Dr. Alan Stern, an engineer and planetary scientist who has worked on dozens of NASA projects, has expressed his view that one of the reasons we’ve not detected any alien lifeforms or civilizations is that many of them could well be far below frozen seas and deep oceans.
Stern, who currently works at the Southwest Research Institute in Texas, made the comments last week whilst speaking at the 2017 Division for Planetary Sciences. He was discussing the Fermi Paradox, named after physicist Enrico Fermi, which highlights the contradiction between the theoretical estimates on the number of alien civilisations and the complete lack of any proven contact.
The argument goes that given the sheer number of stars in the galaxy, the large number that are similar to the Sun, the age of the Milky Way, the fact that we have made it into space in a fairly short time and that you could theoretically cross the galaxy in a few million years means that we should have been contacted or visited by intelligent aliens already.
The Drake Equation is a sort of educated best guest at the number of civilizations that might exist and it generates a huge number. Even if you put in some very conservative numbers it returns a high value for the Milky Way and billions of results for the Universe, you can play about with it using this great interactive version on the BBC.
Stern, whose involved in both the Moon Express venture and New Horizons Pluto mission suggests that the majority of planets with biology and civilization are ocean worlds, cut off from any outside communication and hard to spot. The paper points out that many oceans, even in our own Solar System, are interior ones. These are covered in thick layers of ice or rock and if that is repeated elsewhere in the galaxy then the majority could be like this.
Stern also points out that these protected oceans offer excellent shielding from many of the events and forces that can harm or destroy life. The likes of asteroid impacts, changes in atmosphere, radiation, climate change and other astrophysical hazards have their impact much reduced if you are under meters or even miles of protection.
He further theorises that this protective layer would also hinder any electromagnetic communication and that such civilisations might not even be aware they are below the surface of the planet. They might also be unlikely to explore off the planet even if they did, given the huge logistical tasks of moving large amounts of water around.
It’s a fascinating read and fairly short, you can view the document here.
Of course it could also be that even life is common outside our Solar System, that intelligent life is much rarer or that civilisations tend to destroy themselves fairly quickly. Both of these would mean there would be little chance of contact given the distances involved and the vast number of planets.
The first step to putting some real bones on the Drake Equation are already underway with the identification of exoplanets in the habitable zone of various stars. A huge leap forward would be the discovery of life on another planet in our Solar System that had developed independently. That would mean the entire Universe if probably teeming with life of some sort, though not necessarily intelligent.
What do you think of Stern’s ideas?