[ad_1]
Close-up of Mars taken by NASA’s Hubble Space Telescope. New research suggests the Red Planet may be too small to hold large amounts of surface water.
NASA / WireImage
Hide caption
Legend switch
NASA / WireImage
Close-up of Mars taken by NASA’s Hubble Space Telescope. New research suggests the Red Planet may be too small to hold large amounts of surface water.
NASA / WireImage
All the evidence suggests that Mars once had flowing water, but many bridges, orbiters, landers, and rovers have confirmed one undeniable fact: any liquid water that once existed on its surface is long gone.
A Leeds at Washington University in St. Louis found the reason: Mars, which is about half the size of Earth and just over a tenth the mass of our aquatic world, can be very small .
The idea of the Martian Ocean Hypothesis suggests that Mars had not only liquid water, but a lot of water. But the new study’s co-author, Kun Wang, says his team’s findings, which were published this week in Proceedings of the National Academy of Sciences, Pour cold water over the concept.
“The fate of Mars was decided from the start,” said Wang, assistant professor of earth and planetary sciences. advertising. “There would likely be a minimum size requirement for rocky planets to contain enough water to support life and plate tectonics.”
This is because the low mass and low gravity of Mars allows volatile elements and compounds such as water to escape more easily from its surface into space.
Researchers led by Zhen Tian, a graduate student of Wang’s lab, examined 20 Martian meteorites 200 million to 4 billion years old, dating back to a time when the solar system was still a training mess .
The researchers analyzed a somewhat volatile element – potassium – to help understand the behavior of water on Mars.
Speaking to NPR, Wang said the team measured the ratio of the two isotopes of potassium – potassium 39 and potassium 41 – in meteorites. In low-gravity environments, such as Mars, potassium-39 is more easily lost to space, leaving behind a higher proportion of the heavy isotope, potassium-41. Water behaves in much the same way. way, indicating that most of it would have been lost in space during the formation of Mars.
This is something Wang and his colleagues have seen even in the oldest meteorites, suggesting that they have been a problem for Martian water from the start.
The team also looked at samples taken from the Moon and an asteroid, which are smaller and drier than Earth or Mars, to study the isotopes of potassium they contain. They found a direct relationship between mass and birds – or lack thereof – in the samples.
The liquid water that remained on Mars, Wang says, carved out the canyons, river basins and other now dry formations that we see there today. But that water would probably also disappear if it wasn’t trapped as ice at the poles of Mars, as the planet’s climate has become colder, he notes.
Findings could help improve the search for habitable exoplanets
The research also has implications beyond our solar system. As scientists search for planets around other stars, the holy grail in their quest is to find those capable of supporting life, which means they are neither too hot nor too cold.
Even though a planet revolves around its star in the so-called Goldilocks area, it is the right distance away to be hot enough for liquid water without being too hot to support life, it may be too small to hold water. ‘water.
“This probably indicates a lower limit for a planet’s size to be truly habitable,” Bruce MacIntosh, deputy director of the Kavli Institute for Particle Physics and Cosmology at Stanford University, told NPR. “Understanding this result is important – there is evidence that minor planets are more common than large planets, so if minor planets are dry, there are fewer habitable worlds than we thought. ”
He adds, however, that only the “most optimistic exoplanet astronomers” would currently list a Mars-sized exoplanet as a candidate for habitation.
Source link
