The ancient Mars was only occasionally hot and wet, a new study indicates.
Although the Martian surface is bone dry today, it is clear that liquid water flowed over it billions of years ago. The planet is marked by river channels, and ancient lakes lie on the floors of several craters – including Gale and Jezero, which are currently being investigated by NASA’s Curiosity and Determination, respectively.
But it remains unclear, and a topic of substantial scientific debate, how ancient Mars really was. Was the planet long ago constantly hot and wet, or was it almost always icy, with only sporadic soft stretches allowing passing water to flow?
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A new study reinforces the latter view, suggesting that it took dramatic events to warm Mars’ cold heart, and that such old aberrations never lasted long.
“Mars has been heated at times when its atmospheric composition is changed by the supply of volcanic gases and meteorite impactors,” co-author Joel Hurowitz, a geoscientist at Stony Brook University in New York, said in a statement. .
These hot spells caused water to flow over the surface and form rivers and lakes and the rocks and minerals that connect us to water. March, ”Hurowitz said.
The new study, led by Robin Wordsworth of Harvard University, presents a new climate model of ancient Mars. The model takes into account a variety of factors, including the effects of volcanic eruptions, which cast greenhouse gases into the Mars air, and the escape of hydrogen from the atmosphere to space.
The hydrogen escapes, powered by the solar wind, shot up dramatically after Mars lost its protective global magnetic field. About 3.7 billion years ago, the once thick Martian atmosphere was only 1% as dense as the present earth, and the era of rivers and lakes on the surface of the Red Planet came to an end.
The new study, published online today (March 8) in the journal Natural Sciences, help build that era and the potential of Red Planet’s lives. This indicates, for example, that the ‘wet’ Mars was still very cold, with an average annual surface temperature below minus 28 degrees Fahrenheit (minus 33 degrees Celsius).
“The dynamic history of Martian environments presented here indicates opportunities for the emergence of life during hot, wet intervals when reducing conditions would benefit prebiotic chemistry, but also challenges for the sustainability of surface life in light of frequent and, over time, prolonged intervals of predominantly cold and dry oxidizing environments, ‘Wordsworth and his colleagues wrote in the new study.
‘Reduction conditions’ refer to an atmosphere in which oxidation – the removal of electrons from atoms and molecules – is prevented or minimized. In contrast, oxidation is common in ‘oxidizing environments’.
Oxygen is commonly suggested bio signature – a possible sign of life that you can look for in the atmosphere of alien planets. Interestingly, the new model predicts that Mars had an oxygen-rich atmosphere over the long period “without requiring the presence of life, indicating that O2 detection may in some circumstances be a ‘false positive’ for life. “wrote the researchers in the new study.
Mike Wall is the author of “Out there“(Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.