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Some Things Are Better Left Unsaid

April 20th, 2004 · No Comments

Olivia Judson, an evolutionary biologist at Imperial College, has written a piece in the New York Times yesterday called Some Things Are Better Left on Mars, where she argues that the risk of infection by Martian lifeforms far outweighs any scientific gain from bringing back rock and soil samples. Given that we know organisms on Earth can survive in extremely harsh conditions, and the terrible lessons we’ve learnt from history of the first encounter between human populations without resistance to novel pathogens (e.g. the Americas and influenza), why should we risk it?

I’ll tell you why: her two main reasons are totally worthless. Firstly, organisms adapt to survive within a narrow range of conditions; while humans can live almost anywhere on the surface of the planet, we cannot live underwater, nor can we live underground at high pressures or temperatures above 50C or below -50C (and this is a generous estimate). We can’t live in an atmosphere that doesn’t have a particular pressure of oxygen, and there are plenty of chemicals that would be harmful or even fatal to us. Similarly, there are organisms that can live above 50C, or at high pressures or in different atmospheric mixes – but those organisms would drop dead, or at the very least become totally inert in any environment other than that which they are adapted to.

Mars has an atmosphere that is 100 times thinner than ours, mostly carbon dioxide, with a completely different chemical environment, much less water and much colder and dimmer. The planet is exposed to different radiation, different winds and different weather cycles. There is no environment on Mars, even underground, that remotely resembles Earth or more importantly, the human body. There may well be extant life on Mars in the form of extremely hardy micro-organisms adapted for low temperatures, low pressures, carbon dioxide atmosphere and low nutrients. They probably have a very slow metabolism due to a lack of energy inputs. If you put any of those organisms in the mostly water, 37C environment, high pressure and alien chemical environment of a human body, they would die.

And this ties into the argument that we should be afraid of novel organisms because of the influenza plague. Sure, we’d have every reason to be wary if there happened to be humans (or even remotely mammal-like organisms) on Mars, since they’d have provided an environment for pathogens to evolve that’s similar to our bodies. But there aren’t.

Even supposing that we did bring back harmful micro-organisms from Mars, the safety measures proposed for any sample return mission are nothing short of gargantuan. The samples would be returned to the highest class of biohazard facility, at or above the level required for highly infectious lethal human pathogens such as ebola; namely, sterilised, pressurised, air-tight facilities with multiple layers of redundancy and safety. There would certainly be a purpose-built facility for any sample return missions. I’ve also heard proposed for sterilising the returning spacecraft with a rocket exhaust while in orbit.

I find it totally puzzling why the New York Times would run such a badly-informed article as this, and I’m also confused as to why Judson would wish to make herself into a fool by writing it. Perhaps she does have a good reason for opposing a Mars sample return mission; unfortunately for all of us, it isn’t in her article.

Tags: bio · science · space

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