Monday, January 26, 2009

Pena Blanca Springs Meteorite

On an August day in 1946, at the Gage Ranch, a few miles southeast of Marathon, ranch hands and children shook themselves off as they splashed out of the swimming hole brimming from the waters of the Pena Blanca Spring. The cook at the nearby Catto House sat in a chair on the porch. Sweat trickled down her forehead as she washed beans in a pot. A cabrito smoked in a pit and in the distance an old Ford truck with cowboys dusted up a caliche road.

A boom in the sky followed by a noise that sounded like a car running on a flat tire interrupted the otherwise clear day. A herd of horses nearby began to snort and hoove in the dirt. The old Ford had already parked at the tank and the cowboys were looking up. A second later they were dripping wet.

“It looked,” the cook said. “like a black bag falling out of the sky, with white dust coming out of it.”

When asked about the incident four days later by meteorite collector O.E. Monnig of Ft. Worth, Mrs. Catto, slammed her fist against her palm to illustrate the impact of the meteorite hitting the water. “I feel mighty lucky,” she said.

Meteorites fall everyday onto the earth, but few are found, fewer seen in descent and only a handful have ever been heard. They flash in the sky as they enter and burn in the earth’s atmosphere and are termed meteorites when they make it to the earth’s surface. Meteors, however, vaporize in the atmosphere and never land. The cosmic velocity of a 1000 pound meteorite can reach 24 miles a second in space but once in our atmosphere, gravity and friction can slow it down to as little as 250 miles per hour. The sound the swimmers heard was a sonic boom and the flat tire effect came from the scalloped profile of the rock sizzling through the air.

Scientists dated the Pena Blanca Springs Meteorite at 4.5 billion years old or about the same age as the earth, coinciding with the formative epoch of our solar system. Meteorites generally consist of fragments from asteroids that hover mostly in the Asteroid Belt between Mars and Jupiter though sometimes meteorites contain parts of other planets or moons. Imprisoned by the gravity of our solar system, these rocks wander in space, some beyond Pluto until they collide with planetary atmospheres such as ours.

The estimated weight of the Pena Blanca Springs Meteorite was about 200 lbs before it shattered against a bed of novaculite rock running under the tank. It contained organic compounds including carbon, oxygen and hydrogen and gave off a slight sulphur dioxide odor. It also contained amino acids, the proteins necessary for constructing life.

The chances of being hit by a meteorite are rare. Some scientists calculate that if you lived on 400 acres of land, you’d have to wait a hundred thousand years to chance see a meteorite hit your domain. That’s the odds. And the formation of life, proteins compounding to kick start life out of stardust are astronomically improbably – but still possible.

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