In the Milky Way, Kepler data point to stars with planets smaller than Neptune orbiting in the liquid water zone. There are at least nine so far, larger than 1.2 times the diameter of Earth, smaller than Neptune,
and probably rocky. Hence, the probability that we are not alone keeps rising, as it does when we consider various scenarios unlike Earth’s.
For example, a small star about the size of Jupiter, only 39 light years away in the constellation Aquarius, has three planets orbiting in the “habitable zone.” Their orbits are 4 to 73 days long, so they may be stuck with one side facing their small sun, which would make an intermediate zone quite permanently temperate. The questions then arises—how old is the sun and how long has the planet had temperate
Of course, those not the only questions to ask. Here’s another idea recently proposed by Joann Wendel of NASA/Goddard/SD May 23, 2016: She suggests that Earth managed to jump-start life because solar flares were “…bombarding Earth with energetic protons and radiation much more frequently four billion years ago. The early sun was not very bright, but the flares may have heated the Earth enough to keep water liquid and charge its atmosphere’s chemistry, forming organic molecules out of simple inorganic substances. Hence the prospects for life emerging on planets orbiting young stars are worth considering.
When solar flares were applied to a model of Earth’s very early atmosphere (Nitrogen2, carbon dioxide, methane and water vapor), ionized atoms tore apart those substances, making them much more
reactive. Hydrogen cyanide could have formed and reacted with water to form “…molecules necessary for life.” These include amino acids, the complex sugars required by nucleic acids (RNA and DNA), and nitrous
oxide. The latter could have warmed the atmosphere.
Thus, perhaps suggested, the phrase habitable zones of habitable exoplanets should be changed to biogenic zones, where water stays liquid and the atmosphere is energized to make the biomolecules of life.
Another question to ask is whether plate tectonics is required for life to evolve on a rocky planet. It certainly helped Earth along. Plate tectonics kept our climate temperate by cycling carbon. Also, cold slabs
still cool the interior and help maintain the magnetic field, while “…subducting heat from the core.” Thus climate, mantle and core have made life possible here, suggesting that plate tectonics, temperate climate and magnetic fields are “necessary for life.”
The role of radiation could also play a role in creating life. Jupiter’s radiation could split water and excite hydrogen and oxygen reactions, perhaps in the surface cracks of Europa. They run deeper than Earth’s and dark ones could be sea salt.
Finally, the role of caves in aiding life’s emergence was suggested by an article in EOS April 15, 2016. “Planetary caves are practically everywhere…” as are vents and fissures associated with water ice plumes on the moons of our solar system planets. Cave-like features provide subsurface access to 2000 Martian and 200 lunar locales. The hunt is on for “biosignatures” in such places. Let’s hope we can come up with the money to arm our instruments with the tools suggested by astrobiologists: mass spectroscopy, laser-induced breakdown spectroscopy, energy dispersive spectroscopy, and visible spectrum cameras for use with cellular automation algorithms. Stay tuned.
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. coming in 2016)
Excerpts, Synopses, Reviews, On Writing, Characters and More-
Reviews of significant books- http://www.goodreads.com/Cary_Neeper
How the Hen House Turns- http://www.ladailypost.com
Complexity, Bio, Bibliography and Links- http://caryneeper.com
Astrobiology– http://astronaut.wpengine.com search:Who’s Out There