In reading Summers’ and Trefils’ Smithonian book (2017) “Exoplanets,” I was struck by two of the authors’ observations: the abundance of water everywhere, and the absence of life anywhere–even its possibility. Most
of the exoplanets we have found so far are either too far from their host sun, or too close, or too something else. Furthermore, the authors (and other current writers) have noted in some detail the long list of lucky “accidents” that our Earth has enjoyed that made the evolution of life possible, as we know.
It’s worth reading Peter Ward’s book “Rare Earth” again, to remind us that Earth’s many “unusual” events were “necessary for an advanced civilization to develop:” the right size of planet in the water-friendly zone of its star, far enough away from the galactic center, with a large planet farther out, a planet with plate tectonics and the right tilt to produce ice ages, along with a lovely moon to stabilize the planet’s axis of rotation and produce tidal pools. Ward’s answer to the Fermi Paradox is simply that “there’s nobody there in the rest of our Milky Way galaxy.”
Of course, everything is improbable, given a list of events leading to any event–so “Exoplanet’s” authors point out that Ward’s argument says “nothing” about other “paths to life on another planet.” Without going into the details of the Great Filter, driven by the “laws of natural selection” should we oppose SETI and hope we are not discovered by more intelligent others?
The presence of water “everywhere,” makes the possibility of life like ours seem to be a certainty–somewhere. There are several likely places for life in our tiny corner of the Milky Way: primarily on Europa or ancient Mars. Soon we’ll be sniffing the atmospheres of exoplanets for signs of tell-tale oxygen. Finding water may not be a big surprise. Water is found “all over the place.” Subsurface oceans have been found in our solar system: Europa, Callisto, Ganymede, Enceladas and probably Titan. Earth’s ocean covers 73% of our planet’s surface.
Why is that just right for life? We have enough water to avoid a runaway greenhouse (like Venus) and not too much. (We need some dry land) Again, Summers and Trefil tell us that the emergence of life on Earth took a
“whole constellation of processes.” A Heavy Bombardment of plantesimals melted the early Earth all the way through so that heavy material sank and lighter basalts rose, while just enough light granite came to the
Earth’s surface to form our continents.
Still open to question is where all our ocean’s water came from. It might have been brought in by meteorites or comets or by outgassing from the interior;. What kind of asteroids brought it is still a question, but a ration of 20:40:40 % of water from outgassing, asteroids and comets is a reasonable current guess.
So why does Io have no water, while subsurface oceans exist on Europa, Callisto and Ganymede? Six large exoplanets are known to be ocean planets. Steam and ice worlds are other possibilities. All take
advantage of water’s strangeness, like its expanding when it gets colder than 4 degree C and its refusal to raise its boiling point with its atomic weight. Water’s electrons are arranged in unique ways. It has 13 phases or more that force its molecules into interesting arrangements that effects how it acts. It deserves watching as we explore the
Recent observations have suggested ways that the properties of water contributed to “kick-starting” life. In Science News.org/August 17, 2019, Carmen Orahl reported on a “new study” showing that on the edges
of “puddles or coastlines” microdroplets of alpha hydroxy acids could have tripped RNA to “merge and break apart,” encouraging molecules to give rise to life.
The authors discuss the role of microdroplets and “relevant nonbiomolecules” in the emergence of life. The droplets could trap and hold molecules such as RNA and allow protein to retain its function, allowing fatty acids to assemble around one droplet. Not just biolmolecules, but others, like alpha hydroxy acids, might have played
“supporting roles in the emergence of life” both here [on Earth} and elsewhere.”
Stay tuned for more speculation about where Earth found the water to invent life, the life that still requires it.
Author of The Archives of Varok
The View Beyond Earth (Book 1.)
The Webs of Varok (Book 2.)
Nautilus Silver Award 2013 YA
ForeWord IBPA finalist 2012 adult SF
The Alien Effect (Book 3.)
An Alien’s Quest (Book 4. Released Nov.21, 2016)
Excerpts, Synopses, Reviews, On Writing, Characters and More-
Reviews of significant books- www.goodreads.com/Cary_Neeper
How the Hen House Turns- www.ladailypost.com
Complexity, Bio, Bibliography and Links- caryneeper.com
Astrobiology- astronaut.com search:Who’s Out There