A month after a spectacular meteor exploded over Chelyabinsk, Russia, on Feb. 15, several samples of the meteorite were sent to UC Davis for analysis.
Three scientists – Qing-zhu Yin and Ken Verosub in the Department of Earth and Planetary Sciences and Doug Rowland in the Department of Biomedical Engineering – worked with the pieces.
The trio are part of an international team of researchers assembled by Olga Popova of the Russian Academy of Sciences and Peter Jenniskens, a meteor astronomer with NASA and the SETI (Search for Extraterrestrial Intelligence) Institute to study the event.
The team, consisting of 59 scientists from nine countries, published its findings in the Nov. 7 issue of Science magazine.
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Yin spoke to the The Sacramento Bee about the work he and his university colleagues did on the Chelyabinsk meteorite.
This meteorite fell in Russia. How did you get involved in this project?
I got contacted by Peter Jenniskens from NASA. We started working together on the California meteorite (the Sutter’s Mill meteorite, which fell in the Sierra foothills on April 22, 2012) followed by the Novato meteor, which fell on Oct. 17, 2012. Then in February of this year, there was this meteorite, so we’ve been busy.
What were you and your colleagues supposed to determine about this meteorite?
My team at UC Davis was responsible for the characterization of the meteorite – what kind of mineralogy material (it is made of), what was its chemical and isotopic composition, what was its age. We also did an X-ray CT scan on the stone – a nondestructive method – to determine density and used a super conducting cryogenic magnetometer to determine the meteorite's magnetic properties.
What did your team’s analysis show?
This particular meteorite is made of ordinary chondrite. About 80 percent of all meteorites belong in the ordinary chondrite category.
Chondrite is the oldest building block of a planet. When solids start to aggregate, the first thing that is formed is chondrite.
If this type of event happens again, the chances of finding this kind of material is very high, so we need to study it in great detail.
The CT scan showed what the structure of the rock looks like inside. The magnetic grains show that it went through a violent shock a long time ago.
How old is the Chelyabinsk meteorite?
It’s 4,452 million years old. It’s younger than most meteorites, which are generally in the ball park of 4,565 million years.
What does it mean if it’s younger than most meteorites?
The meteorite was heavily shocked – it was full of impact veins, which means that something had crashed into it, or it had crashed into something else. It was on the cosmic shooting ground.
Under high pressure and temperature, the minerals won’t remember when it was formed. After its formation, it had melted and reset the clock.
The impact veins are very typical for this Russian meteorite. It’s why it broke easily in the upper atmosphere (of Earth).
Where was it formed? When did this collision happen?
It came from the asteroid belt between Mars and Jupiter, which is the main belt for asteroids. It was in the Flora cluster and was floating around in a larger rubble pile.
It broke out 1.2 million years ago, when it started orbiting by itself.
What caused this meteroid to come to Earth?
The gravity instability of Jupiter. Any hiccup and it will alter the orbit of the asteroid. Some of them will impact the moon, Earth, Venus or even the sun. Or they get sent out farther from Jupiter.
What’s significant about the Chelyabinsk meteoroid strike?
It is a small body (it’s thought to have weighed about 14,330 short tons). If it’s bigger than one kilometer, it’s easier to detect. But to detect something that is 10 meters or 100 meters, anything less than one kilometer, that’s a difficult task.
The explosion was equivalent to 600 kilotons of TNT (by comparison, the bomb that destroyed much of Hiroshima, Japan, in 1945 had an explosive force of about 12.5 kilotons), and even though it fell in a rural area and far from the sea, there is a very large area – 6,000 square kilometers – where you see the damage.
What is your takeaway from participating in the study of the Chelyabinsk meteorite?
This is not too big, but it started to cause damage and that’s not good.
This one came during the day, where we cannot see it against the sun. But half of the Earth is day, and half is in the night, so we have a 50/50 chance of being able to see it.
If an asteroid is perturbed and not staying in orbit, we need to be able to predict that.
We need the technology to take surveys and have sensors to see where they are. It’s what we need to know if we don’t want to become dinosaurs.
Editor's Note: This article has been changed from an earlier version to correct various inaccuracies. Corrected on Nov. 18, 2013.