New York: A new study has found that Mars may be just too small to hold onto large amount of surface water-essential for life to thrive on the Red Planet.
"Mars' fate was decided from the beginning," study co-author Kun Wang, an assistant professor of Earth and planetary sciences at Washington University in St. Louis, said in a statement.
Although Mars has no liquid water on its surface today, remote sensing studies and analyses of Martian meteorites dating back to the 1980s posit that Mars was once water-rich, compared to Earth.
The study team — led by Zhen Tian, a grad student in Wang's lab — examined 20 Mars meteorites, which they selected to be representative of the Red Planet's bulk composition. The researchers measured the abundance of various isotopes of potassium in these extraterrestrial rocks, which ranged in age from 200 million years to four billion years. (Isotopes are versions of an element that contain different numbers of neutrons in their atomic nuclei.)
While Mars has no liquid water on its surface today, remote sensing studies and analyses of Martian meteorites dating back to the 1980s posit that Mars was once water-rich, compared to Earth.
NASA's Viking orbiter spacecraft -- and, more recently, the Curiosity and Perseverance rovers on the ground -- returned dramatic images of Martian landscapes marked by river valleys and flood channels.
Researchers have proposed many possible explanations, including a weakening of Mars' magnetic field that could have resulted in the loss of a thick atmosphere.
The researchers found a well-defined correlation between body size and potassium isotopic composition.
"It's indisputable that there used to be liquid water on the surface of Mars, but how much water in total Mars once had is hard to quantify through remote sensing and rover studies alone," Wang said. "There are many models out there for the bulk water content of Mars. In some of them, early Mars was even wetter than the Earth. We don't believe that was the case."
The findings also have implications for the search for life on other planets besides Mars, the researchers noted.