Stephen Baxter - The Science of Avatar

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 fluids 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.

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.