Thoughts on Life’s Diaspora

Here is a continuation of the discussion regarding Panspermia, which is the idea that life can move from one planetary body to another, in effect seeding a lifeless world. It is a claim that is passed off as science fiction conjecture, in some circles; as perhaps a claim not entirely worthy of scientific investigation. Others, both scientists and laypeople, helpfully counter that the idea of panspermia, as it concerns the origins of life on Earth, is just passing the problem from one place to another without answering the fundamental question, which is "How did life first arise?"

I disagree with the first point, and largely agree with the second. The search for life outside of the Earth IS a goal worthy of scientific investigation. Due to the very reasons that the origins of life are, thus far, inexplicable, so should we regard with seriousness the search for extraterrestrial life as part of the effort to understand the mystery of life's origins. We have no clear answers as to why life arose here on Earth. Even if we do find that mysterious genesis and it sheds some light on the process, we will probably not have a clear understanding of the events that transpired in life's first steps. That will be the case until we have a clear, unambiguous example of non-Earth life with which to compare us to.

It is in the spirit of this discussion of life's origin that Panspermia comes to mind. The idea that life is capable of moving from one planetary body to another is important to note because it frees life from the arbitrary confines of the planetoid of its birth. This is necessary because it appears that some forms of life have the capacity to survive this transition from the planet or moon of its birth to that of a lifeless world. Most notable are creatures called Water Bears, which can get up to 1.5 millimeters in size. A European Space Agency mission purposefully exposed Water Bears to the vacuum of space, deadly radiation and all. Already noted for their relative toughness here on the Earth, it turns out that Water Bears - also known as Tardigrades - survived the exposure. Some even went on to reproduce AFTER their exposure!

Another example of the Panspermianic property of life are the Apollo missions. Between July 20 1969 and December 14 1972, 12 human beings walked on the surface of the moon. These two examples underscore the possibility that life is capable of taking on many forms and can survive what we would normally consider cruel environmental conditions. Life is also very much capable of colonizing new territory and holding on to it tenaciously. Once, life teemed in the oceans but was totally absent on exposed land. Later, the seas and the continents filled with life but the skies appeared utterly empty. Now the air is filled to the brim with birds, bats and a plethora of insects. Even microbes have been found in the air above us - a total of 3 new species were found in the Earth's stratosphere (31,000 feet - at about the height that airlines cruise) by Indian scientists.

With these examples in mind, is it impossible to consider that life can even be ejected from its homeworld by an impact event, or by such mechanisms as the geysers of Enceladus, to pass a short distance of space and make a new home on some other planetary body? Or, can life be so bold as it appears to be on the good Earth, to colonize LEO (Low Earth Orbit) and beyond through the natural process of evolution? It seems that once life springs into being that there is no stopping its propagation and expansion.

Check out Exoplanetology's take on Panspermia
Read some of Andrew Rushby's thoughts on Panspermia