Colonise, decarbonise, repeat

SpaceX has landed a bit of spaceship on a robot boat.

Elon Musk, the CEO of SpaceX, is re-using chunks of his spacecraft with the very specific aim of bringing the costs of space travel down, and eventually, facilitating the colonisation of the moon, and Mars. Later this year, Musk will reveal the design of the Mars Colonial Transporter and their spacesuit. Broadly, Musk describes the colonisation of other planets as a way to ‘back up’ the species – read this long but supremely worthwhile post on the topic. You won’t regret it.

“This concept—making human life multi-planetary in a self-sustaining way—is often called “planetary redundancy.” Musk calls it life insurance for the species. I call it backing up the hard drive”

Musk’s other efforts have been directed towards finding technically sound, economical solutions to decarbonisation – through Tesla’s electric vehicles and battery storage systems, and Solar City’s rooftop solar PV deals.

“If we don’t find a solution to burning oil for transport, when we then run out of oil, the economy will collapse and society will come to an end. If we know we have to get off oil no matter what, we know that is an inescapable outcome, why run this crazy experiment of changing the chemical composition of the atmosphere and oceans by adding enormous amounts of CO2 that have been buried since the Precambrian Era? That’s crazy. That’s the dumbest experiment in history, by far”

Inevitably, critics feel a mild rush of joy when they feebly counter that rocket launches produce carbon emissions:

These repeated assertions reminded me of a talk I listened to some time ago, by Professor Steve Rayner, James Martin Professor of Science and Civilisation at Oxford University. In the talk, Rayner outlines three options for halting the momentum of climate change:

  • Alter the technology we use to generate energy
  • Alter the climate using technology to reverse the impacts of carbon emissions
  • Forcibly reduce the population

As Rayner points out, the third option is unthinkable, obviously. The second is currently (arguably) technically impossible to achieve safely, and the first is extremely difficult (trust me. I’m trying.)

It’s not going to happen soon, but if we use a small quantity of fossil fuels to transfer a collection of human beings to another planet, that actually has a major impact on the Earth’s climate system – essentially, a way to achieve point 3 – a reduction in the population of Earth, and a subsequent reduction in the output of fossil fuels. Except, you do without genocide, which is always nice.

So: what if a single Australian citizen bought a trip to Mars, on a SpaceX craft? Handily, someone at Quora has calculated the emissions from a single Falcon 9 launch already – around 2,902 tonnes of co2 for 12 yearly trips, or 241.833 tonnes per trip.

The Next 10 Green Innovation index shows that in 2013, we were leading the world in terms of per-capita emissions – around 18 tonnes per person per year. You’d need to be off-planet for around 14 years before your off-planet trip started being a net saving for the planet:


It’s pretty clear that spacecraft transferring humans to Mars wouldn’t carry just one person, but I’d also guess that a single large ship would use up significantly more fuel.

Let’s just go with SpaceX’s Dragon V2 crewed variant, which carries seven people, seen below test-firing the emergency rockets that move the crew to safety in the event of an explosion.


A high-capacity module pulls back our ‘break-even’ x-axis intersection point much earlier – almost immediately after the launch:


The launch emits 242 tonnes of carbon emissions, but within the first year you save 126 combined tonnes of emissions from the absent Australians, and in the second year, you’ve saved 252, and so on.

Okay, let’s get totally ridiculous now. What if we launched all of Australia’s 23.13 million inhabitants into space, bound for Mars, using Dragon V2 modules? You’d need to launch 3,304,286 rockets in year 0, but you’d save 12,107,454,673 tonnes of emissions by year 30. It’s bonkers, but who knows. We might see it in our lifetime. There are hundreds of thousands of flights per day.

If you were to rely solely on this approach for decarbonisation, you’d encounter some major problems. This assumes consumption on planet #2 is emissions-free – it might not be. But then..would a terraformed Mars even consider greenhouse gases a problem? But we’d have to send equipment, vehicles, habitats etc on rockets, too, which changes the angle of our payback-line slightly. Even with our seven-person flight, you’d have to pack serious supplies, which also slightly lengthens the ‘payback time’.

Knowing people as we do, it’s likely that only the wealthy would be able to afford the move – creating an interplanetary wealth disparity. These less-wealthy groups might also not be able to afford modern formats of clean-energy technology, leaving one planet subject to serious harm whilst the other prospers. This already happens – fossil fuel advocates are strongly targeting developing countries.


Using a small amount of fossil fuels to acquire a larger saving is a pretty common feature of technological decarbonisation. If you want to build a wind turbine, a solar panel or an electric car, you’re currently locked in to using energy-intensive fossil fuels to make the machine, which then offsets many more times this amount through the machine’s lifetime. Most recently, this came up around the issue of de-icing wind turbines in cold climates using a helicopter:

kellychartfixed (1).jpg

This chart seems to fit a fairly common pattern. Consider wind and solar manufacture – I used this meta-study as a source for construction emissions, and this Climate Council report as the source for Australian emissions intensity in 2011:


Australia’s emissions intensity does change slightly over time and location, but you get the idea. Critics focus on the small red rectangle, and are blind to steep green drop that occurs over the lifetime of the machine. The same thing will eventually apply to using rocket launches to reduce the strain of human beings on the Earth’s climate system – focus solely on the launch; ignore the net benefit.

Interplanetary colonisation will eventually be a key part of sustaining our lifestyles in a way that doesn’t sabotage our future. It won’t be easy or simple, but if we really try, we can make it fair, and relatively cheap. If we’re smart, we’re learn from our mistakes on Earth, and avoid locking ourselves into costly errors. I suspect SpaceX’s efforts will play a big part in this, and I’m optimistic about the future.

Header image – SpaceX/Flickr

  1. Love that you took on this topic Ketan, and its an interesting perspective. Musk’s endeavour ignites in me a boyish excitement that is hard to describe. Given your interest I very strongly recommend that you invest some time in reading through Kim Stanley Robinson’s Mars Trilogy. No one, to my knowledge, has run a greater or better thought experiment about human colonisation of mars and KSR is quite rightly very widely recognised as not only one our greatest living science fiction writers but as an environmentalist and a futurist visionary of remarkable depth and integrity. I’m sure Elon’s a big fan.

    Anyway, once you get to book three (Blue Mars), the storyline concentrates on the relationship between a young independent Martian society of around a hundred million people and a seriously compromised Earth that is crippled by over-population, resource scarcity, advanced sea-level rise and extreme climate events. There is immense pressure from Earth for Mars to accept a steady influx of immigrants, and this is enshrined in the Martian independence treaty. Quite aside from the cultural issues that ensure from over-rapid immigration on Mars, the pertinent bit is that such a policy cannot, under any circumstance, alleviate the environmental pressure on Earth. Robinson does the maths on this. I can’t remember the figures but they’re quite detailed. They basically say that even with the maximum conceivable amount of human transfer (consider orbital windows, available fuel, etc), even using entirely hypothetical fusion-propulsion tech that only exists in the books, the effect of emigration would be a drop in the ocean compared to expanding pressures of population on Earth. What the characters in the book conclude is that Mars is indeed a planetary insurance policy. It can also act as a source of technological innovation, a political influence (and inspiration), even a provider of aid to some extent. But Earth is on its own with respect to its own problems because the distances between the two worlds is so vast that they must forever remain independent biospheres.

    Liked by 1 person

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