Water may emerge in connection with the formation of terrestrial planets, according to a new analysis of a Martian meteorite called North West Africa (NWA) 7533.
An artist’s impression of the young Mars. Image credit: M. Kornmesser / ESO / N. Risinger, skysurvey.org.
“There are two hypotheses about the emergence of water,” said Professor Martin Bizzarro, a researcher in the Centre for Star and Planet Formation at the University of Copenhagen.
“One is that it arrives on planets by accident, when asteroids containing water collide with the planet in question.”
“The other hypothesis is that water emerges in connection with the formation of the planet.”
“Our study suggests that this hypothesis is correct, and if that is true, it is extremely exciting, because it means that the presence of water is a product of the planet formation process.”
If the team’s theory proves correct, life in planetary systems may have had better chances of developing than previously assumed.
Their research shows that there was water on Mars for the first 90 million years of the planet’s existence.
“In astronomical time, this is a long time before water-rich asteroids bombarded the planets of the inner Solar System like Earth and Mars, according to the first hypothesis. And this is very sensational,” Dr. Bizzarro said.
“It suggests that water emerged with the formation of Mars. And it tells us that water may be naturally occurring on planets and does not require an external source like water-rich asteroids.”
The 4.43-billion-year-old Martian meteorite NWA 7533. Image credit: Meteorites.tv.
NWA 7533, the 4.43-billion-year-old regolith meteorite studied by the team, originates from the original Martian crust and offers unique insight into events at the time of the formation of the Solar System.
“We developed a new technique that tells us that Mars in its infancy suffered one or more severe asteroid impacts,” said lead author Dr. Zhengbin Deng, a researcher at the Université de Paris.
“The impact, NWA 7533 reveals, created kinetic energy that released a lot of oxygen. And the only mechanism that could likely have caused the release of such large amounts of oxygen is the presence of water.”
Liquid water is a precondition for the assembling of organic molecules, which is what happened at least 3.5 billion years ago at the emergence of life on Earth.
“The new analysis of NWA 7533 shows that the asteroid impact on Mars released a lot of greenhouse gasses into the atmosphere,” Dr. Deng said.
“This means that the carbon dioxide-rich atmosphere may have caused temperatures to rise and thus allowed liquid water to exist at the surface of Mars.”
The findings were published in the journal Science Advances.
Zhengbin Deng et al. 2020. Early oxidation of the Martian crust triggered by impacts. Science Advances 6 (44): eabc4941; doi: 10.1126/sciadv.abc4941