The Science of Avatar

The Science of Avatar

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by Stephen Baxter

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Audiences around the world have been enchanted by James Cameron's visionary Avatar, with its glimpse of the Na'vi on the marvelous world of Pandora. But the movie is not entirely a fantasy; there is a scientific rationale for much of what we saw on the screen, from the possibility of travel to other worlds, to the life forms seen on screen and the ecologicalSee more details below


Audiences around the world have been enchanted by James Cameron's visionary Avatar, with its glimpse of the Na'vi on the marvelous world of Pandora. But the movie is not entirely a fantasy; there is a scientific rationale for much of what we saw on the screen, from the possibility of travel to other worlds, to the life forms seen on screen and the ecological and cybernetic concepts that underpin the 'neural networks' in which the Na'vi and their sacred trees are joined, as well as to the mind-linking to the avatars themselves.

From popular science journalist and acclaimed science fiction author Stephen Baxter, THE SCIENCE OF AVATAR is a guide to the rigorous fact behind the fiction. It will enhance the readers' enjoyment of the movie experience by drawing them further into its imagined world.

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The Science of Avatar

By Stephen Baxter


Copyright © 2012 Stephen Baxter
All right reserved.

ISBN: 9780316133470


“What lab experience do you have?”

“I dissected a frog once.”

Dr. Grace Augustine and Jake Sully

This book is about the science behind James Cameron’s movie Avatar. And to explore that science we’ll access behind-the-scenes secrets of James Cameron and his team.

But an awful lot of the science in Avatar is right up there on the movie screen. All you have to do is observe it.

Imagine it’s the year 2154, and you’re on Pandora, moon of the gas giant Polyphemus, planet of Alpha Centauri. You are following combat veteran Jake Sully down the ramp from the Valkyrie shuttle that has just brought you down from the orbiting starship Venture Star. You are at Hell’s Gate, the main operating base of RDA—the Resources Development Administration—which is here to mine this world for the supremely valuable “unobtanium.” Jake, though, is to report to Dr. Grace Augustine, to take part in the “avatar” programme she heads: his mind will drive a surrogate body intended to make contact with the Na’vi, natives of this world.

But you’re not thinking about any of this just now. You’ve just arrived, on an alien world. What do you see? What can you hear, smell, feel?

Actually, as you have your exopack mask glued to your face, all you can smell is canned air. Perhaps the sky is an odd colour, due to Pandora’s subtly different mix of atmospheric gases. Maybe there are funny-shaped clouds. You could hardly miss the two suns of Alpha Centauri, and that big old Jupiter-like world hanging in the sky. You might see little of Pandora’s native life, which has been pretty much excluded from Hell’s Gate.

You notice an odd feeling of lightness: a bounce in your step, a feeling that your head is full, like having a cold, a peculiar looseness in your internal organs. If you’ve trained on the smaller worlds of the solar system, the moon and Mars, you recognise these sensations; it was similar there. What you’re feeling is Pandora’s low gravity.

But then a huge mining truck roars past—and, with Jake, you see arrows sticking out of a tyre.

This is Jake’s very first observation of the Na’vi, the natives of Pandora. And this alone tells him, and you, a great deal about them.

To begin with, the Na’vi must be smart, with cognitive skills at least similar to modern humans’. Even an arrow—with a shaft, a head, some kind of flight—is a multi-part tool. On Earth, only humans have ever made such things, as far as we know, not the chimps, none of our hominid forebears with their chipped stone tools. Another proof of smartness is the fact that the Na’vi evidently targeted the tyres, which look like the vehicle’s weak point.

But how did the arrows get there? You already know that the Na’vi have a roughly humanoid form. You saw avatar bodies being grown in tanks aboard the starship from Earth. And given that, you might speculate (correctly) that a bow was used to fire those arrows. But you’re on another planet. How likely is it that an alien life form would develop a bow-and-arrow technology?

Well, on Earth, bow-and-arrow technology was independently invented several times. It seems to have emerged first by 8000 B.C. in Germany, but was separately developed by North American natives, who had no contact with the Old World between around 11,000 B.C. and the arrival of Columbus. The isolation of the continents has provided us with natural laboratories to study cultural evolution. Many things were invented independently, such as farming, wherever the local resources made them possible. Archery is one of these—although it didn’t always occur. The Aborigines of Australia never developed it; instead they used a throwing stick, like the South American atlatl, that they called a “woomera”—a word later adopted for the Australian space launch centre.

So it’s not a great surprise for you to discover the Na’vi using archery, after another independent invention, on another world entirely.

And nor might you be surprised to hear Jake being told by Colonel Miles Quaritch of SecOps, head of security at Hell’s Gate, that the Na’vi like to dip their arrows in a “neurotoxin” poison. The South American Indians similarly fought back against the Spanish conquistadors with arrows and darts coated with deadly frog slime, strychnine, and curare, an alkaloid that causes fatal paralysis.

But, of course, the first thing ex-Marine Jake will have noticed is that the Na’vi are evidently hostile. Just like the Spanish on Earth in pursuit of gold, the twenty-second-century conquistadors of RDA, here in pursuit of unobtanium, have come face to face with hunter-gatherers of the forest.

All this Jake, and you, could deduce just from that very first observation on Pandora, of arrows in the tyres.

Audiences around the world have been enchanted by James Cameron’s visionary movie Avatar, with its glimpse of the Na’vi on their marvellous world Pandora. And, like Jake Sully in his psionic link unit, many haven’t wanted to wake up from the dream: “Avatar withdrawal” has become a common syndrome.

But the movie is not entirely a dream, not entirely fantasy. There is a scientific rationale for much of what we saw on the screen. This isn’t a surprise, as the creators consulted specialists and used their own scientific knowledge to make it so. Take archery, for example. The movie’s designers have given the Na’vi no less than four kinds of arrows and seven kinds of bow, ranging from children’s practice toys to the mighty “X-bow” with two crossed supports, for use at long range in aerial attacks. And Jake will discover that the bows are integral to Na’vi culture; after completion of the Iknimaya initiation trial a young Na’vi hunter is allowed to carve a bow from a branch of Hometree, the clan’s mighty natural home.

Behind what we see onscreen is a fully realised, if imaginary, universe. Much of this we don’t even glimpse, but it all adds to the authenticity of the movie’s vision, and to its cultural value. My own career has been (mostly) built on what’s known as “hard” science fiction: that is, science fiction in which you try to stick to the laws of science as we understand them, with reasonable extrapolations and consistency. The appeal of the best hard science fiction is that it allows us to explore the meaning of our own humanity in the context of the universe revealed by our endlessly unfolding scientific knowledge. And that’s just how it is with Avatar.

Like Jake wondering about the arrows, like Dr. Grace Augustine in her endless quest for “samples,” in this book we will be field explorers of the science of the fictional Avatar universe. We’ll take our lead primarily from what we see onscreen, but we will dip into the rich universe James Cameron and his team have developed behind the scenes. In places you’ll find me speculating about some feature of the Avatar universe without giving a definitive answer. At the time of writing only the first movie has been released; two sequels and tie-in novels are planned, in which we will learn much more about the worlds of Avatar

This is a book about science, but we will always have to be aware that we’re dealing with a movie: a story, a piece of fiction. James Cameron wrote a first treatment of the movie in 1995, but his vision of the Na’vi, for instance, dates back to paintings he created in the 1970s. His development of the universe of Avatar was a dialogue between this primary visions and the work of artists, designers and consultants, who were encouraged to use real-world scientific knowledge and imagery to flesh out a consistent, credible universe. But at all times the need of the audience was paramount. Cameron urged his creators to “find the metaphor” for each element of the movie. Thus the banshees’ “metaphor” is an ultimate vision of birds of prey.

Every element we see onscreen is there primarily to serve a narrative purpose, or to provide a striking image—and Avatar has plenty of narrative drive and rich imagery. Conversely, if the movie didn’t work in terms of narrative and imagery, all the good science in the world wouldn’t save it. So, as we explore the movie’s universe, we will always allow the creators “creative licence.” They created a world that feels alien, yet with enough points of familiarity that the movie audience is not constantly floundering in strangeness. Thus a Na’vi’s face has faintly catlike or leonine features: elements of the familiar used to give a sense of strangeness.

Incidentally, no doubt you’ll find a few places where you’ll entirely disagree with my interpretations and conclusions. That, too, is part of good science.

If you’re reading this book, I’ve assumed you’re familiar with the movie itself, and that you’re interested in the science, but I haven’t assumed any prior knowledge of the scientific topics involved. If you’re interested in following up further there is a list of further sources at the back of the book, including sources which will give you much more detail on elements of the movie itself; the emphasis here is on the science context. We’ll follow the logic of the movie storyline, but you should be able to dip into the book at any point you’re particularly interested in.

Avatar, among other things, is a story of a journey. Jake Sully travels from Earth to the stars. On Pandora, in his quest to save the Na’vi, he discovers his full humanity. And finally he ventures beyond humanity altogether. Our journey will track Jake’s. And ours will begin where Jake’s does: on Earth, in the mid-twenty-second century…



“See, the world we come from: there’s no green there. They’ve killed their mother…”

Jake Sully



In the movie Avatar we see very little of Earth. There are just a few brief scenes of Jake Sully with the body of his twin brother Tommy. What we hear about it makes for a grim scenario, however. As Jake tells Eywa, the forest goddess of Pandora, there’s no green left.

There’s a little more detail in deleted scenes in a draft screenplay by James Cameron (dated 2007 and available online): “Jake stares upward at the levels of the city. Maglev trains whoosh overhead on elevated tracks, against a sky of garish advertising… Most of the people wear filter masks to protect them from the toxic air… It is a marching torrent of anonymous, isolated souls.”

Jake’s Earth is evidently a world where the problems we face today have run to extremes, a world of overpopulation and over-development, of resource exhaustion and climate collapse, of pollution and extinctions. And it’s a world of warfare too. Miles Quaritch and Jake Sully, as serving soldiers, fought in such diverse arenas as Nicaragua and Venezuela—and we see plenty of military technology on Pandora in the course of the movie (see Chapter 20).

Unfortunately this is a future that is all too plausible. And it’s all because of farming.

Ten thousand years ago every human on the planet lived much as the Na’vi do, by hunting, fishing, and harvesting the fruits of the great wildwoods. And there were very few of them, only around three thousand people in the whole of Britain, say.

But with the development of farming much higher population numbers began to appear. The Earth’s resources were exploited much more intensively, including the planet’s mineral wealth. We began this process by digging deep mines to extract the best flint, working chalk seams with reindeer-bone axes.

Today there are around seven billion of us. We are reaching global limits on such essential resources as oil, coal, even fresh water. We use about a third of the planet’s land for our farms and cities, and consume perhaps forty per cent of its biological productivity—an astounding amount for a single species.

And we are increasingly aware of the impact we are having on the planet. There is an intense controversy about the extent to which the climate change we appear to be experiencing is affected by human action, and whether further impact can be averted if we change our ways. I think it’s fair to say that some environmental scientists believe that humans have been affecting the climate since the Industrial Revolution, if not even earlier; some are sceptical.

But whether it has been caused by human intervention or not, the evidence of climate change is all around us, and alarming news about the planetary life-support systems on which we all depend has become all too familiar.

How bad are things, and how bad might they get? It’s not an easy question. The way aspects of the environment interact with each other is poorly understood, and it’s an irony that we are only coming to understand the biosphere just as it is fraying at the seams.

However, in 2009 a team of environment and earth science specialists at Sweden’s Stockholm Environment Institute made a systematic map of the planet’s natural life support systems, to see how far we have pushed them already, and how much further we can go before our own survival is threatened. The exercise was a comparatively cool appraisal of where we are now and where we are going. The team came up with nine “dimensions,” each with an estimated safe boundary.

The bad news is that of the nine dimensions we have already exceeded three boundaries. The team’s measure of climate change is the level of carbon dioxide in the atmosphere. This crucial greenhouse gas occurs naturally in the air, but we are injecting more through burning fossil fuels. The “safe” boundary the scientists established is around twenty-five per cent higher than the “natural” pre-industrial level, but we passed that mark twenty years ago. Our impact on biodiversity is measured by extinction rates, which far exceed the background “natural” rate. We are destroying habitats, introducing alien species like weeds and rats, generating pollution and perhaps causing climate change—or we are just over-hunting. It’s thought that a tenth of all bird species, a fifth of all mammals, and a third of all amphibians are under threat. We know the ecosystems on which we depend, natural communities of plants and animals, rely on biodiversity, but we don’t know how much biodiversity they can afford to lose before they collapse, as happened after the great mass extinctions of the past such as the asteroid strike that killed off the dinosaurs. The nitrogen cycle is a relatively newly identified problem area. Nitrogen is essential for all living things, but only a small proportion of the planet’s inventory (most of the atmosphere is nitrogen) is of a usable form. We are “fixing” far too much of the useful stuff out of the air (by a factor of four) through the industrial manufacture of fertilisers, inefficient farming, and other processes.

The middling–bad news is that we seem to be approaching the boundaries in three other areas. We are using up far too much of the planet’s available fresh water supply—about a quarter of the world’s rivers no longer reach the ocean for at least part of the year. We are devoting too much land to human uses, such as crop-growing and urban development, and as a result we are losing the “ecosystem services” performed by forests, grasslands and wetlands, such as replenishing the air and stabilising the soil. Rising acidity in the ocean is another problem we’ve only recently identified; acidity eventually kills off such species as corals, and a less fertile ocean is less able to absorb carbon dioxide from the air.

In two more areas the science is too patchy even for the boundaries to be established: aerosol loading, the injection of soot, sulphates and other particles into the air through industrial processes and burning, and chemical pollution, where we have a handle on the impact of some pollutants such as DDT but the effect of others is unknown.

At least there is still time for recovery on all the dimensions. And there is actually some good news! The last dimension is ozone depletion: one environmental issue with a (relatively) happy ending.

In 1982 British scientists discovered a thinning of the ozone layer in the stratosphere over the Antarctic. This reactive form of oxygen screens Earth’s surface from the sun’s invisible but lethal ultraviolet radiation. Chemist Paul Crutzen and others confirmed that the culprit was CFCs, chlorofluorocarbon compounds. CFCs were used in spray cans, refrigerators and Styrofoam. Once released into the air, CFCs were broken up by sunlight and released free chlorine that reacted with ozone, thus removing that isotope of oxygen from the stratospheric layer where it collects. Life on Earth has evolved under the shield of the ozone layer, and has no natural protection against the sun’s ultraviolet. If the ozone layer had collapsed completely, allowing the world to be blasted by solar radiation, humans would have been afflicted by skin cancers and cataracts, and whole ecosystems would have been damaged.

However, the danger was recognised in time. In 1987 a protocol banning the release of CFCs was signed, the ozone depletion was halted, and Crutzen and others shared a Nobel Prize. At least this example shows that we are capable of concerted action on a global scale to avert the threats we face.

But—as seems to be the case in the Avatar future—what if we fail? How bad could it get?



Jake Sully’s Earth is a world where, he says, there is no green—where, we have to infer, the natural order has entirely broken down. Is this possible? And could humanity even survive on such a world?

As we face a bottleneck of resource depletion and environmental collapse, it’s not hard to imagine a nightmarish future of warfare and famine, social collapse, disease and mass migration, punctuated by climate catastrophes like drought, flood, and hurricanes spinning off the warming oceans. Richer countries or groups of countries may become fortified blocs. As always, the poorest will be most vulnerable, for they live close to the limit of sustainability anyhow. But none of us would be immune.

And things could get a whole lot worse than that.

Climate change could stop being gradual. Some scientists predict that if the world’s natural cycles are pushed too far we could reach a “tipping point” into a sudden, much greater disaster. Among the tipping-point triggers could be the abrupt release of deposits of methane and carbon dioxide, currently trapped under permafrost layers around the rim of the Arctic Ocean and elsewhere. These vast volumes of greenhouse gases would make global warming suddenly accelerate.

Another much-discussed tipping point is the possible collapse of the ocean current known as the Gulf Stream, which brings warm water (and air) to the north Atlantic. If this were to fail, coastal regions, including the east coast U.S., Britain and Scandinavia, could suffer a dramatic and sudden cooling. This scenario was (over) dramatised in the movie The Day After Tomorrow (2004). And it may have happened in the real world, triggering the “Younger Dryas” episode beginning around thirteen thousand years ago, in which the world’s emergence from the last Ice Age was interrupted by a thousand-year reversion back to glacial conditions.

A 2003 report commissioned by the Pentagon imagined sudden climate collapse triggered by something like the Younger Dryas. The consequence would be a sharp reduction in the world’s “carrying capacity,” its ability to feed us all. Amid the subsequent wars, droughts and huge population movements there would be a collapse of states and federations like the European Union, and a breakdown of international order. This was an extreme scenario, but then it’s the job of defence departments like the Pentagon to dream up and prepare for the worst case.

The very bleakest future predictions of all make grim reading. In the 1970s James Lovelock devised the famous theory of “Gaia,” our world seen as a network of flows of energy and matter, “a dynamic physiological system that has kept our planet fit for life for more than three billion years” (and perhaps Gaia has a parallel in Pandora’s Eywa; see Chapter 29). Now, Lovelock says in his latest book The Revenge of Gaia, “The world is fighting back… The bell has started tolling to mark our ending… Only a handful of the teeming billions now alive will survive.”

Is there anything we can do about this?

For a start we might go beyond the “green” activities already prevalent in the modern world: recycling, saving energy, conserving the remaining wild.

Perhaps we could rescue threatened portions of the biosphere itself. There are already over a thousand gene banks around the world, storing millions of plant seeds. Animals are being “stored” as frozen tissue samples, for example at the Frozen Zoo at San Diego Zoo in California, in the hope that if all else fails these creatures could be revived as clones some day. The Zoological Society of London is even considering a bank of frozen corals. And some scientists are considering how to preserve ecosystems on a larger scale—whole landscapes, perhaps—in order to allow evolution a large enough arena in which to continue.

But there are gentler possibilities. American environmentalist Paul Wapner argues that we should soften the lines between “us” and “nature.” For example, Wapner suggests, instead of building a fence to divide forest from city, we should create zones of selective logging. Forests would gradually shade into suburbs that would be intentionally wildlife-friendly, and there would be migration corridors for wildlife and plenty of exposed ground. There might be no wilderness, but the suburbs would be wilder, and we would all become wardens of the wild things around us. Ecologist Dickson Despommier has another interesting proposal: we should raise crops and animals in the cities, in “vertical farms,” large high-rise buildings. Then we could afford to allow the countryside to return to the wild—and we would drastically cut the cost of transporting food.

But if the situation continues to deteriorate, such small-scale initiatives might not be enough. We can imagine frantic efforts to put Gaia back together again on a much larger scale. This is geoengineering: rebuilding the Earth.

Geoengineering solutions can be vast in scale, but are generally based on two simple principles. Earth intercepts heat from the sun; and an excess of carbon dioxide in the air traps that heat. So to reduce the retained heat you either reduce the amount of solar energy the planet soaks up in the first place, by reflecting it away—“albedo manipulation”—or you take carbon dioxide out of the air—“carbon sequestration.”

One sequestration method is to liquefy atmospheric carbon dioxide and pump it under pressure into deep rock layers, or into the deep sea. (It was in 1970s studies of solutions like this that the term “geoengineering” was first coined.) This is already being done, for instance at natural gas plants in Norway. The challenge is not to generate more heat in the process than you’re saving by removing the carbon dioxide.

On the other hand the most ambitious albedo-manipulation schemes are to assemble immense solar reflectors in space. In 1929 the German-Hungarian space visionary Hermann Oberth suggested using huge orbiting mirrors to reflect sunlight to the polar regions, to alleviate the Arctic night. The Russians actually tested a twenty-metre space mirror in 1993, unfolded in Earth orbit from the Mir space station. The idea of using space mirrors to deflect light from an overheating Earth has been explored by American energy analysts. There are less dramatic schemes, such as using naval guns to fire aerosol particles into the high atmosphere, and thus to screen out the sunlight. Other possibilities have been explored in science fiction. Kim Stanley Robinson’s Forty Signs of Rain and its sequels (from 2004) dramatised the collapse and artificial restarting of the Gulf Stream, and in my own Transcendent (2005) I had engineers stabilise the methane deposits at the poles.

Many people instinctively recoil from such drastic tinkering with the planet. It feels hubristic, arrogant. In our myths only the gods fooled around with the weather, like the deities in Homer’s Odyssey who created storms to blow Odysseus around the Aegean Sea. And the science is definitely uncertain. As I said, Lovelock’s “Gaia” hypothesis depicts the Earth as a complex web of interlocking feedback processes. Until we understand how this web works it’s hard to be sure if our meddling will make things better, or worse. There is even a danger that a geoengineering solution would actually encourage us to continue to commit our biospheric sins in the mistaken belief that we could clear things up later.

However, there is plenty of serious talk about geoengineering. In 2009 Britain’s prestigious Royal Society produced a major report on the “science, governance and uncertainty” of geoengineering, and in 2011 the idea was debated by the highly influential Intergovernmental Panel on Climate Change (IPCC), the UN’s climate science body.

Your optimism in our ability to handle something like geoengineering might be dented if you read some of the fractious arguments being waged today in public forums about climate change, but at least we are talking. Perhaps even the arguments are a sign of a (slowly) emerging global consciousness, of how we’re groping towards becoming a mature planetary civilisation. Certainly if things deteriorate there might come a point where we have no choice but to try drastic solutions.

But perhaps, in the end, if things got bad enough, a new and shocking paradigm would emerge: let it die.

With enough power and raw materials I suppose it would be possible for mankind, or a large chunk of it, to survive even on a world with little or no ecology left at all. It might be like colonising an alien world, with domes over the cities, and gigantic air-scrubbing machines, and food factories churning out processed blue-green algae. The tremendous energies that had been devoted to failed geoengineering efforts could now be devoted to artificial life-support systems for a planet.

I wouldn’t underestimate what it would take to replace the lost “services” of the ecology. Consider the humble tree, for example—the tree, so central to the Na’vi’s culture and lifestyle. Trees prevent land erosion, they provide a weather-sheltered ecosystem in and under their foliage, they help maintain the atmosphere by producing oxygen and reducing carbon dioxide, they provide crops from apples to rubber—and, when they die, they give us a remarkably flexible building material, in wood. There are thought to be some four hundred billion of these giant servants on the planet (see Chapter 29). We would have to spend some serious money to build mechanical equivalents of all that. (And if we did, perhaps the last trees would end up in a tree museum, as in the Joni Mitchell song.)

How would it be to live on such a world? The fragmentary visions in Avatar give us a hint. There have been all-city planets in science fiction, such as in Isaac Asimov’s 1954 novel The Caves of Steel, which depicted a world of claustrophobic metal-walled corridors. And consider the dismal dead-Earth vision of Cormac McCarthy’s novel The Road.

I imagine a world of vast mines and huge engines, of foul, smog-choked air and dead oceans, where every sip of water and breath of air has to be passed through a filter first. (Maybe the exopacks used on Pandora are based on technology developed to survive on Earth.) I imagine a world still flaring with war over its remaining resources, just as in Avatar. I imagine a world of intense control and surveillance, mediated by the super-powerful artificial minds of the future (see Chapter 19). I imagine a planet like a vast shanty town, where the plight of the poor and the vulnerable would be dreadful.

And we would miss mother Earth badly. Already we are disconnected from the ecology that nurtured us, and don’t fit the world around us. Our brains are still hardwired to avoid long extinct predators, which is why our bodies are flooded with adrenaline in response to everyday hassles, as if they were lethal threats. This is the “pronghorn principle.” The pronghorn is a North American antelope-like creature that runs ridiculously fast, a now useless ability it evolved to flee the vanished predators that once hunted it. We would be desperately unhappy on a dead Earth, and we might not even understand why.

For better or worse however this does seem to be the sort of world into which Jake Sully was born—and a sense of what we’d have lost is dramatised in Jake’s first wondrous reaction to the living world of Pandora. But our world isn’t like this yet.



We always have to be aware that Avatar is a movie, and what we see onscreen is there primarily to serve a narrative purpose. Avatar is a movie of hopeful awakenings, from Jake Sully emerging from cryosleep (suspended animation) in orbit around a new world, to the movie’s very last frame when he makes a final wakening as a Na’vi, fully committed to his new world. But hopeful awakenings are much more effective, for story purposes, if you have a nightmare to wake up from.

There’s nothing new in dark portrayals of the future. My generation, born in the fifties, was brought up with the Cold War, a mind-numbing stalemate that could have triggered a mass nuclear war: a future terminated by a wall of blinding light. Western culture has a deep-rooted expectation of apocalypse just around the corner that seems to date back at least as far as the Book of Revelation. We’re always fearing the worst; it’s just that the worst we can imagine changes with time.

Perhaps apocalyptic thinking is valuable, in some circumstances. Maybe our habitual pessimism about the future is a kind of folk memory, a grandmother instinct warning us not to be complacent, to make us expectant of drastic future change, as we have experienced change in the past (such as the Ice Ages). None of this minimises the real threat posed by such problems as climate change. But a recognition of our habit of apocalyptic thinking casts a clearer perspective on our hopes and fears.

And as regards the near future, maybe we’ve still got time to avert the green apocalypse.

I doubt we really could kill off our “mother.” I’m lucky enough to live in a rural community in the north of England. Looking out of my window as I write I can see “nature”: hills, a river, forests, fields. But in fact almost everything I see save for the basic shape of the landscape is artificial, made that way by human intervention, and almost all of it is less than two centuries old. The green I see is mostly crops, or grass for the sheep, or the pine trees of the managed forests. But the wild creatures persist, at the edges: in the hedgerows, underground, at the coast, in the river valleys, the birds in the air.

It’s the same even in the heart of our greatest cities. The city of Pripyat was built to house nuclear workers from Chernobyl, and was abandoned after the disaster. After just a couple of decades its open spaces were green, and the paving stones were so smashed and lifted by tree roots they looked as if they had been through an earthquake.

Gaia has proven pretty resilient in the face of mega-disasters such as the impact of asteroids, like the one that knocked out the dinosaurs sixty-five million years ago. The daddy of all extinction events, the “end-Permian” catastrophe possibly triggered by eruptions in Siberia a quarter of a billion years ago, nearly ended multicelled life on Earth altogether. But life, though much depleted, made it even through the end-Permian, and the grand story of recovery and evolution began again.

Compared to such horror shows our feeble efforts at “ecocide” really don’t amount to much. For example we’ve barely touched the hardy old life forms believed to live in the “deep hot biosphere,” inside the rocks, kilometres down beneath our feet (see Chapter 22). Even if we blasted off the topsoil and irradiated the oceans, those ancient survivors would some day emerge to begin the story of life once more. It is a kind of cold comfort that if we were to disappear tomorrow the wild would take back a recovering world remarkably quickly.

There’s no doubt we face a complex and challenging near future. But, as the example of the ozone layer recovery shows (Chapter 1), we are capable of facing up to problems on a global scale, and resolving them. I think we’ll survive the green apocalypse, chastened and changed perhaps, and by the time those now young grow old, their children will have found something entirely new to worry about.

But we may need the resources of other worlds to save this one.



“Killing the indigenous looks bad, but there’s one thing shareholders hate more than bad press—and that’s a bad quarterly statement.”

—Parker Selfridge



The Resources Development Administration (RDA) is a mighty impressive organisation, judging by what we see of it in Avatar.

Consider its competences. It mounts interstellar missions on a huge scale, transporting and building vast industrial and military infrastructures. It mines an alien world. It wages war against the natives. It brings resources back to Earth—and it turns a profit in doing so.

RDA came about because of the discovery of unobtanium on Pandora. After telescopes in the solar system discovered planets of the nearest star Alpha Centauri (see Chapter 13), with Pandora particularly showing tantalising hints of life and strange magnetic effects, two unmanned spacecraft were sent to the system, using prototype versions of the technologies that would one day power Venture Star (see Part Three). From Pandora, landers sent back images of the floating rock masses that would become known as the Hallelujah Mountains, and the landers sampled an “unidentifiable mineral” (later called unobtanium) that seemed to be involved in the exotic physics that was keeping those mountains afloat (see Chapters 15 and 16).

The potential for industrial development, and huge profits, was immediately obvious. Corporations and governments quickly formed the Resources Development Administration, an international quasi-governmental consortium, to manage the development of resources from Pandora. RDA was to have complete control over operations on Pandora, but is accountable to shareholders (as administrator Parker Selfridge is all too aware), is limited by treaty in its military operations—no weapons of mass destruction—and is obliged to work on Pandora “for the good of all mankind.”

And then a blue face was seen peering intently into one of the landers’ cameras, and things got complicated…

RDA’s skills wouldn’t have come out of nowhere. Before mankind could launch an interstellar mining operation, governments and corporations would have developed off-Earth operations on a smaller scale, starting with the worlds of our own solar system, feeding a resource-hungry Earth—and all the while making a fat profit in the process. What’s interesting about that is, while we’re not likely to see humans reach the worlds of other stars in our lifetimes, we could well get to see proto-RDAs exploiting the worlds of our solar system.

And maybe that will start with another small step on mankind’s nearest neighbour, the moon. A small step, followed by the chewing of a drill-bit in the lunar dirt.

I once met a man who, like Jake Sully, journeyed through space to another world. He travelled only about a light-second, not four light years. The trip took him three days, not six years. He didn’t need suspended animation, though on the way back, exhausted, he did sleep a lot. But, like Jake, he too walked on a low-gravity world. His name is Charles Duke, and he flew to the moon in 1972 aboard Apollo 16.

I interviewed Duke over lunch in a hotel in Bond Street, London. He told me how the handling of the Apollo lunar lander reminded him of the fighter planes he flew earlier in his career: “It was like being a rough acrobatic pilot. Oh, great ride…” Duke’s low-gravity moonwalks were actually typical of our near-future experience in space. Aside from the four gas giants, Earth is the largest world in the solar system; anywhere humans can land in the sun’s family we’ll find the gravity lower, just as on Pandora.

Then, during his journey home, with the spacecraft suspended between Earth and moon, Charlie Duke assisted in a space walk to retrieve instrument records. “As I floated out, the Earth was off to the right, probably about a two o’clock low, real low. I could see it beyond the hatch, beyond the Service Module. And it was just a little thin sliver of blue and white. And then I spun around this way and directly behind me there was this enormous full moon, and it was, I mean it was overwhelming, that kind of feeling. And you could see Descartes, you could see Tranquillity, all the major features, and it just felt you could reach out and touch ’em. No sensation of motion at all. The sun was up above my eye line but it’s so bright you don’t look at it. And everything else was just black…” He mimed for me his spacecraft, suspended between Earth and moon and sun. What an experience! Even a moonwalk would have some familiar features—ground below your feet, a sky above, a horizon. Duke’s walk between the worlds was something no human being had enjoyed before Apollo, in all our evolutionary experience—which is one reason why, in my opinion, we should continue to send humans into space.

But even as Duke was having his astonishing adventure, President Nixon’s administration was making the decision to can the later moon flights. For the foreseeable future American human spaceflight would be restricted to just the low-orbit hops of the space shuttle. It might have been very different: building on the successes of Apollo, Americans might already have reached Mars. But they didn’t.

Forty years later it’s easy to forget that human beings walked on the moon at all. And it’s easy to forget that the Apollo astronauts didn’t just go there “in peace for all mankind,” as the plaque on Apollo 11’s lunar lander said, or just for the science, or even just for national prestige. Just like RDA on Pandora, they went there in search of resources.

And today, would-be prospectors of the sky are again looking out at the solar system with calculating glints in their eyes.

Before 1969 the exploration and colonisation of the solar system, beginning with the moon and working outwards to Mars and beyond, was pretty much a given. In a favourite novel of my boyhood, Leigh Brackett’s Alpha Centauri—Or Die! (1963), this is nicely summed up in a few lines (Chapter IV): “There are men in space again… [The message] was heard and repeated. Inward from Mars it travelled, across Earth and Venus and into the sun-bitten, frost-wracked valleys of Mercury. Outward from Mars it travelled, to the lunar colonies of Jupiter and Saturn, to the nighted mining camps of the worlds beyond…”

Our view of the solar system then, going back centuries to the pioneering telescopic observations of Galileo, was that it was a family of worlds, most if not all of which would host life. Why shouldn’t there be life? Earth is just another planet; if life is here it ought to be everywhere.

And, following old theories of the formation of the planets, it was thought that the further out your world was from the sun, the older it would be. So “young” Venus, blanketed in cloud, was thought to be a world of ocean and swamp, the seas fizzing like soda pop from excess carbon dioxide, the land probably dominated by dinosaur-like monsters. And Mars, further out from the Earth, must be older than Earth, and host to an advanced, ageing civilisation—and, being older, Mars must be drying out. Around 1900, astronomer Percival Lowell put these ideas together with tentative, blurred telescopic observations of Mars to construct one of the most beautiful (if most wrong) theories in the history of science. Lowell believed the Martians were working together on a planetary scale to fix their own climate change crisis, their own ecocide; they had built a global network of canals to use polar cap meltwater to irrigate the drying fields. Lowell believed he saw these canals through his telescope.

This was the Mars that inspired some of the greatest works of early science fiction, including H. G. Wells’ The War of the Worlds (1897), in which the Martians reverse the Avatar story and come to our world for its resources—including human blood!—and Edgar Rice Burroughs’ “Barsoom” novels, beginning with A Princess of Mars, serialised from 1912. In Burroughs’ books “John Carter, gentleman of Virginia” is transported to a Mars of warring tribes and exotic multilegged beasts, and finds a beautiful humanoid girl to fall in love with, “Dejah Thoris, Princess of Helium.” James Cameron says that his absorption in science fiction of all kinds over thirty years fed into the creative process behind Avatar, and he was specifically inspired by Barsoom, and the adventures of John Carter, a soldier on Mars.

Burroughs allowed for Mars’ low gravity, by the way. Like the Na’vi, some of his Martians are taller than humans—“fifteen feet tall.” And on Barsoom there are immense life-sustaining machines of the kind I speculated in Chapter 2 must support a post-ecocide Earth: “Every red Martian is taught during earliest childhood the principles of the manufacture of atmosphere…”

This, anyhow, was the solar system, bursting with life and ripe for colonisation, that shaped the expectations of the early space explorers. So it was quite a shock when the first unmanned spacecraft sailed past Mars in 1964, over an area where “canals” were expected to be seen (even though it was no longer thought they would be artificial)—only to find craters, like the desolate moon.

And then there was the moon itself. It might be lifeless but, before the Apollo missions, space visionaries believed that the apparently barren moon would harbour hidden riches for future human colonists—especially water. As late as 1968, Arthur C. Clarke, in The Promise of Space, wrote, “The most valuable substance of all—as it is on Earth, when in short supply—would be water… [Water] certainly exists on the moon; the question is where, and in what form.” But Apollo brought a grave disappointment. Analysis of the moon rocks seemed to show not the slightest trace of water, either now or in the past. The dark lunar “seas” proved to be made of basaltic dust, not organic sea-bottom scum. To many, even inside the space programme, Apollo, intended as a first step into the cosmos, in the end served only to prove that we cannot colonise space.

So the space planners turned away from the old dreams. Moonwalkers like Charles Duke were suddenly left stranded. And if you wanted to write science fiction about Barsooms and other inhabited worlds, you had better set them among the stars, like Avatar.

But maybe we jumped to conclusions. Since Apollo we have come to suspect that the sky is after all full of riches, even the much-maligned moon. But to reach them, we’ll first have to get off the Earth.



It has always been difficult to make the first step off Earth and into space.

It’s easy on the moon, with its one-sixth gravity. Charlie Duke and his colleague aboard their tiny Apollo lunar module were able to return to lunar orbit with an engine and fuel tanks you could have fitted in a camper truck. By comparison, to climb out of Earth’s gravity well, the space shuttle stack was over fifty metres tall and weighed around two thousand tonnes, most of which was fuel, and oxidiser to burn that fuel. If Earth’s gravity was just a little stronger, in fact, no chemical-fuel rocket system like the shuttle would be able to escape from Earth. And if not for the pressure of military requirements which drove the development of rocketry, we might never have reached space at all; the first astronauts and cosmonauts rode into orbit on converted ballistic missiles.

The space shuttle worked, flying for three decades, despite the design flaws that led to two terrible accidents. But now the programme has been cancelled. And in February 2010 President Obama also dropped funding for NASA’s follow-up “Constellation” programme, which would have replaced the shuttle with a new range of human-rated rockets and spacecraft. The hope is that private industry will step up to the plate with a replacement launch system. Obama’s intention is evidently that the money freed up by not having NASA develop its own vehicles will help prime the pump for a new age of access to space. But for now it looks as if U.S. astronauts will have to hitch rides to orbit on Russian rockets.

Space is an expensive business, however, especially as a start-up. There’s a saying in the business that you need to spend billions to make millions out of space. But there are individuals with such means, and a drive, it seems, to make childhood ambitions come true. Companies like SpaceX and Blue Origin are rushing to develop their own launch systems capable of taking humans safely to orbit. NASA would be a customer, as would companies like Virgin Galactic, with its plans to take passengers on hops into space. SpaceX was established by South African dotcom entrepreneur Elon Musk, one of the creators of Paypal, and Blue Origin was founded by Jeff Bezos, the president of Amazon. This is new money being leveraged to achieve old dreams.

However, while the money might be new many of the designs are relatively conservative: capsules launched aboard chemical-rocket firecrackers, just like Apollo. Even the space shuttle had bits that were either discarded, like the external fuel tank, or had to be fished out of the ocean and rebuilt, like the solid rocket boosters.

What we need is not another throwaway rocket system. What we need is a true spaceplane. What we need is Avatar’s Transatmospheric Vehicle Valkyrie.

The space shuttle was boosted by rockets to orbit, but then could only glide back to Earth, unpowered. A true spaceplane would be capable of taking off unaided from a runway like a conventional aircraft, reaching orbit, and then returning to land. (In the industry jargon this is SSTO—single stage to orbit.)

This is an old dream. Before the development of Project Apollo the U.S. Air Force dreamt of spacecraft with wings. It flew the famous X-15 rocket plane, and it funded extensive research into “lifting bodies,” capable of very high-speed flight. Some of this research fed into the space shuttle programme, and today the USAF is experimenting with a scaled-down spaceplane known as the X-37B.

There are technologies on the horizon that could be developed to achieve a true SSTO craft. One promising technology is the “scramjet”: a supersonic combustion ramjet, which would enable aircraft to reach extremely high speeds within the atmosphere. A conventional “ramjet” draws in air to collect oxygen with which to burn its fuel, but the airflow within the engine is subsonic (below the speed of sound), so if the craft itself is travelling faster than sound, the intake of air has to be slowed down, creating drag. But in a scramjet the air passing through the engine can be supersonic—faster than sound, inside the engine itself. This enables the aircraft itself to reach much faster speeds.

The fastest air-breathing aircraft to date is NASA’s X-43A which has reached Mach 9.8 (that is, 9.8 times the speed of sound) using scramjet technology. In theory it is believed that scramjets could reach almost orbital velocity (which is Mach 25). The great advantage is in weight savings; unlike a rocket such as the space shuttle, a scramjet would need to carry virtually no oxidiser to burn its fuel, extracting it all from the air.

This is how the Valkyrie flies. Four times the size of the space shuttle, with its black heat-resistant tiles and white insulation reminiscent of the shuttle’s bodywork, the Valkyrie returns from orbit using friction with the atmosphere to brake, like the shuttle, and glides most of the way home. But to return to orbit it uses air-breathing turbojet engines to get off the ground, and switches to a scramjet mode at three times the speed of sound. It has rocket engines for the final burn to orbit. All this is powered by a fusion engine.


Excerpted from The Science of Avatar by Stephen Baxter Copyright © 2012 by Stephen Baxter. Excerpted by permission.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

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