Opals discovered on Mars could suggest the planet may have once been home to life, researchers suggest. The precious stone, known as a fire opal for its distinctive red, orange and yellow coloration, was discovered in a Martian meteorite.
Nakhla, the meteorite in which the stone was discovered, is currently owned by the Natural History Museum, located in London. Millions of years before landing it landed, the rocked was blasted off the Red Planet by a powerful strike from an unknown object. The object is named after a town in Egypt where the stone fell in 1911.
Researchers utilized an electron microscope to discover trace amounts of the precious stone. This finding confirms readings from Martian rovers that opal exists, at least in small quantities, in the crust of the Red Planet. The stone was likely created by the interaction of water with silica, a process that is seen on our home world.
"We know that on Earth opals like these are often formed in and around hot springs. Microbial life thrives in these conditions, and opal can trap and preserve these microbes for millions of years. If Martian microbes existed, it's possible they too may be preserved in opal deposits on the surface of Mars," Martin Lee from the School of Geographical and Earth Sciences at the University of Glasgow said.
This was the first time opals from Mars have ever been detected in an asteroid recovered here on Earth, researchers report. This story led to the discovery of several pieces of the object and later became a minor legend among astronomers. Signs of biological activity, although indefinite, were seen in the meteorite in 1999 and 2006.
In 2013, the same team that made this discovery found secondary material in Nakhla, formed by the interactions of water with the minerals augite and olivine. This was the first direct evidence of water dissolving the surface of the Red Planet.
The Nakhla meteorite fell to Earth on June 28, 1911, witnessed by a large number of people. Around 22 pounds of debris in approximately 40 pieces, was found scattered around an area 2.8 miles across. The largest piece recovered weighed just over four pounds. Two of the pieces were donated to the Natural History Museum. Legends hold that a dog was killed by a piece of the Nakhla meteorite, although the story remains unconfirmed.
Future examination of the Martian surface could focus on the study of opals, in an effort to better understand the history of the planet, including the possibility of ancient life on the world.
Analysis of Nakhla, including discovery of opals material within the object, was profiled in Meteoritics and Planetary Science.