The main mass of a rare meteorite that exploded over California’s Sierra foothills in April 2012 will be preserved for current and future scientific discoveries, thanks to the collaborative efforts of five U.S. academic institutions.

It has found a permanent home divided among the University of California, Davis; the Smithsonian Institution’s National Museum of Natural History in Washington, D.C.; American Museum of Natural History in New York City; The Field Museum of Natural History in Chicago; and Arizona State University in Tempe. Together, the institutions have successfully acquired the biggest known portion of the Sutter’s Mill meteorite.

The meteorite is considered to be one of the rarest types to hit the Earth — a carbonaceous chondrite containing cosmic dust and presolar materials that helped form the planets of the solar system.

Its acquisition signifies enhanced research opportunities for each institution and ensures that future scientists can study the meteorite for years to come.

“With these museums and institutions storing the meteorite’s main mass, it leaves it in a pristine condition to preserve for future generations to study,” said UC Davis geology professor Qing-zhu Yin. “Fifty or 100 years from now, we may have new technology that will enable later generations to revisit the meteorite and do research we haven’t thought of. This gives us a better chance to realize the full scientific value of the meteorite, rather than have it be just a collector’s item.”

The meteorite formed about 4.5 billion years ago. While it fell to Earth roughly the size of a minivan before exploding as a fireball, less than 950 grams have been found. Its main mass weighs just 205 grams (less than half a pound) and is about the size of a human palm.

The main mass was X-rayed by CT scan at the UC Davis Center for Molecular and Genomic Imaging. This was the first time a meteorite acquisition was CT scanned before its division among a consortium of institutes, allowing prior knowledge of each piece’s contents. Then it was cut into five portions, reflective of each institution’s investment, before being delivered to the institutions.

The portion of the main mass acquired by each institution includes:

• American Museum of Natural History: 34 percent
• Smithsonian Institution’s National Museum of Natural History: 32 percent
• The Field Museum of Natural History: 16 percent
• Arizona State University: 13 percent
• UC Davis: 5 percent

When the meteorite landed near Sutter’s Mill, the gold discovery site that sparked the California Gold Rush, it spurred a scientific gold rush of sorts, with researchers, collectors and interested citizens scouring the landscape for fragments of meteorite. The institutions that have acquired the main mass were among those that acted on this rare scientific opportunity to gain insights about the origins of life and the formation of the planets.

At UC Davis, for instance, the meteorite fell just 60 miles east of the main campus. Yin immediately traveled to the site with students and colleagues, looking for specimens and reaching out to the public to provide meteorite donations for science. He confirmed for the original discoverer of the main mass that it was carbonaceous chondrite. Yin and his UC Davis colleagues have also X-rayed the meteorite and determined its age and chemical composition.

“It just happened in our backyard,” said Yin. “I felt obligated to do something, and I still do.”

Involvement from the other institutions included:

• The American Museum of Natural History worked closely with Yin to secure specimens of the Sutter's Mill meteorite right after its fall, and performed nondestructive computed tomography (CT) scans of several specimens kindly loaned by their finders. These scans were used to determine the density of several samples to very high accuracy, confirming the type of meteorite represented by Sutter's Mill.
• The Field Museum of Natural History found several presolar stardust grains in two smaller pieces of the meteorite donated by private collector Terry Boudreaux. Presolar stardust grains are the oldest solid samples available to any lab and are essentially time capsules from before the solar system formed 4.6 billion years ago.
• Arizona State University’s Meenakshi Wadhwa, director of the Center for Meteorite Studies, was contacted by Robert Haag, the private collector who owned the main mass. She then contacted the other institutions to initiate its joint acquisition.
• The Smithsonian’s National Museum of Natural History prepared the meteorite for study by dividing the chondrite using high-precision thin-blade saws. The sample preparation plan was designed to maximize available material for research. The divided chondrite was then distributed to each institution for further analysis.. 

Last spring, UC Davis alumnus Gregory Jorgensen and donor Sandy VanderPol provided nearly 3 grams of the Sutter’s Mill meteorite to Yin’s lab at UC Davis. Those 3 grams allowed UC Davis to learn the meteorite’s age and chemical composition. The university’s recent acquisition of another 10 grams of the main mass will allow for even further research, including searching for presolar grains and performing isotopic analysis.

UC Davis’ section of the meteorite was funded by a portion of Yin’s Chancellor’s Fellowship.