Scientist: small comets bombard Earth daily
May 28, 1997
Web posted at: 11:19 p.m. EDT (0319 GMT)
BALTIMORE (CNN) -- Thousands of comets the size of small houses bombard the Earth's atomosphere every day, and may account for all the planet's water, according to a University of Iowa physicist.
The comets break up into water vapor as they enter the atmosphere, physicist Louis Frank told the American Geophysical Union meeting on Wednesday.
"We find objects coming in about the rate of 20 every minute, one every three seconds," Frank said. "It looks like a small, small two bedroom house and it weighs 20 to 40 tons."
Frank captured images from cameras aboard NASA's Polar satellite, cameras he developed after earlier and cruder satellite data he had collected and analyzed was ridiculed.
He first presented his small comet theory in 1986, and wrote a book, but some colleagues have been slow to accept it.
"This relatively gentle 'cosmic rain' -- which possibly
contains simple organic compounds -- may well have nurtured the development of life on our planet," Frank said.
The images show what Frank describes as small, loosely packed
snowballs encased in shells. As they approach the Earth's atmosphere, the comets break apart, producing clouds of water. They do not contain the dust and metals of bigger comets.
"They don't have those things that glow so brightly that you would see," Frank said. "If they were built like big comets, then you would see these fantastic glows in the sky.
Instead they are dull glowers, comprised of oxygen, hydrogen, nitrogen and carbon that disassemble into separate gases and shower the Earth, resulting in about one inch of water every 10,000 years, according to Frank's theory.
But Frank said that over the course of billions of years,
even this minuscule amount of water would be enough to fill all of Earth's oceans.
The Polar satellite, which orbits high above the Arctic
Circle, tracked the snowballs as they disintegrated. Using a filter that detects visible light emitted by water molecules, Frank determined that the snowballs consist mainly of water.
According to data provided by the Polar satellite, the snowballs are no danger to people on Earth or astronauts, spacecraft or airplanes because they break up at altitudes from 600 miles (965 km) to 15,000 miles (24,140 km).
The National Aeronautics and Space Administration is backing Frank's claim, with some reservation.
"NASA is not yet convinced that we know how many of these, and how much they weigh, and how much water they're providing to Earth," said the agency's Steve Maran.
"But it's obvious to us there are dark spots in our satellite pictures, and these are incoming water-bearing objects."
Scientists have long theorized that billions of years ago, large comets slammed into the globe, seeding it with minerals and chemicals.
Correspondent Ann Kellan and Reuters contributed to this report.
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