Now the Falcon Heavy engines from SpaceX are about to be tested, the idea that humans are going to colonize at least some of the planets in our Solar System is now starting to actually look credible, even imminently so. And so of course we are all waiting with bated breath to see if we will find ET once we get there. The scientific consensus is starting to zero in on the idea that it’s more likely than not that we will find some form of life somewhere in the Solar System, even if it’s primitive bacteria or possibly something less than that. Of course, anything that would suggest life or proto-life would be a momentous find.
But here’s a thought. We indubitably have life on Earth. And in fact we had life well before we humans came along. In fact we had life on Earth at least as far back as 3.8 billion years ago. Is there any chance that somehow some of that life managed to escape Earth to migrate to other planets in our Solar System? Mars, the Moon, Titan, Europa, and so on?
We’ve known for a while that one mechanism that can cause stuff from one planet to get to another is the ejecta from meteorite impacts. These can cause ejection of surface material with so much power that escape velocities are significantly exceeded and ejecta blasted into outer space from where it can end up on other planets. We have seen this in our current planets (e.g. Mercury).
And you might have noticed recently that a small meteorite found in Egypt turns out to date from before the formation of the Solar System. So it must have come from somewhere in interstellar space, maybe ejecta from a planetary body since it contains metals and diamonds. So we have evidence that meteorites can land on a planet – ours – together with whatever constitutes its particular payload.
Since Earth formed some 4.5 billion years ago it has suffered countless meteor strikes. One of them is the famous meteorite that (supposedly) wiped out the dinosaurs, some 60 million years ago. That strike was obviously humongous, probably enough so that it also ejected some terrestrial material out into our Solar System. If so did this contain some living material like DNA or bacteria? Even dinosaur DNA? I’m not the first to think this, so it’s not such an outlandish idea.
Of course the dinosaur meteor strike was one of uncounted millions. Only a few were likely of this magnitude but that’s enough to think that Earth could have been emitting life forms of some description for millions if not billions of years. So its isn’t such a wild idea to think that if we do indeed find life on other planets in our Solar System, it might not be ET, it’s just cousin Joe. Or Aunt Dino. It might even be surprising if any life or proto-life we do find on these planets was not from Earth.
OK so maybe living material couldn’t survive the space journey because of radiation, or space mice (joke, courtesy of A Hitch-Hikers Guide to the Galaxy). I’ll leave that analysis to minds far more perspicacious than my own. But what if living material can indeed survive such a journey?
Some of you no doubt thave heard of the concept of panspermia, the thesis that life on Earth resulted from us being hit by objects like meteors that were carrying life or proto-life material from other locales, probably outside the Solar System. It’s a trendy and feasible idea that life didn’t start on Earth: we just were the happy (?) recipient of a gift from the stars.
But the idea that the Earth was a life donor rather than a life recipient provides a totally different perspective. We might have been sending our gift of life not just to other planets in our own Solar System but to countless others outside it. Could we one day, in the very distant future, land on an exoplanet that has life that actually originated on Earth? That the denizens of the planet could feel that we were the guilty party that gave them the life forms that inhabit their particular planet?
Could we indeed be the origin of some – all? - life in the Universe?
This is all very fanciful but certainly not impossible. It means that astro-biologists have to be alert to the possibility that any life we find in the Solar System might come from here rather than an “alien” galaxy, civilization or biology.
Despite Galileo we might just be more important than we think.
At least it’s a timely antidote to the thesis that humans are really totally insignificant on a cosmic scale.
We probably need a bit of encouragement right now given terrestrial trends that make us look like we are going to snuff out all possibility of Earth-originated panspermia once and for all.
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