A Large Terrestrial Planet Orbiting A Yellow Dwarf

After an extensive sky survey covering the planetary systems of a wide range of mid- to high-mass long-lived stars, a number of interesting systems were identified. Although scientists have traditionally focussed on stars suitable for life, with some success, the decision was made to widen the parameters for consideration to larger and more luminous examples in order to prevent observer bias. In particular, a fairly large and hot star was located whose planetary atmospheres showed a number of interesting features. The star was named Sol.

Sol is on first examination not the ideal location for life-bearing worlds. The star itself is considerably more luminous, hotter and more short-lived than our own and there is a notable absence of planets in the habitable zone, occupied by asteroids in this system. Moreover, there is an unusual absence of any planets with the mass of Planet, and therefore moons such as our home world, where life can arise and evolve straightforwardly, are completely lacking. The problems with life arising in this system are multiple. The lifetime of the star is relatively short, the system inside the asteroid belt is above the boiling point of ammonia, which in any case tends to get broken down by the radiation.

In the inner system, there are a large number of moons, all of which are however not particularly hospitable to life. Although three of the four gas giants have large moons, only one has a substantial atmosphere and is too cold for life as we know it to thrive or even appear there. Even so, this proved to be the most hospitable environment and a base was established there from which to mount missions to the other worlds in the system. None of the moons were at all promising. However, just out of curiosity, it was suggested that we investigate the inner system, in spite of its presumed hostility to life.

The situation did not at first appear very promising. There was only one relatively large satellite and even it was too small to maintain an atmosphere. The fourth planet had two small asteroid-sized moons which were even less promising, and the inner two planets had none at all. Two of the planets were large, and of these the outer planet was the host for the single large satellite, although it was considerably smaller than Planet itself. The fourth planet is close to our own world in size but is less dense and has very little to no ammonia on its surface and a tenuous atmosphere incompatible with the existence of most liquids.

Although slightly less hostile than the second planet, the host planet attracted attention because of its rather unpromising moon. It was found that, most improbably, the moon was of such a size and distance from the planet that it would perfectly cover the planet’s star from some locations on the planet, a situation which may well be unique in our Galaxy. This attracted attention to the solid surface of said planet, henceforth referred to as Sol III.

Sol III is a large, hot and rocky planet with a highly corrosive atmosphere and a surface largely covered in an expanse of molten dihydrogen monoxide rock, a substance henceforth referred to by its systematic standard name of oxidane. Runaway exothermic chemical reactions periodically occur on the surface where the likes of thunderstorms and volcanic eruptions trigger destructive processes which it might be thought would completely transform the surface. However, it has been found that in many cases this reaction can be limited by the presence of the liquid oxidane, which prevents dioxygen and the compounds in question coming into contact. Although the atmosphere is mainly (di)nitrogen, over a fifth of it consists of free dioxygen at sea level, becoming ozone some distance above the surface. Although the moon shows captured rotation, Sol III does not, rotating once every 24 hours. This has the consequence of causing the molten rock to flood the margins of the isolated land promontories twice every rotation. Any organism able to survive the extreme heat of most of the solid planetary surface unfortunate enough to find itself in such a location would be swiftly boiled to death by such events. Even away from the lava fields, liquid rock often falls from the sky, so there is little respite elsewhere on the planet.

There are exceptions to these conditions. There is a small area on the west side of one of the southern land promontories where this precipitation rarely or never takes place and many other regions close to the equator where it’s a relatively uncommon event, and these areas are free from the rivers and other bodies which make conditions so hazardous. The liquid is also quite corrosive and somewhat acidic compared to ammonia and tends to eat away at the solid surface of the planet. There are clouds of vaporised rock higher in the atmosphere which sometimes reach ground level. Near the poles the situation is slightly more hospitable, since these areas stay below oxidane’s melting point, and near the south pole temperatures are comfortable through most of the planet’s orbit and relatively normal crystallised oxidane.

Surface gravity is about triple our own, which would make it difficult to tolerate for long, and immersion in liquid would be one strategy to enable us to survive for long periods on the surface Sol is bluer than our own sun, with the result that the landscape, seascape and items within it have a blue tinge. This particularly applies to the lava plains dominating the surface and the sky when free of cloud. The higher gravity also flattens the solid surface, most of which is below the level of the lava, reducing the relief still further.

Considering the oxidane as a simple bulk substitute for our own ammonia, the chief difference between Sol III and our home moon is that the majority of the world is covered by an interconnected body of water, into which streams and rivers tend to feed, unlike our system of independently interconnected lake networks. Its mineral nature is emphasised by the presence in solution of many minerals, partly due to the strongly solvent properties of the liquid. More than half the solid surface is in permanent darkness and only just above oxidane’s melting point, though still far above the levels compatible with life as we know it. Also common here is a manifestation of the even hotter interior of the planet, also found on land, where even the silicate minerals melt and flow like ammonia. The silicate volcanism of Sol III, though, is physically still quite similar to our own oxidane volcanism, except that the volcanoes produced tend to be flatter and have less steep sides.

Technical terms have had to have been invented for the surface features of the planet. The lava fields are referred to by the arcane classical term “ocean”, and the giant island promontories as “continents”. Although the ocean is a single entity, there are also lakes on the surface which are not linked to them. These tend to be purer oxidane because of the reduced volume and time available to dissolve the underlying rocks. The ocean itself is conceptually divided into four sub-oceans, referred to as “northern”, “western”, “eastern” and “southern”. Currents running along the last three also mean that there is in a sense a further ocean not separated by land from the others. There are six continents. A relatively hospitable one is situated in the southern polar region, where the temperatures remain low enough for practically the whole surface to be lava-free. The corrosive atmosphere and high gravity, of course, remain. Most of the surface from the northern coasts of the polar continent is molten although the smallest continent, referred to as “Southern” is relatively free of precipitation. There are then two triangular continents, both linked to northern ones, referred to as “West Triangle” and “East Triangle” . The larger one, East Triangle, has two large areas free of precipitation but like Southern is extremely hot. West Triangle has a small stretch with practically no precipitation. Adjoining East Triangle is the Great Continent of the northern hemisphere. This is the largest continent of all, and its northeastern region is again cool enough not to kill someone quickly. The same is true of the final continent to be mentioned, the Lesser Northern Continent, although this and the Great Continent become very hot nearer the equator.

The surface of the planet is young. Unsurprisingly, the oceans are in constant motion, but the oxidane also eats away at the solid surface over a much longer time scale, although the occasional catastrophe can make major changes very quickly. WInds are another significant erosive factor. Also, in a process not found on our home world, the surface as a whole is constantly remodelled over a period of millions of years and the continents move around, collide with each other forming island chains and mountain ranges and split apart. This is, however, a very slow process. One consequence of this along with the erosion is the near-absence of impact craters.

A paradox of Sol III is how such a hot planet with a highly reactive atmosphere can remain in a fairly stable state rather than all the dioxygen reacting with the surface rocks and being removed from the atmosphere. The solution to this is quite remarkable: there are two balanced biochemical processes, one combining oxidane and gaseous carbon dioxide into energy-storage compounds with the aid of stellar radiation which releases the toxic gas as a waste produce, and another which combines the energy-storage compounds with dioxygen and releases carbon dioxide. Things were not ever thus. The planet went through a stage early in its history at an equable temperature, though still higher than our home world, with a harmless and hospitable atmosphere. Then, a certain group of microbes developed a mutation causing them to release the poisonous gas and the pollution of the atmosphere killed much of the biosphere. Hence not only is there life on the planet, in profusion in fact, but it actually requires the extreme high temperatures, molten lava and toxic atmosphere to survive. Although there are a few less extreme environments on the surface free of oxygen, all life on the planet uses molten oxidane to survive. Only a very few species could survive at temperatures we would consider comfortable or even survivable, and at such temperatures they’re in a dormant state from which they can only emerge in conditions of extreme heat. There is no true overlap between conditions life on Sol III would find tolerable and our own definition of survivable conditions.

Leaving microbes aside, some of which have biochemistry a little closer to our own with the proviso that they don’t employ ammonia, the larger organisms on the surface fall into three categories, which are covered below. It might be thought that the high gravity would make a buoyant environment more suitable for life, and in fact there is indeed more life living within the oxidane than out of it, there is also plenty of life outside these conditions. Although land life on Sol III tends to be smaller and stockier than the kind we’re familiar with, it’s as diverse and widespread as it is on our home world. One difference is that our own life originates from three different stocks due to our independent lake networks, whereas all life on Sol III is related because it originated in the ocean, or at least spent a long time evolving there before becoming able to leave it and exploit other niches.

One form of macroscopic life tends to use a prominent green pigment to absorb red light from the star to drive a nutrition-synthesising process. Its reliance on red light may reveal how life on Sol III is at a disadvantage compared to life on worlds near to redder stars. It’s this process, known as photosynthesis, which was responsible for poisoning the planet and causing the extinction of most life forms earlier in its history. Most large organisms reliant directly on photosynthesis do not move much of their own volition and the terrestrial varieties often bear colourful genitals which attract motile organisms to bear their semen to other members of their species and fertilise their eggs.

Another form of life tends to be able to move of its own accord and survives by consuming the bodies of other, often living, organisms. Their anatomy and physiology is usually centred around their need to move dissolved gases around their bodies, which they often manage using a system of tubes and one or more pumps. Their reliance on dioxygen and need to remove carbon dioxide gas from their tissues necessitates that all of their bodies need to be in close contact with a respiratory fluid, and all of the larger organisms also have entire body systems to deal with gases, either dissolved in the water around them or present in the air. In the case of the dominant class of animals, as they are known, on the land, this has limited their size as they rely on tubes open to the atmosphere. Incredible though it may seem, most animals can’t survive more than a few minutes without a constant supply of dioxygen.

The third form of life forms a kind of bridge between living and non-living parts of the food chain. Like the photosynthesisers, these are largely sessile and immobile, and tend to live off a substrate consisting of the dead or diseased bodies of other organisms. They do not photosynthesise. Many of them consist of subterranean mats of fibres which produce occasional fruiting bodies above ground level. Some of them are also parasitic. Without this group of organisms, there would be an ever-increasing unusable biomasse which would eventually cause all advanced life on Sol III to grind to a halt.

Animal evolution on Sol III went in a somewhat surprising direction. Unusually, a particular kind of fluid-living animal developed a hard internal skeleton and its descendents were able to use it to aid their movement rather than the more usual arrangement of holding them in place. These have proliferated into a variety of forms, though they constitute a small minority of species on the planet and animals themselves occupy much less biomasse than the plants (the photosynthesisers). Of all these species, one rather large, by the standards of the planet, type has become dominant over the planet through a technology based initially on the use and control of the runaway oxidative reaction and the discovery of language, which is acoustic and mediated by means of the organs which evolved to exchange gases. Remarkably, in spite of the intense gravitational field, these animals are able to achieve an erect bipedal gait.

It should be noted that the pace of animal life on Sol III tends to be very frenetic. This seems to be due to the high temperature and the employment of dioxygen as a means of releasing chemical energy. This hyperactivity doesn’t apply to plants to the same extent. It’s all the more so for those animals whose bodies rely on their own heat to drive their metabolism, and unsurprisingly this includes the technological species. Dormancy is a less significant phase of life for many animals living on the planet, partly because the years are shorter and in many parts of the world the seasons are less extreme. However, many species do become dormant on a diurnal basis for a considerable fraction of the planet’s rotation period, often when it faces away from the star, and depriving them of it for surprisingly short intervals leads to increasing mental derangement. The need of such organisms for food, oxidane and their respiratory gas is quite extreme compared to our own. This constitutes a barrier to space travel, as it means they are unlikely to be able to survive interstellar space voyages as easily as we can. This may not be a bad thing because there is a tendency for some members of the species to be quite violent, but this is also likely to be self-limiting. However, it’s probably better not to speculate too much about this aspect of their nature without more data.

One major lesson to learn from the complex life present on Sol III is that we may have restricted views on what constitutes an hospitable environment for the advent and evolution of advanced life forms. Before this discovery, the proposal that a sophisticated biosphere could exist on a planet two-thirds covered in molten rock with a dense caustic atmosphere capable of eating through metal, with a high gravitational field and temperatures far above boiling point over most of its surface, circling an ageing Sun much hotter and more massive than our own would have seemed ridiculous to all. These life forms can not only tolerate living with acidic molten rock in an aggressively reactive atmosphere but have evolved in tandem with it to the extent that depriving them of the gas for more than a few minutes is uniformly fatal and they need a continual intake of liquefied dihydrogen monoxide to survive more than a couple of rotations of their home world. Who knows what the inhabitants of Sol III might consider suitable conditions for life given their own extreme circumstances?

Any resemblance to Arthur C Clarke’s ‘Report On Planet Three’ is not entirely coincidental.

Planetary Chauvinism

“Chauvinism” is quite an old-fashioned word for prejudice against a particular group. Nowadays each has its own word, generally consisting of the name of the type of group plus “-ism”. It comes from a Bonapartist soldier called Nicolas Chauvin, who insisted on maintaining his support for Napoleon after the Bourbon Restoration, and was then extended to apply to any type of fanatical devotion to or against a group or cause. In the light of the dangers posed by the use of the word “terrorism”, it might be worth bringing it out of retirement to refer to a particular kind of fanaticism which doesn’t currently have an obvious word to describe it, although “fanatic” is a less ostentatious option.

The use of “male chauvinist pig” apparently dates back to the 1930s CE. It has a rather old-fashioned tone to it now, but maybe it deserves reviving. For a start, it doesn’t lend itself to referring to sexism both ways, which is a contentious issue. It can only mean prejudice against women and girls. “Female chauvinism” is also used sometimes. A notable aspect of it is that it refers to the individual in the group to which there is a bias rather than a group, one member of which there’s a bias against. “Racism”, for example, refers to the category of race and not to a specific ethnicity, but very often refers to White racism against others, and this centring on the member of the group responsible for the prejudice is quite helpful conceptually. I don’t think “White chauvinism” is a common utterance, although there’s an interesting Communist pamphlet with that title dating from 1949, but it works quite well as a way of emphasising Whiteness and White fragility. However, the word has long since gone out of fashion in these uses.

A more specific use of the word “chauvinism” seems to have started with the well-known science populariser Carl Sagan in the late 1960s. He uses it to refer to biasses in ideas about extraterrestrial life. Examples would be “carbon chauvinism” and “water chauvinism”. The idea here is that a particular characteristic of life as we know it on this planet leads us to conclude that all life must have that characteristic, and this restricts the places and circumstances in which we might consider or look for other kinds of life. It might even affect how we view life on this planet because of the possibility of a “shadow biosphere”. It’s conceivable that even on, or perhaps in, Earth, there are other forms of life which don’t share our chirality or chemistry. For instance, the phenomenon of desert varnish, a dark coating which forms on rocks in arid areas, has been suggested as the action of undiscovered life forms which are not like the ones we know about, and a more outré suggestion is that silicon-based organisms live within this planet but never come anywhere near the surface. Carl Sagan, if I recall correctly, described himself as a carbon chauvinist but “not that much of a water chauvinist”. That is, he couldn’t conceive of a way biochemistry could emerge if it wasn’t based on carbon, although he did believe in the possibility of other elements substituting for some of our own. Here are a few entries from his Encyclopedia Galactica:

This one appears to have carbon, hydrogen and oxygen like us but lacks nitrogen, sulphur or phosphorus. It also utilises helium, which must be non-chemical. Germanium and beryllium also have no biological rôle on this planet, and it looks like this civilisation has no historical association with planets.

More details of the same explain further. They are not a single species but an alliance of some kind, perhaps symbiotic, and can apparently only survive in interstellar space because they depend on superconductivity, which only occurs at a low temperature.

This is us:

The last entry might be a bit depressing! This was in 1980.

I mention chauvinism now because I’ve had some difficulty wording my writing in this blog recently. There is an issue with the way we can refer to what I’m going to call “worlds” for argument’s sake in this paragraph. We tend to talk about planets as potential abodes for life, including technological cultures, but this is rather misleading. Considering our own Solar System, we have one body which is established to have had life on it for æons, our own Earth, but other worlds have been considered. At the moment the candidates seem to be: the upper atmosphere of Venus; the surface and oceans of Earth (quite a strong candidate that one!); Mars; the upper atmosphere of Jupiter; the interior oceans of Europa, Ganymede and Callisto; the surface and interior ocean of Titan; the interior ocean of Enceladus. There are a couple of weaker candidates in Ceres and Pluto. That gives us four planets, two dwarf planets and five moons. Hence even in our own system the possible places for life as we know it are mainly non-planetary, and constantly referring to “planets” in other star systems as places where life might evolve or appear without technological intervention starts to sound rather prejudiced. Maybe planets tend to be less suitable than other types of world.

The reason for most of these possibilities in our Solar System is that they have internal oceans. Europa and Enceladus in particular have rather suitable ones. Ganymede, Callisto and probably Titan also have liquid interiors but they’re more like Earth’s mantle than oceans, which might make them less friendly to life as the supply of other elements than hydrogen, oxygen and perhaps nitrogen might be very limited or non-existent. The geysers on Enceladus, on the other hand, do contain organic molecules with molecular weights above two hundred daltons, which is slightly larger than glucose, so the complexity may be considerable, and this is the only place off-Earth so far where such large molecules have been detected. Another very common finding, even in places where life is very unlikely, is tholins, which are reddish tarry organic substances present on many asteroids, centaurs, Titan, Europa, Rhea, Pluto and Ceres, although it isn’t clear that tholins are responsible for the red terrain on Pluto. Tholins are like the “cousins” of organic life forms, because they’re generated by the action of radiation such as cosmic rays on simple organic compounds. They’re bound to be common on small solid planetoids and comets throughout the Galaxy, and the question arises of whether we are the black sheep of the family in that we’re the rare exception, or whether life is just what happens instead of tholins in similarly widespread conditions.

It seems moons with sub-“terranean” oceans are a likely place for life to develop provided there’s an energy source and sufficiently varied elements, along with sufficiently low salinity. That last criterion may be surprisingly hard to satisfy. The total amount of liquid water in the Solar System is many times that found in our oceans, and the proportion of water on the moons involved is also much greater than that of the oceans to Earth. The energy source may be the Sun but is more likely to be tidal forces acting on the moon from surrounding large moons or the large planet it orbits, or it may be radioactivity as it is with our planet’s interior. If intelligent life arose in these conditions, it might be blind, unable to produce fire and unaware of anything beyond its ocean, since there would be a thick layer of ice above it. That said, it might also be tempted to drill a hole in that ice to see what’s outside or perhaps follow the course of a geyser or cryovolcano out into space, and it would be easier to leave most moons’ gravity wells than Earth’s, particularly as only Titan among these has a significant atmosphere, since they’re much smaller and less dense than this planet. It’s still possible that some kind of exothermic reaction could replace fire in their technology, but they might be stuck in the stone age if they exist at all.

I’ve already talked about exotic life in neutron and ordinary stars, which are of course not planets either, and there are also “rogue planets”, which wander through interstellar space too far from any stars to become associated with them. These will have been hurled out of star systems at some point, but life could possibly still arise on or in them if there is volcanism, or in any moons of the type mentioned if they’re tidally heated. In a sense these are actually proper planets, because the word planet means “wanderer”, which is what these do rather than orbit, which is what we tend to think of planets as doing. This actually means that etymologically these aren’t planets at all. Not only is Pluto not a planet, but nor is Mercury, Jupiter or Mars. In fact Pluto is in that sense more of a planet than the others because its orbit is more erratic and probably chaotic then theirs. However, it’s a fallacy to take the original meaning of a word as gospel and base one’s arguments on that, as can be seen with the idea that homophobia is misnamed because it’s hatred rather than fear. Maybe “heterosexual chauvinism” would be a better way to describe that combined with biphobia and panphobia.

There is also the question of what a technological species or perhaps intelligent machines would do if it got into space. In the mid-1970s, a plan for a rotary space colony about a mile in diameter (it was an American project, which might explain the units) situated at the L-5 gravitational equilibrium point between Earth and Cynthia was put together, and on this idea was built the expectation that if humans did move out into space, they might not actually be very interested in settling on, for example, Mars, when tailor-made orbital environments could be devised much more easily. It’s debatable whether such habitats are economically viable and the first would depend on the existence of industry on Cynthia to work, but there are different motives for going into space such as rescuing some, and that’s a very small fraction, of the species from a major asteroid strike or some other mass extinction-type disaster, and the motives of aliens would of course be unknown. Nonetheless it makes a lot of sense to bypass planets entirely and just build wheels in space, and beyond that perhaps Dyson spheres and ringworlds. Extending this far enough into the future, perhaps the most suitable places for habitation wouldn’t be found near Sun-like stars at all but the likes of blue supergiants like Rigel or the Pleiades rather than the likes of α Centauri or τ Ceti, because the former have very deep habitable zones and plentiful radiation. These are also the names that turn up in Golden Age science fiction because people have actually heard of these places. ETs might also board space arks, initially to get to nearby stars but take so long to get there that they no longer see the point of disembarking once they reach their destinations, and just carry on voyaging. There’s another answer to the Fermi Paradox: aliens leave their home worlds, establish colonies in space or launch spaceships to nowhere (leaving any place?) and their original abodes just go wild again. Also, we’re looking at the wrong stars for technosignatures.

There is one more really wild possibility: maybe life evolves in space and stays there. Life evolving in space isn’t a particularly new idea. Fred Hoyle and Chandra Wickramasinghe claimed in 1974 that the reddening of distant galaxies attributed to the expansion of space is in fact explained by microörganisms absorbing their light and they weren the first to claim that life here comes from elsewhere. More recently it has been noted that the whole of the early Universe had the right conditions for life, being fairly warm, dense and having all the right elements in close proximity to each other, for the kind of life we know about. Cosmic strings, of course, also existed by this point, so if that kind of life exists at all, it may have done so even before that happened. This is leaving out all the other possible kinds of life, such as plasma, and there have been thoughts about life based on liquid helium or superconductors, although I don’t know how that would work in detail. All of this is very vague.

To finish then, perhaps we think too much about planets when we consider alien life. It is in fact notable that we don’t seem to have a simple word to refer to heavenly bodies which are not stars in general. Maybe if we had a future, we would find ourselves eschewing both Earth and other planets just to live permanently in space and things here could go back to how they were before we evolved. They probably will anyway after we’re extinct. Meanwhile, maybe there are countless civilisations in the Universe trapped under heavy atmospheres or the bottoms of frozen over oceans in eternal darkness who don’t even know there is anything else, while out there between the stars are wraith-like beings thousands of kilometres across with their own societies, or living starships who evolved on their own. It has been said, after all, that the Universe is stranger than we can imagine.

. . . Not As We Know It . . . Captain

If your first language is English and you’re over about thirty-six, I’m guessing, you may well remember this song. If you’re a bit older you’ll also remember their song about Arthur Daley, and you’ll also know who that was. I only realised recently that there was a claymation video for it though, because in 1987 CE I wasn’t watching television, with the exception of the repeat of ‘The Hitch-Hikers’ Guide To The Galaxy’.

One of the oft-repeated lines, alleged to be a quote from the original series, was Spock saying “Well, it’s life Jim, but not as we know it. . . Captain”, with a distinctive pause at the end of the verse before the Spock impersonator says the final word. It won’t surprise you to know that just as Kirk or anyone else never said “beam me up, Scotty”, this is a misquotation. The closest Spock comes to saying it is “no life as we know it” in ‘Devil In The Dark‘, when in fact he says it twice, and that episode in particular refers to a very common suggestion regarding “life, Jim, but not as we know it” – silicon-based life.

I have already discussed this here:

Without re-watching the video, my conclusion was that there are two ways in which life which could be said to be silicon-based are possible. Because silicon compounds are often bioactive, and silicon-based structures do exist in organisms on this planet, a situation could arise where much of an organism’s biochemistry involves silicon compounds, even including hormones and much of the hard parts of their body, but at core still carbon-based. The alternative is that a narrower range of silicon compounds which are however particularly versatile could be used in a manner similar to the difference between binary and higher-based ways of representing numbers. It can still be done, but the binary representation of the number eleven takes four bits but only one duodecimal digit. Hence silicon-based life could still exist but be more “long-winded” than carbon-based, and consist of relatively larger molecules than the already very large macromolecules found in terrestrial life such as muscle protein and cellulose. However, although I think it’s likely to be possible, I don’t think it would emerge of its own accord or be able to survive outside a specially designed environment, mainly because silicates are very stable compounds and once silicon has entered such a state it would be difficult to remove it. If you watch an exposed microchip under a microscope, you can see it visibly degrading and not-so-gradually oxidising. An environment containing silicon-based life of this kind would have to be free of oxygen and water. Silicon in water liberates hydrogen and combines with oxygen to become silica, and this may not happen with the silicon compounds used for life, but there’s a risk of producing bonds which are so strong that ordinary biochemistry can’t sever them all the way through silicon-based biochemical pathways.

Only the lightest atoms are able to produce more than single bonds. This includes boron, carbon, nitrogen and oxygen. As far as I know, no heavier element is able to form more than single covalent bonds. This means that the structures of molecules made up of chains or rings of silicon atoms may be rather limited, although silenes do contain double silicon bonds. Moreover, the stability of longer chains of silicon atoms is lower than that of carbon chains with the same number of atoms in them. Nonetheless, I do believe silicon-based biochemistry is possible and I will now cover some of the possibilities.

By Zephyris – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=15027555

DNA is a well-known helical polymer used to store genetic information. Silicates have various forms, consisting of sheets of hexagonally-arranged silica tetrahedra sharing vertices, alternating such tetrahedra with opposite orientations, simple chains of the same, or helically-arranged such chains. This is interestingly close to DNA, although it’s only a single helix and the unit is silica groups. There are also double chains known as amphiboles, linked via shared oxygen atoms. Some asbestos minerals are amphiboles. If these are able to form extra bonds with bivalent atoms of various kinds, the result would be a very similar molecule to DNA, with a potentially readable code, although how it would come uncoupled, be transcribed, what it would be transcribed into, and how it could replicate and recouple are different questions, which may not have answers. Nevertheless, this is a potential storage medium, perhaps one which would need to have more “steps” than DNA per codon. This illustrates what I mean by molecules needing to be relatively larger, although on the other hand the actual rungs are smaller because they only consist of two atoms.

Closer analogues with organic compounds are the silanes and silanols. The former are silicon-based versions of the alkanes such as methane, butane and propane. Like them, silanes are flammable, and become more flammable the longer their chains are because longer chains are less stable. In the case of alkanes, similar substances can be derived from them in the form of long-chain fatty acids, with a -COOH group on one end. These are just ordinary organic acids which happen to have very long chains, and in organisms they’re often joined together by a glycerol residue at one end into kind of E-shaped molecules, used to store energy and form cell membranes. Eicosapentanoic acid is quite a well-known essential fatty acid. It has mixed double and single bonds, like all polyunsaturated fatty acids, and twenty carbons per molecule. By contrast, the highest silane has only six carbons, and is entirely saturated because they only have single bonds.

Silanols are the silicon-based versions of alcohols, although many of them are in fact organosilicon compounds rather than containing no carbon. They’re more acidic than their organic equivalents and can be used in shampoos to improve the pH balance of the scalp and hair. Another class of silicone compounds in common use is the cyclosiloxanes, which are hormonally active, found in cosmetics and toiletries and are persistent in the environment. As far as this particular biosphere is concerned, these substances are concerning, but their bioactivity suggests that in other circumstances they could be functional as biochemicals. Many of these contain oxygen bonds, which may be why they aren’t broken down. It may not be that they are merely difficult to process in organic biochemistry, but just difficult to do so in any circumstances conducive to chemically-based life, and if that’s so, the chances are that compounds with silicon-oxygen bonds may break down in other ways but not in such a way as to become usable again by living systems. This would ultimately result in a silicon-based biosphere having all its silicon locked up with oxygen, which is how things are here.

It would be interesting to attempt to replicate the Miller-Urey experiment with silane instead of methane. This was an attempt to replicate the chemical conditions of Earth soon after formation to discover whether biochemicals found in life today would form, and it succeeded. It used water, ammonia, methane and hydrogen, and resulted in the production of such compounds as the amino acid glycine and the sugar ribose. However, although this is a fruitful exercise, it doesn’t reflect the kind of conditions likely to exist in any real situation. The interstellar medium does contain silane and several other silicon compounds, so this is not entirely unrealistic, but the concentration of silane and other silicon-based substances is much lower than their carbon-based equivalents.

A strong argument against silicon-based life could be made on the basis of the existence of organic life on this planet. Silicon is almost a thousand times more abundant that carbon, and yet life developed based on this far less widespread element. This might, though, result from other conditions being unsuitable such as the presence of water, which is however the most abundant compound in the Universe. For silicon to combine with ease in other ways, oxygen would have to be relatively scarce. On Earth, oxygen is the most abundant element in the crust, much of it combined with silicon, and I may be wrong but I find it hard to imagine a rocky planet whose situation is different enough to enable silicon to form other compounds routinely. Oxygen is the third most abundant element in the Universe as a whole, and is more than a dozen times as common as silicon. It isn’t necessarily that silicon-based life is impossible so much that other factors make it unlikely ever to happen on its own, without intervention.

That said, there might be a reason for manufacturing silicon-based microbes, for example, to reclaim plastic waste or as part of a manufacturing process. In a sense, microbes are highly complex nanotech devices, and organic life forms can only do so much because the range of conditions in which they can function is limited. The same applies to silicon-based life, but this is a potential advantage as it prevents the “grey goo scenario” of self-replicating devices eating up the planet. This brings up the issue of exotic solvents.

Although silicon biochemistry is bound to be very different to its carbon-based equivalent, what I’ve described so far is substantially similar, and as such it would require a solvent. It can’t use water unless silicon enzymes are able to catalyse in those conditions without being damaged. Silicon-based life attempting to use water is like carbon-based life attempting to use mercury as a substitute for water, which would combine with the sulphur in proteins and destroy their structure, except more severely because any silicon atom with free electrons would bind to the oxygen, liberating hydrogen incidentally, but also knackering the structure of its macromolecules. This is the big problem with silicon-based life in fact, and although I’ve suggested that entirely artificial silicon-based life forms could be used to clean up the environment, they would have to be exposed to water to do their job, which would be very harmful to them. Although glass, silica and many other silicon compounds are excellent at keeping water out without reacting, some kind of solvent would need to get in there with the molecular machinery that’s actually doing the living, i.e. the metabolism, if the biochemistry has any similarity to that of life as we know it.

One possibility here is methanol. This is the simplest alcohol, with this structure:

Somewhat ironically, the reason why this might work is probably that it has a carbon atom bound to the oxygen, which is stronger than a silicon-oxygen bond, so silicon will not pull it away from the molecule and annihilate its own structures. Methanol is found in the interstellar medium, and there’s no reason why it wouldn’t occur on planets. Its melting point is -97°C, so in an atmosphere it’s entirely possible that liquid methanol could exist on the surface of a planet, though above the melting point of water ice it would do so as a mixture with water, which would be unsuitable, so if there are worlds with methanol oceans that might be a start. However, methanol is not as abundant as water, unlike another candidate solvent, sulphuric acid. Sulphuric acid is widely distributed in our own solar system, on Venus, Mars and Io for example, and this suggests that there are whole planets out there with sulphuric acid oceans, or at least lakes. Sulphuric acid seems to be much better at supporting diverse silicon chemistry than water is.

It isn’t entirely true that silicon never forms double bonds. This occurs in silene, for example. I have to be honest here and confess that I don’t know if the existence of a double bond in silene means it can occur in any other situations. While bonds are under consideration, it’s worth looking a bit more closely at the differences between carbon and silicon chemistry. The covalent radius of a silicon atom is 117 picometres compared to carbon’s 77, but the length of the silicon-oxygen bond is 163 pm compared to carbon’s 143, from which the radii must be subtracted, leading to a shorter bond length outside the covalent radius for silicon, which makes the molecules more potentially crowded for the latter and so less diverse. There just isn’t the space around silicon atoms for there to be as much variety per atom.

That said, one thing I haven’t considered yet is the question of siloxanes. Is it possible that rather than envisaging an oxygen-free environment for silicon-based life, we should be thinking in terms of just letting it happen and seeing where that would lead us? Siloxanes include both cyclical compounds and silicon oils and rubbers, all of which have their parallels in carbon-based biochemistry. Silanols are siloxanes in a sense because they have the silicon-oxygen bond, and it’s possible to build other compounds from them. Oxidation leads to the formation of silica, so this may ultimately be an unstable situation for life to exist in, but perhaps for a short period it could.

Life as we don’t quite know it, that is, still relying on complex chemistry and solvents, has certain requirements. By definition, it needs a solvent, which in our case is water but could hypothetically be various other compounds including the aforementioned sulphuric acid and methanol, but also potentially formaldehyde, ammonia or hydrogen sulphide, which I’ll talk about in a bit. It needs enough different kinds of chemicals to perform various functions, and it needs the right balance between chemical stability and reactivity. It can’t afford to have a “doomsday pathway” where an essential and irreplaceable function causes a reaction to practically inert compounds, because this would end up locking all of the central elements up in those substances, and this appears to be what silica is in the case of silicon-based life. On the other hand, this could be useful in biotechnology to protect the environment, as it amounts to artificial organisms cleaning themselves up after their work is done.

Hence I would say that silicon-based life of this kind is possible if it was carefully designed and functioned in a highly specialised and protected environment, but it could never kick-start itself. It’s feasible that a sealed vessel in a lab could be provided with an appropriate solvent, be free of water and oxygen and be seeded with a variety of silicon-based chemicals by an intelligent life form or machine intelligence and then either spontaneously assemble into simple life forms or be purposefully manufactured as such, and there are also reasons for doing this, but there is very probably no world anywhere in the Universe where this happened on its own. In fact, if we did happen to find a planet or moon with silicon-based life on it, it would be good evidence for the existence of intelligent life somewhere.

Having said all that, there are other ways in which life could be silicon-based than simply imagining the mimicry of organic biochemistry, and perhaps all these stringent requirements just mean that biochemistry as such only really applies to our own very specific kind of life. Nowadays, classical computers are silicon-based, with doping from other elements, e.g. traces of arsenic to alter the atomic structure and allow them to function as arrays of transistors. However, this requires conditions where elemental silicon can form or be deposited, which are hard to imagine. It’s also interesting from the perspective of whether intelligence has to be alive. It’s possible to imagine some kind of crystalline process occurring on a planet where transistors or other switches grow out of inorganic materials which never fit the criteria of life but nevertheless evolve and increase their information processing capacity until they count as intelligent. This, however, is evolution and that would arguably make something alive. For instance, it would reproduce. A much more straightforward way in which intelligent machines could appear would be through what we’re doing now with our development of artificial intelligence, and many have claimed that a solution to the Fermi Paradox, for instance, is that interstellar intelligence is entirely machine-based. Considering the current trends in AI, space travel, nanotech and genetic engineering, a combination of applications of these in the long term could lead to self-replicating intelligent spacecraft who would be very much at home in interplanetary space if not interstellar, the problem there being energy sources, which could be addressed by going into a sleep mode and coasting, perhaps for centuries, to reach resources, which is far more practical for a machine designed to do that than a human, although for all we know other intelligent life forms might be absolutely fine with dormancy over long periods due to the conditions they evolved to cope with. Such entities probably wouldn’t consist of biological materials as we understand them and the usual restrictions on biochemistry assumed above wouldn’t apply. No solvent would be needed, a few inorganic compounds and elements would be sufficient and so forth.

Returning to “life as we know it” to some extent, there are several possible biochemical options which have not been mentioned yet. Prominent among these is boron. Like carbon and silicon, boron avidly forms covalent compounds though with three bonds rather than four. It forms three covalent bonds and is a metalloid, with some properties typical of metals and some of non-metals. The compounds it forms are often based on polyhedral forms, either closed or like a basket, in which atoms of other elements can be incorporated. It has at least eight different pure forms (allotropes), similar to carbon’s diamond, graphite, fullerenes and bucktubes. On a molecular level it tends to form icosahedra and there is a fullerene-like form consisting of forty atoms. It also has an extensive chemistry with an affinity for ammonia.

Hence boron chemistry can go in two directions towards complex structures with behaviour. On the one hand, it can be like conventional biochemistry, but with ammonia rather than water as a solvent, so it can have complex carbon-like chemistry. This might involve boranes, which are explosive in oxidising environments such as our own lower atmosphere but would be more stable in a reducing atmosphere, such as one mainly consisting of hydrogen. Boranes are boron hydrides, but differ in shape from hydrocarbons because they tend to form the basket shapes mentioned already, or icosahedra. It can form double bonds like carbon. Hence it’s possible to imagine boron-based life living in a hydrogen-rich atmosphere in conditions where ammonia is liquid and acting as a solvent, on a relatively cold world whose temperature is around -77°C or above, how high exactly depending on the atmospheric pressure. Such conditions are possible on the super-Earth/sub-Neptune planets which are in fact the most common of all types of planet but are not found in this Solar System, which is a puzzle, provided they are just outside the “Goldilocks Zone” for our kind of life.

On the other, there’s the possibility, which also exists for carbon, of nano-“machines” being built from the structures which pure boron forms. Hence there is perhaps another route into life which is not really biochemical. The interesting thing about boron, and it can be interesting in spite of its name, is that it kind of straddles biochemistry and nanotech in a way carbon doesn’t. With carbon, the structures of biochemistry are of course exceedingly useful and versatile, but they generally consist of polymers. Boron is able to form molecules with unusual structures which are kind of quasi-crystalline and can work both mechanically and chemically.

There is, however, a big issue with boron I haven’t mentioned yet. It’s rare. It’s less common than the next fifteen elements, up to scandium, and also the second rarest of the four lightest elements, beryllium being much more scarce due to the difficulty of its formation. Hence, whereas boron has exciting possibilities as a basis for life, like silicon it’s unlikely ever to happen without intervention. If anything, it’s more likely even than silicon to act as the basis for biochemistry, but silicon is the seventh most abundant element and boron the thirty-fourth. It’s possible that shortcomings in silicon chemistry prevent silicon-based life, but in the case of boron it could merely be its scarcity compared to carbon.

This probably exhausts the possibilities of elements as the basis for life using similar biochemistry to our own, but it doesn’t have much relevance to other possibilities for life. I’ve already mentioned plasma-based life, to which chemistry isn’t very relevant and it is possible that we’ve got a bit too hung up on chemistry as the only possibility. Another couple are associated with neutron stars. Firstly, there is the option explored by Robert L. Forward in his ‘Dragon’s Egg’ novels. Forward imagines that neutrons on the surface of such a star could combine in various ways like atoms do into molecules, and have their own equivalent to chemistry. They would however have lives millions of times faster than ours, and he also supposed that their life expectancy would be around half an hour, which is quite reasonable. There is a second suggestion concerning the interior of a neutron star which was explored by Stephen Baxter in his Xeelee series, which I haven’t read and don’t understand, and there is also the Orion’s Arm version, which may be related, of Hildemar’s Knots. These are quite difficult to understand and explain, but seem to depend on the probable fact that the interior of a neutron star is likely to be superfluid and have quantised microvortices of rotation. In order to explain this, helium II is a little closer to everyday experience.

Helium is the only baryonic matter with no solid state under pressures encountered routinely on the surface of this planet. This is a little abstract as it also has the lowest boiling point of any substance, and therefore can’t be stably surrounded by a gas under pressure since everything else is solid at that temperature. There are two common isotopes of helium, helium-4 and helium-3, and because of the way spin works, one consists of bosons and the other of fermions. Above a certain temperature, all helium behaves rather like an ordinary liquid except for being almost invisible, but below it, the helium-4 isotope becomes what’s referred to a little confusingly as helium II. At a much colder temperature, helium-3 also enters this state, which is referred to as superfluidity, and is a macroscopic quantum state. It behaves as a mixture of ordinary fluid and a fluid with no viscosity at all. It can climb vertical surfaces and it flows more easily through small holes than large ones. It conducts heat at the speed of sound, a feature also found in superconductors which means that effectively a small amount of helium II is always at the same temperature throughout. With respect to Hildermar’s Knots, the important property of superfluids is that when they’re stirred, they continue to rotate forever because they have no viscosity, and the vortex formed is quantised, and due to the peculiar nature of half-integral spin things then become really confusing. Neutron stars spin very fast and this, I think, stirs the interior superfluid neutronium into quantised vortices, each exhibiting a single quantum of angular momentum and also of magnetic flux. This results in a dense tangle of filaments. Something called the Urca Process involved in the cooling of neutron stars leads to an excess of left-handed electrons which become spin currents. The topology of these filaments changes if they touch, leading to a wave being emitted through the medium. Braids of these filaments amount to life because they can consume left-handed electrons, the braids can store information and the waves propagate signals like nerve impulses. In Orion’s Arm, Hildemar’s Knots can’t relate to the Universe outside their neutron star and regard it as an abstract mathematical problem rather than the Universe. Likewise, attempting to get one’s head round what quantised vortex filament braids in neutronium within neutron stars actually are is very like trying to solve an abstract mathematical problem. It isn’t clear to me how much of this is handwaving, but if it isn’t, it’s an interesting observation because it means that both modes of life regard the other as arcane and abstract. Also, neither can approach or exist in the other’s realm. This goes beyond “environment” because the interior of a neutron star and the kind of space compatible with atomic matter are so different that they hardly make sense to each other. Although a neutron star is only the size of a medium-sized city considered from the outside, they will distort space to some extent on the inside, and the amount of matter within them is enough to make half a million Earth-sized planets. Moreover, all of this would be happening on an absolutely minute scale.

There’s a second kind of theoretical filamentous life which may exist within less extreme stars, made of cosmic strings. Before I launch into this, I want to point out that I have my doubts about the very basis of this life form. There is an issue with magnetic monopoles, and it goes like this. We’re used to the idea of positive and negative electrical charges and the idea that one can exist without the other. There are positrons, protons, electrons and muons, all of which have isolated charges which are not paired by their opposites, although they attract each other. It might be thought that south and north magnetic poles could also exist alone, but this has never been found, and if a bar magnet is cut in half sideways it just becomes two smaller bar magnets with a north and south pole each. This seems to go on no matter how many times it’s done. Remarkably, this was discovered in the twelfth Christian century and the reason for it has never been discovered. Physics as it stands today often insists that magnetic monopoles must exist somewhere, but if they do, none have ever been detected and I personally don’t believe they exist. If they do, they would form a kind of exotic matter whose orbitals would be much smaller than those of electrons in atoms, but they would be somewhat like them nevertheless and crowd together like atoms, and consequently they would be extremely dense and yet not at all of the kind of matter which makes up superdense objects we know about such as white dwarfs and neutron stars. Because they’re so dense, it’s possible that they’re only found inside massive objects such as planets and stars. That’s the first bit.

The second bit can be explained by combing hair. I have a double crown, meaning that I can’t really have a parting. There are two whorls on my head. Most people have only one because their bodies are not covered in the kind of hair which grows, or grew, on their head, but if it was everyone would have a double crown. This is presumably the case for other species of ape, and of course for cats and dogs, to take two examples. These are known as topological defects and are thought to exist in the Universe because of the way it formed. Space only appears to be Euclidean. Two parallel lines do not in fact stay the same distance apart but will meet at a finite distance, but it appears to be Euclidean to most observers outside an immensely strong gravity well. However, space is markèdly non-Euclidean near a cosmic string because it’s a defect in space, such that a circle around such an object would have less than 360°. This peculiarity makes them very dense but their width is similar to that of a proton. They behave as one-dimensional objects, and a kilometre long stretch of a cosmic string would be more massive than Earth. This gives it an unimaginably huge density, and it may be that they are responsible for the clumping of matter seen in the Universe, where galaxies form into clusters and filaments because they have all fallen towards the strings. That said, there could also be cosmic strings whose “non-Euclideanness” is opposite, such that circles around them would have more than 360°, and these would have immensely negative mass. If these exist, it would be possible to move away from them faster than light, so they probably don’t, but that doesn’t mean the ones with psitive mass don’t either.

Both magnetic monopoles and cosmic strings are topological defects like partings and hair whorls in geometry, so they have an affinity to each other. Monopoles might appear as if threaded onto a cosmic string, and when this happens, the resultant beaded “necklace” could have something like chemistry. Neither may it have escaped your attention that this sounds once again rather like DNA, the difference being that magnetic monopoles can only be of two types, south and north. At this point it’s necessary to define the nature of life, which for the purposes of this suggestion has three characteristics. It can encode information. This is the thing which it’s difficult to understand how plasma life cells would be able to do along with the microspheres mentioned in that same post, and which for now constitutes a problem in imagining how plasma-based life is possible. Our own life solved it with DNA and RNA, initially at least. Another characteristic is that such information carriers must be able to replicate before they’re destroyed. This has an interesting dynamism with it which appeals to my Marxist brain, as it means life can only be considered as having a history from cradle to grave. The final characteristic is a surce of free energy, which considering we’re talking about life inside living stars is not exactly in short supply.

Were it as simple as magnetic monopoles lined up on a cosmic string, equilibrium would prefer north and south poles to alternate and no real information could be stored on the necklace, but each monopole could be further split into two semi-poles, making four possible semi-poles which do not necessarily annihilate each other as hey would if they were simply monopoles and their corresponding antiparticles. This makes four base-pairs which can exist on their own strings, which is remarkably similar to the structure of DNA, with four possible encoding items each of which can couple with precisely one other partner situated on a different string or strand.

This whole possibility is not intended so much to represent a real situation, although it may, as to show how different life might be to how we generally understand it. If a situation that different to carbon-based proteinaceous organic life using water as a solvent can exist, the sheer variety of possible life forms is enormous, which multiplies the possible locations suitable for life many times. The way things are here, including all these possibilities, the habitable zones for life around stars has been expanded, the types of planets or moons involved are also more varied, there are at least two possibilities on and in neutron stars and there’s a further possibility inside ordinary stars. Then there are possibly multitudinous other types of life that haven’t even been thought of. So once again, even in a Universe where there were very few Earth-like planets, many other possibilities exist and the Cosmos could once again be seen to be teeming with life. The only problem is how to recognise it.

Artemis And Doomsday

Right now, the chances are that everyone reading this is a basic human like me, living on Earth, or at an outside chance, in low Earth orbit (who am I kidding‽). Consider that condition. What are the chances that that’s what you are if human life goes on and our descendants fan out into the Galaxy? I’ve gone into this many times of course, and the Doomsday Argument, as this is called, is flawed, but it’s worth going into it again for the purposes of applying it to the situation in which the human race finds itself today.

I’ll just recap briefly. There was a guy who visited the Berlin Wall in the 1960s and predicted that it would come down at approximately the time it did through estimating the probability of where he was in the total number of visitors to the Wall, using only probability, statistics and the time since it had been put up. His name was Brandon Carter, and he later applied a similar argument to estimating how long the human race has left based on the assumption that one is about half way through the total number of human births. When I did this calculation based on my own date of birth, the 1977 CE estimate that 75 thousand million people had been born before me, which covered the past six hundred millennia and a doubling period somewhere around three decades, as it was at the time, it gave me the result that the last human birth would take place around 2130. There are various silly aspects to this argument. For instance, if Adam existed and had made this calculation just before Eve appeared, he would conclude that the human race would be most likely to end with Eve’s death. By the way, I am not fundamentalist and therefore do not believe Eve and Adam ever existed. I just want to make that clear.

Although this is not a particularly marvellous argument, I do think a similar one works fairly well in one particular area, as I’ve mentioned before. It does in fact seem fair to assume the principle of mediocrity about one’s own existence. In that respect, it’s fair to assume I’m a typical example of a human and have been born at a time when prevailing conditions are “normal”, i.e. that the fact that I find myself living at a time when we have only ever lived on one planet and are not cyborgs to a greater extent than Donna Haraway claims. Transhumanism is not the usual human condition and there are neither orbiting space colonies nor settlements on other worlds. If we even settled ten other worlds they would only need a population over the whole period humans dwelt on them about equivalent to the current population of this planet for us to be outnumbered, and that’s a very modest estimate of how human history would unfold if we began to live elsewhere than on this planet. It would be more likely for there to be numerous settlements, either in the form of space stations or people living on other habitable planets. Say there were a million planets settled, which is still a conservative estimate for the number of suitable planets in the Milky Way, and they were settled for only a thousand years each. That’s an æon of human life on other planets. For it to be more probable for us to be here now than there then, it would need the population on each of those planets to average out at less than seven dozen. That is clearly absurd, so we have to conclude that as a species we will never settle on any other planets or build any permanent space habitats, or that our existence here and now just happens to be fantastically impossible.

For this to be the case, we have to conclude that our efforts to go into space are also only ever going to be very minor to non-existent, something which is confirmed right now by the fact that only twelve people have ever visited another celestial body. Even that was difficult because one crew didn’t make it. Now we’re supposed to try again with the Artemis Project, the current plan to go back to where Apollo went. Incidentally, I’ve long thought that one of the issues with the conspiracy theory is that getting there is only equivalent to going round the world ten times. Patrick Moore had a car which had gone further than twice that distance, and the average flight crew probably notch that up in a couple of weeks. Not that it wasn’t an amazing achievement. But humanity didn’t go on to do anything else afterwards, is the issue.

We’re confronted with a problem in the current moment then. It’s looking like there will be more people walking about up there in a couple of years, but if that happens it looks suspiciously like this version of the Doomsday Argument will have been refuted. But before I go there, I want to talk about Brooke Bond.

In 1971, Brooke Bond brought out a series of collector’s cards on the Space Race which started with Sputnik 1 (let’s Russ that up a little: Спутник-1) and proceeded through the various early satellites, planetary missions and the like up to Apollo and then past into the future. I collected the cards and got the book to stick them in. It must’ve been 1971 because it had the pound marked in both shillings and “p”, and they only did that in that year if I recall correctly. Anyway, it was from this publication that I learnt of the plan to send a human mission to Mars via Venus launching in the late ’70s. I remember looking at the years and thinking “1979” and “1980” looked really strange and futuristic, like the numbers on the public library date stamp which had yet to be used. But yes, there was a tentative plan at that point to send astronauts to Venus and Mars which everyone seems to have forgotten. There have in fact been a very large number of such proposals, but I didn’t know that at the time:

Actually, looking at this I realise I got it the wrong way round. They were going to visit Mars first and then do a Venus flyby. My confusion arises from the fact that there were so many different plans to do this. The Russians even considered a Venus mission to be launched in the early 1960s. I remember eagerly awaiting this, in full expectation that it would happen, and the dates passing with nothing to show for them, and how disillusioning it all was. This was a feature of my life at the time. When they found CFCs were destroying the ozone layer and that carbon dioxide emissions were causing climate change, I was convinced that they’d just go, “right, lets take the fluorocarbons out of aerosols and stop using fossil fuels”, and it’s the same kind of disappointment, from which you can see that I wasn’t your typical space nerd or environmental activist, because I suspect rather few people were equally enthusiastic about Green politics and astronautics, but that’s who I am. There is a seamless disappointment there. It’s all part of my same imaginary world, and it was very hard to cope with at the time. I can’t believe how slowly everything except IT progresses, and it’s also weird that IT did advance that quickly compared to everything else. I have certain theories about that, not conspiracy theories but something else, which I’ll leave for another time.

The space-based Doomsday Argument, which I’m going to call “Space Doomsday”, can easily explain why this didn’t happen, although maybe “why” is the wrong word here. The immediate reason the Mars mission didn’t happen was budgetary cuts to NASA in 1970. However, considering our lives as a relatively random sample of human history, we are aware that it’s improbable that human space exploration will ever make much progress, or we probably wouldn’t be here sitting on this single planet where we originated. It’s possible but improbable. The idea that we will in fact end up doing this isn’t ruled out by the fact. It’s similar to the idea that if you have lung cancer, you have probably been a long-term tobacco smoker. That’s something you can reasonably conclude about someone’s previous life given their current condition, although it may also be that they got it from passive smoking or asbestos exposure, for example. It isn’t a dead cert, but it’s probable. Hence it’s probable that something would happen to prevent people from landing on Mars, assuming of course that the expansion into space follows such activities, and in that sense Space Doomsday has predictive power, or perhaps forecasting power. We know we’re here on Earth, so we can reasonably believe the human race does not have a spacefaring future. A slightly less reasonable conclusion is that there will be no human missions to other celestial bodies in our future.

This could potentially lead to a weird version of “Moonlanding” denial conspiracy theory. Obviously I accept humans landed on Cynthia six times owing to not being delusional in that respect, but suppose Artemis happens. I am wedded to the idea that humans will never go there again because of Space Doomsday, so if they do go there I’m tempted to deny that due to it not fitting in with my world view, and the same applies to any planned Mars mission. Am I perhaps a tinfoil hat conspiracy theorist in the making? If someone believed in Space Doomsday in the 1960s, would they have ended up denying the Apollo missions were real? If the news that Artemis does succeed appears in the media and we see pictures from the lunar surface and the rest, it’s fair to conclude that we probably have gone there in a second batch of missions, but one’s belief in Space Doomsday could be so strong that it would lead to K-skepticism. For me, that would be motivated by depressive thinking, but others might have more positive reasons for doubt, such as the idea that it isn’t appropriate for so much money and resources to be spent on space missions when there are enough problems on this planet to be addressed.

Speaking of this planet, there could be a link between these two major sources of disappointment emanating from my childhood. Alternative futures are possible from these. In one, we simply don’t go into space much. Perhaps robotic probes become ever more sophisticated, take over from us, and colonise the Galaxy themselves, or maybe there’s just no impetus to do so and we all become more focussed on whatever’s going on down here. This is a relatively positive future compared to the other one, which is that this apparent lack of concern for environmental disaster simply wipes out the human race in a few years, before anyone gets the chance to go to Mars. This chimes with the apparent, though egocentric, forecast that the last human birth will occur around 2130.

The interesting thing about Space Doomsday is that it seems to have predictive power. For instance, it predicts that there will be a reason why nobody will go to Mars or the Artemis project won’t come to fruition. In fact, Artemis has indeed met with problems. The plan is for at least eight missions, the first two of which won’t involve a lunar landing. Artemis I is an unoccupied test of the spacecraft which will orbit Cynthia and return, splashing down on Earth, next year (2022). Artemis II happens the year after and involves a crew orbiting Cynthia, which would be the first time anyone has left cis lunar space since 1972. 2024 is expected to see humans back on the surface for the first time since Apollo, and a series of missions after that will involve building a lunar base for permanent habitation. This looks like the point of no return for human settlement in space, although it might just not happen or not go any further. But in order to be “scientific” about this, I need to define exactly what I mean by the statement that humans will never settle on other worlds or establish a permanent presence in space. That initial statement looks wrong for a start because of the International Space Station, which is a permanent presence. Otherwise, I’m moving the goalposts, and I might say after Artemis I, “well I never said the hardware wouldn’t work” or after Artemis II, “well I never said nobody would ever leave cis lunar space again” and so on. I need to be more precise, and base it on evidence.

My claim is based on the idea that the total number of human births is likely to be at most 150 thousand million. More than this and the chances of living now rather than later in history fall below fifty percent. In fact, therefore, it’s possible to forecast from this position that the total population of space will always be less than seventy five thousand million minus the population still on this planet. In fact if it were ever close to being that high, that would seem to herald the extinction of the human species for probability-related reasons, which suggests further that there will never be self-sufficient space colonies or that some perhaps solar-related disaster will befall life in this Solar System.

Artemis is supposed to lay the foundations for the eventual exploration of Mars. This in itself means it’s unlikely to succeed, not because that’s over-ambitious but because it means it does in fact appear to be a stepping stone to people living permanently off Earth, which either can’t happen or is likely to end in disaster, or at best peter out. Hence it can be expected that there will be major snags in the program. Now it’s difficult to tell whether I’m seeing patterns where there are none, as any major long-term complicated undertaking is likely to meet with the occasional problem. Thinking again of our hypothetical Space Doomsday person living in the ’60s, they might focus on the Apollo I fire and the Apollo XIII disaster as signs that it wasn’t going to work, that there would turn out, for example, to be insurmountable safety obstacles to strapping three guys into a seat on top of a hundred metre column of high explosive. I mean, who’d’ve thought it? But there were six successful missions as well as more successful translunar incursions (excursions?). It is probably true, speaking from my deeply uninformed position, that the risks taken on those missions were much higher than they would be today, and presumably are on the Artemis program, but maybe not. I confess to not paying much attention to Artemis because I don’t want to be disappointed again, so I don’t know much about it.

There are sound economic reasons for returning, including the presence of metals such as titanium more easily accessible than here and, if fusion ever happens, and that’s another thing which seems infinitely deferred, helium-3 in the soil, and water is now known to be available, in the form of ice in the parts of polar craters in permanent shadow, freeing a base from the necessity of a water supply from Earth. It was detected by the Clementine mission in March 1996, in Shackleton Crater.

The spacesuits for Artemis have been delayed, it was announced this August. This will prevent a 2024 landing, since they won’t be ready until April 2025 at the earliest. That puts it later than the next presidential election, and if for example Trump is re-elected, which unfortunately is still possible it seems, he could cancel the program before then. The current space suits are not intended to be used for extensive periods on the lunar surface, hence the need for new ones. One reason for the delay is budget cuts and another is the pandemic. But you could look at it, rather unscientifically, as a curse or fate. There is reason to deduce that something will always stop it happening because it’s possible that we can be confident nobody will ever go there again or to Mars at all. The details of the cause are apparently not available, but right now they seem to include Trump, the pandemic and budget cuts.

The Artemis program involves the building and transport of infrastructure and equipment separately from the crewed missions. This is a factor in its demise. If it was just about astronauts visiting without setting up a permanent base, it could well go ahead as that’s a less significant step in establishing a foothold elsewhere in the Solar System. Hence the crewed lunar orbital mission is more likely to happen, although this is also a step on the way. It would also be more likely to happen if it wasn’t supposed to be a preliminary to going to Mars. There was a plan, decades ago, for the first astronaut to arrive to start putting together a permanent lunar base, which it’s possible to predict wouldn’t happen for the same reason.

I’m not going to deny that a lot of this post is motivated by depressive thinking, although I’m not actually depressed just now. To counter that, I want to point out that depressive realism helps one perceive unpleasant truths, one of which appears to be that our descendants are trapped on this planet forever. And I’m not even saying that Earth is not a wonderful and beautiful place. It’s for this exact reason that humans should move many of their activities, and for that matter bodies, into space, off this planet, to preserve it and allow it to recover. Moreover, there was always going to be positive fallout from space travel, such as the Overview Effect, the Spaceship Earth concept, the discovery of the possibility of nuclear winter, the reminder Venus gives us of how easily climate change can get out of hand, not to mention the various technological benefits. Nonetheless, some people would see being stuck here as a positive thing, and it has positie aspects. It means, for example, that there is no escape from the effects of pollution, reduced biodiversity and anthropogenic climate change, except that maybe there is for the rich and powerful but not the poor and oppressed.

So wouldn’t it be nice if we had a lunar base, went to Mars and built space colonies for the people left here on Earth?