The Science of Avatar

by Stephen Baxter

  The unobtanium mines on Pandora resemble open-cast mining operations here on Earth—and especially the huge operations now underway around the world to extract oil sands.

  Oil sands (also known as tar sands) are a kind of bitumen deposit. Bitumen is a dense and sticky form of petroleum that can collect in layers of sand or clay and water. Such deposits occur around the world, and in fact were exploited in ancient times in the Middle East for the water-proofing of reed boats, and creating Egyptian mummies. The world’s largest deposits are in Canada and Venezuela, each of which is said to have reserves equivalent to the world’s total reserves of crude oil. (Maybe this is why Jake Sully was sent to fight in Venezuela.) The Athabasca Oil Sands, in Alberta, Canada, have been the scene of the commercial extraction of bitumen since 1967. The Athabasca operation employs what are said to be the biggest power shovels and dump trucks in the world. The oil sands themselves are typically in a layer fifty or so metres deep, sitting on top of limestone strata. To mine them you have to clear the land of trees and brush, then remove what the miners call the “overburden,” the topsoil and layers of peat, sand and gravel, and then the extraction is done. This is roughly the technique used in the Pandoran unobtanium mines.

  The modern extraction process, which requires huge amounts of energy for steam injection and refining, was until recently considered uneconomical—but that’s changed through a combination of better technology and rising oil prices. Production in Canada has grown to the extent that the country has become the largest contributor of oil and refined products to the United States. Environmental issues are regularly raised. State and national governments apply strict rules; for instance all such projects are required to implement a land reclamation plan. But environmentalists object that oil sands extraction processes generate more greenhouse gases per barrel than the production of conventional oil.

  Meanwhile, at the time of writing there are plans to open up a huge iron ore mine in Arctic Canada, far to the north of any operation of a similar scale previously—an opportunity provided, ironically, by the global-warming retreat of the polar ice. Just as on Pandora, there is native fauna to be moved out of the way, including caribou, Arctic foxes and polar bears, and local people to deal with in the Inuit.

  I suppose that if the world suffers the ecocide we looked at in Chapter 2 we can expect such operations to proliferate. Nobody would care about the impact on the environment, because there would be no environment to save, any more than on the lifeless moon. Certainly satellite views of the operations in Athabasca and elsewhere are starkly reminiscent of Avatar’s scenes of unobtanium mining on Pandora.

  The principal unobtanium mine, humanity’s most distant industrial operation, is known as RDA ESM 01—RDA Extra-Solar Mine 01. Operators in sealed cockpits use chemical charges to break up the overburden, which is then removed with excavators, dozers and dump trucks. The unobtanium ore is removed with excavators and trucks, but a pure enough deposit can spontaneously levitate, requiring specialised belt diggers to feed into covered trucks. Over the thirty years of its expected lifetime the three pits of ESM 01 will eventually merge into a crater four kilometres across. But RDA is already looking at further deposits to develop.

  All this is very plausible. Today we’re pretty competent at mining the Earth. And we are already working out how to mine other worlds.

  In Avatar’s 2154, human colonies exist on the moon and Mars. And in our time there have been several studies on how you might mine these new worlds.

  What is there to mine on the moon? Well (see Chapter 6), there’s water, maybe in trace amounts in the lunar soil, and helium-3, the right isotope of the element for the most effective operation of fusion plants, which is lacking on Earth. But these treasures are thinly scattered—it would be like harvesting dew—and strip-mining on a vast scale would be required. Imagine robot tractors crawling across the lunar surface, scooping up the regolith, processing tonnes of the stuff to sift out the minute fractions of water and helium-3, and perhaps baking the rest to extract oxygen. As for power, the unshielded sunlight is an obvious energy resource; perhaps areas of the wide, flat lunar seas could be melted to form gigantic solar-energy collectors.

  The lunar conditions will invalidate much of our terrestrial experience of heavy industry and manufacturing; we will have to rethink everything. Moon dust, shattered by meteorite rain but unweathered, is extraordinarily abrasive, as the Apollo astronauts learned when they tried to make their spacesuit seals for their second or third moonwalks. The vacuum makes most lubricants useless; they would just boil away. And the low gravity causes problems with simple things like fluid flow, because of novel bubble effects in liquids. Lessons we learn on the moon, however, could be transferred to other worlds. It’s strange to think that low-gravity adaptations made to the feed lines on a Samson rotorcraft to enable it to operate on Pandora, for example, might have been learned on the humble moon.

  In the Avatar future, in fact, RDA does maintain a lunar helium-3 facility. And the mining operations must have left a mark. Maybe by Jake Sully’s day the face of the moon in the sky, more or less unchanged for billions of years before humans came along, is pocked and scraped by mines, and the dust seas gleam, covered by tremendous solar-panel mirrors.

  Meanwhile the best plans we have to get to Mars and back involve industrial processing of Martian resources from the very first landing—in fact, we would need to make a start even before humans get there. According to Robert Zubrin’s “Mars Direct” proposal, Mars would be reached with a wave of spacecraft capable of manufacturing their own return fuel from Mars’ carbon dioxide atmosphere, at a fraction of the cost of hauling that fuel all the way from Earth (the Apollo craft carried their own return fuel to the moon).

  The key ingredient to support life, however, is as always water. And there seems to be plenty on Mars. As Percival Lowell suspected there is water-ice on Mars’ surface at the poles, just waiting to be scooped up. At lower latitudes, the spaceprobes have found evidence of water in the past: for example, what appear to be the remnants of gigantic, catastrophic flooding episodes, and perhaps even the tide marks of ancient seas. Where did all the water go? Perhaps it was drawn into aquifers in Mars’ interior by geological processes like the great subduction flows on Earth; Mars, smaller than Earth, cooled more rapidly, making its crust and mantle more able to trap and store water. Thus the first large-scale industrial operations on Mars are likely to be drilling for water—and the technical challenges there are almost as severe as on the moon.

  From 2004 to 2007 I worked with a team from the venerable British Interplanetary Society on a design study of a manned base at the Martian north pole. It was a weighty study; project leader Charles Cockell is a professor of astrobiology at the Open University. And in the course of the study we worked on proposals on how you’d drill on Mars, specifically in our case because we wanted to extract an ice core. Just as on Earth, such cores, drilled from ice caps built up by snowfall year on year, contain records of climate variations reaching deep into the past.

  Deep drilling, the kind you’d need to go down kilometres to a low-latitude Martian aquifer, is hugely challenging in terms of mass, power and manpower. Rotary drilling as we use on Earth is a tested technique, relatively low power, mechanically simple, and easily fixed in case of failure. But it requires a heavy support infrastructure, and in the dusty, cold, high-friction Martian environment any moving-part system would be vulnerable to many failure modes—lubrication failures, abrasion of bearings, loss of seal integrity.

  A deep borehole will always require stabilisation to keep it from collapsing. The way this is done on Earth is to pump in a “working fluid” such as water or mud slurry. Water or mud will not work in Martian conditions; either would freeze immediately. Possibly some low-temperature lubricant oil would be suitable, but it would be very expensive to import such a fluid from Earth: you’re looking at tonnes of material, and if lost such a fluid load could not be replaced. The trick is to use working f
luids produced from local materials, and the best bet may be to liquefy Mars’ carbon dioxide atmosphere. Unfortunately, carbon dioxide plus liquid water yields carbonic acid, a weak acid but corrosive; you would have to keep temperatures low enough throughout the borehole that ice chips do not melt, which will affect drilling rates, and to use corrosion-resistant materials.

  This brief experience taught me a lot about the challenges of transferring heavy industrial operations to another world. In Pandora’s low gravity and toxic air, every tool, every machine, every material used will have to be redesigned, every technique re-examined.

  And on Pandora the intense magnetic fields around unobtanium deposits are a novel significant problem for industry. Machines and tools can’t contain any ferromagnetic elements such as iron, cobalt or nickel because they would become so strongly magnetised their moving parts would seize up. Even some non-ferromagnetic elements like manganese become magnetic when combined with other elements, which limits the use of steel alloys and other materials. There are compounds that will work, such as tungsten carbide, but these are exotic and expensive. In addition, whenever you move a conducting material in a magnetic field electrical currents are induced. These can heat the material, interfere with circuitry, and interact with the global magnetic field to produce a resistance to motion. A miner swinging a pick would feel like he was underwater, and the faster he moved the hotter the pick would get—not that a human miner would be allowed anywhere near an unobtanium lode.

  Still, by the time RDA reaches Pandora it will be able to build on decades of experience of mastering hostile environments in the solar system. And everything we learned on Earth, since the days thousands of years ago when we were chipping flint nodules out of chalk beds, will have been rethought.

  19

  COPIES, CELLS AND COMPUTERS

  In the movie Avatar we only glimpse Earth, but we see a lot more of the human colony on Pandora, the “Resources Development Administration Extra-Solar Colony,” more popularly known as Hell’s Gate.

  And here we get to see some of the technological advances achieved by mid-twenty-second century Earth.

  One challenge of the operations we see on Pandora is the sheer mass of the machinery required, such as the mining gear, the military hardware, the fixed structures at Hell’s Gate and elsewhere. Interstellar flight is always likely to be expensive, and the more mass you have to haul out, the more expensive it gets.

  Given this, it would make sense to manufacture as much of your equipment as you could on Pandora using in situ resources. To get things up and running quickly you might bring out smart but lightweight components such as electronics from Earth, while manufacturing dumb but heavy components on Pandora.

  And the way RDA achieves the latter is by using a much-advanced version of a novel manufacturing technique called stereolithography, or “3D printing.”

  This is a kind of photocopying of solid objects, in which computer-controlled machines build up a component by spraying on layer by layer. Typically, systems working today have used plastics, but there have been experiments using metals and ceramics. Advantages of the technique are its ability to construct more complicated and intricate shapes than any other primary manufacturing technology, and its flexibility—one system can turn out any component you like, whereas otherwise you’d have to bring along specialised plant for each type.

  Today, commercial systems are used to manufacture items like jewellery, but they are also being trialled on a larger scale, for example in projects where buildings are constructed layer by layer by robots pouring fast-setting concrete. There are also home-workshop experiments you can download, such as the “Reprap” project, the Replicating Rapid-prototyper, devised by Adrian Bowyer of the Buckinghamshire Chilterns University College in England. As you can imagine, there are fascinating intellectual property rights issues to be resolved around this technology.

  Even on Earth, if we could manufacture a lot of what we need at home we might cut transport costs significantly. And stereolithography certainly cuts the cost of transport to Alpha Centauri, where the RDA manufactures its own ground vehicles, mine equipment, weapons, building elements, even clothing. As we’ll see, however, the use of this technology imposes some constraints on the kinds of machinery that can be used on Pandora.

  Remarkably, experiments at the Massachusetts Institute of Technology have tried using the 3D-printing technique to make artificial human bones. In the course of Avatar we get a look at a number of other medical advances.

  Former Marine Jake Sully is stranded in a wheelchair, the result of a traumatic injury he suffered on active service. He’s aware that a “spinal” can be fixed, but only at a price beyond the means of his veteran’s benefit. In the context of the movie, Jake’s paralysis serves a key narrative function. Like his eco-devastated Earth it provides another extreme starting point for his personal story; it makes Jake vulnerable to manipulation by Quaritch—and it amplifies the joy he feels, and we share, when he first drives his avatar body, and is able simply to run again.

  But it is good to know that in the real world some steps are being taken towards alleviating this terrible condition.

  A “spinal” is a spinal cord injury. The spinal cord is a long, thin bundle of nervous tissue that extends from the brain. The cord is contained for protection in the bony vertebral column. Together, cord and brain make up the central nervous system. The cord’s main function is to transmit neural signals between the brain and the rest of the body: “motor information,” data about the body’s movements, travels down the cord from brain to body, and “sensory information,” data recorded by the senses, travels back up the cord from body to brain. The cord also has some independent functions; it serves as a centre for coordinating various reflexes.

  It’s estimated that in the United States, for example, there are some forty cases of spinal cord injury per million people per year. The spinal cord can be damaged by trauma, as in Jake’s war injury, or through a tumour, or through a developmental disorder like spina bifida, or a neurodegenerative disease. The vertebral bones or the discs between the vertebrae can shatter and puncture the cord itself. In the more severe cases, such as Jake’s, a patient can suffer a significant loss of motor and sensory functions to major areas of the body, all the way to full body paralysis (quadriplegia) below the site of the injury. In addition a patient can suffer bowel and bladder malfunctions, a loss of sexual function, spasticity and neuropathic pain, and in the longer term muscle atrophy and bone degeneration.

  Current treatments amount to administering anti-inflammatory agents or cold saline immediately after the injury. These wouldn’t help Jake walk again. It seems that at present, despite the dreadful outcome of a spinal cord injury, there is comparatively little research being done into new treatments, because of the small (in percentage terms) number of sufferers.

  But there are some promising developments. Treatment involving neuronal protection, and even the regeneration of damaged neurons, are being investigated to treat conditions like Alzheimer’s Disease and Parkinson’s Disease, conditions of the central nervous system which have some similarities to spinal cord injuries.

  Stem cell treatment seems the most promising approach to neurological regeneration, and attracts a lot of publicity. Stem cells are found in most multicellular organisms. They can renew themselves through cell division, but can also differentiate into a range of specialised cell types. They can be found in embryos, where they go on to produce all the specific tissues the embryo requires. There are also adult stem cells which can act as a repair mechanism for the body, replenishing damaged specialised cells.

  In their application in medicine, stem cells are introduced into injured tissues. The cells come from the patient’s own body, so there is no risk of rejection. With proper management the stem cells can be trained to differentiate into the kind of cells needed to repair the damage. The first successful stem cell treatment was as far back as 1968, a bone marrow transplant. It is hoped th
at stem cell treatments will one day transform medicine by treating conditions ranging from cancer to cardiac failure.

  For “spinals” like Jake’s these treatments are in their infancy. It has proved difficult to persuade stem cells to differentiate into spinal motor neuron cells, the type of cell that transmits messages from the brain to the spinal cord. But some success was reported in this in 2005 by researchers at the University of Wisconsin-Madison. And in 2010 the first spinal-injury patient was treated with human-embryonic stem cells.

  Another bit of evidence we see of advanced biomedical knowledge in Avatar’s twenty-second century is the creation of the avatars themselves, derived from “human DNA mixed with DNA from the natives”—the Na’vi. This is a topic we will return to in Chapter 31, but for now we can note that this is a remarkable achievement of genetic engineering.

  Here at the beginning of the twenty-first century, genetics is another area of rapid advance and great promise for medicine. A gene is a unit of inherited material encoded by strands of the double-helix molecule DNA (that’s how it works in creatures from Earth, at least). The idea of gene therapy in medicine is to insert genes into an individual’s cells to treat conditions such as hereditary diseases, where harmful mutant versions of a gene can be replaced with functional ones. The idea was raised in the 1970s, and the first attempts focused on diseases caused by single-gene defects, such as cystic fibrosis. The first successful treatment in the U.S. took place in 1990, when a four-year-old girl was treated for a genetic defect that left her with an immune system deficiency. In a trial in London in 2007 a patient was treated for an inherited eye disease, and in 2009 researchers in America gave enhanced colour vision to a squirrel monkey, in experiments hopefully leading to a cure for colour blindness.