Scientists believe diamonds in meteorite hail from lost planet in our solar system
Meteorite fragments belong to unique type of rock that is poorly understood
A new study suggests that diamonds found within a meteorite that landed on Earth in 2008 were created by an early lost planet in our solar system.
On Oct. 7, 2008, asteroid 2008 TC3, an 80-metric-ton rock measuring 4.1 metres in diameter, lit up the sky over the Nubian Desert in Sudan.
Although astronomers knew the rock — which belongs to the Almahata Sitta group of meteorites — didn't pose a danger to people, they were anxious to collect samples, hoping it could reveal more about the formation of our solar system.
By looking at the diamonds in asteroid 2008 TC3, the researchers hoped to find an answer about the origin of the meteorite.
Our early solar system was a chaotic shooting gallery. After the sun formed roughly 4.5 billion years ago, dust and debris collided and formed larger bodies. Astronomers believe that as many as 10 lost planets once existed.
"Some of [these bodies] collided and were destroyed. Some were thrown out of the solar system," Farhang Nabiei, lead author of the paper and a scientist with the Earth and Planetary Science Laboratory at the Ecole Polytechnique Federale de Lausanne in Switzerland, told CBC News.
"But we don't have information from them. We don't have much evidence from those specific planetary embryos."
That's what makes this latest discovery potentially exciting.
The key is in the diamonds
Almahata Sitta meteorites belong to an ancient group of asteroids called ureilites, which are rocks that have been melted and are rich in carbon. They contain graphite and tiny diamonds and are extremely strong, similar to what we may find in Earth's mantle.
Diamonds form in one of three ways: from a shockwave that transforms the mineral graphite into diamonds during a high-energy impact, such as the collision of objects; growth from carbon-rich gas vapour in the early solar nebula; or under extremely high pressure inside a body, like what occurs here on Earth.
You're doing solar system geology.- Peter Brown, Western University
In all cases, there must be a certain amount of pressure, measured in gigapascals. Using special electron microscopy, the scientists discovered the diamonds in asteroid 2008 TC3 formed under pressures exceeding 20 gigapascals, something that can only occur in a Mercury- to Mars-sized object from the embryonic solar system.
"We've often wondered, what is the parent body that formed this thing?" Peter Brown, professor at Western University's department of physics, who wasn't involved in the new study, told CBC News.
Now that question may have been answered.
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"The particularly exciting thing is, [the researchers] have a really strong case with the pressures that they're measuring to say there really is no other way around the fact that this had to be a really big body present early in solar system history."
Mining the solar system
A better understanding of how the diamonds formed in an early planet helps scientists on a number of levels. Not only does it shed light on how our own planet formed — and how we came to be — but it could help us in the future, as companies consider asteroid mining.
"You're doing solar system geology," Brown said. "You're doing prospecting to tell you where you should go. The more we understand how these things formed, the better we're going to be in terms of going out and assessing where the resources are."
Ultimately, however, it's about putting the pieces of the puzzle together and getting a complete picture of our early solar system.
"We have to know more about our environment and how we've come to be," Nabiei said. "Everything started with the stars."