Meteor sheds light on watery solar system
Wet meteorite Liquid water existed over a far wider area of the solar system than originally thought, a new study confirms.
The findings, reported in the Proceedings of the National Academy of Sciences, come from an analysis of the Villalbeto de la Pena meteorite which streaked through the evening skies over Spain on the 4th of January 2004.
"The discovery extends our knowledge of what water was doing when our solar system was forming', says Dr Kathryn Dyl, from Curtin University in Western Australia, who led research.
"This is a condrite meteorite that originated in the asteroid belt between Mars and Jupiter, a region of the solar system thought to be too cold for water to exist in a liquid state."
Dyl and colleagues collected 50 segments of the Villalbeto de la Pena meteorite from an area of about 100 kilometres radius.
They used a new type of ultraviolet laser at the University of California in Los Angeles to study an area of the meteorite just 100 by 600 microns wide.
"This allowed us to measure the ratio of oxygen 17 to oxygen 18 isotopes in the meteorite, and examine changes in the mineral structure," says Dyl.
They focused on an unusual rock called a feldspathic clast that had melted and fused on to the surface of the meteorite.
The changes Dyl and colleagues found could only have been caused by water, either as a liquid or steam, reacting with the minerals in the rocks.
The findings add to previous evidence of water-rock interactions in chondritic meteors, and according to co-author Professor Phil Bland, also from Curtin Univesity, support the idea that objects thought to be dry almost certainly contained water.
The changes in the rock observed by Dyl, Bland and team could have only resulted from hydrothermal conditions, where water "cooks" the minerals in the rock.
To date the timescales of water-rock reactions have been largely unknown, but the researchers have shed light on how fast the changes occurred.
"They would have happened on relatively short time scales of one to ten years and at temperatures of between 750 and 850 degrees Celsius," says Dyl.
"That's far shorter than the geologic times scales normally thought to have been needed for such processes."
Bland describes the "cooking" time as a "bizarrely short for what we'd normally think of as a geological process where hundreds of thousands of years is quick".
He thinks the discovery means asteroids and meteors slamming into each other in the asteroid belt, were doing more than just crushing rocks.
"May be they were swapping water around as well," says Bland.
Understanding such water-rock interactions in meteors has widespread implications, say the researchers.
They say it has implications for the formation of planetary bodies, the dlievery of water to the inner Solar System, and the formation of prebiotic molecules.
The team now want to examine other meteorites to see if they find similar characteristics.
One candidate is a meteorite detected in 2010 by a network of meteor spotting cameras set up across the Nullarbor Plain in outback southern Australia.