Tagish Lake Meteorite Holds Clues to How Life Began
The Tagish Lake meteorite at the Royal Ontario Museum has revealed some vital secrets to researchers. Find out what they discovered about the origin of life.
Growing up, I can remember making at least three trips to the Royal Ontario Museum (ROM). The central attraction was the renowned Dinosaur Hall. The massive fossilized skeletons were a source of awe and wonder for every child who saw them for the first time.
There were many other attractions in the displayed collections. We could examine suits of armour, exotic artifacts from China and all sorts of plants and animals. It was always a big outing.
The dinosaurs are still the ROM’s most prized exhibit, but in recent years another iconic artifact also draws crowds. It’s the Tagish Lake meteorite.
SPECTACULAR EXPLOSION AND FIREBALL IN UPPER ATMOSPHERE
The meteorite fell to Earth on January 18, 2000. It made its entrance into our atmosphere with a spectacular explosion and fireball in the upper atmosphere. Ninety-seven percent of the original meteor vaporized.
What was left burst into more than 500 pieces, which landed on the icy surface of the Taku Arm of Tagish Lake on the border between British Columbia, Canada and the Yukon Territory. A resident collected the fragments and research facilities took charge of them while they were still frozen. The meteorite is officially called “Tagish Lake.”
In April of that year, another expedition, led by the University of Calgary and the University of Western Ontario, gathered more fragments that had penetrated the northern British Columbia snow. The most pristine meteorite fragments are in the collections of the Royal Ontario Museum and the University of Alberta.
RARE ROCKY METEORITE CONTAINS THE BUILDING BLOCKS OF LIFE
Tagish Lake is what scientists call a carbonaceous chondrite. They’re a rare form of rocky meteorite that often contains amino acids, the building blocks of life.
This week, the Proceedings of the National Academy of Sciences published a study by an international group of scientists and led by ROM researchers. The team used state of the art techniques to map the individual atoms in fluids contained in the meteorite.
Carbonaceous chondrites like Tagish Lake formed as part of the origin of our solar system 4.5 billion years ago. They accreted out of a rotating disk of dust and debris around the sun. So did the Earth and all the other planets.
THESE METEORITES CONTAIN CLUES ABOUT HOW LIFE BEGAN
As a result, these meteorites contain clues about how the Earth began. They retain some of the oldest molecular fluids in the solar system.
The team used atom-probe tomography, which allows scientists to make three-dimensional images of individual atoms. They examined the boundaries between the grains of magnetite that make up Tagish Lake.
Dr. Lee White, Hatch postdoctoral fellow at the ROM, is the lead author of the study. As he explained, “Atom probe tomography gives us an opportunity to make fantastic discoveries on bits of material a thousand times thinner than a human hair.”
MATERIAL A THOUSAND TIMES THINNER THAN A HUMAN HAIR
They found tangible remnants of water along the boundaries between the magnetite grains and in their pores. These remnants provide the first evidence that the fluids in which Tagish Lake formed were alkaline and rich in sodium.
Fluids like that would be ideal for supporting the formation of amino acids. That could mean that there were living microbes as early as 4.5 billion years ago.
“We know water was abundant in the early solar system,” Dr. White explained, “but there is very little direct evidence of the chemistry or acidity of these liquids, even though they would have been critical to the early formation and evolution of amino acids and, eventually, microbial life.”
“FORMATION OF AMINO ACIDS AND EVENTUALLY MICROBIAL LIFE”
One of the reasons that Tagish Lake was such a good specimen for this work is its custodians have handled it very carefully. Ever since it was collected, staff have never exposed it to water or heat above room temperature.
Co-author Beth Lymer, a Ph.D. student at York University, explained why this careful storage has been vital. “The more variables that we can constrain, such as temperature and pH, allows us to better understand the synthesis and evolution of these very important molecules into what we now know as biotic life on Earth.”
Knowing the chain of possession of the specimen gives the researchers confidence. They believe they can associate the fluids they have found to conditions on the asteroid from which Tagish Lake came.
RICH IN AMINO ACIDS AND ORGANIC COMPOUNDS
Based on that, we can say that the original asteroid contained the ideal fluids for the formation of amino acids. We know that other carbonaceous chondrites are rich in amino acids and organic compounds.
Similar meteorites bombarded the early Earth. It’s entirely plausible that they were the source of the molecular building blocks from which life began, or that the early Earth had a similar chemical composition to the original asteroid.
The ROM’s study also supports vital upcoming research. Other teams can use these same atom-probe tomography techniques in the future on specimens of planetary materials brought back to Earth by spacecraft.
PLANETARY MATERIALS BROUGH BACK TO EARTH BY SPACECRAFT
Applications could include NASA OSIRIS-Rex mission. It involves landing on the asteroid Bennu and bringing back a small sample of material for research purposes.
There is also a proposal on the table at NASA for a Mars Sample Return mission. It would send another rover to Mars to gather samples and then use a rocket to bring those samples back to Earth for study.
The ROM researchers can use their Tagish Lake techniques to develop analytical methods for research on the planetary materials brought home from these and similar NASA missions.
DEVELOP ANALYTICAL METHODS FOR RESEARCH BY NASA MISSIONS
As Beth Lymer put it, “Amino acids are essential building blocks of life on Earth, yet we still have a lot to learn about how they first formed in our solar system.”
We always have more to learn if we dare to know.
Royal Ontario Museum
Evidence for sodium-rich alkaline water in the Tagish Lake parent body and implications for amino acid synthesis and racemization
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