Chicago Meteor Shower a Windfall for Area Scientists
Bijal P. Trivedi
National Geographic Today
|May 13, 2003|
Around midnight on March 26, hundreds of meteorites rained on the Chicago suburbs of Park Forest and Olympia Fields, about 35 miles (56 kilometers) southwest of downtown.
The larger meteorites punched holes in roofs and dented cars. One meteorite embedded itself in the Park Forest fire station.
"We were asleep when it happened," says Phillip Jones, a retired electrical designer who lives in Olympia Fields. "My youngest granddaughter came into our room saying she had heard a noise but we told her she was dreaming and to go back to sleep."
The next morning, Jones found a foot-wide (30-centimeter) hole in the ceilingthen a second hole through the kitchen floor into the basement.
Jones' daughter reported that there seemed to be a furry animal in a pile of laundry in the basementit was, in fact, a six-pound, six-inch-wide (2.7-kilogram, 15-centimeter) remnant from the origin of the solar system, about 4.5 billion years ago, fuzzy with roof insulation.
The morning after the shower, Meenakshi Wadhwa, a planetary scientist and associate curator at the Field Museum of Chicago with an international reputation for the study of meteorites, particularly those from Mars, was driving to work when she heard a radio report that people were bringing meteorites to the Park Forest police station to be held as "evidence." She took a detour.
Meteorites, Big Business
Wadhwa is used to searching farther afield. She has trekked to Antarctica for meteorites.
She has also set her sights on Mars. Wadhwa is co-investigator of SCIM (Sample Collection for Investigation of Mars), one of the four missions competing for a NASA expedition to the Red Planet in 2007. SCIM is the only mission that plans to return to Earth with samples.
At the Forest Park police station, residents had brought in 15 to 20 meteorites. "It was pretty exciting," Wadhwa says. "This is the freshest material I have ever seenit had landed just a few hours earlier."
"This is the first time that a meteorite shower has hit such a populated area," says Wadhwa. "It is amazing that nobody got hurt."
Wadhwa wasn't the only interested party. A throng of meteorite collectors and dealers was haggling with residents.
"It looked like an open air bazaar," says Steven Simon, a research associate at the Geophysical Sciences department at the University of Chicago and a colleague of Wadhwa's who lives in Park Forest.
Meteorites are big business. Many of the Park Forest meteorites ended up on eBay within a few days. A meteorite dubbed the Park Forest "Smasher"weighing 145 grams (five ounces)is currently at auction for $5,000.
"We were competing directly with dealers to acquire the rocks for the museum," Wadhwa says. The Field Museum spent about $30,000 to acquire about six pounds (2.7 kilograms) of meteorites for the collection. Almost none of the new material came from public donation.
The meteor shower occurred when a meteoroid about the size of a small car hit the Earth's atmosphere, Wadhwa believes. Its provenance may have been the asteroid belt between Mars and Jupiter, 167 million miles (270 million kilometers) from Earth.
Collision Course with Earth
"(The Park Forest meteoroid's) orbit may have been on a collision course with Earth," says Wadhwa. "Many objects cross Earth's orbit, and there are many near misses. NASA even has a program to discover objects that may endanger the Earth."
Between 50,000 and 100,000 tons (one hundred and two hundred million pounds) of space dust and meteorites fall on the planet every year. Wadhwa knows the territory. In 1999 the International Astronomical Union named an asteroid for her: "8356 Wadhwa."
Asteroids and meteoroids are believed to have formed about 4.5 billion years ago from clouds of dust and gasthe same material that condensed to form the sun and all the planets. In fact, says Wadhwa, analyses of the sun's composition "reveals an almost perfect match with carbonaceous chondrite meteorites."
Wadhwa and Simon have already begun to analyze the Park Forest meteorites. She has sliced the rocks into wafer-thin slivers and examined them with an electron microprobe.
Some areas of the rocks seem to show areas of meltingwhich suggests to her that "they were battered around with other asteroids," Wadhwa says.
Wadhwa and Simon will co-author a study of the Park Forest collection for the July meeting of the international Meteoritical Society in Munster.
The Park Forest meteoroid turns out to be one of the more common chondrite types found on Earth. But Simon points out that "every little rock is another piece of the puzzle to the formation of the solar system."
Wadhwa has returned to Park Forest. "It was a bit of a pilgrimage," she says. "There was nothing scientific I got out of it. I study these things, and it is just exciting to see the evidence. I wanted to see the hole in the roof with my own eyes."
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