By Dr. Gary Deel, Ph.D., J.D.
Faculty Director, School of Business, American Military University
This is the fourth article in a four-part series discussing the probabilities of extraterrestrial life elsewhere in the Milky Way galaxy.
In the first article in this series, I discussed the Drake Equation and its suggestion that intelligent life could exist elsewhere the Milky Way galaxy. In the second article, I examined the Fermi Paradox, which implies that the lack of extraterrestrial contact at this point in the galaxy’s evolution cannot be reconciled with what we should expect to see according to Drake. In the third article, I looked at the ongoing Search for Extraterrestrial Intelligence (SETI) and its efforts to locate extraterrestrial life beyond Earth. In this article, I review two potential candidates for extraterrestrial life.
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Extraterrestrial Life in Our Own Solar System Is Possible
There are reasonable suspicions that life might exist in our own solar system, even if that life ends up being only primitive in nature. Some primary candidates have been identified as potential hosts to different types of life, based on what we know about Earth-based life. Two of the most interesting candidates are Mars and Europa.
Mars Is the Most Obvious Candidate for Other Life
The most obvious candidate is Mars. Despite its dismal appearance, Mars is strikingly similar in characteristics to Earth. Mars is slightly smaller than Earth, but not so small that life could not survive the reduced gravity.
Also, Mars has close to a 24-hour day/night cycle. It is within the habitable zone of our host star, or the range within which water can exist in a liquid form.
In fact, Mars experiences above-freezing temperatures at the equatorial regions during its summer months. Some of our rovers have even recently detected evidence of briny liquid water flows on its surface.
However, Mars is far from a paradise, at least for humans. Mars’s biggest flaw is a lack of a magnetic field.
Because Mars is geologically inactive, there is no protection from the intense solar wind from our Sun. As a result, Mars has a very thin — almost nonexistent — atmosphere. This lack of atmospheric pressure, the poor protection from cosmic radiation and the absence of gases which would be necessary for aerobic organisms to survive make Mars fairly hostile to the kinds of complex life found on Earth.
This is hardly news, though. Our photography of the Martian surface and our visits on the ground have more or less confirmed that there are no ‘little green men’ living on the red planet.
However, many of Earth’s anaerobic, microscopic organisms would do just fine on Mars today, especially below the surface where the Martian crust would block much of the harmful solar radiation. Future missions to Mars — including manned space expeditions — plan to explore the possibility that the planet might in fact still be home to a microbiome of sorts.
Europa Would Also Be a Candidate for Extraterrestrial Life
The other primary candidate for extraterrestrial life in our solar system is one of the moons of Jupiter: Europa. Europa is a frozen water world on its surface, as it is far outside of the habitable zone which would allow for liquid surface water.
In fact, it is so cold at the Jovian orbit distance that other elements like methane — which is a gas on Earth — have been photographed in lakes on the surfaces of some moons.
However, some of our deep space research efforts — including photographs from the Hubble Space Telescope and the Galileo probe — have revealed geysers of liquid water bursting from cracks in the surface of Europa, shooting hundreds of miles above its surface.
Astronomers have deduced that the immense tidal forces from Jupiter are putting dynamic pushing and pulling pressures on Europa. This friction within Europa’s rocky core is causing geothermal activity, which in turn generates heat.
Scientists think that this heat is warming the interior of the planet and maintaining a liquid ocean underneath the frozen surface. This is important because everywhere on Earth where we have sustained bodies of water — even in the coldest and darkest regions of our own oceans — we find life thriving. That said, plans are underway by the National Aeronautics and Space Administration (NASA) to visit Europa, penetrate the surface ice and explore this ocean for life.
Unlike Mars, it is completely unknown whether or not life on Europa — if it exists at all — could be sophisticated or merely microscopic. After all, some species of whales on Earth have brains bigger than cars. Dolphins are thought by some to rival the intelligence of humans.
To be fair, both of these examples are air-breathing mammals that could not survive in a subsurface body of water. The only way we will know what lies underneath Europa’s shell is to go and see.
Life may indeed be a rarity in the universe, but we’ve hardly ruled out all the possibilities. Over the next century of space exploration, we hope to narrow in on the precise probabilities concerning whether or not life, in fact, exists elsewhere. Perhaps one day, we will finally and definitively answer that most meaningful of questions: Are we alone in the universe?
About the Author
Dr. Gary Deel is a Faculty Director with the School of Business at American Military University. He holds a J.D. in Law and a Ph.D. in Hospitality/Business Management. Gary teaches human resources and employment law classes for American Military University, the University of Central Florida, Colorado State University and others.
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