(From Reuter Information Service)
SAN FRANCISCO (August 1, 1997 8:33 p.m. EDT) - A NASA physicist said on Friday he had found what may be the fossilized remains of extraterrestrial microorganisms in a meteorite, providing more evidence that life may have existed beyond Earth.
Astrophysicist Richard Hoover said that while investigating samples of the Murchison meteorite that fell on Australia in 1969, he had found complex structures that appeared to be biological.
"It is potentially the case that it's signs of life from somewhere other than the planet Earth. That is a real possibility that must be considered," Hoover told Reuters in a telephone interview from San Diego.
Hoover, an astrophysicist at the National Aeronautics and Space Administration's George C. Marshall Space Flight Center in Huntsville, Alabama, cautioned that more study was needed and he could not say for sure where the microscopic structures came from.
Hoover's work appears to support the findings of U.S. scientists who announced last year that they had found possible fossilized microbes in a meteorite from Mars.
In a scientific paper presented at a conference in San Diego this week, Hoover said he had concluded that the Murchison meteorite contained "a population of indigenous microfossils," shaped like mushrooms, stalks or filaments.
The mushroom-shaped bodies "are considered to represent the carbonized remains of biological forms," he wrote.
Hoover obtained images of the forms using an environmental scanning electron microscope and analyzed them with x-ray energy dispersive spectroscopy.
The bodies resembled some types of bacteria, but experts had been unable to identify them as known earthly microbial groups, Hoover said. He said the bodies resembled other unidentifiable forms found in another meteorite by earlier researchers.
"It is concluded that this population of complex structures may represent remains of extraterrestrial microorganisms which lived within or contaminated the parent body of the Murchison meteorite at various times during the past 4.4 billion years," Hoover wrote.
The parent body of the Murchison meteorite is unknown, but Hoover said there was strong evidence that it did not come from Earth, the moon or Mars and may have come from a comet or asteroid.
He said the structures he had observed appeared to have arrived on Earth with the meteorite and not be something that found its way there after it landed.
It was also possible that asteroid impacts on Earth billions of years ago could have catapulted materials from Earth into space and that any microfossils in the meteorite could have originated on Earth. But the same thing could have happened on Mars or another body, he said.
"We are doing additional work to determine what (the structures) are ... and to determine if we can obtain carbon isotope measurements to give an idea of whether they are terrestrial or extraterrestrial in nature."
He said that earlier this year a scientific team in Russia reported finding similar structures within the Murchison meteorite.
Hoover said scientists must continue studying meteorites.
"The meteorites are messages from space. They are bringing us information that we must study and learn, telling us where to go to seek conclusive proof for the existence of extraterrestrial life," he said.