Researchers may have figured out why Mars became uninhabited
According to scientists, “the primitive biosphere of the planet had the effect of self-destruction.”
A new climate modeling study suggests that ancient microbes caused a climate change on Mars that made the planet less habitable, possibly leading to their extinction.
The article was published in the journal Nature Astronomy .
According to the study, simple microbes that feed on hydrogen and emit methane may have flourished on Mars around 3.7 billion years ago, around the same time that primitive life took hold in Earth’s primordial oceans.
But while on Earth the emergence of simple life gradually created an environment conducive to more complex life forms, the exact opposite happened on Mars, according to a team of scientists led by astrobiologist Boris Sauterey of the Institut de Biologie de l’Ecole Normale Supérieure (IBENS) in Paris.
Sautray and his team ran sophisticated computer simulations that simulated the interaction of what is already known about Mars’ ancient atmosphere and lithosphere with hydrogen-consuming microbes like those that existed on ancient Earth.
The researchers found that while on Earth, the methane produced by these microbes gradually warmed the planet, Mars instead cooled, driving the microbes deeper and deeper into the Earth’s crust to survive.
“At that time, Mars was relatively humid and relatively warm, between minus 10 and 20 degrees Celsius. On its surface was liquid water in the form of rivers, lakes, and possibly oceans. But its atmosphere was very different from Earth’s,” the scientist said.
Being farther away from the Sun than Earth, and therefore naturally colder, Mars needed these greenhouse gases to maintain a comfortable temperature for life.
But when these early microbes began to consume hydrogen and produce methane (which acts as a powerful greenhouse gas on Earth), they actually slowed down this warming greenhouse effect, gradually making ancient Mars so cold that it became inhospitable.
As the planet cooled, more of its water turned to ice and surface temperatures dropped below minus 60 degrees Celsius, pushing microbes deeper and deeper into the crust, where warmer conditions persisted.
While the microbes may have originally lived comfortably just below the sandy surface of Mars, over the course of a few hundred million years they were forced to retreat to depths of more than 1 km, simulations have shown.
Sautray and his team identified three places where traces of these ancient microbes were most likely preserved closer to the surface.
These locations include Jezero Crater, where the NASA rover is currently hunting for rock samples that may contain traces of this ancient life, and two low-lying plains: the Hellas Plain in the mid-latitudes of the southern hemisphere and the Isidis Plain north of the Martian plain.
Extraterrestrial life may be hiding in “terminator zones”
In a study published in the Astrophysical Journal, astrophysicists set out to find out if exoplanets could support life.
Astronomers have come to the conclusion that on the surface of some exoplanets there is a strip that may contain water, necessary for the existence of biological life. The terminator zone is the dividing line between the day and night sides of an exoplanet.
Many exoplanets are planets outside the solar system held by gravity. This means that one side of the planet is always facing the star they orbit, while the other side is in constant darkness.
The water on the dark side will most likely be in a frozen state, while on the light side it will be so hot that the water should just evaporate.
The terminator zone would be a “friendly place” – neither too hot nor too cold – in which liquid water could support extraterrestrial life.
Dr. Ana Lobo of the University of California, said: “The day side can be scalding hot, much uninhabitable, while the night side will be icy, potentially covered in ice. You need a planet that’s the right temperature for liquid water.”
“We’re trying to draw attention to planets with more limited amounts of water that, despite not having widespread oceans, might have lakes or other smaller bodies of liquid water, and that climate could actually be very promising.”
“By exploring these exotic climate states, we are improving our chances of finding and correctly identifying a habitable planet in the near future.”
The researchers created a model of their climate by analyzing different temperatures, wind patterns and radiative forcing, and found the “correct” zone on exoplanets that could contain life-supporting liquid water.
Researchers who are looking for life on exoplanets will now take into account the fact that it can hide in certain areas.
Astronomers discover the strongest evidence for another Universe before the Big Bang
The notion of the Big Bang goes back nearly 100 years, when the first evidence for the expanding Universe appeared.
If the Universe is expanding and cooling today, that implies a past that was smaller, denser, and hotter. In our imaginations, we can extrapolate back to arbitrarily small sizes, high densities, and hot temperatures: all the way to a singularity, where all of the Universe’s matter and energy was condensed in a single point.
For many decades, these two notions of the Big Bang — of the hot dense state that describes the early Universe and the initial singularity — were inseparable.
But beginning in the 1970s, scientists started identifying some puzzles surrounding the Big Bang, noting several properties of the Universe that weren’t explainable within the context of these two notions simultaneously.
When cosmic inflation was first put forth and developed in the early 1980s, it separated the two definitions of the Big Bang, proposing that the early hot, dense state never achieved these singular conditions, but rather that a new, inflationary state preceded it.
There really was a Universe before the hot Big Bang, and some very strong evidence from the 21st century truly proves that it’s so.
Although we’re certain that we can describe the very early Universe as being hot, dense, rapidly expanding, and full of matter-and-radiation — i.e., by the hot Big Bang — the question of whether that was truly the beginning of the Universe or not is one that can be answered with evidence.
The differences between a Universe that began with a hot Big Bang and a Universe that had an inflationary phase that precedes and sets up the hot Big Bang are subtle, but tremendously important. After all, if we want to know what the very beginning of the Universe was, we need to look for evidence from the Universe itself.
Read the full article here.
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