Let’s Talk About Panspermia
Let’s Talk About Panspermia
My favorite theory for the origin of life on Earth is panspermia. The only other theory I can think of is abiogenesis, which is interesting in its own right. However, for me, it lacks the xenomorph /Zerg like quality I admire in life.
Anyone familiar with Greek and/or the word sperm might deduce panspermia involves life traveling through space and seeding planets. There are a few different ways for it to occur and a few different organisms that might be able to survive a trip in space. First let’s take a look at what kind of life can survive space travel.
The Goldilocks Zone
Most life on Earth lives within a fairly narrow range of parameters. Environments where it’s not too hot, not too cold, not too acidic, not too basic, not too radioactive etc. Unfortunately for most life on Earth, this means it has zero chance of surviving unassisted in space. However there is an interesting group of organisms that could possibly survive the harsh conditions of space.
Extremophiles are types of organisms, mostly microbes, which thrive in extreme Earth environments. For instance, Methanopyrus kandleri is a type of bacteria that lives on the hydrothermal vents found in the deep ocean. M. kandleri currently holds the record for surviving in extreme temperatures, 252° F.
Thermococcus gammatolerans is another record holding microbe. Like M. kandleri, T. gammatolerans is found in the deep ocean at hydrothermal vents. While it also survives in hot conditions, 190° F, this organism’s claim to fame is its resistance to radiation. T. gammatolerans is able to withstand 3 x 106 rads of radiation. For comparison, a lethal dose of radiation for you and me is 500 rads.
The list of extremophiles goes on. Some that like it really cold, some that like it really hot, and some that like it really acidic. There are even organisms, oligotrophs, which survive in low nutrient environments. It seems that nearly every Earth environment once thought too harsh to support life, does support life. This is good news for the panspermia theory. If life can survive deep in the earth’s crust, in sheets of ice or in pools of radioactive liquid, why not space? While this all looks good on paper, theory and reality are often two entirely different things. Are there any organisms we know of that can survive in space?
Since the Gemini space flights in 1966, biological research in space has taken place to answer that very question. There are some promising results. But surviving in space is one thing. Getting around in space is a completely different story, and as far as we know bacteria has not started a space program. So how would a living organism get for point A to point B?
There’s lithopanspermia which involves organisms hitching a ride on rock from one place to another. Key to this theory is the ability for living organisms to survive the trip from the surface of the planet to space, then survive the transit in space and finally survive the entry into the new planet.
All of those steps involve extreme conditions ranging from extreme temperatures, extreme pressures and extreme radiation. The host rock may offer some protection from these conditions, but if not you’d need some hardy organisms. There’s also pseudo-panspermia which doesn’t involve living organisms but the chemicals necessary to promote life being deposited on the surface of the planet by way of meteorites.
And then there are aliens. The thought is life on Earth was, purposefully or otherwise, started by extraterrestrials. By far my favorite theory for the extraterrestrial origin of life on Earth is the Cosmic Garbage theory proposed by Thomas Gold. It’s the thought that Earth was at one point E.T.’s landfill.
Something about life evolving from the waste products of a super-advanced, space-faring species resonates with me.
“Sowing our interstellar wild oats”
Some have even suggested undertaking our own panspermia, which might not be a bad idea. After all as far as we know, we’re it when it comes to life. Why not sow our interstellar wild oats?
Whether life on Earth came from the primordial soup, a meteorite with some passengers or the engineers from Prometheus , the truly phenomenal thing is the robustness of life. In the words of Dr. Ian Malcolm “If there is one thing the history of evolution has taught us it’s that life will not be contained. Life breaks free, it expands to new territories and crashes through barriers, painfully, maybe even dangerously.”