Germophobes have it tough on our planet. With microorganisms outnumbering us by factors of billions, it’s an uphill battle to sterilize just about anything. Even our space probes are teeming with germs, and as we go out looking for life on Mars and possibly on Europa or even Titan, there’s a very real risk that we could pollute the alien biospheres of these worlds with bacteria from ours, tainting the results of our research. There’s even an official term for something like this. It’s called forward contamination. But while astrobiologists generally see this is a hurdle to finding and studying alien species, some people think that we might have a duty to spread a little bit of our world to ensure that life arises on other planets. It’s a heady notion and it raises important and potentially profound questions about life in our galaxy and the implications of seeding life across space.
First and foremost, there’s the question of whether our microbes will survive in an alien environment for years on end. True, there have been tests on how well Earthly extremophiles deal with the vacuum and radiation of space, but none of them have ever tried to see if these creatures would really take root on another world. It could be that there’s nothing for our microbes to metabolize on alien planets. No water means no solvents for key chemical reactions and the organism dies. If there’s no food, there’s no energy too keep up the chemistry. If there are already alien bacteria trying to eek out a living, the alien creatures and our spores could start a big competition for the available food until one overtakes the other, or part ways completely until the biospheres of the planet are split between the natives and the invaders. Without the proper environment, you can also forget about the evolution of intelligent life or even macroscopic life. And even if it does evolve, chances are that their shared ancestry with us would’ve helped these organisms come into existence, but they most probably won’t look anything like what we know on Earth according to the theory of evolution.
Secondly, we need to consider whether it’s really our duty to be exporting our germs to the rest of the universe and what role we would play in the evolution of alien life. The choice would depend on the person’s opinion of course, since there’s not law of nature that would forbid us to send a microbial Noah’s ark to another planet if we have the time to wait until the probe gets there, or feel content to launch it towards a star system as fast as we can and leave it to its fate. In the future, we could even launch small probes at relativistic speeds and get a chance to do some interstellar mad science within a human lifetime. But should we? What if we kill a species of native aliens with our intrusion? What if we snuff out a potential evolutionary story unfolding on a world near us, with a rich history of bizarre extraterrestrial creatures we could study for decades otherwise? Just as easily (or with a whole lot of effort, depending on the planet’s conditions and differences in chemistries) as we could seed life, we could snuff it out. There’s also the question of whether we could even prevent it from happening as nothing we launch into space is a picture of sterility. Germs hitch rides of spacecraft all the time. However, they don’t seem to take to Mars all too well since they’ve never been detected by our rovers.
Finally, we should note that if we, a species which barely started leaving its own world in the last six decades, are already thinking about seeding life across the universe, who says that it hasn’t happened already with a more technologically advanced civilization? Could we, in our search for life, visit potentially habitable worlds, drop seeds of new life, and become responsible for an intelligent version of panspermia? And could we be a small part of a much larger collection of intelligent species which has been doing this for countless eons? If that’s really the case, it won’t answer the question of how life in general got started, but it would add a very interesting twist in the story of how life arose on certain planets. Could we be the result of an alien experiment in forward contamination 3.5 billion years ago and the species that indirectly sparked all life as we know it has vanished into extinction by now? Maybe the elusive “Creator” is really a passing spacecraft? Could we call a serious attempt to jump start life on another planet on our part an exercise in playing God? Or should we just stick to studying asteroids and comets loaded with organic molecules and precursors to genomes instead of picturing an entire swath of space as a possible new habitat for terrestrial life?