Mythbusting Thriller Science: Space bacteria #3 (Crichton’s Andromeda Strain)

Should we be afraid of space germs?

In previous posts, Crichton’s “myth” that bacteria could survive in space and travel to earth (possibly from another world) was CONFIRMED.  In The Andromeda Strain, the microbes that land in the Arizona desert aren’t the cute little guys who ferment grain into beer.  They’re ruthless killers, wiping out a whole town and threatening the end of the world if containment fails.

Is this part of the myth plausible too?  How likely is it that space bacteria, once on earth, would be deadly human pathogens?

The answer is not likely, but remotely possible.

In the normal earthly realm, bacteria and humans have co-evolved to survive with each other.  Some bacteria ignore us, some use us for shelter, some actively help us, and a few–only a tiny fraction of all the species–cause illness.  To do so, disease-causing bacteria must find a way past our many defenses, such as our skin, acid in our stomachs, and of course our sophisticated immune systems.  The chances of a random space bug having the necessary adaptations to infect a human being are infinitesimally small.

BUT…if such a germ did land on our planet, the odds of it causing a devastating plague are relatively high.  This is the natural pattern when a new germ encounters a “naive” population (people who have no immunity against it).  Smallpox, brought to the Americas by European explorers in the 16th century, is a good example.  Native peoples were virtually eradicated by this “new” disease, which had reached a kind of equilibrium in Europe.

Something else to worry about is the effect of space travel on bacteria carried by astronauts.  One study showed that culturing Salmonella bacteria in zero-gravity made them three times more likely to kill mice when the bacteria returned home.  (In case you’re wondering, the space-grown germs formed something called a biofilm, which acts as a protective coating.)

So go ahead and be terrified when you read Crichton’s book, but save your real-life fear for that guy coughing up a lung next to you in coach class on your next flight.

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