Problems of Sustaining Settlements on Mars: Somewhere to Live.

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

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

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

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

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

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

Advertisements

The Need for, and the Problems of, Recycling

The modern economies rely on the supply of raw materials, and of these, elements are the most critical because there are no alternatives to them. Businesses will collapse if certain elements became unavailable, and the British Geological Society puts out a “risk list” of elements that have a risk of supply disruption. The list is debatable, because it includes political risk, thus the most risky from their perspective are the rare earth elements, the problem here being that China is essentially the main producer and reserve holder. These elements’ risk factors also depend on their demand, thus if there is no known use for something, it has zero risk because even if there is none of it, who cares? However, the overall conclusion is, we could have a problem. As in many such issues, not everyone agrees. Staff at the University of Geneva have published a report arguing that there is no shortage, at least for the foreseeable future. They argue you can mine over three kilometers below the Earth’s surface, or in the oceans. Whether you want to do this, or can even find the deposits, is less clear.

There is no shortage of elements but the bulk of them are distributed in very low concentrations in rock, or seawater. It may surprise some to know that there is plenty of gold in seawater. The problem is, it is rather dilute, and of course there are massive amounts of other materials. Thus there is about eleven tonnes of gold in a trillion tonnes of seawater. Good luck trying to get it out. Same with the rare earth elements. They are not especially rare; however they are particularly rare in workable deposits. Part of the problem is their chemistry has a certain similarity to aluminium, and as a result, they tend to be spread out amongst feldsic/granitic material and as microscopic inclusions (mixed with a lot of other stuff) in basalt. Rather interestingly, there are massive deposits on the Moon, where, as the Moon cooled down, the various rocks crystallised into solids, and one of the last of the liquids to solidify was KREEP, a mix of potassium (K), rare earth elements, and phosphate (P). This also indicates the reason why we have ore deposits on Earth: geological processing. Taking gold as an example, it, and silica dissolve in supercritical water, and as the water comes to the surface and cools down, the gold and the silica come out of solution, which is why you find gold in quartz veins. There are, of course, a variety of geological routes to make ores, but geology is a slow process, so once we run out of easy to find deposits, we have a deep problem. And on a planet such as Mars, there has not been so much geological processing, and no plate tectonics.

One way out of this is recycling, if you can work out how to do it and make a dollar. One big user of rare elements is mobile phones. Thus the “swipe-screen” uses indium/tin oxide, the electronics use copper, silver and gold for carrying current, tantalum for microcapacitors, and neodymium in the magnets. These are the critical elements, and in general there are no substitutes for their specific uses. However, the total number of elements used can be up to sixty. The problem for recycling is first, to get hold of the old ones, as opposed to have them lying about or thrown in the trash, and then to separate out what you want. If you simply melt them, you get a horrible mix. The process could be simplified if the phones could be split into parts, thus only the screens contain indium, but how do you do that?

Early on in my scientific career, I was asked by a company to devise a means of recycling coloured plastics. I did this, a pilot plant was built, a few bugs were ironed out and we could recycle coloured polyethylene to get a very light beige product that could be made into new coloured products by the addition of pigments, and the casual user would not know the difference between that and new plastics for most uses. So this should have been a success? Well, no. There were two problems. This was during the oil crisis of the seventies, and what had happened was that there was an oversupply of new polyethylene in the world. Such surplus was dumped on the New Zealand market, where “it would not do any harm”. That dumping made the venture economically unsustainable. Some time later, the dumping stopped, but by this time the original company had lost interest. Also, the manufacturers introduced more cross-linking, and in a quick demonstration, the process did not work without altering the conditions beyond what had been assumed. There were ways around that, but the warning was clear: the manufacturers were not being friendly to recycling as they kept their information close to their chests. Such changes really hinder recycling. However, that was not the worst: new laminates started appearing, and these were a horror for recycling because the two or more different plastics put together as layers do not separate easily, and any product made from a resultant mix will be of very low quality.

So, we can either have a problem with elements, or we can recycle. Recyclers tend not to have the high technology of the multinational corporations, so my recommendation is, manufacturers should be made to design their goods in a way that aids recycling. For example, a laptop or a mobile phone has lithium ion batteries. It is also essentially impossible to get the battery out when it dies and leave the item in a workable condition. It might suit the manufacturer to force the consumer to buy another laptop as opposed to a new battery, but as the technology matures, is that good enough? Similarly, if the motherboards could be removed/replaced, that would aid recycling and also reduce demand for new gadgets. When I was young, people fixed things. I think it is time to return to those times, and also make objects as recyclable as possible. The problem then is, how do you manage that in a market where competition rules, and the consumer does not think about recycling when he or she buys a new product?

Settling Mars and High Energy Solar Particles

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

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

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

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

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

Accordingly, a solution to the problem of high-energy solar particles on settlers on Mars would be to put a strong enough magnetic field at the Mars sun L1 position, so as to bend the path of the solar particles away from Mars. What is interesting is that very recently Jim Green, NASA Planetary Science Division Director, made a proposal of putting such a magnetic shield at the Mars-Sun-L1 position. For a summary of Green’s proposal, see http://www.popularmechanics.com/space/moon-mars/a25493/magnetic-shield-mars-atmosphere/ .

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

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

Substitutes for fossil fuel

In my previous two posts I have discussed how we could assist climate change by reflecting light back to space, and some ways to take carbon dioxide from the atmosphere. However, there is another important option: stop burning fossil fuels, and to do that either we need replacement sources of energy, or we need to stop using energy. In practice, reducing energy usage and replacing the rest would seem optimal. We already have some options, such as solar power and wind power. New Zealand currently gets about 80% of its electricity from natural sources, the two main ones being hydro and geothermal, with wind power coming a more distant third. However, that won’t work for many countries. Nuclear power is one option, and would be a much better one if we could develop a thorium cycle, because thorium reactors do not go critical, you cannot make bombs from the wastes, and the nuclear waste is a lot safer to handle as the bulk of the radioactive wastes have very short half-lives. Thermonuclear power would be a simple answer, but there is a standard joke about that, which I might as well include:

A Princeton plasma physicist is at the beach when he discovers an ancient looking oil lantern sticking out of the sand. He rubs the sand off with a towel and a genie pops out. The genie offers to grant him one wish. The physicist retrieves a map of the world from his car, circles the Middle East and tells the genie, ‘I wish you to bring peace in this region’.

 After 10 long minutes of deliberation, the genie replies, ‘Gee, there are lots of problems there with Lebanon, Iraq, Israel, and all those other places. This is awfully embarrassing. I’ve never had to do this before, but I’m just going to have to ask you for another wish. This one is just too much for me’.

Taken aback, the physicist thinks a bit and asks, ‘I wish that the Princeton tokamak would achieve scientific fusion energy break-even.’

After another deliberation the genie asks, ‘Could I see that map again?’

So, although there is a lot of work to be done, the generation of electricity is manageable so let’s move on to transport. Electricity is great for trains and for vehicles that can draw power from a mains source, and for short-distance travel, but there is a severe problem for vehicles that store their electricity and have to do a lot of work between charging. Essentially, the current batteries or fuel cells are too heavy and voluminous for the amount of charge. There may be improvements, but most of the contenders have problems of either price or performance, or both. In my novel, Red Gold, set during a future colonization of Mars, I used thermonuclear power as the primary source of electricity, and for transport I used an aluminium chlorine fuel cell. That does not exist as yet, but I chose it because for power density aluminium is probably optimal for unit weight, and chlorine the optimal for the oxidizing agent because chlorine would be a liquid on Mars, and further under my refining scheme, there would be an excess of it. Chlorine has the added advantage that it reacts well with aluminium and the aluminium chloride will contribute to the electrolyte. As it happens, since then someone has demonstrated an Al/Cl battery that works very well, so it might even be plausible, but not on Earth. One basic problem with such batteries is an odd one: the ions that have to move in the electrolyte usually interact strongly with any oxygen atoms in the electrolyte, thus slowing down, and reducing the possible power output. That is another reason why I chose a chloride mechanism; it might be fiction but I try and make the speculative science behind it at least based on some correct physics and chemistry.

So, in the absence of very heavy duty batteries, liquid fuels are very desirable. As it happens, I have worked in the area of biofuels (and summarised my basic thoughts in an ebook Biofuels) and with a little basic arithmetic we find that to replace our current usage of oil, and assuming the most optimal technology, we would need to add another amount of productive land equal to our total arable farmland, and that is simply not going to happen. That does not mean that biofuels cannot contribute, but it does mean we need to reduce the load.

There is more than one way to do that. In one of my novels I came up with the answer of having everyone live closer to work. Where I live, during the rush hours there are streams of cars going in opposite directions. If they all lived closer to work, this would be unnecessary. Everyone says, use public transport, except that if you do, you see the trains are choked at that time of day. Such an option would require a lot of social engineering because the bosses want work done at centres where they think it should be done, while the workers cannot afford to live anywhere even vaguely nearby. That means social engineering is required, and people tend to object to that, and politicians will not impose it on the bosses.

As mentioned in my last post, a slightly better option is to grow algae. Some of these are the fastest growing plants on the planet, and of course as far as area is concerned, the oceans are unlimited, at least at present. Accordingly, it should be possible in theory to solve this energy problem. The problem is, though, with the technologies I have recommended here, they all require serious development. We know in principle how they all should work, except possibly nuclear fusion, but we do not know how to put the technology into a useful form. Meanwhile, with the low price of oil there is no incentive. Here, the answer is clear: a serious carbon tax is required on fossil fuels. I would like to see the resultant money being at least in part spent on developing potential technologies. Maybe this is my personal bias coming through – the promising algal technology I was working on collapsed when fund-raising was scheduled for the end of 2007, and thanks to Lehmans, that was not going to succeed. I am not alone. I am familiar with at least three other technologies of which I had no involvement but looked extremely promising, but they ran out of funding. As a society, can we afford the waste?

Remedies for Climate Change: (1) Reflect!

In my post of a week ago, I raised the issue of climate change, and argued that because there is a net power input to the surface now, due to reduced cooling caused by the blanket effect of the so-called greenhouse gases, even if we stopped producing such gases right now, we would still have serious problems because the current rate of net ice melting would continue. Now, it is all very well to moan about it, but the question is, what should our response be? This is too complicated for one post, so this will start a small sequence, although not all will be consecutive.

The easiest response is to do nothing and keep going as we are. Eventually, the sea will rise by about 60 meters. That would drown London, Beijing, and a number of other cities, in fact almost every port city, and it would remove a huge amount of prime agricultural land. Suppose we do not wish that, what can we do? In logic, there are four main options: lower the heat input; raise the heat output; store input energy as chemical energy; increase snow precipitation on polar regions so that it makes up for the increased melting. The last option means we accept everything else, such as increased temperatures and worse storms, but we protect our land. Obviously, we should also reduce our output of so-called greenhouse gases, because while even stopping this output does not solve the problem, at least it stops making the problem increasingly more difficult.

You may argue that such options suffer from failure to be practical. Possibly, but unless we investigate, how do you know? Another argument sometimes put forward is we should not do anything because there could be unintended consequences. That too is true, but is drowning London and starving a great fraction of the population a desired consequence, because that is what happens if we do nothing?

Lowering the heat input is most easily achieved by reflecting more radiation to space i.e. increase the albedo of the planet or place reflectors in space. Increasing the albedo is probably most easily done by increasing cloud cover. One proposal I have seen to do that is to spray seawater into the air. The biggest single problem with this proposal is that there appear to be no readily available analysis of the costs and benefits. How would we power the sprays? If that were done through solar, or wind energy, that would be more helpful than doing it by burning diesel. How long would such salt-laden clouds last? We simply don’t know. Some might argue that clouds contain water, which is itself a powerful blanket material. That is true, and it is why cloudy nights are warmer than cloudless ones, nevertheless there should still be a significant net benefit, because the reflection to space is of visible and even ultraviolet light, whereas the blanket effect merely affects infrared light, of a moderate frequency range, although it does it 24 hrs/day.

How about space reflectors? The cost would be enormous, although there is one possibility. Suppose one could develop solar-powered lasers that were sufficiently powerful to ablate space junk. You do not need a major mirror, but merely a large surface area. If you could boil away the metal and condense it as dust, that would still qualify as area. As an aside, it does not need to be that bright, although it should be. If sunlight is absorbed in space, that is almost as effective because the dust then re-radiates the energy as heat, and most will be directed to space.

It is also possible that there could be other minor ways of contributing. Thus the concept of everyone painting their roof white, as suggested by physics Nobel laureate Steven Chu, or even using aluminium for roofs is often rejected as making contributions that are too small, nevertheless, every ordinary householder still has to paint their roof or replace it at some time, and does it hurt to be helpful?

Another possibility might be to inject something into the exhaust of jet engines at high altitude. The point here is the jets are flying anyway, and you would end with micron-sized white dust in the contrails. Materials have to be chosen so they do not form slags in the engines, hence the choice depends on technical details of which I am unaware. Materials, in order of higher melting point dust, might range from a mercaptan or dialkyl sulphide (no solid, but would produce sulphuric acid on oxidation, which would condense water vapour and make clouds), diethyl zinc (which would produce white zinc oxide, melting point 1975 oC, and hence would remain as a dust in any working engine) or alkyl silanes (which would produce silicon dioxide, similar to volcanic ash, with a melting point above 1600 oC. The actual melting point depends on the form of the solid).

Finally, there is also the possibility of growing certain crops that give off gases that may increase cloud cover. Thus certain marine algae are reported to give off mercaptans, which would be photooxidised to sulphuric acid and thus form clouds, and also each molecule would remove some number of photons from the solar input. Removing ultraviolet also removes the corresponding heat input.

An important point to consider is that all light that is not reflected to space is either converted to heat eventually, or is locked away as chemical energy. The Earth continually presents to the sun a cross-sectional area of about 40.5 x 10^12 square meters. You can work out for yourself the area required to reduce the solar input by whatever per centage you wish, after correcting for whatever efficiency you choose, but as you can see, it is a very large area, no matter what.

It may strike you that trying to solve this problem this way is simply too difficult and expensive. Possibly, but my argument is we are wrong to rely on one king hit. For me, this is the problem to be solved by a thousand cuts, so to speak. In later posts I shall add thoughts on the other alternatives. However, the above thoughts seem to me to form the start of a concept. There are some things we might try that either might have other benefits or are reasonably cheap to put into practice, and these should take some form of precedence. But the overall conclusion is clear: there is simply insufficient data available to reach any reasonable conclusion.

Construction, Greed, and Regulations

In my previous post, I used the production of drugs as a reason why a government is required for optimal outcomes. Of course, this also requires efficiency and purpose from the government, and admittedly performance is not always very good. That does not mean that governments should be abandoned and everything left to the private sector. No. What it means is the governments need to be booted into efficiency. In this post I shall address construction, and here the performance of government has often been patchy, but invariably the worst outcomes have arisen when minimalist governments were in place. Leave it to the private sector has produced the effects of greed.

The first example comes from ancient Rome. Romans were great constructors, and two of the examples included the provision of sewers and aqueducts. Both of these are for the public good, but neither can easily be made profitable for anyone else to provide them, or at least they could not in ancient Rome, nor in most modern countries. One of the advantages of the Roman government making them was also that they were made well. In terms of sewers, the Cloaca Maxima, built in the fourth century BC and upgraded by Augustus apparently still drains the Forum Romanum and some nearby area. The Romans built to last. The aqueduct that went around the side of Vesuvius survived a pyroclastic blast, and served all of its targeted cities but those that were buried until late in the fifth century, when maintenance was abandoned with predictable results. (The two main ones that were not served were Herculaneum and Pompeii.) I suppose there is an argument that had there been shoddy construction, we would not know about it, but most certainly there was none on the major projects. Why not? One reason may well have been that if you tried to cheat the state in ancient Rome, the penalties tended to be somewhat more severe than we dish out to our worst criminals. One option was to be sold to provide entertainment, and most miscreants would not provide it a second time.

Move forward to Tudor times in England. Ever wondered what caused the Great Fire of London? We don’t really know, but we have a very good idea what caused a number of lesser fires that caused wipe-outs of significant parts of towns. It was caused by the then recent invention of the chimney, and any reasonably well-off Tudor person would have one in his house – or maybe two, one at each end. Chimneys had to be made of brick, with substantial heat barriers, etc, but a few unscrupulous builders found that they could make a lot more money if they built the middle part of the chimney with wood. It was much faster to build, and as long as the owners did not let the chimney soot up, it probably did not matter. The problem was when it did soot up and was not properly swept; now the wood burnt rather nicely, and since the wood connected to the rest of the house, so did the house.

Fast forward to New Zealand. Up until the start of the 1980s, the country had strong building regulations, but by the mid 1980s, there was a bout of deregulation. The market always knew best, said the politicians. My view is the politicians were just plain lazy and could not be bothered doing any more than they absolutely had to. Anyway, there was a building boom, with houses, apartment blocks, and some larger building complexes. Many of the larger ones have not survived in their original form, and one, in Christchurch had short lateral steel reinforcing, so that when the earthquake came along, the flexing of walls in different directions meant there was insufficient length to bridge the gap, and the building pancaked. That was real saving – a few inches of steel missing per girder saved a few dollars and killed many of those trapped in it, thanks to slack governance. In Auckland, there were designs that would never have passed the previous building codes, and that used “new better value materials”. Ten years later, the buildings were found to be horribly leaky and rot and corrosion meant that effectively they were the next best thing to worthless. To make a few extra dollars for the builders and building materials suppliers, many of whom then wound up their companies so the owners had no legal resort, the purchasers easily lost a few hundred thousand dollars each. Here, the innocent lose, because when you buy a house, how many of you really know what the interior of it looks like.

Then, recently, in Taiwan an earthquake flattened a building. The concrete walls apparently had empty oil cans in the walls to save concrete. Concrete has tremendous compressive strength, so as long as the walls etc stayed vertical, there was no problem, as normally such walls have an enormous surplus strength. Unfortunately, concrete has a very poor flexural strength; it either moves as a block or it breaks. In an earthquake, the lateral forces and the cans meant that there was insufficient strength for it to move as a block.

My question is, why should citizens die because someone wants to make a few dollars and cannot be bothered to explain what the risks of using it are? The only organization strong enough to stop this is a government. It is needed, and “I can spend my money better than it can,” is just another form of stupidity or greed.

The Space Elevator

One of the problems for humans having settlements off-Earth is the huge cost of getting the supporting materials there, and the great bulk of that cost is actually in getting the stuff out of Earth’s gravitational field. If you look at a chemical rocket, you start with a huge monster, and cart up only trivial amounts, the reason being that the great bulk of the initial mass is the mass of the fuel necessary to get the rockets going, and the mass of the metal needed to contain the fuel.

One proposal to get around this is the space elevator. The idea of this is simple in concept. At about 35,800 km above any point on the equator the orbital angular velocity is the same as that of the Earth, and hence you have a point in space where a satellite is always above the same point. At the risk of annoying some physicists, if we reduce the problem to one dimension, the centrifugal force arising from the orbital motion is exactly the same as the force heading towards the Earth and the angular velocity is the same. Now, suppose we put a cable between Earth and this geostationary point, and make the cable strong enough that we can run an elevator up and down it. Now the work done is the same as using an elevator, and an electric motor can power it. But as it stands, this won’t work because where before the centripetal force was that of earth’s gravity, now it has the force from the weight of the cable added to it. This can be corrected by adding corresponding centrifugal force, achieved by extending the cable further and attaching a massive body to it. As long as it stays put, its centrifugal force will cancel the weight of the cable, so if all this is done carefully, you have an elevator cable that you can run things up and down and transfer everything to a geostationary satellite.

From an economic point of view, the space elevator should lift material up there at least 8 times cheaper than the most favourable prediction from rockets, and its capital cost is estimated to be about $20 billion. So, why do I think this is a non-starter?

First, there is the issue of materials. The cable appears to need to be at least 40,000 km long. Something like titanium is far too weak for the task, but it has been speculated that carbon nanotubes might be satisfactory. However, you are not going to make a 40,000 km long nanotube, so some sort of composite will be required. The strength is that of the weakest part. The composite has to be at least as strong as the nanotube, and adhere as strongly, and also retain that strength indefinitely despite space weathering. I do not believe such a material is possible.

The next problem is, where do you put this cable while you are making it? You have a single length that is 40,000 km or so long. Where do you store it while you are making it? Assuming you make it in sections, how do you know the joins will be strong enough? How do you know there are no weaknesses deep within the cable? Then specifically where do you assemble it? How? A coil? How flexible are such nanotubes, and why is the composite sufficiently elastic? What is the proposed radius of the coil? Since it has to be on the equator, how many notice the equator is basically wet?

Now, suppose this huge cable is coiled up somewhere, how do you get it into position? You cannot really take it up with a rocket because the exhaust will ignite your carbon. Oops! On top of that, the rocket has to go up and counter the Earth’s rotation. But just suppose you get this massive weight up there, how do you hook it to the counterweight? The asteroid, recall, is NOT in geostationary orbit but will have quite a relative velocity. Your propulsion unit has to arrive at exactly the right time, with thrusters supporting the whole weight of the cable, and somehow this has to be joined to the asteroid while still supported by the rocket until the junction is firm. And even if you think you can manage this, how can you be sure that nothing will go wrong? One slip, one miscalculation, and 40,000 km of cable comes hurtling back to Earth. That is enough to wrap itself around the planet, causing serious damage to anything in its path. Then, supposing all this can be done, how do you get it down again safely at the end of its working life? In part because I have designed and overseen the construction of a chemical plant, and have seen what can happen with engineering, and I know one should always start off small, to iron out the bugs. That is not possible here and I just do not have sufficient faith in such a one-off engineering feat.