Dealing with seasons in Science Fiction and Fantasy

The concept of a year divided into four equal parts–spring, summer, autumn and winter–is a northern European one, and the images that go with these seasons are even more so. The northern European seasons are determined by the position of the sun in the sky, and therefore the temperature.

(just to be clear, the seasons are determined by the inclination of the earth’s axis to the plane of rotation and have very little to do with the distance from the sun–more about that later)

Even on Earth, there are many places where the seasons don’t conform to this four-part structure at all. Anyone who has lived on or near the equator can tell you that the four seasons are total rubbish. The “summer” is isn’t any less warm than “winter”, and trees lose their leaves either not at all, whenever they damn well please, or in response to a dry period. Even further away from the equator, seasonal rainfall is a much more dominant factor in determining the season. Before the European concept of spring, summer, autumn and winter was adopted (read: enforced) in these regions, native peoples had much better ways of describing local seasons. They usually involved the absence or presence of rain.

If you live on the equator or anywhere 23 degrees north or south of it, the sun passes over twice a year. The closer you are to the equator, the more equal these parts of the year are. When we lived in Townsville (19 degrees South), the sun was usually in the north except for about three weeks in mid-summer during which it blasted down on the side of the house that never received any sunlight in the rest of the year (hint: my poor plants were usually not impressed by this state of affairs).

The passing over of the sun coincides with a downward air stream, a humid zone, where there is a lot of rainfall. The air cells on either side become much drier until you hit the tropics of capricorn and cancer, where the air stream is upwards. This is where the earth’s deserts are. Another, similar, dry-wet band lies to the north, but here the effect of temperature takes over as season-defining factor. These bands of air volumes where weather–and humidity–circulates are called Hadley cells, and all planets with atmosphere have them. Mars does. Titan does. Venus does. How many cells there are depends on the speed of the planet’s rotation speed and its overall temperature. Titan is cold and doesn’t rotate very fast, so there is only one air cell.

Earth’s orbit is relatively circular, but it is still closer to the sun during the southern hemisphere summer. Closer to the sun means that earth moves faster during that period. So when looking only at the influence of the sun, the southern hemisphere summers are shorter and hotter than the northern hemisphere ones, and the winters on the southern hemisphere are longer and colder. Because this is such a small effect, it gets lost in other influences, such as the mitigating factor that the southern hemisphere is mostly ocean.

But imagine if the orbit was much more noticeably elliptical, like Mars.

So what does all this have to do with SFF writing?

Well, unless your planet’s axis of rotation is perfectly at right angles with the plane of movement around its sun, there will be seasons. Venus is an example of a planet without seasons. The size of the planet and its rotation speed will influence the strength and number of air cells. Anywhere close to the planet’s equator, these cells will have a much greater influence on seasons than the position of the sun in the sky. If you place a colony on a planet, the colony is likely to be on the equator, because it’s easier to launch ships.

In fantasy, a warm climate (anywhere more tropical than mediterranean) means that most likely your seasons will be controlled by rainfall. If your planet is large, warmer and/or has a shorter day than Earth, it means that the weather systems will be much more violent. Think massive cyclones.

If your planet orbits two suns, it is highly likely that its orbit will be very elliptical, as well as much wider than for a single sun. So your year will be much longer, and your seasons won’t fall into neat spring-summer-autumn-winter divisions at all.

p47179

Jupiter’s moon Io: some facts

His Name In Lights is set on Jupiter’s moon Io, which has captured my interest for some time. I have at least one other Io story in the making. Expect an announcement about A Perfect Day Off The Farm fairly soon. In that story, I explain the concept of stick farms, which is something that would actually work.

If you came here from the novella His Name In Light’s product page on my author site, click this link to go back after you’ve read this

Io is a body slightly bigger than Earth’s Moon which orbits Jupiter at roughly the same distance as the Moon orbits Earth. It is the closest of the larger moons of that planet. Jupiter, of course, is much, much bigger than Earth, and this has all sorts of consequences for its neighbourhood.

Io was discovered in 1610 by Galileo when he was looking at Jupiter and noticed three little dots close to it. Moreover, the dots were placed in a straight line (that’s a dead giveaway for a planetary or any kind of system that involves things orbiting each other), and on top of that, the next day, the dots were in different positions. The discovery of the four Galilean moons (Io, Europa, Ganymede and Callisto – the god Jupiter’s lovers in ancient mythology), proved Galileo’s hypothesis that other planet-moon systems existed and that, by extrapolation, the Earth was not the centre of the universe, nor the centre of the solar system.

You can see Jupiter and its dancing dots with a decent set of binoculars in the night sky. Because Jupiter is so large and has so much gravity, the moons race around the planet like bats out of hell, and their positions are visibly different every day.

Being the closest moon, Io orbits Jupiter every 42 hours. Since the circle it describes is the same size as the Moon’s orbit around Earth, it means it’s moving at a speed of over 17 kilometres per second. By comparison, the Moon moves at a speed of one kilometre a second. This thing is racing!

The same applies for the other three moons, Europa (3.5 days), Ganymede (7.15 days) and Callisto (16 days). All move at comparatively high speed, which is why they’re so much fun to observe. You can see them move.

The moons’ gravities also interact with each other, since all of them are roughly the size of our Moon and quite close together, astronomically speaking. They have developed a pattern of orbital resonance, where Io will orbit exactly twice within one orbit of Europa, and Europa will orbit twice with each orbit described by Ganymede. Which also means that Io will orbit exactly four times for one orbit of Ganymede. Callisto is the odd one out and isn’t playing this game.

This orbital resonance means that the three moons will frequently line up in a straight path and will be at cross-angles to each other at other times. This means that there are huge tidal forces exerted on each of those moons, but especially on poor little Io.

When telescopes became good enough to observe very fuzzy details of the surface, scientists thought at first that there were two moons. Sections of the surface are highly reflective, and later pictures of the moon show a kaleidoscope of colours in yellows, greens and reds, leading to the nickname ‘pizzaface’.

We now know that Io is made primarily of sulphur and silicates (aka ‘rock’). The atmosphere is very thin and patchy and when present consists of sulphur dioxide. There is no water at all, in contrast to the other three Galilean moons, which have significant percentages of water on their surface. It is thought that radiation from Jupiter has evaporated any water present on the surface.

Because of the huge tidal forces, Io is the most volcanic body in our solar system. On Earth, we think of tides as something that affects water, but that is just because water can easily move, so we notice the effect. Rock can’t move, so it gets hot in response to tidal forces. This is why the interior of Io consists of molten rock.

Geologists on Earth define an active volcano as one that has been known to exhibit activity within the last 400 years. Under that definition, every single feature on the 400-long list of mountains, depressions and rifts on Io is an active volcano.

In fact, the moon is so volcanic that there are no impact craters, like we can see on the Moon or Mars. That’s not because nothing’s ever hit Io, but because the evidence gets covered up pretty quickly. Essentially, Io is continuously being turned inside-out by its own fart-holes.

The spread of volcanic ash across the surface of Io amounts to an average of 1cm per year. At a geological scale, that’s massive.

It also means that any robotic craft or permanent fixture you were to put on the surface would need some sort of mechanism to keep itself un-buried from this material. To make matters worse, it’s most sulphur as well as Sodium and other elements that are Not Conducive to effective mechanical operation of equipment.

Mountains on Io are up to 8 kilometres in height. Some are volcanoes, but many are not, at least not at the top. The volcanic outlets are more likely to be at the bottom of the mountain.

Why? Well, imagine a layer of ice floating on water. Now pile ice chips on, and more ice chips and more ice chips… and eventually the layer of ice will start to protest, to buckle and twist and break, sink in one place and tilt upwards at another. Ah! Now we have mountains. The logic then also dictates that the breaks (= places where magma can rise to the surface) are next to the mountains.

What else would be special about Io?

The day on Io is 42 hours, the same as its orbital period. Because the moon is tidally locked with Jupiter, like our Moon, it always shows the same side to the planet. Which in turn means that a day on the moon is the same length as one orbit around the planet. On Io, however, this has an interesting complication.

As it races around Jupiter, Io experiences an eclipse every day when it goes into the shadow of Jupiter. The eclipse lasts 2.5 hours and in that dark time it gets so cold that the pathetic cover of sulphur dioxide that passes for atmosphere condensates on the surface as snow, only to sublimate again when the sun returns.

In fact, it is highly likely that the time of the eclipse is the darkest time of day on Io. At night, the Jupiter-facing (subjovian) side would have Jupiter in the night sky. To be honest, Jupiter will take up a very significant portion of the night sky. Think of the light it would reflect back to Io.

This only applies for the side that always faces Jupiter, though. On the other side, you would never see the planet, but you probably get some interesting views of the other moons.

No discussion about Io is complete without mentioning radiation. Every celestial body that has a magnetic field has Van Allen radiation belts. A magnetic field traps particles, either from the solar wind or cosmic radiation, in a donut-shaped torus around the planet. Crossing those belts at between 1000 and 60,000km from the Earth was one of the main concerns for the Moon astronauts. At about 370km, the International Space Station stays well clear of them.

Io orbits–you guessed it–smack bang in the middle of Jupiter’s Van Allen belt. Jupiter is the second-most magnetic object in the solar system (after the Sun). Io helps the particle soup along a bit by constantly spewing volcanic stuff into space.

All this amounts to a massive radiation load. So much that if you were to step onto the surface unprotected, you’d be dead in minutes. Radiation would also affect the operation of any robotic equipment you’d send there.

So, as you can see, there are serious challenges to doing anything on Io, and a lot of places in the solar system that are easier to visit. But Io is also one of the most interesting places in the solar system.

Reference: Io After Galileo, A New View of Jupiter’s Volcanic Moon. Rosaly M.C. Lopes and John R. Spencer (2006). Springer. 366pp. ISBN 978-3540346814.

Be warned, this book is pretty darn expensive. For those with a more casual interest, Io’s Wikipedia page has an extensive list of scientific references, some of which can be read or downloaded for free online. If you are interested in buying this book, you can get a copy here: Io After Galileo: A New View of Jupiter’s Volcanic Moon (Springer Praxis Books / Geophysical Sciences)

Find out where to buy His Name in Lights



Patty writes hard Science Fiction, space opera and fantasy. Her latest book is Trader’s Honour, in the space opera series The Return of the Aghyrians. If you’d like to be kept up-to-date with new releases, remember to sign up for Patty’s new release newsletter.

epsilon eridani

How many people are needed for a space colony?

Shifting Reality is set in a space station orbiting Epsilon Eridani b. The planet, which my characters call Sarasvati, is a gas giant which I have given rings, and the station’s main industry is the harvest of ice from these rings for the production of water, oxygen and fuel. The station is one of four human settlements in the solar system, three of them mining stations. These four settlements survive as independent communities, if not entirely from each other, then certainly from Earth, 10.5 lightyears away.

All of which raises the question: just how big does a community need to be to be truly independent, while maintaining the standard of living we’re accustomed to?

Let us take a few steps back and ask a question that will probably sound stupid, and variations of which make up many jokes: how many people does it take to change a lighbulb.

Duh, I hear you say. Changing a lightbulb is so easy, that’s why the jokes exist. I totally just googled “lightbulb jokes” and there is an entire site devoted to them, from which this beauty: How many porn actresses does it take to change a light bulb? A: Well, it looks like 2 of them are really doing it, but the real answer is actually none. They’re just faking it. Mwahahaha! Lightbulbjokes.com

Anyway, the point is, changing a lightbulb is an extremely easy task.

Or is it?

Think of all the assumptions underlying the word lightbulb: that we know what it is, what it does and how it works. That there is a reliable supply of electricity. That there is a company that makes ladders. That we have a house that has a ceiling for a lightbulb to hang on.

So, how many people does it really take to change a lightbulb? How many people does it take to make sure that lightbulbs can exist and work so that the Irishmen, or Canadians, or porn actresses, can change them?

There’s the manufacturing: the glass, the metal, the factory that puts it together and puts it in a box. There is the mining. There is the power stations and the industry associated with making them work (coal mining, hydro-power and dams, wind farms, whatever). None of those industries will work without buildings or other places to house them. People make these buildings. Those places need to be cleaned and maintained and you need people to do this. None of those companies can survive for very long without an influx of new workers, so there are places for the new generation to be trained. Looking further into the future, each of those companies needs to make provisions to allow their workers to look after the very young. None of any of these people do well without food, so there are the people who cook, and they, or course will need something to cook, so you need agriculture, after all those people have used transport to get to their work, and would like to flush the toilet after they’re done, and would also very much like to buy all the items they need in a shop. And doing all of this naked could get rather embarrassing, not to mention cold. I have not yet mentioned the internet, or medical care.

By the time the insignificant light bulb is screwed into its insignificant fitting, many people have made contributions to it. Yes, many of those contributions are exceeding fleeting, but in terms of our question–how many people would a truly independent human colony need–by no means insignificant. All those things need to work and need to be in place before someone can climb up the ladder and change that lightbulb.

Medieval humans spent a hideous amount of time simply surviving: chopping the wood, hunting the game, toiling in the fields. They might have been smart, but only the very rich ones had the time to do something with it, by buying labour to do their domestic work. When technology lifted, the growing of food was one of the first things to be large-scale outsourced to other parts of the population. Ditto with the building of houses, the very basic level of health care, the making of clothes, the raising of farm stock. Then: transport. Many people who first bought cars still did a lot of their maintenance themselves. The cars, of course, were manufactured, but these days very few people maintain their own cars. Your car might even need a computer technician. The making of clothes has gone the same way. Of course none of us, barring people in remote areas, ever produced our own electricity or looked after our own water and sewerage.

Each time living standards jump, we add an extra level of service, with associated necessary people to maintain it. If you are astonished by how many people’s efforts have touched the humble light bulb, you will be blown away by the number of people who have breathed over the space program.

I wanted to know what the web says about minimum population requirements, and if you google “how many people are needed for a space colony” the number that’s most quoted is ten thousand. I haven’t discovered the source of this number. Will quote it here when I find it.

Ten thousand is a large-ish village. My husband’s family lives in a town roughly that size. It’s very agricultural, so food isn’t a problem. There is a council that maintains roads and sewerage. But no one makes washing machines. And if someone is sick, you have to go to the hospital in the city. There is also no high school, and I’m not even speaking about a university.

Picturing that village with the people in it, it is my guess that if the rest of the world disappeared, they’d survive fine, but it would be accompanied by a very sharp drop in living standards.

Yeah, yeah, I can hear the protests. You train the people. And they multi-skill. Yep. Sure. And the people starting the colony could decide to only include smart people, and not take loafers, and expect everyone to put in their very best effort. But you know what? That will only work for so long. Loafers, disagreers and political stirrers are born. We’re in space 10 lightyears from Earth. What are you going to do? Execute them? And the last time a society as a whole tried to give everyone jobs and be hyper efficient, we called it communism. Ain’t gonna work.

What is more, society needs a fairly large proportion of people who are happy to just consume stuff. A lot of the above services will only work well at large scale. Ten thousand might be a nice number for a seeder population or might be a genetically justified number (it gets quoted in this respect), but it’s not a long-term viable population.

Approaching the problem from the other side, and forgive the macabre-ness of the following: if a quarter of the world population disappeared overnight, would our standard of living drop?

Yeah, yeah, I hear you, it depends on which ones. You could argue bluntly that the world could well do without the poorest people, but don’t go telling me that the rest of the people could just go on living as before. For one, who made that shirt you’re wearing?

A quarter isn’t that much, so what about if half the world population vanished, and let’s be fair and distribute the vanishing evenly over the entire population. Three and a half billion people, and you’d miss half the people who normally share your table at dinner. Don’t tell me worldwide standard of living wouldn’t be affected.

OK, still, it’s a matter of choosing the right people, and training. But, in order to have the same standard of living, those supposed ten thousand colonists will need the same access to extremely specialist medical care that we have. We have this care because people are allowed to specialise–because they outsource everything else. Forcing fewer people to do the same work means unspecialising them. A jack-of-all-trades will not do the same job as a specialist. End of story.

But, you can automate tasks.

Yes, and each level of technology you jump will require more dedicated specialists to maintain it. Dog, meet tail.

You need more than ten thousand. Substantially more. You need something the size of a decent city, just to maintain our current western standard of living.

Oh, I forgot, we expect these folk to maintain an interstellar space service as well…

Aggression in alien species–yes or no?

Picture pilfered from a game site. Apparently the game is called 'Alien'

Last year at worldcon, I attended a panel that dealt with scenarios following a potential first contact. We’ve discovered there are intelligent aliens. What should we do? Talk to them? Hide?

One of the opinions voiced was that if you create a situation where aliens come to Earth, they must be ‘aggressive’. I’ve thought about this a long time in terms of population ecology (which is what I was trained to do) and have come to the conclusion that yes, this is correct, and no, it is not.

The problem lies, I think, with the fact that population ecology attaches a different meaning to the word aggressive than the general public does.

An aggressive species is one that actively colonises available niches, one that has the resilience and comfort range to thrive in a wide range of conditions, and one that produces vast numbers of seeds/eggs/young. Such species will often tolerate high population densities. They will be found at the disturbed edges of established communities (roadsides, building lots). They will have short lifespans, and will often provide food for a lot of species higher in the community’s development.

Rabbits are aggressive species. When given new open land (think golf courses and paddocks), they breed like crazy. Until the trees move in, and the foxes, but by this time, rabbits have already moved onto the next open ground.

Human society, by comparison is an ecological community by itself. Within each human culture, there are those who will colonise new niches and those who build on that colonisation effort. Whether you talk about the first early Africans who moved into colder climates, the first Chinese who moved to Australia, or the first English people who moved to Dubai, it doesn’t matter. Within their community of origin, these ‘first’ groups paved the way for others, in a purely ecological sense. In a plant community, these two functions would be performed by two different species. We can conclude that humans are good at colonising within a fairly narrow temperature range, and are good at holding our territory once we have it.

Are we aggressive? Moderately so, probably. Many writers have dreamed up situations in which ‘truly aggressive’ aliens come to visit us. And this is the part where people confuse aggression with violence.

Ecological aggression–the type that will lead to colonisation of new territory–is a characteristic that needs both back-end pressure (it’s too busy in the home country) and an aim (we need new land). Ecological aggression does not mean destruction. It means invasion of an available ecological niche through settlement and breeding.

If a storm blows over a tree in a forest, and subsequently the pigs dig up the surrounding area for roots, invasive plant species (ones we call weeds) will come up in the newly-bared soil.

Taking this analogy to aliens, or a situation where humans are the invaders, what the newcomers will want is a space to live. They are not numerous enough to take on the population of an entire planet in a battle, and why would they, anyway. The locals are their best bet to learn about what’s available on the planet. They may want to trade, for technology, for unknown riches, or just for a pair of hands to do some work. But they’ll want a place to live for their expanding community.

They will most likely be friendly and cooperative, but oh-so-aggressive.

How much science does there need to be in Science Fiction?

This is a question that gets asked a bit in writer’s forums, and frankly, I have some trouble with it. I mean, it’s called Science Fiction, isn’t it?

Yes, I know there are many stories out there that don’t seem to have any science at all. Look at Star Wars, for example. It’s so full of semi-magical rubbish that you can hardly call it Science Fiction and… yeah, yeah. That said, how do you know that some real science wasn’t behind the inspiration for some of the admittedly cool worldbuilding? Sure, there was a lot of stuff that’s plain impossible and more like magic, and overall, Star Wars is probably closer to fantasy. But, you wanted to know how to write better and more sellable Science Fiction, right? You’re not writing Star Wars and your name isn’t George Lucas, so let’s forget about them and all those stories that have questionable science. You want to sell a story to a good magazine. How much science do you need?

In the last year, something changed for me. I went from being able to sell stories at semipro level to being able to sell them at pro level. In my case, I can pinpoint the exact moment of change. It was that hot Sunday afternoon in January 2010 when I went to Officeworks and bought that pair of titanium scissors. I became interested in titanium and after reading about it, I cobbled together a number of ideas into a strange ecosystem that relies on titanium. From there, it was only a small step to invent characters and a story. Ultimately, not that much science made it into the story, but the science inspired almost every bit of worldbuilding the story has.

The story I wrote next, Party, with Echoes, which I sold to Redstone SF, had even less science visible in the story, but that doesn’t mean none went into the writing of it. In fact, since it’s set on Europa, I bought a book on the moon. The same book has given me ideas for further stories.

His Name in Lights, which I sold to the Universe Annex of the Grantville Gazette, has even more science, and more of it made it into the story, but again, the science formed the basic inspiration for many elements in that story. The science told me what should happen, and gave me ideas for cool scenes. Having asked myself the question: could one possibly sign-write on the clouds of a gas giant, I set about writing a story that involved just this.

The quality of my stories took a big leap when I decided to start taking the science in Science Fiction seriously, and using the science to inspire and guide the story rather than tacking some pseudo-science onto an existing story, and hoping no one noticed. About using facts in Science Fiction, someone at the Analog forum said this very true thing: don’t think no one will check; they will. Very true. You have to get the facts right. Better still, make sure you’re one step ahead of the editors and readers in terms of research.

So I think those people who ask how much science a Science Fiction story needs don’t fully understand the concept of the genre. Science is not optional. Science Fiction is, breathes, and lives science. The inspiration for it is the science. The resulting story may or may not have an obvious science component, but without the science extrapolation or inspiration, it would be dull, commonplace or clichéd.

That doesn’t mean dull, clichéd stories don’t get written. Heck, sometimes they even get published. But if you want to give yourself the best chance at getting published in a decent Science Fiction venue, it is my strong feeling that you had better start looking after the science other than spending five minutes on Wikipedia checking the most obvious facts.

When I talk about science, I include the social sciences. There are many great stories that can be written about concepts in such fields as psychology, political science and linguistics.

You do not need a PhD in any of these fields to learn about them. Your readers will probably never have heard about the interesting concepts you have used as inspiration for your fiction, and therefore, the stories will have that spark of being different and fresh, as well as feeling authentic and interesting.

Unobtainium. So… what exactly is this stuff?

I will probably damage my reputation by saying that I enjoyed last year’s top-grossing movie Avatar on many levels. Even the science, while highly popularised, did not contravene too many known laws of physics and facts of biology. Except for one thing, and that one thing has bugged me ever since. In hindsight, it’s quite amazing how long I allow stupid trivialities to bug me.

Anyway, Unobtainium.

I mean, seriously? Which script editor worth their salt would leave such an obvious ersatz-name in the finished product? What on Earth were they thinking?

As writers do when the going gets tough, I googled it. Apparently, Unobtainium, also spelled Unobtanium, is jokingly referred to in engineering when there is a need for a material that doesn’t (yet) exist. The term is also used to indicate materials that are extremely rare. In the movie, it’s a MacGuffin. What it does is not important. Only that it is rare and very valuable and thus is the reason for the hero’s quest.

Fine by me. I just wish they called it something else.

But it keeps nagging. There is that scene in the movie, you know, where the evil and hapless company director whose name I’ve already forgotten, picks up the sample that floats above a hollow dish. It makes me wonder what this stuff is. It looks metallic, and it floats. By what mechanism and what would people do with it?

First up, why does it float? It seems to me that it needs the dish to stay up in the air. That would suggest a magnetic field. Aside from the fact that I’m unsure that a bowl-shaped dish would emit the right shape magnetic field to keep an object afloat (I’m thinking it would need to be horseshoe-shaped), I’m wondering what the benefits of such material would be. Given a magnetic field strong enough, many materials could be made to float. Maglev trains work on this principle. The floating capacity would depend on the density of the material, the size of the sample and the strength of the field, and two of these can be varied by the observer. Creating a stronger magnetic field just requires more electricity, negating the value of the material. The repelling force that holds the sample in the air can only be as strong as that induced by the magnetic field, so to stay up, the sample must be very light. It could be a very light-weight, strong material. OK, but is that really valuable enough to raze an entire planet?

Secondly, it could be some sort of anti-gravity material. I’ve thought about how this could work, but am drawing blanks. If, for example, the material consisted of atoms of negative matter, each of these atoms would repel each other (as opposed to attracting each other, which is what regular atoms do), and the material wouldn’t stay together in a clump (hint: this is why we haven’t found any negative matter). But let’s suppose some sort of property existed that rendered the material inert to gravity.

Fine, but why stop at gravity? It’s nothing but a force (actually, it’s an acceleration, but let’s not get too technical). A material cannot know if a force applied to it is the result of gravity or something else. Would this type of Unobtainium resist being pushed or picked up? Ah, but it would only be moved if physically in contact with the object doing the pushing or pulling.

Fine. We have just established that Unobtainium would be an excellent material for making heavy lift, single stage to orbit space ships. Stuff that negates gravity. Woo-hoo!

Except now we’re in orbit. How do we come down in a space ship that wants to go the other way? Er…?

So what about you? What do you think would make an element exceedingly valuable?

P.S. I’m sure there is a short story in some of this. Somewhere.

Humans in space

A while ago, I asked on Twitter what people would like me to blog about. One person (you know who you are) said: the effect of space travel on human beings. I promised that I would write about it, but that I wanted to read one more book before I did so. That book is Packing for Mars by Mary Roach. I have now read it (highly recommended), so here we go: the effect of space travel on human beings, with an eye on the future and the science fiction writer.

As one might expect, there are two types of effects long-term space travel has on human beings: physiological and psychological effects. Each of these effects mentioned below is probably worthy of a separate blog post, but let’s start with the overall first.

The physiological effects themselves can be split into two sections: lack of gravity and what I shall call external threats.

External threats are simple: accidents and radiation. Both are managed at the space ship design level and crew training stages. Good design will limit radiation exposure. The risk is solar flares, but it is a known and theoretically manageable risk. Manned missions to—say—Mars will contain shielding (best material: water, since the ship will have to carry plenty of that anyway). There will be advanced warning for the crew to take shelter in a fortified part of the craft. Accidents are obviously less predictable, and can be expected to be serious and fatal. Space travel is not without risk. Nor is getting into a car.

By far the most serious and insidious effect of space travel on human beings is the bevy of problems caused by the lack of gravity. We have evolved to live with gravity. On the short term, its absence causes disorientation and nausea. Individuals vary in their responses to weightlessness and astronaut training famously involves weeding out those most seriously affected. People with abnormalities to the inner ear may be completely unaffected, but having a deaf crew member could pose challenges of its own. It’s interesting to note that all mammals can be made to suffer from motion sickness, except rabbits and guinea-pigs (thanks to Mary Roach for that tidbit of information).

Other short-term effects of the absence of gravity are the loss of taste and appetite, the disruption of the digestive system, the pooling of blood in the upper body and the inability to sleep. Most of these effects will disappear, or at least become less prominent, after a few days as the body adjusts.

Far more serious is the loss of bone and muscle mass. Exercise helps, but doesn’t completely prevent the decrease of bone density in long-term space-travellers. And that loss can be significant, comparable with that suffered by a sufferer of extreme osteoporosis.

That said, there is a fairly simple solution: artificial gravity through rotation. At the moment, it is beyond the engineering limits of current missions, but once people overcome problems associated with sending manned missions to Mars or further, giving the inhabited section of a ship or station a constant rotation should not be too hard.

The psychological effects of space travel are associated with the fact that you’re isolated in a tin can, a long way from anywhere, with people who, like partners in a stifling marriage, start to irritate you more and more.

This makes psychological screening important. The first chapter of Packing for Mars describes seemingly inane tests done by the Japanese Space Agency (JAXA) in order to select possible astronauts, and unravels some reasons for these tests. Most importantly: how do you react to boredom? How do you react when something unexpected happens? There are huge differences between people, and in an isolated group of people, these differences may make or break a mission.

An obvious partial remedy is to send larger missions in larger ships. The lack of privacy and the inability to get away from each other conspire to make any inter-personal problems worse. The human being is a curious type of herd animal. We want to be close, but not too close to each other. It seems that a larger mission will be the answer in the long term.

Growing crops in space #2

In truth, this post should read ‘Growing crops in artificial environments’, because it applies equally to crops grown in a hypothetical space station as it does to crops grown on the Moon, or Mars or any fictional celestial body.

I’ll start off with a few open doors:
– All crops we grow as food today exist in some form in the wild. In all of those cases, humanity has bred better varieties to the point where the original plant bears no more than a passing resemblance to the crop variety. For example, compare a wild rose with the ones you buy at the florist. It’s hard to believe the commercial rose is directly descended from the wild rose. This has come about by selecting varieties with desirable characteristics (in other words: mutations) and propagating them, selecting the best plants out of that crop, and so on, and so forth. While the selection process is human-driven, there is nothing unnatural about the commercial rose’s DNA.
– All plant species evolved to be suited to their native climate. The banana is a tropical crop and will do poorly when temperatures are too low. Similarly, the banana evolved to grow in a climate where the temperature range is fairly narrow (in other words: where it’s always hot), and where the daylength doesn’t vary much either. Never thought about this? Well, here’s an everyday illustration: I live in Sydney (33 degrees south). I go to the gym at 6.30 most mornings. At that time, the TV in the gym has the news on. It’s summer right now, and at 6.30 it’s pretty light in Sydney. If, however, the news program crosses to someone in Cairns (16 degrees south), you’ll see that it’s still pitch dark over there. If they cross to someone in Hobart (42 degrees south), it has been light down there for ages. These three cities are more or less on the same latitude. In winter, exactly the opposite will happen. It will be light in Cairns, dusk in Sydney, and still pitch dark in Hobart.

To sum up, Cairns has much less annual variation in the length of its day. This is, incidentally, why daylight saving in the tropics is neither sensible nor desirable. Trust me, I lived there. You do not want daylight saving. (/soapbox).

What does this have to do with crops?

Well, you’ll probably have noticed that most crops are highly seasonal. People in our cities don’t notice this so much, because food suppliers use two mechanisms to extend availability: 1. storage (if you buy apples in February, I can guarantee that they’re about year old), 2. different source areas (with its handy dual temperate/tropical climate, Australia can grow temperate crops in winter in the tropics and in summer in the temperate regions. Surprise, surprise, most of our staple vegetables are temperate crops).

But the tropical crops that are highly seasonal (fruit trees—the banana is NOT a tree) are only available in summer. This is why mangoes come onto the market in November and tail off in January.

(for the record: Australia imports almost none of its essential fresh food)

OK, seasonal crops. Bowen mangoes flower in late August, and the fruit is ripe in the first week of November.

Why does the mango tree flower in August? Because, as in animals, plant reproduction is a hormonally-induced process that responds to triggers.

These triggers are:

– Temperature. Many plants need a cold period to flower. If you’re sick of your Phalaenopsis orchids always flowering in May, put them in a cool room at 15C for two weeks, and they’ll flower any time of the year.
– A dormant period. This is especially important in temperate plants. Dormancy is often controlled by temperature, but only because temperature triggers the production of certain plant hormones. Are you a Sydneysider who has lived in Europe? Have you ever noticed how the paltry few European oak trees in Sydney hardly lose their leaves in winter, much less produce acorns? This is why. No loss of leaves = no dormant period = no acorns.
– The real biggie: daylength. Almost all plants will react to changes in daylength by speeding up their maturity, or delaying it. This is what you are doing trying to grow a crop outside its native climate zone. Parsley, a temperate herb, is a natural biannual, but when you grow parsley in the tropics, it will neither flower nor die after two years. Parsley needs a short day (in other words: a temperate winter) to induce flowering.

And now you’re taking this hotchpotch of plants with their varying requirements into space and growing them in a controlled environment. Each species has its own maturity triggers and sensitivities. Some plants (tomatoes) are pretty much insensitive to anything you throw at them. Others (wheat, maize, rice) can be far more fussy. And daylength rhythms can be disturbed by something the strength of a street light at night (ever noticed how oak tree branches surrounding a street light are weeks ahead of the rest of the tree?)

If you want anything approaching the full range of crops you can buy in a regular supermarket, you’d have to make some adaptations to your artificial environment design. You could modify the artificial environment but supplying a few chambers with different conditions, or you could breed plants that are less sensitive to daylength (this sensitivity is controlled by a single gene). In any case, taking everyday Earth crops into space for mass food production will require a lot of thought. That, or your characters will get mightily sick of eating tomatoes.

So you want to be a space farmer?

You are writing space-based Science Fiction, and have decided your world is going to have a self-sufficient space station, base or space ship. A lot of Science Fiction books have this assumption in common. Any human colony, whether on a moving vessel, space station or on the surface of a planet, will need to produce its own food, since vast distances and transportation costs will make import unpractical. Being self-sufficient means growing stuff to eat. Here are a few points to consider to make your food production system more realistic.

There is a fair bit written about the design of the habitat. It ideally needs to be in the habitable zone of a star or closer to make optimal use of light. Artificial light is expensive and mineable energy is scarce in the depths of space. If you do position a habitat far from a star, make allowances for vast amounts of energy needed to grow plants. Without cheap and easy solar energy, the energy source would probably have to be nuclear and would have to be shipped in.

Other requirements run parallel with those for human habitation. The habitat needs to have radiation shielding. It needs to have adequate air circulation, temperature control and day-night cycles.

(ETA: this interesting article was published a week or so after I wrote this post. It deals with the effect of radiation on crops and how it seems plants can evolve to deal with it)

As an agricultural scientist, I often get annoyed when SF books suggest that ‘magic happens’ inside a food-producing habitat. You just chuck in the necessary elements, wave your fingers and POOF, there is food on the table.

In reality, things are lot more tricky than that. Once you add a biological element to your controlled environment, the system becomes complex and liable to unexpected and sudden failure.

The nutritional needs for plant growth are simple enough, but since you’re in space, you’ll have to cart everything in. Plants need the following to grow: Main elements: C, H, O. Main nutritional elements: N, P, K. Also essential: S, Ca, Fe, Mg, Mo, Mn, B, Cl, Zn and Cu. A lot can be recycled, but you’ll need to replenish occasionally.

One of the lessons learned from the Biosphere 2 experiment is that maintaining a viable ecosystem in a closed environment is damn hard. Biosphere 2 was a mixed ecosystem, containing many species. An agricultural centre aboard a facility in space is more likely to contain a much smaller range of species, making it much more vulnerable. For example, the grass family (maize, wheat, rice), the nightshade family (potato, tomato, capsicum, egg plant), the cabbage family and the cucumber family (pumpkin, cucumbers) provide a huge chunk of our daily vegetable needs. A virus only need take out one of those families and you have a severe problem.

Closed ecosystems are extremely vulnerable to pests & diseases resulting from less-than-optimal air circulation and light conditions. When something goes bad, it does so in spectacular fashion, quickly and without easy remedy. I’ve seen this happen several times… in glasshouses… on Earth.

For that reason, you’ll want backups. Don’t rely on one system, or one crop, or one station.

There will have to be some artificial tofu-like foodstuff produced for easy protein and nutritional value. Most plants are extremely wasteful in their useful crop/waste ratio. Compost works very well on a farm in the open air, but in a space station, it just…. stinks.

A process of rigorous, dare I say neurotic, quarantine will be necessary. You cannot risk anyone bringing in the tiniest mite or aphid from outside.

Some crops and livestock are much more suited to high production per unit area than others. Use tropical crops with a fast cropping cycle (C4 crops such as rice and corn) over temperate crops. Breed varieties of crops which can efficiently utilise a higher-than-usual CO2 percentage. Plants grow bigger in low-gravity conditions, and use more water.

There are some crops you won’t be able to grow no matter what. They’re either too expensive to grow or for some mysterious reason defy all attempts at growing them in any sort of health or quantity in a controlled environment. You can’t always explain why this happens. Biology is funny like that. Of course, those crops will be the most valued.

Where are you going to get your initial seed-stock and how are you going to conduct breeding and renewal? I could see a situation where each growing condition requires a different type of plant. The more variety, the less risk of wipe-out due to disease.

To sum up, a food production scheme needs to be reliable and robust. Diversity is the key to risk-spreading. My guess is you’ll probably end up having to resort to some quick & dirty chemical shortcuts, such as mining O2 from comets to make sure you have the capacity to quickly act in case of impending ecosystem collapse due to disease.

Communication in space

Electromagnetic waves, whether gamma ray, microwave, radio or visible light frequencies, travel through vacuum at the speed of—well, uhm—light.

When on Earth, this means communication is pretty much instant. If the distance travelled in one second by a photon, a light particle, were a string, it would wrap around the Earth almost five times.

You will notice that if your call goes via satellite, there is a small time lag. This is because your voice has to travel all the way up to the satellite in Earth orbit, and back down again. Communication satellites generally reside in geostationary orbit, at 35,000km above the Earth** so there is still a small, but noticeable time lag.

This time lag becomes larger the further you go.

If you were to call someone on the Moon, at 380,000km from Earth, your voice would take a bit over a second to get there.

Travelling time for a signal from Earth to the planets, travelling outwards:
Mars 19 minutes
Jupiter, 47 minutes
Saturn 74 minutes
Uranus 174 minutes
Neptune 258 minutes
Pluto 271 minutes

We say that Mars is 19 light minutes from Earth. Note that a light minute, like a light year, is a unit of distance, not time. A light minute is sixty seconds times 300,000 kilometres, which is the distance traveled by light in one second.

That’s right. If you were on the outer edge of the solar system, a radio signal would take at least four hours to get back to Earth, and another four hours to get a reply, presuming the receiving party doesn’t have to think about the response for too long. At this point in time, barring magic and wormholes, this is the fastest possible travel between these points. Immediate communication by radio between Earth and even Mars is physically impossible. This is an important point to consider if you write space-based Science Fiction

Think of the consequences:

You’d have to think very carefully about what you say. Your questions would have to be very detailed, efficient and concise. No chit-chat.

If there was an emergency, you’d have to figure things out by yourself.

If you were facing a hostile alien army, you would not have the time to ask a base on Earth if it was OK to attack, because by the time you got a reply, you might have been shot to bits.

On top of this, the strength of a radio signal is directly related to the square of the distance from the signal. Double the distance between transmitter and receiver, and the signal is reduced to a quarter of the strength. This would severely limit your options to communicate if you were talking to someone in the outer reaches of the solar system.

There might well be political consequences for your made-up solar system-wide human empire. They would suffer a lack of communication reminiscent of that which existed in the early days of European colonisation. They had no radio and letters took months to get to their destination. Lack of efficient communication may well have contributed to the fact that those new colonies went their own way within a generation, even if they were nominally still within the formal colonial structure. Eventually, wordwide communication problems were solved by radio and the telephone.

That won’t happen so easily to distances from here to the outer planets. Unless we find faster-than-light communication, which physics tells us is impossible, even the solar system will probably be too big for a connected human empire. For coherence of a human society, communication is essential.

**Geostationary orbit is the altitude at which an object orbiting the equator of a planet or moon travels at the same speed as the rotating body. In this way, the orbiting object is always in the same position over the surface of the planet or moon.