The Face of Mars


In 1976, the Viking 1 mission began taking photographs of the surface of Mars, in part to find landing sites for future missions, and also to get a better idea of what Mars was like, to determine the ages of various parts of Mars (done by counting craters, which assumes that once the great bombardment was over, the impacts were more or less regular over time if we think in terms of geological timing.) On the Cydonia Mensae, an image came back that, when refined, looks surprisingly like a face carved into a large rock. Two points are worth mentioning. The first is, if it were such a head, the angle of the light only allows you to see the right side of the head; the rest is in deep shadow. The second is all we received of this object was 64 pixels. The “face” is clearly a butte standing up from the surface (and there are lot of these in the region) and it is about 2.5 km long, about 1.5 km wide, and something like up to 800 m above the average flat ground at its highest point. As you might imagine, with only 64 pixels, the detail is not great, but there is a crater where the right eye should be, a rise that makes the nose, and some sort of “crack” or depression that hints at a mouth, but most of the “mouth” would be in the shade, and hence would be invisible. The image was also liberally splattered with black spots; these were “failed pixels” i.e. a transmission problem. What you see below is that primary image.

640x472 pixels-FC

So, what was it? The most obvious answer was a rock that accidentally looked like a face. To the objection, what is the probability that you could end up with that, the answer is, not as bad as you might think. There are a lot of mesas and rock formations on Mars, so sooner or later one of them might look like something else. There are a number of hills etc on Earth where you can see a head, or a frog, or something if you want to. If you think about it, an oval mesa is not that improbable, and there are a lot of them. There are a very large number of impact craters on Mars, so the chances of one being roughly where an eye would be is quite high (because there is quite a bit of flexibility here) and there are really only two features – the eye and the “mouth”. The rise for the nose only requires the centre to be the highest part, and that is not improbable. As it happens, when you see the whole thing, the left side of the head has sort of collapsed, and it is a fracture offshoot from that collapse that gives the mouth.

However, the image caught the imagination of many, and some got a little carried away. Richard Hoagland wrote a book The Monuments of Mars: A City on the Edge of Forever. If nothing else, this was a really good selling book, at one stage apparently selling up ot 2000 copies a month. Yep, the likes of me are at least envious of the sales. So, what did this say? Basically, Hoagland saw several “pyramids” near the Face, and a jumble of rocks that he interpreted as a walled city. Mars had an ancient civilisation! Left unsaid was why, if there were such “Martians” did they waste effort building pyramids and carving this Face while their planet was dying? For me, another question is why does something this fanciful become a best seller, while the truth languishes?

So what caused this? I don’t know, and neither does anyone else. It is reasonably obviously caused by erosion, but what the eroding agent was remains unknown. If you believe Mars once had an ocean, the Cydonian region is roughly where one of the proposed shorelines was. It could also be caused by glaciation, or even wind erosion, aided by moisture in the rock. The freezing/thawing of water generates very powerful forces. What we need is a geologist to visit the site to answer the question, although there would be far more important things to do on Mars than worry about that rock.

Suppose it was carved by a civilization? I included that possiblity in my novel Red Gold. In this, one character tried pulling the leg of another by announcing that it was “obviously carved” by aliens with the purpose of encouraging humans to go into space. “It is worth it,” the aliens would be saying. So why is it so rough? Because the aliens were plagued by accountants, who decided that the effort to do it properly was not worth the benefit; if humans cannot take the hint from the roughly hewn rock, so be it.

It also figures in another of my novels: A Face on Cydonia. Again, it is intended as a joke in the book, but on whom? Why did I do that? Well, I started writing when I heard that Global Surveyor was going to settle this issue, so I thought I should try to have something ready for an agent. However, Global Surveyor, which took very narrow strip images, and could have taken two years to cover this area, took only a few weeks. Out of luck again! Fortunately, the story was never really about the rock, but rather the effect it had on people.

A quick commercial: if anyone is interested, the ebook is at 99 cents on Amazon (or 99p) for the first week of September. The book is the first of a trilogy, but more about people being taken to levels higher than their abilities, and also about what causes some to descend to evil. It also has just a toiuch of science; while you can ignore this and just consider it a powerful explosive, it has the first mention of a chemical tetranitrotetrahedrane. That would be a really powerful explosive, if it could be made, but the more interesting point is why is that there?


The Rivers of Mars: How and Why?

My first self-published ebook was about how to form a theory. The origin of this has an interesting history: Elsevier asked me to write a book, and while I know what they thought they were going to get, I sent back a proposal that I thought they could never accept, largely to get them off my back. They accepted it, at that stage, so I had to write. The problem for me was, it took somewhat longer than I expected; the problem for them was the time taken, the length, and then, horrors, they found out I was not an academic with lots of students forced to buy the book. The book was orphaned, but I was so far on I thought I might as well self publish it. The advocated methodology is that of Aristotle, and oddly enough, most of his scientific bloopers arose because he ignored his own instructions! So, let me show what I made of it on one of my projects: how did Mars ever have flowing rivers? Why I chose that is a story best left for a later post.

The first step is to state clearly what you know. In this case, Mars has some quite long what seem like riverbeds, and they start sometimes from the coldest parts of Mars. The longest goes from highlands 60 degrees south and stops somewhere near the equator, and these can only reasonably be explained by fluid flow. Almost certainly water is the only fluid there in sufficient volume, so it had to be at least part of the flow. However, water freezes at 0 degrees Centigrade, the average temperature on Mars now is about minus 60 degrees C, and when the rivers were flowing the sun had only about 2/3 its current heat output.

The next step is to ask questions. To start, how did water flow, starting from high altitude high latitude sites, where the temperatures would be well below that of the rest of the planet? Could we dissolve something in the water to lower the freezing point? Dissolving salts in the water depresses the freezing point, but even the aggressive calcium chloride will not buy you more than forty degrees, so that is not adequate by itself. There are worse problems with this explanation: where did these salts come from, and how could salts get into snow on the southern highlands?

The standard explanation is that there must have been a greenhouse effect, and many have argued for a very significant carbon dioxide atmosphere. There are three problems with this explanation. The first is, it won’t work. Anything less than ten atmospheres pressure is inadequate, and at three atmospheres, the carbon dioxide liquefies. You cannot get sufficient pressure. The second is, the winters on Mars are very long, and carbon dioxide would snow out on the poles, thus reducing the pressure, and because of the albedo of the snow, not all of it would revolatalize, so as the years progressed, the planet would quickly become what it is like now. The third problem is, if there were that much carbon dioxide, where did it go? From isotope fractionation, it appears that about half of the original material that stayed in the atmosphere has been lost to space. Some more could well be frozen out on the poles. However, if there were enough to sustain liquid water for extended periods of time, there should be a lot of carbonates, and there are not. Now it is true we do not know how much could be buried, so maybe that argument is a bit on the weak side. On the other hand, there is plenty of other evidence that the atmosphere of Mars was always thin, although not as thin as now, as there had to be enough to keep water liquid. A number of estimates put it in the 100 millibar range. Further, if it lasted for periods of a few hundred thousand years it could not have been carbon dioxide, at least not initially as otherwise most would have snowed out. Of course it could have been continuously replenished by volcanic action, but if so, there must be very large deposits of carbon dioxide at the poles and that does not appear to be the case. So by asking such simple questions, we have made progress.

The next question is, how did the gases and water get to Mars? This is a rather convoluted question, but the simple answer is, the river flows lasted for only a few hundred thousand years and they started about 1.5 billion years after Mars formed. They also corresponded to significant periods of volcanic eruptions, so the most likely answer for the gases is they came from volcanic eruptions. Most of the water would have too, however it is possible that there were ice deposits near the surface following accretion. The next question is, how did the gases get below the surface of Mars to be erupted?

If we think about them being adsorbed during accretion, then, with the exception of water and ammonia, because the heats of adsorption are very similar for various gases, they would be adsorbed approximately proportional to their concentrations in the disk gases. That would mean, predominantly hydrogen and helium, although these would have been subsequently lost to space. However, neon would also be a very common gas, and to a lesser degree argon, but both neon and argon (apart from argon 40, which is a decay product of potassium 40) are very rare on Mars, so that was not the mechanism.

A commonly quoted mechanism is the volatiles arrived on the rocky planets through comets. That is not valid, at least for Earth, the reason being that the deuterium levels on comets are too high. Another suggestion is they arrived on carbonaceous chondrites. That too does not ring true, first because there would have had to be a huge number more of them, but not silicaceous asteroids, and second, the isotopes of some other elements rule that out. As far as Mars goes, there is the additional point that since it had no plate tectonics, and it had a rocky surface approximately three million years after formation, there is no mechanism to get the gases below the surface.

The only way they could get there is to be accreted as solids. Water would bind chemically to silicates; carbon would probably be accreted as carbides, or as carbon; nitrogen would be accreted as nitrides. The gases are then formed by the reaction of water with the carbides or nitrides, so the amount of gas available depends on how many of these solids were formed, and how much water was accreted. The lower levels of these gases on Mars is due to the fact that the material in the Mars feeding zone never got as hot as around Earth during stellar accretion. The higher temperature in the Venusian accretion zone is why it also has about three times the nitrogen as Earth: nitrides were easier to form at higher temperatures. Water binding to silicates happened after the disk cooled, but before the dust accreted to planets, and Mars has less water because the better aluminosilicates never phase separated because the temperatures earlier were never hot enough. Venus got less water because the disk never got as cool as around Earth and the silicates could not absorb so much.

When water reacts with nitrides and carbides it makes ammonia and methane, and these are most stable under high pressure, which is easily obtained in the interior of planets. If so, this hypothesis predicts that the initial atmosphere would comprise ammonia and methane. This is usually considered to be wrong because ammonia in the atmosphere is quickly decomposed by UV radiation, however, the ammonia will not stay in the atmosphere. Ammonia is rapidly absorbed by water, and even snow, and it will liquefy ice even at minus 80 degrees C. That gets it out of the atmosphere quickly and now there is a simple mechanism why water would flow, and also why it would later stop flowing near the equator and form ice deposits: as it got warmer, the ammonia would evaporate off. The atmosphere would start as methane, but would gradually be oxidised to carbon dioxide, which is why the atmosphere had such a short life. The carbon dioxide would react with ammonia, and eventually the ammonium carbonate would be converted to urea and the water would stop flowing. Thus in this theory under the soil of Mars, provided it has not reacted further, there is just the fertilizer settlers would need.

Where to settle on Mars?

A few weeks ago I wrote an introductory post on Martian settlement issues ( ). 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.

Problems of Sustaining Settlements on Mars: Somewhere to Live.

People who write science fiction find colonizing Mars to be a fruitful source of plot material. Kim Stanley Robinson wrote three books on the topic, ending up by terraforming Mars. I have also written one (“Red Gold”) that included some of the problems. We even have one scheme currently being touted in which people are signing up for non-return trips. So, what are the problems? If we think about settlers making a one-way trip to New Zealand, as my ancestors did, they would find a rough start to life because much of the land was covered in forest, although there were plains. But forests meant timber for houses, some fuel, and even for sale. Leaving aside the stumps, the soil was ripe for planting crops, and you could run sheep or cows. It would have been a hard life, but there would be no reasons to fear instant death.

Mars is different. It has its resources, but they are in an inconvenient form. Take air. Mars has an atmosphere, but not a very dense one. The air pressure is about two orders of magnitude less that on Earth. That means you will have to live in some sort of dome or cave, and pump up the atmosphere to get adequate pressure, which requires you to build something that is airtight. The atmosphere is also full of carbon dioxide, and has essentially no oxygen. The answer to that is simple: build giant glass houses, pump up the atmosphere, and grow plants. That gives you food and oxygen, although you will need some fairly massive glass houses to get enough oxygen. So, how do you go about that? You will need pumps to pump up the air pressure, some form of filters to get the dust out of the inputs, and equipment to erect and seal the glass houses. That will need equipment brought from Earth. Fortunately you can make a lot of glass houses with one set of equipment. However, there are three more things required: glass, metal framing, and some form of footer, to seal in the pressure and stop it leaking back out. Initially that too will have to come from Earth, but sooner or later you have to start making this sort of thing on Mars, as otherwise the expense will be horrendous.

Glass is made by fusing pure silica with sodium carbonate and calcium oxide, and often other materials are added, such as alumina, magnesium oxide, and or borate. It is important to have some additives because it is necessary to filter out the UV radiation from the sun, so silica itself would not suffice. It is also necessary to find a glass that operates best at the lower temperatures, and that can be done, but how do you get the pure ingredients? Most of these elements are common on Mars, but locked up in basaltic rock or dust. The problem here is, Mars has had very little geochemical processing. On Earth, over the first billion years of ocean, a lot of basalt got weathered by the carbonic acid so a lot of magnesium ended up in the sea, and a lot of iron formed ferrous ions in aqueous dispersion. The earliest seas would have been green. Once life learned how to make oxygen, that oxidized the ferrous to ferric, and as ferric hydroxide is very insoluble, masses of iron precipitated out, eventually to dehydrate and make the haematite deposits that supply our steel industry. Life also started using the calcium, and when the life died and sunk to the bottom, deposits of limestone formed. As far as we know, that sort of thing did not happen on Mars. So, while sand is common on Mars, it is contaminated with iron. Would that make a suitable glass? Lava from volcanoes is not usually considered to be prime material for making glass.

So, how do you process the Martian rock? If you are going to try acid leaching, where do you get the acid, and what do you do with the residual solution? And where do you do all this?

While worrying about that, there is the question of the footer. How do you make that? In my novel Red Gold I assumed that they had developed a cement from Martian sources. That is, in my opinion, plausible. It may not be quite like our cement, which is made from limestone and clays heated to about 1700 degrees C. However, some volcanic eruptions produce material which, when heated and mixed with burnt lime make excellent cements. The main Roman cement was essentially burnt lime mixed with some heat-treated output of Vesuvius. Note once again we need lime. This, in turn, could be a problem.

My solution in Red Gold to the elements problem was simply to smash sand into its atoms and separate the elements by electromagnetism, similar to how a mass spectrometer works. The energy input for such a scheme would be very high, but the argument there was they had developed nuclear fusion, so energy was not a problem, nor for that matter, was temperature. No molecules can survive much more than about ten thousand degrees C, and nuclear fusion has a minimum temperature of about eighty million degrees C. Fine, in a novel. Doing that in practice might be a bit more difficult. However, if you don’t do something like that, how do you get the calcium oxide to make your cement, or your glass? And without a glass house, how can you eat and breathe? Put you off going to Mars? If it hasn’t, I assure you once you have your dome your problems are only beginning. More posts on this some time later.

Martian Fluvial Flows, Placid and Catastrophic


Despite the fact that, apart localized dust surfaces in summer, the surface of Mars has had average temperatures that never exceeded about minus 50 degrees C over its lifetime, it also has had some quite unexpected fluid systems. One of the longest river systems starts in several places at approximately 60 degrees south in the highlands, nominally one of the coldest spots on Mars, and drains into Argyre, thence to the Holden and Ladon Valles, then stops and apparently dropped massive amounts of ice in the Margaritifer Valles, which are at considerably lower altitude and just north of the equator. Why does a river start at one of the coldest places on Mars, and freeze out at one of the warmest? There is evidence of ice having been in the fluid, which means the fluid must have been water. (Water is extremely unusual in that the solid, ice, floats in the liquid.) These fluid systems flowed, although not necessarily continuously, for a period of about 300 million years, then stopped entirely, although there are other regions where fluid flows probably occurred later. To the northeast of Hellas (the deepest impact crater on Mars) the Dao and Harmakhis Valles change from prominent and sharp channels to diminished and muted flows at –5.8 k altitude that resemble terrestrial marine channels beyond river mouths.

So, how did the water melt? For the Dao and Harmakhis, the Hadriaca Patera (volcano) was active at the time, so some volcanic heat was probably available, but that would not apply to the systems starting in the southern highlands.

After a prolonged period in which nothing much happened, there were catastrophic flows that continued for up to 2000 km forming channels up to 200 km wide, which would require flows of approximately 100,000,000 cubic meters/sec. For most of those flows, there is no obvious source of heat. Only ice could provide the volume, but how could so much ice melt with no significant heat source, be held without re-freezing, then be released suddenly and explosively? There is no sign of significant volcanic activity, although minor activity would not be seen. Where would the water come from? Many of the catastrophic flows start from the Margaritifer Chaos, so the source of the water could reasonably be the earlier river flows.

There was plenty of volcanic activity about four billion years ago. Water and gases would be thrown into the atmosphere, and the water would ice/snow out predominantly in the coldest regions. That gets water to the southern highlands, and to the highlands east of Hellas. There may also be geologic deposits of water. The key now is the atmosphere. What was it? Most people say it was carbon dioxide and water, because that is what modern volcanoes on Earth give off, but the mechanism I suggested in my “Planetary Formation and Biogenesis” was the gases originally would be reduced, that is mainly methane and ammonia. The methane would provide some sort of greenhouse effect, but ammonia on contact with ice at minus 80 degrees C or above, dissolves in the ice and makes an ammonia/water solution. This, I propose, was the fluid. As the fluid goes north, winds and warmer temperatures would drive off some of the ammonia so oddly enough, as the fluid gets warmer, ice starts to freeze. Ammonia in the air will go and melt more snow. (This is not all that happens, but it should happen.)  Eventually, the ammonia has gone, and the water sinks into the ground where it freezes out into a massive buried ice sheet.

If so, we can now see where the catastrophic flows come from. We have the ice deposits where required. We now require at least fumaroles to be generated underneath the ice. The Margaritifer Chaos is within plausible distance of major volcanism, and of tectonic activity (near the mouth of the Valles Marineris system). Now, let us suppose the gases emerge. Methane immediately forms clathrates with the ice (enters the ice structure and sits there), because of the pressure. The ammonia dissolves ice and forms a small puddle below. This keeps going over time, but as it does, the amount of water increases and the amount of ice decreases. Eventually, there comes a point where there is insufficient ice to hold the methane, and pressure builds up until the whole system ruptures and the mass of fluid pours out. With the pressure gone, the remaining ice clathrates start breaking up explosively. Erosion is caused not only by the fluid, but by exploding ice.

The point then is, is there any evidence for this? The answer is, so far, no. However, if this mechanism is correct, there is more to the story. The methane will be oxidised in the atmosphere to carbon dioxide by solar radiation and water. Ammonia and carbon dioxide will combine and form ammonium carbonate, then urea. So if this is true, we expect to find buried where there had been water, deposits of urea, or whatever it converted to over three billion years. (Very slow chemical reactions are essentially unknown – chemists do not have the patience to do experiments over millions of years, let alone billions!) There is one further possibility. Certain metal ions complex with ammonia to form ammines, which dissolve in water or ammonia fluid. These would sink underground, and if the metal ions were there, so might be the remains of the ammines now. So we have to go to Mars and dig.






Settling Mars and High Energy Solar Particles

Recently, the US government announced that sending people to Mars was a long-term objective, and accordingly it is worth looking at some of the hazards. One that often gets airing is the fact that the sun sends out bursts of high-energy particles that are mainly protons, i.e. hydrogen atoms with their electrons stripped off. If these strike living matter, they tend to smash the molecules, as they have energy far greater than the energy of the chemical bond. These are of little hazard to us usually, though, because they are diverted by the earth’s magnetic field. It is this solar wind that is the primary cause of auroras. The solar wind particles knock electrons out of gas molecules, and the light is generated when electrons return. As you might guess, if these particles can knock out enough electrons from molecules to generate that light show, the particle flux would be quite undesirable for DNA, and a high cancer rate would be expected if some form of protection could not be provided.

The obvious method is to divert the particles, and electromagnetism provides a solution. When a charged particle is moving and it strikes a magnetic field, there is a force that causes the path of the charged particle to bend. The actual force is calculated through something called a vector cross product, but in simple terms the bending force increases with the velocity of the particle, the strength of the magnetic field, and the angle between the path and the magnetic field. The force is maximum when the path is at right angles to the magnetic field, and is actually zero when the particle motion is parallel to the field. The question then is, can we do anything about the solar particles with this?

The first option would be to generate a magnetic field in Mars. Unfortunately, that is not an option, because we have no idea how to generate a dynamo within the planet, nor do we know if it is actually possible. The usual explanation for the earth’s magnetic field is that it is generated through the earth’s rotation and the iron core. Obviously, there is more to it than that, but one thing we know is that the density of Mars is about 3.9 whereas Earth is about 5.5. Basalt, the most common mix of metal silicates, has a density ranging from 3 to 3.8, but of course density also increases with compression. This suggests that Mars does not have much of an iron core. As far as I am aware, it is also unclear whether the core of Mars is solid or liquid. Accordingly, it appears clear there is no reasonable hope of magnetizing Mars.

The alternative is to put an appropriate magnetic field on the line between Mars and the sun. To do that, we have to put a properly aligned strong magnetic field between Mars and the sun. The problem is, bodies orbiting the sun generally only have the same angular rotation about the sun as Mars if they are at the same distance from the sun as Mars, or on average if they are orbiting Mars, in which case they cannot be between, and if they are not between all the time, they are essentially useless.

However, for the general case where a medium sized body orbits a much larger one, such as a planet around a star, or the Moon around Earth, there are five points where a much smaller object can orbit in a fixed configuration with respect to the other two. These are known as Lagrange points, named after the French mathematician who found them, and the good news is that L1, the first such point, lies directly between the planet and the star. Thus on Mars, a satellite at L1 would always seem to “eclipse” the sun, although of course it would be too small to be noticed.

Accordingly, a solution to the problem of high-energy solar particles on settlers on Mars would be to put a strong enough magnetic field at the Mars sun L1 position, so as to bend the path of the solar particles away from Mars. What is interesting is that very recently Jim Green, NASA Planetary Science Division Director, made a proposal of putting such a magnetic shield at the Mars-Sun-L1 position. For a summary of Green’s proposal, see .

The NASA proposal was focused more on reducing the stripping of the atmosphere by the solar wind. If so, according to Green, such a shield could help Mars achieve half the atmospheric pressure of Earth in a matter of years, on the assumption that frozen CO2 would sublimate, thus starting the process of terraforming. I am not so sure of that, because stopping radiation hitting Mars should not lead to particularly rapid sublimation. It is true that stopping such charged particles would help in stopping gas being knocked off the outer atmosphere, but the evidence we have is that such stripping is a relatively minor effect.

The other point about this is that I made this suggestion in my ebook novel Red Gold, published in 2011, which is about the colonization of Mars. My idea there was to put a satellite at L1 with solar panels and superconducting magnets. If the magnet coils can be shielded from sunlight, even the high temperature superconductors we have now should be adequate, in which case no cooling might be required. Of course the novel is science fiction, but it is always good to see NASA validate one of your ideas, so I am rather pleased with myself.

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.