California meteorite reveals secrets thanks to crowdsourcing

Recently published research describes a collection of meteorite pieces that landed in California in April. The study came about through a group effort dubbed "crowdsourcing" by the lead scientist.   

|
NASA / Eric James
A handful of Sutter's Hill meteorite fragments collected April 24, 2012, two days after the fall. Two months later, the scientists reported having 77 meteorite fragments.

Barely eight months after a fireball lit up California and Nevada skies, the first scientific paper is out examining the meteorites it left behind.

"It was done very quickly," said Peter Jenniskens, a meteor researcher who suddenly found himself managing a small army of volunteers when the Sutter's Mill meteor broke up April 22.

Dozens of scientists jumped to Jenniskens' aid as he searched for meteorite fragments. But less publicized will be the volunteers who phoned in reports of meteorites, or sent in pictures and video of the fireball by e-mail.

Jenniskens' team commandeered an airship to search for fragments. Meanwhile, the team caught a lucky break — Doppler radar information from nearby weather stations showed the track of the meteorite. Adding this data to the pictures and video sent in by volunteers, the scientists could reconstruct the impacting asteroid's early history. [Photos: Fireball Drops Meteorites On California]

According to Jenniskens, the paper, to be published Friday (Dec. 21) in the journal Science, was made possible by the mass crowdsourcing effort that enabled a large amount of data to be collected in a short time.

"It's all very important, and it's fantastic how this came together," said Jenniskens, a meteor astronomer at the Search for Extraterrestrial Intelligence (SETI). "For me, it was personally very exciting."

Peeling back the years

The Sutter's Mill meteorite turned out to be a rare type — a carbonaceous chondrite that contains information about the early stages of the solar system. The meteorite pieces originated in a space rock that was perhaps as much as 3.3 yards (3 meters) across.

A space rock is called an asteroid or meteoroid until it hits the Earth's atmosphere. The resulting fireball is then called a meteor until it hits the ground, at which point it is dubbed a meteorite.

The asteroid that would later impact California orbited the sun in the asteroid belt between Mars and Jupiter, making about three trips around our star in the time it takes Jupiter to orbit once. Such a ratio, known as a resonance, is common in the solar system — some of Jupiter's moons are in resonance with each other, for example.

The asteroid's resonance was a little "off" from a perfect 3 to 1 ratio. At some point, Jupiter's strong gravity muscled the asteroid out of its normal orbit and sent it on a trip to the inner solar system. This pushed the asteroid into a new orbit that brought it in as far as Mercury's orbit when it got closest to the sun.

This is where history begins to blur. The weathering of the meteorite fragments suggested the space rock was only 50,000 to 90,000 years old when it hit Earth — basically a blink of an eye in the solar system's nearly-5-billion-year history. This is fortunate, as Jenniskens' team discovered carbonaceous chondrites are fragile and begin to break up around that time frame.

The team suspects the meteor that hit Earth may be a fragment from a larger asteroid.

Blast through the atmosphere

In all, 77 fragments were found from the Sutter's Mill meteorite. These totalled less than 2 pounds (0.9 kilograms) of material. But the meteor weighed about 88,200 pounds (40,000 kilograms) when it hit the atmosphere.

"Quite a lot of material was lost," Jenniskens said.

The meteor's speed clocked in at 17.8 miles (28.6 kilometers) a second, which is faster than any previously recorded meteorite fall. After hitting a peak brightness about 35 miles (56 kilometers) above the ground, the meteor broke apart at an altitude of roughly 30 miles (48 kilometers.)

The atmosphere did a number to the outside of the meteorite bits, which were heavily damaged by the time they got into Jenniskens' lab. However, the interior was better preserved.

Only a handful of the fragments have been analyzed so far, but early results show that carbonaceous chondrites are highly complex.

The meteorite is a breccia, meaning that it's a coalition of different kinds of material. By examining the meteorite with X-rays, the researchers were able to separate out several different components.

The scientists also saw changes in the composition of fragments recovered before and after a large rainstorm that took place two days after the fireball was seen. The mineral oldhamite, for example, dissolved in the fragments exposed to moisture.

"This thing is diverse, even on a small scale," Jenniskens said.

But just how diverse will be a matter for future research. There's still a drawer full of meteorites that have barely been touched since they were first delivered to the lab. As such, Jenniskens anticipates this one meteorite event will deliver years of research to his team.

Follow Elizabeth Howell @howellspace, or SPACE.com @Spacedotcom. We're also on Facebook and Google+.

You've read  of  free articles. Subscribe to continue.
Real news can be honest, hopeful, credible, constructive.
What is the Monitor difference? Tackling the tough headlines – with humanity. Listening to sources – with respect. Seeing the story that others are missing by reporting what so often gets overlooked: the values that connect us. That’s Monitor reporting – news that changes how you see the world.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to CSMonitor.com.

QR Code to California meteorite reveals secrets thanks to crowdsourcing
Read this article in
https://www.csmonitor.com/Science/2012/1220/California-meteorite-reveals-secrets-thanks-to-crowdsourcing
QR Code to Subscription page
Start your subscription today
https://www.csmonitor.com/subscribe