After dismantling the suggestion that a Mars mission is too inherently dangerous for humans to undertake, Karl Schroeder has a new target – Science Daily announces a paper that claims that we can’t go to Mars because the spacecraft will fill up with nasty bacteria and make everyone sick [via SlashDot]:

Frippiat and colleagues based their conclusions on studies showing that immune systems of both people and animals in space flight conditions are significantly weaker than their grounded counterparts. They also reviewed studies that examined the effects of space flight conditions and altered gravity on virulence and growth of common pathogens such as Salmonella, E. coli and Staphylococcus. These studies show that these bacteria reproduce more rapidly in space flight conditions, leading to increased risk of contamination, colonization and serious infection.

The basic facts there are quite true, but they’re being deployed alongside some invidious assumptions, as Schroeder points out:

This doesn’t mean that space flight is intrinsically dangerous.  It means that badly shielded tin-can environments that aren’t spun for gravity are a bad idea.  And that is quite a different conclusion.

Prolonged exposure to zero gravity weakens the immune system, so don’t expose astronauts to prolonged zero gravity.  Invest in some research into how to spin the spacecraft.  Then spin the spacecraft.

Secondly, shield the damn things.  The only reason why radiation is considered an issue is because it’s expensive to transport heavy shielding into orbit. One solution would be to use lunar water; simply put bags of the stuff around the ship.  That makes it heavier and hence requires more fuel… but now the problem can be seen for what it is, a simple problem of launch costs.

Spaceflight is not bad for our health.  Cut-rate spaceflight that avoids the obvious solutions is.

Those obvious solutions are, of course, a function of the launch cost issue – there’s a solution for pretty much everything if you can just get the necessary hardware up into orbit, but that’s not an option while we’re constrained by the limitations of rocketry.

I suspect that we’ll get there eventually, provided we survive our short- to medium-term future. After all, sailing ships were almost impossible to keep disease-free at first, until some smart minds got focussed on fixing the problems – and the motives for those fixes were profit and colonial expansion, which are likely to be exactly the same factors that propel us out of the gravity well. Perhaps the commercial space operators will break out of the rocketry box, given the chance.