A hot topic of debate for everyone from sci-fi junkies to conspiracy theorists is the idea of alien invasion. The truth of the matter of alien invasion hits a lot closer to home than most would like to think, giant tripods and laser beams aside; in many cases, we’re the aliens. Scientific American’s excellent piece on forward contamination--that is, the contamination of other worlds with Earth’s microbes--explores the concepts and history of the study of forward contamination in the space race. Let’s run through it and it’s implications.
A planet like Mars could contain a sensitive ecosystem that Earth’s diverse microbiology could contaminate, even killing organic life. It would also have a decent chance of ruining specimens if they also contained Earth material, creating a bias of micro-organisms.
Early travel to the moon had the same concerns, but not the same sort of technology that space agencies use today to “clean” craft that will make the long journey through space. The Viking lander missions tried to kill off the bacteria before sending the crafts to the moon, but baking the craft (even at 230 degrees) won’t kill all bacteria. Does that mean we contaminated the moon? Could we be contaminating Mars?
In reality, it’s likely that we already have. Not us as in humanity, but us as in the Earth. There’s evidence that collisions with comets or asteroids upon the planetary surface expels material into space, which can travel throughout the galaxy. This is known as an “impact transfer”, and scientists suggest it’s been happening for billions of years. It’s likely that some very hardy bacteria could survive in a sort of stasis while travelling through space, waking up upon finally reaching the surface of some distant world.
The million dollar question, of course, is this: Is there a possibility that microbes from an infant Earth could have made it to Mars billions of years ago, possibly when it was warm and wet? Or did the opposite happen, making us all of Martian origin?
Cue the scary music and hats off to science for bringing a little bit of science fact, not fiction, into the realm of possibility. Now at least I have an excuse when someone says I’m not from this planet.
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