Endemic Universe

May 18, 2011

Extremophiles are organisms on Earth that can tolerate boiling temperatures, freezing cold, crushing deep-sea pressures, toxic environments or deadly radiation. Creatures like tardigrades, the so-called water bears, can survive grueling conditions for human beings with no harm. In a process called panspermia, life or its precursor can be spread across vast distances by comet and meteorite impacts on planetary bodies.

    During cataclysmic events like a volcanic eruption or a meteorite impact, these extremophiles can get sent into the upper atmosphere on a hunk of rock and even get launched into outer space. If these creatures were encased in a layer of rock sufficiently think enough to keep them protected by the harsh radiation and cold vacuum of space, some might be able to encapsulate themselves in a spore and ride out an excursion through our inner solar system. Some bacteria and even animals can  form dehydrated spores that leave them in a state of suspended animation called cryptobiosis; cryptpbiosis is a metabolic state that resembles death, but when conditions become more favorable to these organisms in stasis, they revive themselves and come back to life, so to speak. Extremophiles are of interest to us as astrobiologists because such organisms could potentially survive a transit from one planetary body in our solar system to another. Any stowaway microbes from our world that hitch a ride on a meteor or asteroid could potentially survive the impact on another planet like Mars and colonize that planet if conditions.
    Some speculate that it may even be possible to send a bacterium across the stars from one solar system into another, but the odds of that would be significantly lower than a transit within a solar system. However, astrochemistry can produce complex organic molecules like benzene and even ribose sugar. These chemicals are the precursors to life and their creation in such a hostile environment like space may mean that life is common in the universe. And if these chemicals could be made in space, then panspermia would send these building blocks down onto a suitable planet. Some scientists speculate that water was brought to Earth via comet impacts after the formation of the Earth. An analysis of the water on Earth shows that the hydrogen in water is sometimes made of a heavier deuterium isotope. Based off of this analysis,  researchers have suggested that the water delivered to Earth from space only contributed a modest amount when compared to the amount out-gassed through the crust during the formation of the Earth. On Areios, water brought by comets plays even less of a role in the amount of water on the planet. Because of Areios’ larger mantle and greater mass, more water gets outgassed from the crust and that water gets held in the atmosphere for longer because there is more gravity on Areios to hold it down.
    Then there’s the issue of directed panspermia of life; could an intelligent race seed the universe with life? There is a concept known as the Fermi paradox which asks that if the universe is about 14 billion years old and even if an alien civilization could traverse our galaxy at a rate of 1/1000 the speed of light, then it could take an alien civilization 100 million years to colonize the galaxy. This means that in the span of the age of our galaxy, an intelligent species could have conquered our galaxy 140 times in that window. Of course, the earliest civilizations couldn’t have formed until terrestrial planets formed, but even if the first intelligent species didn’t get started until 10 billion years ago, that’s still 100 times the duration a species would need to colonize a whole galaxy. Fermi then wondered; what was holding a species back? Maybe colonization is impossible. If we can travel the universe in warp-powered star-ships, then maybe we can send unmanned probes as our emissaries to the starts. Locked safely away in our far-flung satellites, we could include some freeze-dried samples of extremophiles. Our probes wouldn’t seek out new life and new civilizations, but would rather look for uninhabited planets capable of sustaining life to drop their payload of ready-made bacteria to get a new colony of earth life ready.

Even moving at a fraction of the speed of light, a spacefaring civilization should have been able to colonize our galaxy by now. Where are they?


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