Meteorites May Have Brought Water to Earth and Mars

Rare, carbon-containing rocks could have created conditions suitable for life on both planets, two new studies suggest

A meteorite
Winchcombe meteorite Trustees of the Natural History Museum

Last year, a rare space rock known as the Winchcombe meteorite lit up skies across the United Kingdom before crashing onto a driveway in Gloucestershire, England. Researchers were able to collect pieces of the rock within 12 hours of its landing, meaning it was relatively uncontaminated with Earthly materials, unlike most meteorites found, writes Science News’ Lisa Grossman. 

“It’s as pristine as we’re going to get from a meteorite,” Ashley King, a planetary scientist from London’s Natural History Museum, tells the publication. “Other than it landing in the museum on my desk, or other than sending a spacecraft up there, we can’t really get them any quicker or more pristine.”

King and her colleagues examined the rock, and, in a paper published Wednesday in Science Advances, they propose that similar meteorites may have delivered water to Earth during the solar system's youth. It is one of two new studies suggesting space rocks brought water and molecules key for the formation of life to a young Earth and Mars.

The Winchcombe meteorite is a rare type of carbon-rich rock called a carbonaceous chondrite and the first of its kind ever found in the U.K. Only about 4 to 5 percent of all meteorites found on Earth belong to this group of rocks. Clocking in at billions of years old, they provide a glimpse into the solar system’s early history, when they formed in the asteroid belt between Mars and Jupiter. 

Using imaging and chemical analyses, the research team found that the Winchcombe meteorite is made up of 11 percent extraterrestrial water and 2 percent carbon. 

“Meteorites like Winchcombe are a pretty good match [to] the water in the Earth’s oceans and suggests asteroids were the main source of water” on the planet, King tells the Guardian’s Hannah Devlin. It’s “a tantalizing glimpse back through time to the original composition of the solar system 4.6 billion years ago.”

The study also examined video footage from a collaboration of camera networks in the region known as the U.K. Fireball Alliance, as well as doorbell and dashboard cameras, to calculate the rock’s trajectory. Of the 69,000 meteorites found worldwide, only 40 were photographed as they arrived as a fireball, including the Winchcombe meteorite, per the U.K. Fireball Alliance. 

Using this data, the team estimated the meteorite came from near Jupiter and began its journey toward Earth around 300,000 years ago, reports Science News

“It’s always exciting to have access to material that can provide a new window into an early time and place in our solar system,” planetary scientist Meenakshi Wadhwa of Arizona State University, who was not involved in the study, tells Science News

Earth wasn’t the only planet that received water from carbonaceous chondrites in its early era, suggests another study, also published Wednesday in Science Advances. As space rocks bombarded Mars during its first 100 million years, they brought water—enough to form a planet-wide, 300-meter-deep ocean, researchers say.

The team examined meteorites that had come to Earth from Mars in order to estimate how much water reached the early Red Planet. Those carbonaceous meteorites also contain organic molecules—meaning that Mars had prime conditions for the formation of life long before Earth did, per New Scientist’s Jacklin Kwan. 

Simon Turner, a geochemist at Macquarie University in Australia who was not involved in the study, tells New Scientist that the examined meteorites might not be representative of Mars as a whole.

But to Martin Bizzarro, a cosmochemist at the University of Copenhagen in Denmark and co-author of the paper, this is definitive evidence of a way that water reached Mars. “I think this is the first time where we have a smoking gun,” he tells the publication.

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