There’s a few competing theories around how life came to be on our planet. One of them is the theory of abiogenesis, the idea that the building blocks of life assembled themselves from the primordial soup of the Earth to eventually give rise to life as we know it today. As an origin for all life it makes sense as it had to come from somewhere although whether or not it was how life came to be here is still up for question. Indeed the competing theory for how life originated here comes in the form of panspermia, the notion that our world was somehow seeded with life from planets elsewhere. Whilst it’s likely impossible to prove either of these theories they do lead to some interesting areas of scientific research, the latter of which just bore some interesting fruit.
One of the biggest questions with the idea of panspermia is whether or not the building blocks of life could survive in the harsh climate of space. We have known for some time that simple forms of life are able to tolerate the conditions of space for what seems like an eternity but given the time frames involved it’s far more likely that their genetic components would be the only things that would survive the long journey through space. Whether or not DNA could survive some of the most harsh conditions, like plunging back into the Earth’s atmosphere at re-entry speeds, is a question that researchers at the University of Zurich attempted to answer.
The results are quite intriguing, showing that the DNA molecules (which were applied to the outside of the craft with no shielding to speak of) was still viable upon returning to Earth. Whilst it’s far from a long duration spaceflight, the TEXUS launch system is a sub-orbital platform, it does show that DNA is very resilient to the harsh conditions experienced in space, lending credence to the idea that our Earth may have been seeded with genetic material of alien origin. Just how that material would have ended up finding it’s way here though is another question entirely, although it is an interesting one.
Genetic material lacks the capability to launch itself into space and so the only way it finds its way off a planet (bar ours) is to hitch a ride on a cataclysmic event. Large asteroids that impact a planet shoot up all manner of ejecta, some with enough energy to escape their planet’s gravity entirely. It’s a rare event, to be sure, however it’s happened often enough that we’ve got numerous bits of Mars scattered on Earth’s surface and likely bits of other planets that we don’t yet know about. If just a few of these kinds of asteroids hit Earth at the right time our origins of life might lie far beyond our own planet, or possible even our own galaxy.
It never ceases to amaze me just how resilient the building blocks of life are, being able to survive the harshest conditions and still remain viable. This then leads onto us finding life in all sorts of weird places, ones where you’d think it’d be impossible for anything to survive. I honestly can’t wait for the day when we find life on another planet, even if its microbes, as it will tell us so much about who we are and where we came from.