One of the most controversial theories presented on how life began on Earth is panspermia – the idea that some primitive life form riding on a comet or asteroid managed to survive the extreme conditions of space and the fiery plunge through the Earth’s atmosphere to splash down, revive, thrive and become the ancestor of all life on our planet. As farfetched as it sounds, it is not impossible and it would also provide an explanation for why we have not yet found signs of life elsewhere – perhaps it can only be transplanted from planet to planet, star to star, galaxy to galaxy. A recent study has put a new spin on the panspermia discussion by spinning the direction – instead of hardy microbes coming TO Earth on comets, it proposes sending hardy microbes FROM Earth on interstellar comets as a way for humanity to expand across the galaxy and, in a sense, conquer it. Is this really a good idea? Wasn’t this a Star Trek plot or two?
“It may be that habitable planets are common but life is rare. If future advances in telescopes increasingly suggest this is so, humankind might feel motivated to seed lifeless planets with resilient terrestrial organisms or synthetic forms designed to thrive on the target planet. A useful mechanism for achieving this goal at a relatively low cost is to use interstellar comets transiting the Solar System to convey microbial cargoes toward nearby planetary systems, where they could disseminate the inoculum via their dust trails.”
The era we live in may one day be known as the Era of ʻOumuamua, the first confirmed interstellar object to visit our solar system. Its appearance in 2017 has spawned countless discussions about what it might be (space rock, alien ship), where it came from, how many have we missed, and are there any chunks of other interstellar rocks on the bottom of the ocean. Another line of discussions intersects that one through the question of whether ʻOumuamua might have been carrying life forms. If they were not on the inside, could they have been extremophiles on the outside? If they were clinging on for the ride on the rock or in its dust trail, were they the result of accidental biological contamination or intentional placement? In their study, “Directed Panspermia Using Interstellar Comets,” authors Christopher P. McKay, Paul C.W. Davies, and Simon P. Worden (from NASA's Ames Research Center, the Beyond Center for Fundamental Concepts in Science at Arizona State University, and Breakthrough Initiatives, respectively) take on the intentional panspermia discussion from the perspective of humans doing the sending – admitting right up front that “Our scenario raises a number of ethical and technological challenges that need to be addressed.”
“It may well be that a favorable location for life's origin is very different from a planetary environment in which life might be successfully sustained over the long term. Such a state of affairs would actually require some form of transfer mechanism to explain life on Earth. Both processes may be operating.”
Fermi’s paradox puzzles over the lack of evidence of other life forms in a galaxy full of suitable places for life to start and live. This study proposes that a planet suitable for life may not be suitable for abiogenesis – the creation of life. And vice versa. Part of the reason for the scarcity of life might be the randomness of accidental panspermia. That can easily be resolved by directed panspermia. Of course, we are a long way from a Star Trek world where the seeds of life can be transported by starships. However, we now know that interstellar comets pass close by Earth and then head back out into space. Why not try what we suspected another intelligent civilization might have done with ʻOumuamua and place some extremophile life on another comet and send it to another solar system? Do that enough times and Fermi’s paradox is resolved … by humans!
What could possibly go wrong? The authors give their warning:
“A serious argument that might be advanced against panspermia stems from the point of view that life is a planetary phenomenon forming a complex globally distributed web of interdependent organisms that exchange material and information. Therefore, merely dropping a few microbes on a habitable but otherwise barren planet would not successfully seed it. Rather, one would need to send an entire customized ecosystem—a sort of mini-web of life for the inoculum to have any chance of “taking” on the host planet. Determining the minimal subset of organisms required is a formidable challenge that may require significant advances in our understanding of the web of life.”
While we can conceive the idea of directed panspermia and we’ve sent a few probes which have had direct contact with asteroids, we’re a long way from detecting interstellar comets and catching them in time to drop some organisms, and an extremely long way from figuring out what might happen when the organism is planted on another planet or moon. One thing we do know is that there are few if any Earth organisms that might survive such a trip – tardigrades are the best example – and the best solution will probably be genetically altered organisms. Since we haven’t perfected the technology nor argued through the ethics of genetically altered living things that stay on Earth, taking on that discussion in regard to sending such organisms to populate another world should be beyond modern ethicists and philosophers. Of course, they won’t be the ones making the decisions – those will be the people who see a profit in the project.
Another consideration is directing the comet itself so that its path intersects with a selected planet or moon. Should it crash on the planet or merely pass its tail across it? Would a crash ruin the capability of the planet to sustain the life the comet was bearing? Finally, there is the “Who do we think we are that we can populate the galaxy?” question. That answer to that may go back to Fermi’s Paradox – we think we are the only life in the galaxy based on current observations. Perhaps it is OUR destiny to populate it … and beyond. The argument against that, of course, is the idea of panspermia itself … what if WE are the result of another advanced civilization using directed panspermia a few billion years ago to start life on Earth? Is it our destiny to continue to grow life on Earth? Or are we destined to be a biological von Neumann self-replicating machine and continue the process?
“In our vision of a biological universe outlined here, the fundamental objective is to enhance the richness and diversity of life in the universe. Life itself is the message and no further message would need to be embedded in it, although that remains an option, a topic sometimes dubbed genomic SETI.”
The authors conclude that their justification to recommending directed panspermia is “genomic SETI” where life is the message. That leaves this writer with one request for the future generations that finally succeed at directed panspermia – keep the definition at “messaging” … not conquering or colonizing or both.