Meteorites spark mysteries
Posted: Monday, February 25, 2008 8:20 PM by Alan Boyle
Michael Farmer |
Meteorite hunter Michael Farmer kneels at the rim of a crater in Peru.
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Five months after a meteorite made an international splash in Peru, experts are suggesting explanations for some of the space rock's effects - for example, the sickening odor villagers smelled at the crash site, and the bubbles that were seen emanating from the water-filled crater left behind. But a study due to be presented next month also raises fundamental questions about the event. In fact, an international research team declares that the impact "should not have happened" at all.
Yet another study sets forth a mystery surrounding two other meteorites found in Antarctica a couple of years ago. The rocks don't match any other class of meteorite - so where did they come from?
The two studies are among hundreds submitted for the annual Lunar and Planetary Science Conference, scheduled March 10-14 in League City, Texas. The conference offers the cream of the crop in planetary science - focusing on topics ranging from the solar wind, to Mercury and Mars, to the icy dwarfs on the solar system's edge.
The Peruvian meteorite impact comes in for a fresh round of scientific scrutiny in a study submitted by researchers from Brown University and institutes in Peru and Uruguay. Just after the impact was reported, some scientists doubted whether a meteorite was actually responsible for the crater - but subsequent analysis proved that a stony space rock was involved (as opposed to a denser iron meteorite).
Scientists previously thought that stony meteorites on the scale of the one that hit Peru would break apart into little pieces before they hit the ground. The fact that this one survived to create a 40-foot-wide crater threw the researchers what they called a "hypervelocity curveball." They said the standard model used to estimate the effects of stony meteorites will need to be revised as a result.
The study does propose two possible explanations for the reports of "boiling water" seen within the crater: The bubbles could have come from the compressed air that surrounded the meteorite as it blasted into the wet earth - or it could have been caused by clumps of clay that dissolved and frothed as they fell into the crater.
"These two processes may have been responsible for local reports of water bubbling up from the floor soon after impact," the researchers wrote. "While there would have been heat generated at impact, it is unlikely that this could have sustained bubbling an hour later."
Meteorite hunter Michael Farmer, who visited the site last year soon after the impact, has said the sickening odor that villagers said emanated from the crater was most likely caused by sulfurous compounds such as triolite interacting with the ground water - and there's nothing in the latest study that contradicts that suggestion.
The Peruvian meteorite may be in for another shot at fame: Just last week, Living in Peru reported that Japanese investors are interested in building a space museum near the impact site, and that National Geographic is planning a documentary about the meteorite.
Now to the other space-rock study: Meteorite hunters from the Lunar and Planetary Institute and NASA's Johnson Space Center reported finding a pair of specimens in 2006 in Antarctica's Graves Nunataks area.
"These meteorites are not obviously like any other meteorites, so their origin is unclear," the Lunar and Planetary Institute said in its media advisory. "The mineralogy and chemical composition of these meteorites are so unusual that scientists have been struggling to find the right term to describe them. Numerous parent bodies have been proposed. Could they have come from the moon? From Venus? Scientists are currently debating these issues."
The researchers behind the study say they're not finished with their analysis of the rocks, and more findings may emerge at next month's conference. So stay tuned as the meteorite tales and other mysteries are fully brought to light.
