The Martian. Hollywood science!

The Martian: coming to a theatre near you! Even before release, an article turned up in our local newspaper where “experts” criticized the science in this movie. Now, I love it when people start to take science seriously, but is it fair? This story by Andy Weir started life as an ebook, and I purchased it and reviewed it on Amazon well before it took off, mainly because I too had self-published an ebook on Mars colonization and I started reviewing ebooks to help other independent authors. So, is the science OK in the book?

The biggest blooper is the storm (which I have seen in the film trailer). Martian winds can hit up to 200 k/h, but gas pressures are about 1% of Earth’s. Force is rate of change of momentum, so even after correcting for the lower gravitational acceleration and the mass of dust, the forces are comparable to a very gentle breeze here. Of course, if this were corrected there would be no story.

The next criticism of the film was that Matt Damon walks about as if he were on Earth (which he was!). Yes, the Martian gravity is slightly less than 40% of Earth’s, but who cares in a film? Worse, it would be rather difficult to get this exactly right, and if you try, the critics will soon be out finding flaws in what you do. As far as I am concerned, Hollywood is forgiven for this. It just is not worth trying to get it right, especially as the costs will add up, and I doubt getting it right would add many extra seats sold.

I shall be interested to see how close the film follows the book, because there are some more serious issues. The newspaper article mentioned radiation, and suggested that cancer was omitted from the film. I am not so sure that is important because the cancer would not appear until after the film was over, but there is another consequence of radiation, and that would relate to his living quarters, which were described as being like a tent and made of something flexible. Polymers need a good molecular weight to remain flexible, and ionizing radiation would very quickly embrittle most polymers, and if there are fibres in the tent material, make the matrix holding it together more porous, and less effective at holding gas under pressure. In my Red Gold, I got around that with two suggestions. The first was that the growing of vegetables was done in triple-layered glass houses. Glass does not degrade because it is held together with ionic forces, and should a sodium atom inadvertently be struck by a proton, well, magnesium will hold it more strongly. Eventually, it will haze, but that will also happen through other mechanical abrasion. My second defence against ionizing radiation was to have a giant superconducting magnet at the Mars-Sun L1 position, which would give a small deflecting nudge to incoming charged particles. This Lagrange point is where the planet and star’s gravitational fields equal the centripetal force required for any body to have the same orbital period as the planet. This position is only metastable, so corrections are needed, but this can be minimized by having the body orbit the position (carrying out a Lissajous orbit). Would this work? I hope so! So far nobody has criticized me for it.

However, another problem in the book, and I shall be curious about how the film does this, revolves around growing potatoes. Mark Watney (the character) needs water. Don’t try what he did, or if you must, try to be just a tad more competent. The method in the book is just plain ugly. Also, there had to be some other way because originally the crew would have needed water. In Red Gold, my method was to condense it from the atmosphere (50% humidity). Of course there is not much atmosphere, but it has to be pumped up to a useful pressure anyway. You cannot live in a space suit. The second method, once you find it, is to dig it up. Mars has plenty of ice, although finding a convenient lump depends on where you are. A more serious problem is nitrogen. You cannot grow things without certain elements in the soil. Potassium and phosphorous are probably there in small amounts in any soil, but nitrogen is different. So far, minor amounts have been found at Gale Crater, but not by other rovers, although in some cases they did not have the capability of detecting it. The Martian atmosphere has very little nitrogen, so unless there is a lot buried, settling on Mars could be difficult. Certainly, the growing of potatoes under the conditions described in the book would need somewhat more nutritious soil than analyses have so far indicated.

Is this important? I think so, because apparently there are people signing up for a one-way trip to Mars. I would hope they know what they are letting themselves in for.


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.

Respect for the top job?

Many of my scifi ebooks look at the question, how do people respond to the group, i.e. following fashion, or responding to conditions imposed by governments, or worse still, by religions? In the first novel of my “First Contact” trilogy, a party of five had found that aliens expected humanity to behave better before it thought about going to other star systems. In my second novel, Dreams Defiled, four of them set out to accomplish difficult tasks. The objective of two was to make things fairer for all citizens, of one to manage the greatest engineering feat of mankind, and of one to try to make the settlements on Mars more achievable. The fifth had only one dream: to be important, by any means possible.

The trilogy is really about for most the desire to comply with the group, for a few, the desire to be different, and for some, the desire to take advantage of everything they can, at the expense of all if necessary. The background is one of economic stagnation, where almost everyone works in a corporation because there are very few resources available for the general population, and because it is the political fashion to do so. There are those who do not, and the majority react badly to them. The story revolves about people who have great ability, but who will be subverted by lesser people, and also of how corruption and lack of attention to maintaining solid moral and ethical values amplifies the evil in weak people. Part of the story involves the tendency of the group of people to pick on those who are not part of the group fashion, and those who would betray anyone for money. Also, the story required the most evil person I could manage to create for the third book in the trilogy.

When I published this, it was with a little tongue in cheek. The mindlessness could not happen. If people stepped too far out of line, public opinion would bring them back into line. There is nothing wrong with opposing government actions, and indeed countries following the British parliamentary system have what is called “the loyal opposition”. The idea is, those who lost the last election have the task of keeping the winners honest, and producing arguments to show the flaws in the policies of the winners. It may not always end up quite so “pure”, but in general, that is supposedly what they do. But surely deliberate subversion is out? We may not agree with the top men (or women) but surely we accept they are there.

Unfortunately, it seems to happen, albeit on a much smaller scale. Recall the birthing issue with President Obama? Let us suppose this was truly an issue, what is the correct way to go about dealing with it? In my opinion, simply provide evidence that there was a problem. Fair enough to raise the issue, but without evidence, it cannot go further. And surely, there would be many others who had looked at this first. Then look at President Obama’s record, including what seems to be referred to as Obamacare. This was a policy announced as a candidate, so when he won the election, surely he was required to carry out such a policy. The people had voted for him, hence they voted for his announced policy. Is that not what the electoral system is supposed to mean? Should not those who lose accept it, at least until the next election?

The real question may be, why does the man at the top polarize opinion so much? Is it because we place too much emphasis on the person at the top? In business, do you really think the man at the top actually does what makes the business work? Or is it all the underlings? While there is the occasional great person at the top, most of the leaders I have met are depressingly ordinary, and have got there largely because they have one big ability: the ability to gest to the top.

The theme, if you like, is the place of the individual with respect to the greater group. Everyone cannot be President, which raises the question, why is doing the best you can be a lesser role? Perhaps one of the most admirable examples was that of Marcus Vipsanius Agrippa. Without Agrippa, Augustus would have been nothing, because Agrippa was the man who won his battles, and he was the person who got things done. When another aqueduct was needed, Agrippa arranged for its construction. And Agrippa was always in the background, leaving Augustus to take the credit. The point is, this did not matter to Agrippa. Governments need more people like this.

Why raise this now? Dreams Defiled will be on an Amazon countdown discount as from September 11, so now seemed to be the time ☺

An “invention” in Science Fiction, or reinventing the wheel!

One thing expected of science fiction authors is they should “invent” something, although obviously only in fiction. Remember the Star Trek “communicator”, which now is recognizable as a flip-open cell phone. In other words, Star Trek anticipated it. How? Well, obviously, as with other real inventions, there was a need. People exploring need to communicate with others, so they had a communicator. Obviously, you want it to be small and convenient, so it was small and convenient.

So, what has this got to do with me? Well, in my novels about the colonization of Mars, there were obvious things that had to be done, and one of these was I thought it desirable to have some sort of plant that would live outside of specialized domes. The reason for this is that people badly need the products of plants, and it would be really helpful if you could grow something out in the wastes. This led to the need to “invent” a plant that could grow outside, and hence the genetic engineers developed the “Mars cactus”. So what would it look like?

One thing that a Mars cactus would not need is spikes. No need to defend against plant eaters because there aren’t any. Obviously it had to defend itself against the bitter cold of night, so what I envisaged was a thick-skinned plant that was more like a “flat rock”, and was very thick. Inside, it had antifreeze. It would still need water, so to start with, some form of watering had to be carried out, and more on that in a later post. The next thing it needed was protection against the UV light, and it needed to absorb heat, and fortunately both of these could be achieved with a dark absorber. Many plants on earth actually have UV absorbers. Also, it had to make something useful, but fortunately it is not that difficult to envisage a plant containing cellulose.

However, the really big problem is any plant growing outside has to be able to reproduce to be useful, so I envisaged what I thought was a sneaky strategy, based a little on my experience with seaweeds. Seaweeds have an interesting sex life. They have male and female forms, and these reproduce if they can be close enough together to fertilize each other. Seaweeds, of course, have the advantage that the water currents may et the gametes get together. The offspring of such fertilization are sporophytes, which do not need fertilizing and they send out clouds of spores that if they take hold of anything, they grow into the male and female forms.

So, my Mars cactus had the following reproductive strategy. It grew tendrils underground, and if these touched a tendril of the opposite sex, an entity grew that would reach up and grow on the surface and when mature would send out clouds of spores. The spores would settle, dig into the ground, and form the tendril form. Does that seem plausible? You may think that is ridiculous, but, as I found out later, it is quite plausible. It is, after all, the reproductive strategy of the mushroom, and mushrooms, and other fungi, have existed for a very very long time. Not reinventing the wheel, perhaps, but reinventing the fungus.