Meteor explosion sets off modern-day Gold Rush
The excitement in the Earth and Space Sciences geochemistry seminar on April 24 was palpable as UCLA Professor John Wasson announced to students that a fireball had streaked across much of North America and exploded near Reno.
The April 22 explosion of a meteor caused an early-morning sonic boom that rattled many in Northern California and Nevada. Scientists estimated it released energy equivalent to 3.5 kilotons of TNT, the size of a small atomic bomb.
The celestial phenomenon galvanized planetary scientists, astronomers, meteorite hunters and collectors eager to find pieces of the space rock. Wasson
, who has devoted much of his career to the study of meteorites to attain a better understanding of the formation of our solar system, urged anyone who could to join the search for fragments.
Pieces of the new meteorite fall were found by Brenda Salverson of Lotus, Ca. Courtesy of Derek Sears and Meteorite magazine.
The vast majority of meteorites are pieces of asteroids, debris leftover from the formation of the solar system. They orbit the sun and sometimes collide with Earth. When they crash through the Earth's atmosphere, they often break into small pieces.
But where should a meteorite hunter look?
They soon had their target area: Weather radar indicated that fragments had fallen northeast of Sacramento. With the discovery of a 10-gram sample in Coloma — California Gold Rush country — the hunt was on.
Several members of the department headed north to try and find meteorite chunks, which hold great commercial as well as scientific value. Associate Professor Jean-Luc Margot, an expert in the formation of planets and Wasson’s colleague, left immediately for Northern California and spent an entire day walking through yards, parks and fields looking for small black rocks that could easily be hidden in the grass.
"It was like looking for a needle in a haystack," said Margot, whose eyes were trained on the ground the whole time as he scanned for pieces of the jet-black rock.
Others were also hot on the trail. Among those who were also searching were scientists from the NASA Ames Research Center in Mountain View, UC Berkeley students, and professional meteorite hunters and dealers. NASA's Search for Extraterrestrial Intelligence Institute even hired a blimp to hover over the area to search for large samples, but so far, they’ve had no success.
Issaku Kohl, a postdoctoral scholar, is analyzing pieces of the meteorite to determine whether the space rock is really a rare CM carbonaceous chondrite.
Scientists became further intrigued when the meteorite was identified as a CM carbonaceous chondrite, one of the most interesting types of meteorite. While meteorite showers happen several times a year, Wasson could only recall two or three such dramatic carbonaceous chondrite "falls" in his entire career. "Chondrites are the first solid objects formed in the solar system," said the cosmochemist. "They are the building blocks of the planets."
When Margot returned empty-handed, he began to track the success of other meteorite hunters
. Since April 22, roughly 500 grams of meteorite have been recovered, a small amount considering that the meteoroid that exploded was estimated to be roughly the size of a minivan. Because so little of it has been found, pieces are now fetching from $500 to $1,000 per gram, many times the current price of gold. Scientists had hoped to find large fragments of the original mass. But to date, the largest piece recovered weighs only 45 grams, measuring about an inch in length.
Wasson has asked meteorite hunters to donate some of what they’ve recovered to science. "The world," Wasson said, "will be doing research for the next 100 years" on the meteorite, which now has the official name of Sutter’s Mill. The first meteorite sample was found in the gravel of a stream, close to the same location where gold nuggets were first discovered in California.
Cosmochemist John Wasson was honored last year when NASA named a newly discovered mineral after him. Wassonite was found in a meteorite that was discovered in Antarctica in 1969.
So far, a few graduate students from UC Davis have forwarded small samples to Wasson’s colleague Ed Young for oxygen-isotope analysis. Young and his team hope to determine conclusively whether the April meteorite is really a rare CM carbonaceous chondrite.
What is particularly interesting about the carbonaceous chondrite variety, Wasson explained, is that it contains the ingredients of life — water and carbonaceous compounds. They were formed at the beginning of the solar system in an oxidizing environment, and, as a result, their metals, magnesium, silicon and iron are largely present as oxides.
"Most CM chondrites have experienced only negligible heating, but they have been significantly altered by water," explained UCLA researcher Alan Rubin. They can serve as models of some early solar-system processes that affected the asteroids.
Wasson has high hopes that meteorite hunters will also agree to put some of their samples on exhibit at UCLA, home to the largest collection of meteorites on the West Coast and the fifth largest in the United States. The collection, some of which had been displayed in cabinets, contains more than 2,400 samples from 1,400 meteorites.
UCLA’s cosmochemists are currently preparing to open the new UCLA Meteorite Exhibit in the Geology Building to the public sometime in late summer or fall. This is the first time the entire collection will be displayed in its own room, a veritable meteorite museum. A sample of Sutter's Mill would be an instant attraction, Wasson said.
To help the public understand the importance of what they will be seeing, Wasson is preparing extensive pedagogical materials for the exhibit. "As the foremost public institution in Los Angeles, UCLA has a prominent role to play in scientific outreach," he said.