it matter? As I noted in the novel, if you want to settle Mars, yes, it would be very helpful to find a natural fertilizer resource. As to whether this happened, something carved out those valleys, and so far suggestions of what are thin and far between.

If anyone is interested, the ebook is on a Kindle countdown special, starting May 1. Besides the story, there is an appendix that outlines the first form of what would become my theory of planetary formation.