Panspermia is a fascinating hypothesis in astrobiology. The name is suggestive of a planet ejaculating debris into space that can one day seed other planets, and that’s rather an apt description. A more scientific definition would be the hypothesis that life exists throughout the Universe, distributed by asteroids, meteoroids and planetoids.
Extremophiles and Panspermia
Recently I wrote about extremophiles and their implications for life on other planets, in particular a type called tardigrades that can withstand the vacuum of outer space and potentially travel to other planets. In digging deeper into the subject it’s plausible that we are descendants of Martians.
Over the past two decades, scientists have learned that 34 meteorites found on Earth actually came from the Martian crust. The Martian origin of these rocks (which are listed for the public on NASA’s Jet Propulsion Laboratory’s website) is not in doubt, because characteristics of gases trapped within match precisely with atmospheric measurements that NASA’s Viking landing craft took in the 1970s. [ suite101.com ]
If it is true that microorganisms jettisoned into space from collisions to planetary bodies can seed other planets, it will go a long way towards what I believe to be our inevitable conclusion that our Universe is teeming with life. This would mean abiogenesis might still be incredibly rare, but one single planet could potentially seed dozens more, which in turn, on a cosmic time scale, seed countless more in turn.
How Far Through the Vastness of Space can the Process of Panspermia Transport Life?
It is possible if this hypothesis is correct that the microorganisms may only be able to survive on asteroids and meteors long enough for a trip within the solar system from which they were originally flung, or it could turn out that they could survive interstellar space, and over the course of thousands, or millions of years, reach other star systems to seed them with life. This is all speculation, but not without its merit.
Tardigrades are merely the hardiest of extremophiles we’ve discovered here on Earth thus far, but if life exists on other planets, we can only begin to fathom how hardy they might be given what environments they may have had to contend with during the process of evolution by natural selection. Perhaps these microorganisms would be far better equip to deal with the harrowing dangers of long term space travel than even tardigrades, hitching a ride on meteors, asteroids and planetoids, and increase the frequency of panspermia.
Did Life Originate on Earth Through Abiogenesis, or Panspermia?
While it’s intensely interesting to imagine that life on Earth may have been seeded billions of years ago by meteor impacts from Mars, the evidence that 34 such impacts have been found on this planet, coupled with the fact we know of extremophiles that could perchance make the journey, is not enough evidence alone to make the case for panspermia a scientific certainty by any measure, but it does make for a compelling hypothesis that warrants further investigation. There is one such avenue of further investigation that is not only open to us, but currently within our reach, though it is dependent upon finding viable DNA strands to study from Mars.
In order to find out whether the origin of life is frequent in the universe, whether panspermia is frequent, or whether both of these phenomena occur frequently, we need to have a strong Martian exploration program.
If life is extant on Mars, we need to isolate actual organisms. If we can do this then the next step would be to determine whether or not they have DNA.
If they use something other than DNA as genetic material then we will need to find out what it is and how it works. If they do use DNA then we will need to sequence it and determine how much the organisms have in common with their terrestrial counterparts. [ astrobiology.nasa.gov ]
This is a captivating field of study to those that look up at the night’s sky and ponder the enormous potential for the most incredible lifeforms, perhaps alien to us in every conceivable way, or perhaps more familiar than we might imagine, playing out their part in the cosmic evolutionary dance of our Universe.
If you have another nine minutes and twelve seconds to spare, check out the below video on panspermia.