Stephen Hawking has warned that humanity must start to colonise a new planet within the next century if it is to survive. Some argue that the colonisation of space should be our era’s version of the great voyages of discovery undertaken in the past, and that we should channel the spirit of the Portuguese and Spanish explorers of the 15th and 16th centuries.
Others believe that the history of colonisation is the wrong model for our approach to space, and that instead we should think of it as our era’s version of the great engineering projects of the past, such as the pyramids or the Great Wall of China. Rather than humanity living on other planets, the priority as they see it is to re-engineer other planets so as to be suitable for earth life such as plants or sea-life (though not necessarily humans).
Such epic projects have, in the past, been a key factor in binding and guiding civilisations and in the great men of civilisations pressing towards some worthwhile goal instead of oppression or decadence.
They have, however, come at a cost and taken some time. Before we set off to colonise or terraform other worlds, we should perhaps ponder whether we have the determination and resource commitment to see it through. It’s easy to declare terraforming another planet our version of past engineering projects or voyages of discovery, but is it really a project of the same order of magnitude, relative to our civilisation’s resources? Or is it still way beyond us?
So, how long did past projects take and how much resources, and how does that compare with what we might need for these space ventures? Let us consider first the Portuguese project to discover if (as they suspected) Africa had a southernmost extent and, if it did, to find a sea route to India.
The average life expectancy in medieval Europe was around 30 (indeed, that was average world life expectancy until the 20th century). The Portuguese started their attempt to round Africa in 1419, and got there in 1498 – some 79 years or 2.6 times the average life expectancy at the time.
Current life expectancy for developed countries is around 80. A project that took around 210 years to complete (2.6 of our civilisation’s average life expectancy’s) would be one that took as long, relative to our lives, as the Portuguese spent rounding Africa. Estimates vary of how feasible it would be to, for example, terraform Mars, but a not-uncommon view is that, all being well, Mars could be converted to a wet planet suitable for plants and invertebrates with a concerted effort over some 100 to 200 years, but that it might take 100,000 years with known or anticipated technologies to render it suitable for humans.
That suggests that, in terms of timescale, the “engineering” version of terraforming Mars might be plausible, relative to past projects, but that the colonising version might need to be independent of terraforming. It might, for instance, require special habitation domes rather than re-engineering the planet’s atmosphere.
The timescale is at least plausible on some versions of the scheme. But what about in terms of resources? The Great Pyramid at Giza is generally reckoned to have been built by approximately 20,000 men working for around 20 years. The population of ancient Egypt at the time was around 2 million. If we assume the workforce was around half the population, so one million, that means those 20,000 workers constituted around 2 per cent of the workforce of Egypt.
Productivity of an Egyptian working on the pyramids was probably at least as high in terms of as the average Egyptian worker, given how systematic the pyramid project was. And the pyramid project was probably at least as capital intensive as the average project. Therefore, we can reasonably assume that a project continuously employing those 20,000 workers constituted at least 2 per cent of Egyptian GDP each year.
Since we are much richer today than the ancient Egyptians, we should arguably be willing to devote a larger proportion of our resources to such projects (less being taken by necessities), but let’s stick to 2 per cent.
If world GDP grows at 3 per cent per annum in the future (which would be slower than its growth over many recent decades, but some slowing should be anticipated as, for example, population growth slows), two per cent of GDP, each year, for 210 years, would constitute around $26,000 trillion US dollars – some 330 times today’s world GDP. Even if world GDP grows at only 2 per cent per annum for the next two centuries, if we spent two per cent per year of that on some epic civilizational project that would still amount to more than 60 times today’s world GDP.
Terraforming Mars may prove quite expensive, but past precedent suggests we should be willing to spend some 60 to 330 times the entire current GDP of the world — i.e. many thousands of trillions of US dollars — on doing it. That should give us a shot.
So, drawing on economic history, we see that terraforming Mars, at least understood as an engineering project rather than as a project of making it habitable for humans, should be doable on a timescale and resource commitment not altogether unlike those past civilisations have been willing to take on.
Are we less than them? Are we content to descend into decadence? Or shall we begin?