Lunar Water

Currently, if people go to the Moon, they will have to take everything they need with them. Shelter might be able to use some local materials, but almost everything else will have to come from Earth. Tools and manufactured items obviously have to be taken, but so must food, air and water. But what happens in the longer run? The expenses that will be run up like that will mean that the Moon will remain a useless lump of rock unless some alternatives are found.

A recent paper (He et al. Nature geoscience https://doi.org/10.1038/s41561-023-01159-6 ) claimed that the Changé-5 rover found water of about 1mg/g in glass beads formed by impacts. They then estimated that there were enough such glass beads across the lunar surface to get 2.7 x 10^14 kg of water. An interesting point was that the water had the D/H ratio approximately equal to solar hydrogen, and the authors proposed the water was imprinted into the beads by the solar wind. Looks like the problem is solved: the surface area of the Moon is 38 million square km, so one square kilometre will give you 7,000 t of water. If there is that much water in glass beads, and we would have at least 7 million t of such glass beads per square km, why did none of the Apollo samples bring back any of these glass beads? My guess is this is something of a gross overestimate. I have no doubt there are glass beads and they truly found water in them, but sorry, the estimate of how many there are must be wrong. The rover may have accidentally found a good deposit.

So that raises the question, is there water on the Moon? First, the information here is mixed. There is a dreadful bias to find what you expect. The original samples brought back from the Apollo missions had a water content, but the people who found it assumed it came from absorption when the samples were on Earth so they disregarded the water. Interestingly, the samples had a D/H ratio that was effectively solar, so the water could not have come from Earth. So the preconceived notion that the moon was anhydrous meant that the possibility of humans staying there for any length of time was not considered to be serious. Had it been found that there was water, maybe the Apollo program would not have been terminated and maybe the space station would not have been built as more effort would focus on the Moon. The history of space travel changed by “I know best”.

“Water” formed by solar winds is well established,  but it is formed as hydroxyl groups. With silicates, the outer surface does not properly complete its bonding, so hydrogen atoms can convert lone oxygen radicals to hydroxyls. The other half of the bond would be a radical that could react with water in the solar wind. That this probably happens is found by the “water” giving a reasonable spectroscopic signal in the evening, but is much weaker during the lunar morning. There are other samples that have  been shown to contain low levels of water. Apatites returned by Apollo had water up to 200 ppm, and some unusual volcanic glasses had water up to 46 ppm. Even more surprising is a claim that one sample of lunar soil contained nitrogen in low levels, and that nitrogen was not solar as it had enhanced levels of 15N.

So, there is water on the Moon. The TV program, “For All Humanity” had a lunar research settlement beside a crater where, deeper down the sun never penetrated. There was ice. Ridiculous? Not at all because NASA crashed a vehicle into such a region and found water of very approximately 5.6% by mass. Associated with the water was (as a % of the water) H₂S 16.5%, NH₃ 6%, SO₂ 3.2%, ethylene 3.1%, CO₂ 2.2%, methanol 1.6%, methane 0.7% (Colaprete et al. 2010 Science 330: 463-468). The water would be trapped as ice in regions where the sun does not strike, as these get extremely cold, rock being a very poor conductor of heat. It has been estimated that at latitudes greater than 80 degrees, water could be trapped in parts of craters that get no sunlight. Where did those minor materials come from? The assumption is that in this case the Moon was struck by some cometary material, and the temporary atmosphere was cold-trapped.

Water is indeed critical, but in some ways nitrogen is even more critical. Going in and out of a habitat is bound to lose air, and nitrogen is critical to dilute oxygen. It is also critical if you want to grow plants. Whether we would want to stay on the Moon for long is a matter of opinion, but at least now it may be more a possibility.

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Success! Defence Against Asteroids

Most people will know that about 64 million years ago an asteroid with a diameter of about 10 km struck the Yucatán peninsula and exterminated the dinosaurs, or at least did great damage to them from which they never recovered. The shock-wave probably also initiated the formation of the Deccan Traps, and the unpleasant emission of poisonous gases which would finish off any remaining dinosaurs. The crater is 180 km wide and 20 km deep. That was a very sizeable excavation. Rather wisely, we would like to avoid a similar fate, and the question is, can we do anything about it? NASA thinks so, and they carried out an experiment.

I would be extremely surprised if, five years ago, anyone reading this had heard of Dimorphos. Dimorphos is a small asteroid with dimensions about those of the original Colosseum, i.e.  before vandals, like the Catholic Church took stones away to make their own buildings. By now you will be aware that Dimorphos orbits another larger asteroid called Didymos. What NASA has done was to send a metallic object of dimensions 1.8 x 1.9 x 2.6 meters, of mass 570 kg, and velocity 22,530 km/hr to crash into Dimorphos to slightly slow its orbital speed, which would change its orbital parameters. It would also change then orbital characteristics of the two around the sun. Dimorphos has a “diameter” of about 160 m., Didymos about 780 m. Neither are spherical hence the quotation marks.

This explains why NASA selected Dimorphos for the collision. First, it is not that far from Earth, while the two on their current orbits will not collide with Earth on their current orbits. Being close to Earth, at least when their orbits bring them close, lowers the energy requirement to send an object there. It is also easier to observe what happens hence more accurately determine the consequences. The second reason is that Dimorphos is reasonably small and so if a collision changes its dynamics, we shall be able to see by how much. At first sight you might say that conservation of momentum makes that obvious, but it is actually more difficult to know because it depends on what takes the momentum away after the collision. If it is perfectly inelastic, the object gets “absorbed” by the target which stays intact, then we simply add its relative momentum to that of the target. However, real collisions are seldom inelastic, and it would have been considered important to determine how inelastic. A further possibility is that the asteroid could fragment, and send bits in different directions. Think of Newton’s cradle. You hit one end and the ball stops but another flies off from the other end, and the total stationary mass is the same. NASA would wish to know how well the asteroid held together. A final reason for selecting Dimorphos would be that by being tethered gravitationally to Didymos, it could not go flying off is some unfortunate direction, and eventually collide with Earth. It is interesting that the change of momentum is shared between the two bodies through their gravitational interaction.

So, what happened, apart from the collision. There was another space craft trailing behind: the Italian LICIACube (don’t you like these names? It is an acronym for “Light Italian Cubesat for Imaging Asteroids”, and I guess they were so proud of the shape they had to have “cube” twice!). Anyway, this took a photograph before and after impact, and after impact Dimorphos was surrounded by a shower of material flung up from the asteroid. You could no longer see the asteroid for the cloud of debris. Of course Dimorphos survived, and the good news is we now know that the periodic time of Dimorphos around Didymos has been shortened by 32 minutes. That is a genuine success. (Apparently, initially a change  by as little as 73 seconds would have been considered a success!) Also, very importantly, Dimorphos held together. It is not a loosely bound rubble pile, which would be no surprise to anyone who has read my ebook “Planetary Formation and Biogenesis”.

This raises another interesting fact. The impact slowed Dimorphos down relative to Didymos, so Dimorphos fell closer to Didymos, and sped up. That is why the periodic time was shortened. The speeding up is because when you lower the potential energy, you bring the objects closer together and thus lower the total energy, but this equals the kinetic energy except the kinetic energy has the opposite sign, so it increases. (It also shortens the path length, which also lowers the periodic time..)

The reason for all this is to develop a planetary protection system. If you know that an asteroid is going to strike Earth, what do you do? The obvious answer is to divert it, but how? The answer NASA has tested is to strike it with a fast-moving small object. But, you might protest, an object like that would not make much of a change in the orbit of a dinosaur killer. The point is, it doesn’t have to. Take a laser light and point it at a screen. Now, give it a gentle nudge so it changes where it impacts. If the screen as a few centimeters away the lateral shift is trivial, but if the screen is a kilometer away, the lateral shift is now significant, and in fact the lateral shift is proportional to the distance. The idea is that if you can catch the asteroid far enough away, the asteroid won’t strike Earth because the lateral shift will be sufficient.

You might protest that asteroids do not travel in a straight line. No, they don’t, and in fact have trajectories that are part of an ellipse. However, this is still a line, and will still shift laterally. The mathematics are a bit more complicated because the asteroid will return to somewhere fairly close to where it was impacted, but if you can nudge it sufficiently far away from Earth it will miss. How big a nudge? That is the question about which this collision was designed to provide us with clues.

If something like Dimorphos struck Earth it would produce a crater about 1.6 km wide and 370 m deep, while the pressure wave would knock buildings over tens of km away. If it struck the centre of London, windows would break all over South-East England. There would be no survivors in central London, but maybe some on the outskirts. This small asteroid would be the equivalent a good-sized hydrogen bomb, and, as you should realize, a much larger asteroid would do far more damage. If you are interested in further information, I have some data and a discussion of such collisions in my ebook noted above.

Did Mars Have an Ocean?

It is now generally recognized that Mars has had fluid flows, and a number of riverbeds, lake beds, etc have been identified, but there are also maps on the web of a proposed Northern Ocean. It has also been proposed that there has been polar wander, and this Northern Ocean was more an equatorial one when it was there about 3.6 billion years ago. The following is a partial summary from my ebook “Planetary Formation and Biogenesis”, where references to scientific papers citing the information can be found.

Various options include: (with bracketed volumes of water in cubic kilometre): a northern lake (54,000), the Utopia basin, (if interconnected, each with 1,000,000), filled to a possibly identified ‘shoreline’ (14,000,000), to a massive northern hemisphere ocean (96,000,000). Of particular interest is that the massive channels (apart from two that run into Hellas) all terminate within an elevation of 60 m of this putative shoreline.

A Northern Ocean would seem to require an average temperature greater than 273 degrees K, but the faint sun (the sun is slowly heating and three and a half billion years ago, when it is assumed water flowed, it had only about two thirds its current output) and an atmosphere restricted to CO₂/H₂O leads in most simulations to mean global temperatures of approximately 225 degrees K. There is the possibility of local variations, however, and one calculation claimed that if global temperatures were thirty degrees higher, local conditions could permit Hellas to pond if the subsurface contained sufficient water, and with sufficient water, the northern ocean would be possible and for maybe a few hundred years be ice free. A different model based on simulations, assuming a 1 bar CO₂ atmosphere with a further 0.1 bar of hydrogen, considered that a northern ocean would be stable up to about three billion years. There is quite an industry of such calculations and it is hard to make out how valid they are, but this one seems not to be appropriate. If we had one bar pressure of carbon dioxide for such a long time there would be massive carbonate deposits, such as lime, or iron carbonates, and these are not found in the required volumes. Also, the gravity of Earth is insufficient to hold that amount of hydrogen and Mars has only 40% of Earth’s gravity. This cannot be correct.

This northern ocean has been criticized on the basis that the shoreline itself is not at a constant gravitational potential, and variations of as much as 1.8 km in altitude are found. This should falsify the concept, except that because this proposed ocean is close to the Tharsis volcanic area, the deformation of forming these massive volcanoes could account for the differences. The magma that is ejected had to come from somewhere, and where it migrated from would lead to an overall lowering of the surface there, while where it migrated to would rise.

Support for a northern sea comes from the Acidalia region, where resurfacing appears to have occurred in pulses, finishing somewhere around 3.65 Gy BP.  Accumulation of bright material from subsequent impacts and flow-like mantling was consistent with a water/mud northern ocean. If water flows through rock to end in a sea, certain water-soluble elements are concentrated in the sea, and gamma ray spectra indicates that this northern ocean is consistent with enhanced levels of potassium and possibly thorium and iron. There may, however, be other reasons for this. While none of this is conclusive, a problem with such data is that we only see the top few centimeters and better evidence could be buried in dust.

Further possible support comes from the Zhurong rover that landed in Utopia Planitia (Liu, Y., and 11 others. 2022. Zhurong reveals recent aqueous activities in Utopia Planitia, Mars. Science Adv., 8: eabn8555). Duricrusts formed cliffs perched through loose soil, which requires a substantial amount of water, and also avoids the “buried in dust” problem. The authors considered these were formed through regolith undergoing cementation through rising or infiltration of briny groundwater. The salt cements precipitate from groundwater in a zone where active evaporation and accumulation can occur. Further, it is suggested thus has occurred relatively recently. On the other hand, ground water seepage might also do it, although the water has to be salty.

All of which is interesting, but the question remains: why was the water liquid? 225 degrees K is about fifty degrees below water’s freezing point. Second, because the sun has been putting out more heat, why is the water not flowing now? Or, alternatively, as generally believed, why did it flow for a brief period than stop? My answer, somewhat unsurprisingly since I am a chemist, is that it depends on chemistry. The gases had to be emitted from below the surface, such as from volcanoes or fumaroles. The gases could not have been adsorbed there as the planet accreted otherwise there would be comparable amounts of neon as to nitrogen on the rocky planets, and there is not. That implies the gases were accreted as chemical compounds; neon was not because it has no chemistry. When the accreted compounds are broken down with water, ammonia forms. Ammonia dissolves very rapidly in water, or ice, and liquefies it down to about 195 degrees K, which is well within the proposed range stated above. However, ammonia is decomposed slowly by sunlight, to form nitrogen, but it will be protected when dissolved in water. The one sample of seawater from about 3.2 billion years ago is consistent with Earth having about 10% of its nitrogen still as ammonia. However, on Mars ammonia would slowly react with carbon dioxide being formed, and end up as solids buried under the dust.

Does this help a northers sea? If this is correct, there should be substantial deposits of nitrogen rich solids below the dust. If we went there to dig, we would find out.

Space – To the Final Frontier, or Not

In a recent publication in Nature Astronomy (https://www.nature.com/articles/s41550-022-01718-8) Byers point out an obvious hazard that seems to be increasing in frequency: all those big rockets tend to eventually come down, somewhere, and the return is generally uncontrolled. Modest-sized bits of debris meet a fiery end, burning up in the atmosphere, but larger pieces hit the surface and the kinetic energy makes comparison of them to an oversized bullet or cannon-ball make the latter seem relatively harmless. In May, 2020, wreckage from the 18 tonne core of a Chinese Long March 5B rocket hit two villages in the Ivory Coast, damaging buildings. In July 2022, suspected wreckage from a SpaceX Crew-1 capsule landed on farmland in Australia, Another Long March 5B landed just south of the Philippines. In 1979, NASA’s Skylab fell back to Earth, scattering debris across Western Australia. So far, nobody has been injured, but it is something of a matter of luck.

According to Physics World the US has an Orbital Debris Mitigation Standard Practices stipulation that all launches should have a risk of casualty from uncontrolled re-entry of less than one in 10,000, but the USAF, and even NASA have flouted this rule on numerous occasions. Many countries may have no regulations. As far as I am aware my own country (New Zealand) has none yet New Zealand launches space vehicles. The first stage always falls back into the Pacific, which is a large expanse of water, but what happens after that is less clear.

In the past thirty years, more than 1500 vehicles have fallen out of orbit, and about three quarters of these have been uncontrolled. According to Byers, there was a 14% chance someone could have been killed.

So what can be done? The simplest is to provide each rocket with extra fuel. Each time it is time to end its orbit, the descent can be controlled to the extent it lands at the point in the Pacific that is farthest from land. So far, this has not been done because of the extra cost. A further technique would be to de-orbit rocket bodies immediately following satellite deployment. That still requires additional fuel. In principle, with proper design, the rocket bodies could be recovered and reused. Rather perversely, it appears the greatest risk is for countries in the Southern hemisphere. The safest places are those at greater inclination than the launch site.

Meanwhile, never mind the risk to those left behind; you want to go into space, right? Well, you may have heard of bone density loss. This effect has finally had numbers put on it (https://www.nature.com/articles/s41598-022-13461-1) Basically, after six months in space, the loss of bone density corresponded to 20 years of ongoing osteoporosis, particularly in load bearing (on Earth) bones, such as the tibia. Worse, these only partially recovered, even after one year on Earth, and the lasting effect was equivalent to ten years of aging. The effect, of course, is due to microgravity, which is why, in my SF novels, I have always insisted on ships either having a rotating ring to create a centrifugal “artificial gravity”. On the other hand, the effect can vary between people. Apparently the worst cases can hardly walk on return for some time, while other apparently continue on more or less as usual and ride bikes to work rather than drive cars. And as if bone loss was not bad enough, there is a further adverse possibility: accelerated neurodegenerations. (https://jamanetwork.com/journals/jamaneurology/article-abstract/2784623). By tracking the concentration of brains specific proteins before and after a space mission it was concluded that long-term spaceflight presents a slight but lasting threat to neurological health. However, this study concluded three weeks after landing, so it is unclear whether long-term repair is possible. Again, it is assumed that it is weightlessness that is responsible. On top of that, apparently there are long-lasting changes in the brain’s white matter volume and the shape of the pituitary gland. Apparently more than half of astronauts developed far-sightedness and mild headaches. Seemingly, this could be because in microgravity the blood no longer concentrated in your legs.

Rocky Planet Atmospheres

Where did the rocky planets get their atmospheres from? This question is not trivial. Planets accrete by some mechanism whereby dust particles form larger objects and sooner or later these form planets. However, when they are small, they are either in a vacuum, or earlier they are in the gas that is falling into the sun and which will make the sun. If they are in a vacuum there is no gas to accrete. If they are in the gas streaming into the star they will absorb some gas more or less in proportion to what is in the gas stream, with some preference of heavier gas per unit concentration. However, that preference will not mean much because the concentration of hydrogen is so high it will swamp out most of the rest. When the rocky planet gets big enough, it will form an atmosphere from the accretion disk gas, so these two mechanisms predict either no atmosphere (accretion after the disk gas is gone) or gas that is predominantly hydrogen and helium.

When the sun ejected its accretion disk, it continued to send out a flux of high-energy UV radiation. What is expected to happen then is this would boil the hydrogen atmosphere into space, and this hydrodynamic outflow would take most of the other gases with it. None of the rocky planets in our solar system has enough gravity to hold hot hydrogen and helium for long. So any gas accreted so far is either underground or lost to space. The rocky planets start without an atmosphere, except maybe residual heavy gas that was not blown away by the strong UV. The only gases that are likely to have been so held are krypton and xenon, and they have an excess of heavy isotopes that indicate they may be such residues.

The next possibility is the gases were trapped underground and emitted volcanically after the extreme UV from the sun had stopped. Now the hydrogen and helium could leak away to space slowly and leave everything else behind. But we know that our atmosphere is not a remnant of gas from the accretion disk held by gravity or absorption because if it were, neon is about as common as nitrogen in those gases, and they would be absorbed at about the same rate and both would be held equally by gravity. If our atmosphere was delivered that way, it should contain at least 0.6 bar of neon, which is many orders of magnitude greater than what we see. Neon is a very rare gas on Earth.

Attempts to answer this question have mixed results, and tend to divide scientists into camps, wherein they defend their positions vigorously. One school of thought has the gases were forced into a magma ocean that arises from the heat of the collisions of entities about the size of Mars. I disagree with this. Should this have happened, the time taken to get the collisions going (originally estimated as 100 million years, subsequently reduced to about 30 million years with some unspecified correction to the calculations to accommodate the planet being here when the Moon-forming collision occurred) the gas would have long gone. And if the calculations were so wrong and it did happen, we are back to the neon problem.

The usual way out of this is to argue the gases came from carbonaceous chondrites, which are supposedly bits knocked off asteroids from the outer part of the asteroid belt. Such chondrites sometimes have quite reasonable amounts of water in them, as well as solids containing carbon and nitrogen. The idea is that these hit the earth, get hot, and the water oxidises the carbonaceous material to liberate carbon dioxide and nitrogen gas. Ten years ago I published the first edition of my ebook “Planetary Formation and Biogenesis”, which contained evidence that this could not be the source of the gases. The reasons were numerous and some of them complex, but one simple reason is the three rocky planets all have different proportions of the different elements. How can this happen if they came from a common source?

Now, a paper has appeared (Péron and Mukhopadhyay, Science 377: 320 – 324) that states that the krypton gas in the Chassigny meteorite, shows Mars accreted chondritic volatiles before nebular gases. I have a logic problem with this: the nebula gases were there before Mars even started forming. There was never any time that there was a Mars and the nebular gases had yet to arrive. They then found the krypton and xenon had isotope ratios that fell on a line between cosmogenic and what they assigned as trapped Martian mantle gases. There is a certain danger in this because the rock would have been exposed to cosmic rays, which lead to spallation and isotope alteration. Interestingly, the xenon data contradicts a previous report by Ott in 1948 (Geochim Cosmochim Acta 52: 1937 – 1948), who found the xenon was solar in nature. It may be that these differences can be simply explained because these are taken from a meteorite and only very small amounts of the meteorite are allowed to be taken. The samples may not be representative. Interestingly Péron and Mukhopadhyay consider the meteorite to have come from the Martian interior, based on the observation by Ott that the sample had been heated to a high temperature and was presumably of volcanic nature. The problem I see with that is that Ott came to the same conclusion for a number of other meteorites that have quite different isotope ratios. It is usually wrong to draw major conclusions from an outlier result. Anyway, based on the argument that Ott thought this meteorite was igneous, this latest paper concludes that its rare gases came from the interior of Mars, and hence show the volatiles did not come from carbonaceous chondrites.

In my opinion, the conclusion is valid, but not for the right reasons. What annoys me is the example that a previous researcher thought the sample might have been volcanic rock is assume to have come from deep in the interior now, while the previous results that do not fit the proposition are put to one side. I think that small differences from two tiny samples show you should not draw conclusions. I know there are funding pressures on scientists to publish papers, but surely everything in their work and previous work they quote should be self-consistent or reasons be found for discrepancies.

Radiation Protection on Mars

The settlement of Mars is a popular science fiction staple. I have written some “Mars novels” myself. One criticism of settling Mars is that the planet does not have magnetic field to deflect radiation, so what is the situation? In my ebook “Red Gold” I suggested a magnetic field be generated by a superconductor placed between Mars and the sun, specifically at the first Lagrange point so it would be there continuously. That would divert charged particles in the solar wind. However, suppose you do not do that, what are the options. An account has been written on May 27, 2022 and is at arXiv:2205.13786.

There are two sources of radiation. The first is from the sun and consist mainly of protons, helium nuclei (5 – 8%) and heavier nuclei (~1%). These arrive with energies ranging from some keV to hundreds of MeV. Very occasionally they go to even higher energies, and their intensity varies with the solar cycle. The other source are the cosmic rays. These are accelerated by supernova shocks and interstellar magnetic fields, and appear to come evenly from all directions. They have similar composition to the solar radiation, but they arrive with far higher energies, their average being in the GeV range, and of particular hazard are the high-charge ions, thus there may be particles up to iron that are stripped of their electrons and are travelling through space near the speed of light. It is this high energy and high charge that makes them so dangerous.

The first defence Mars offers is bulk. A person standing on the Martian surface, particularly in a crater, receives less than half what they would receive in space, and that applies to cosmic rays. None of these have energy anywhere nearly enough to go through a planet. The atmosphere, while thin, offers some protection, and will remove protons with less than 150 MeV energy, and possibly more if in a deep enough crater (which is partly why in “Red Gold” I had my settlement near the bottom of Hellas Planitia, the deepest part of Mars.) Accordingly, the major chronic hazard is cosmic radiation, but a sudden strike by a major solar event is also lethal.

There are two types of shielding. The first is active, the use of magnetic or plasma shields, but currently these are theoretical, such as my suggested L1 superconducting magnetic field generator. The second is passive, which is to place matter between the person and the source. At present we are reliant on passive measures. The better materials for stopping such charged particles are those with a high number density of atoms with many electrons per unit mass, which ends up meaning elements of low atomic number. Materials rich in hydrogen such as water or polyethylene perform well, although nothing practical can totally eliminate cosmic radiation.

For settlers on Mars, interactions with the atmosphere lead to neutrons and gamma rays being dominant. Terrain offers protection, thus being adjacent to a cliff will halve the exposure compared with open terrain. The water in regolith will greatly attenuate neutrons with less kinetic energy than 10 MeV. Liquid hydrogen is probably the best, but its extremely low temperature probably makes it impractical. Organic plastics work well; aluminium, which is used in spacecraft, is somewhat less satisfactory, but οn Μars the regolith is probably optimal, because it is already there and hence is cheap. On the other hand, it has to be bound by something, otherwise the wind will blow it away. The article suggests making bricks from regolith. The simplest protection is to live in caves. However, there may be a shortage of caves. People talk about lava tubes, but much of the volcanism on Mars has been around very large volcanoes, or older ones that erupted more in a pyroclastic fashion. They will be short on caves, while settlers are more likely to head for craters, which are not the obvious place to find caves, although rapidly exiting steam might leave one. One place where there might be caves is the Margaritifer Chaos, where there  are signs of massive water outflows from a very small source.

However, living underground does not help plant growth, and the idea of having huge caverns with lights would require a huge investment in lights. It should be easy to make glass that will be opaque to UV radiation and will offer tolerable radiation protection. Silicate uses light atoms and should compare favourably with aluminium. Further, the danger of cosmic rays is largely long-term health; plants for food are not long-lived. One of the main problems for people settling on Mars is the cost and mass of what they have to take with them. Making bricks from regolith is great because regolith is there. The cost of lifting stuff up from Earth and taking it to Mars is huge, so as much as possible has to be made there. That is why lights for the underground growing of food would be very expensive. But the making of any habitat or plant growing area on the surface requires sealing to prevent gas pressure escaping. In my “Red Gold” I suggest one of the very first things that has to be learned is how to make a cement from Martian materials. The ability to make concrete is the first requirement to make the footers of “glass-houses” to grow plants, and cement is necessary to put bricks together. There is an awful lot of detail that has to be addressed because once settlers get there, if they haven’t got something, they cannot go to the corner store and get it.

Molecular Oxygen in a Comet

There is a pressure, these days, on scientists to be productive. That is fair enough – you don’t want them slacking off in a corner, but a problem arises when this leads to the publication of papers: there are so many of them that nobody can keep up with even a small fraction of them. Worse, many of them do not seem to say much. Up to a point, this has an odd benefit: if you leave a lot unclear, all your associates can publish away and cite you, which has this effect of making you seem more important because funders like to count citations. In short, with obvious exceptions, the less you advance the science, the more important you seem at second level funding. I am going to pick, maybe unfairly, on one paper from Nature Astronomy (https://www.nature.com/articles/s41550-022-01614-1) as an illustration.

One of the most unexpected findings in the coma of comet 67P/Churyumov-Gerasimenko was “a large amount” of molecular oxygen. Something to breathe! Potential space pilots should not get excited; “a large amount” is only large with respect to what they expected, which was none. At the time, this was a surprise to astronomers because molecular oxygen is rather reactive and it is difficult to see why it would be present. Now there is a “breakthrough”: it has been concluded there is not that much oxygen in the comet at all, but this oxygen came from a separate small reservoir. The “clue” came from the molecular oxygen being associated with molecular water when emitted from a warm site. As it got cooler, any oxygen was associated with carbon dioxide or carbon monoxide. Now, you may well wonder what sort of clue that is? My question is, given there is oxygen there, what would you expect? The comet is half water, so when the surface gets warm, it sublimes. When cooler, only gases at that lower temperature get emitted. What is the puzzle?

However, the authors of the paper came to a different conclusion. They decided that there had to be a deep reservoir of oxygen within the comet, and a second reservoir close to the surface that is made of porous frozen water. According to them, oxygen in the core works its way to the surface and gets trapped in the second reservoir. Note that this is an additional proposition to the obvious one that oxygen was trapped in ice near the surface. We knew there was gas trapped in ice that was released with heat, so why postulate multiple reservoirs, other than to get a paper published?

So, where did this oxygen come from? There are two possibilities. The first is it was accreted with the gas from the disk when the comet formed. This is somewhat difficult to accept. Ordinary chemistry suggests that if oxygen molecules were present in the interstellar dust cloud it should react with hydrogen and form water. Maybe that conclusion is somehow wrong, but we can find out. We can estimate the probability by observing the numerous dust clouds from which stars accrete. As far as I am aware, nobody has ever found rich amounts of molecular oxygen in them. The usual practice when you are proposing something unusual is you find some sort of supporting evidence. Seemingly, not this time.

The second possibility is that we know how molecular oxygen could be formed at the surface. High energy photons and solar wind smash water molecules in ice to form hydrogen and hydroxyl radicals. The hydrogen escapes to space but the hydroxyl radicals unite to form hydrogen peroxide or other peroxides or superoxides, which can work their way into the ice. There are a number of other solids that catalyse the degradation of peroxides and superoxides back to oxygen, which would be trapped in the ice, but released when the ice sublimed. So, from the chemist’s point of view there is a fairly ordinary explanation why oxygen might be formed and gather near the surface. From my point of view, Occam’s Razor should apply: you use the simplest explanation unless there is good evidence. I do not see any evidence about the interior of the comet.

Does it matter? From my point of view when someone with some sort of authority/standing says something like this, there is the danger that the next paper will say “X established that . . “  and it becomes almost a gospel. This is especially so when the assertion cannot be easily challenged with evidence as you cannot get inside that comet. Which gives the perverse realization that you need strong evidence to challenge an assertion, but maybe no evidence at all to assert it in the first place. Weird?

Ebook Discount

For a short  time my ebook Spoliation is price reduced on Amazon. Unlike Kindle Countdowns, this discount applies world-wide, and I am experimenting to see how effective this strategy is.

The Board, is a ruthless, shadowy organization with limitless funds that employs space piracy and terrorism. A disgraced Captain Jonas Stryker is acting as an asteroid miner, and when The Board resorts to using a weaponised asteroid to get its way, only Stryker can divert the asteroid. The Board is determined to have Stryker killed, officially he is wanted for murder, so Stryker must expose and destroy this organization to have any future.

A story of greed, corruption and honour, combining science and visionary speculation that goes from the high frontier to outback Australia. The background also gives a scientific perspective on asteroid mining.

Don’t Look Up

No, I am not going to discuss the film, the merits of which you can decide for yourself. However, it might be worth considering some of the things it says about the way we consider and treat science. What the film is supposed to say is that those in society with the power to do something about a crisis wilfully avoid taking action. Consider the excuses for doing nothing.

The film presents a wipe-out event that we will be struck by a comet. The probability of this happening is assessed at 99.8%. So it is not 100%? What we have to recognize that scientific measurements have errors in them. Statistically we make lots of measurements and use a statistical analysis, and while someone in the movie says “Scientists never like to say 100%” that is wrong too. Scientists do not like or dislike; they report the mathematics, and a statistical spread cannot give a 100% because that denies the initial spread. Further, that 0.2% is not physically meaningful either because the errors due to instruments are not randomly probable, but nobody is going to waste time working out the error function for every piece of equipment. Statistical analysis takes care of that. To gain perspective, consider a bag of 1000 50 calibre bullets. You are assured two are blank. One is placed into a gun. What amount of money do you need, if you survive, to put your head in front of the barrel when it is fired?

A second problem for scientists is that long-term realities will be ignored by the public. This more relevant to something like climate change. What are you prepared to do to avoid a major problem fifty years down the track? For many, not a lot, so they ignore the problem on the grounds that it can be dealt with “later”. Related to this are the economic considerations. One response is we cannot afford to do something. When we hear that we seldom see what the costs are of not doing said something. Again, the response might be, but you do not absolutely know that will solve the problem. No, we do not, but that is because we do not think there will be one simple solution for a problem like climate change.

Another response is to rely on technological changes. For an approaching comet, there are probably no other choices. You either construct some space vehicle that will push the comet off course or it strikes you. To make that work, a major investment in development work would be required, since we do not have such a vehicle now. As it happens, for this scenario NASA is doing work, and around the end of September a space vehicle weighing 550 kg will slam into an asteroid called Dimorphos. This is part of a double asteroid system, and we will be able to follow the effect of the impact in fine detail because it will alter the orbital characteristics of Dimorphos as paired with Didymos, the larger companion. The problem with something like climate change is that while technology might fix it, we are not doing the research and development needed to make it work.

Society seems to work against science, simply because people do not trust it. Over 5 million have died with Covid 19, yet we have many very active antivaxxers trying to persuade others not to be vaccinated. The interesting question is why? It is one thing to refuse to be vaccinated yourself, but why impose these views on others?  In their effort το persuade others they spread completely stupid stories. Recall the story that Bill Gates was inserting nano-trackers into the vaccine so he could know what everyone was doing? There are also stories with an element of truth but with no comprehension of relevance. Like our 98.8% above, they focus on the 0.2%. There is a tiny segment of the populations that respond adversely to certain vaccines. The medical profession knows this, and can look out for them and treat them properly if such an event occurs. These stories totally ignore what would happen to these far more sensitive people if the virus struck them. Finally, there is a tendency for navel-gazing. Consider our experiment on Dimorphos. There is a view, “What right have we to change the solar system?” If we took this view to the limit, we would still be hunter-gatherers and our biggest problem would be that lion in the shrubbery planning on eating us. Dimorphos is a lump of rock. It does not have feelings. It is not planning its future. The allied question, do your sensitivities about the Universe and the pristine nature of rocks in it give you the right to prevent the killing of billions of innocent people who do not share your view?

What Happens Inside Ice Giants?

Uranus and Neptune are a bit weird, although in fairness that may be because we don’t really know much about them. Our information is restricted to what we can see in telescopes (not a lot) and the Voyager fly-bys, which, of course, also devoted a lot of attention to the Moons, since a lot of effort was devoted to images. The planets are rather large featureless balls of gas and cloud and you can only do so much on a “zoom-past”. One of the odd things is the magnetic fields. On Earth, the magnetic field axis corresponds with the axis of rotation, more or less, but not so much there. Earth’s magnetic field is believed to be due to a molten iron core, but that could not occur there. That probably needs explaining. The iron in the dust that is accreted to form planets is a fine powder; the particles are in the micron size. The Earth’s core arises because the iron formed lumps, melted, and flowed to the core because it is denser. In my ebook “Planetary Formation and Biogenesis” I argue that the iron actually formed lumps in the accretion disk. While the star was accreting, the region around where Earth is reached something like 1600 degrees C, above the melting point of iron, so it formed globs. We see the residues of that in the iron-cored meteorites that sometimes fall to Earth. However, Mars does not appear to have an iron core. Within that model, the explanation is simple. While on Earth the large lumps of iron flowed towards the centre, on Mars, since the disk temperature falls off with distance from the star, at 1.5 AU the large lumps did not form. As a consequence, the fine iron particles could not move through the highly viscous silicates, and instead reacted with water and oxidised, or, if you prefer, rusted.

If the lumps that formed for Earth could not form at Mars because it was too far away from the star, the situation was worse for Uranus. As with Mars, the iron would be accreted as a fine dust and as the ice giants started to warm up from gravitational collapse, the iron, once it got to about 500 degrees Centigrade, would rapidly react with the water and oxidise to form iron oxides and hydrogen. Why did that not happen in the accretion disk? Maybe it did, and maybe at Mars it was always accreted as iron oxides, but by the time it got to where Earth is, there would be at least ten thousand times more hydrogen than iron, and hot hydrogen reduces iron oxide to iron. Anyway, Uranus and Neptune will not have an iron core, so what could generate the magnetic fields? Basically, you need moving electric charge. The planets are moving (rotating) so where does the charge come from?

The answer recently proposed is superionic ice. You will think that ice melts at 0 degrees Centigrade, and yes, it does, but only at atmospheric pressure. Increase the pressure and it melts at a lower temperature, which is how you make snowballs. But ice is weird. You may think ice is ice, but that is not exactly correct. There appear to be about twenty ices possible from water, although there are controversial aspects because high pressure work is very difficult and while you get information, it is not always clear about what it refers to. You may think that irrespective of that, ice will be liquid at the centre of these planets because it will be too hot for a solid. Maybe.

In a recent publication (Nature Physics, 17, 1233-1238 November 2021) authors studied ice in a diamond anvil cell at pressures up to 150 GPa (which is about 1.5 million times greater than our atmospheric pressure) and about 6,500 degrees K (near enough to Centigrade at this temperature). They interpret their observations as there being superionic ice there. The use of “about” is because there will be uncertainty due to the laser heating, and the relatively short times up there. (Recall diamond will also melt.)

A superionic ice is proposed wherein because of the pressure, the hydrogen nuclei can move about the lattice of oxygen atoms, and they are the cause of the electrical conduction. These conditions are what are expected deep in the interior but not at the centre of these two planets. There will presumably be zones where there is an equilibrium between the ice and liquid, and convection of the liquid coupled with the rotation will generate the movement of charge necessary to make the magnetism. At least, that is one theory. It may or may not be correct.