Scientists discover possible microbe from space
Some scientists believe comets could be vehicles for the spread of
organic material throughout the solar system
November 24, 2000
Web posted at: 1:51 PM EST (1851 GMT)
By Richard Stenger
(CNN) -- An international team of scientists has recovered
microorganisms in the upper reaches of the atmosphere that could have
originated from outer space, a participant in the study said Friday.
The living bacteria, plucked from an altitude of 10 miles (16 km) or
higher by a scientific balloon, could have been deposited in
terrestrial airspace by a passing comet, according to the researchers.
The microorganisms are unlike any known on Earth, but the
astrobiologists "want to keep the details under wraps until they are
absolutely convinced that these are extraterrestrial," said study
participant Chandra Wickramasinghe, a noted scientist at Cardiff
University in Wales.
NASA's Ames Research Center posted a cautious reaction to the report on
its Astrobiology Web site. NASA said the finding is likely to meet
considerable skepticism in the scientific community.
"Aerobiologists might argue that 10 miles is not too high for Earth
life to reside, a possibility that Wickramasinghe appears to accept,"
the statement said.
However, NASA said, a compelling case can be made for the transport of
microorganisms through space aboard comets and meteors.
"A recent discovery indicates that microbes can remain dormant for
millions of years -- enough time to travel from planet to planet," NASA
Disputing critics who suggest that the balloon was contaminated on the
ground, Wickramasinghe said the experiment took place with strict
controls. He does acknowledge the possibility that terrestrial bacteria
could be kicked up into the stratosphere. Living fungal spores have
been discovered at altitudes of 7 miles (11 km).
But observations from this and a related study suggest the presence of
living bacteria far too high in the atmosphere to have originated from
the surface of the planet, according to Wickramasinghe.
"What is present in the upper atmosphere, critics will say it came from
the ground. That is a serious possibility at 15 kilometers, but at 40
or 85 kilometers, you can forget about it," he said Friday.
Wickramasinghe and colleague Sir Fred Hoyle published a report on the
Web Friday about evidence that they say strengthens the hypothesis that
unusual microbes float through the upper reaches of the atmosphere.
Looking at spectral data from the 1999 Leonid meteorite shower, they
detected a bacterial "fingerprint" as the tiny space rocks streaked
across the sky at a height of 51 miles (83 km).
"The bacteria heated at temperatures high enough to radiate and shine
in this (spectral) signature," Wickramasinghe said.
Along with Hoyle, Wickramasinghe pioneered "panspermia," the theory
that outer space seeded Earth with its first life forms about 4 billion
Wickramasinghe holds that primitive life could still be arriving from
space. "If we find microbes at great heights that are not contaminants
from the ground, we have to wonder where they came from. One hundred
tons of comet and meteor organic debris is deposited in the atmosphere
Javant Narlikar of India lead the atmospheric bacteria sample study,
which the Indian Space Research Organization coordinated.
The location of the microbe is what most impressed Wickramasinghe, not
the composition. It seems like a novel strain of a common bacteria
genus on Earth, he said.
Wednesday November 15 11:07 AM EST
Leonid Meteor Shower: Sowing the Seeds of Life?
By Robert Roy Britt
Senior Science Writer, SPACE.com
Data from instruments flown on airplanes during last year's Leonid
meteor shower show that the seeds of life, long suspected to exist in
comet dust, could have survived a fiery passage from space to Earth's
A range of findings, reported by an international team of NASA-led
scientists, provide support for panspermia, which holds that life on
Earth did not spring up spontaneously out of some primordial soup, but
was instead seeded from space.
"Findings to date indicate that the chemical precursors to life --
found in comet dust -- may well have survived a plunge into early
Earth's atmosphere," said astronomer Peter Jenniskens of the Ames
Research Center and the SETI Institute.
The studies were published in a November 14 special edition of the
Netherlands journal Earth, Moon and Planets.
Sowing the seeds
The idea that the seeds of life, or life itself, constantly fall from
space is the central idea of panspermia. Not only did life on Earth
begin this way, the concept holds, but the genetic pool is constantly
modified, even today.
Many mainstream scientists have long derided panspermia. But the view
has shifted noticeably in recent months.
Other researchers have shown that meteors both small and large do not
heat up as much as previously thought, allowing the possibility that
dormant life could arrive on an incoming space rock or, just possibly,
embedded in the dust grain of a comet.
Jenniskens and others said all this work at least supports the notion
that life's recipe -- in the form of organic molecules -- can survive
the trip into the atmosphere.
Chandra Wickramasinghe, a leading proponent of panspermia, cheered the
"I think the results reported by NASA are clear proof that bacterial
particles could survive, hence vindicating panspermia," Wickramasinghe
said. He and astronomer Sir Fred Hoyle have, since the 1970s, argued
that organic particles of bacterial sizes survive entry through the
"However, there is still a tendency to interpret results like this as
merely showing that organics, rather than life, are being added to the
Earth, but the trend is surely moving towards panspermia,"
Wickramasinghe told SPACE.com.
The new study reports on data collected during the 1998 and 1999 Leonid
The annual event, which peaks again this weekend, occurs when Earth
moves through a stream of debris left behind by comet Tempel-Tuttle.
That comet passes through the inner solar system every 33 years, with
its grains of dust zipping along at 160,000 miles per hour (72
kilometers per second) relative to Earth. When they hit our atmosphere,
friction vaporizes many of them. From the ground, we see blazes of
light commonly called shooting stars.
But studying small meteors from the ground can be frustrating. So
Jenniskens and his colleagues at the Aerospace Corporation in Los
Angeles, along with other researchers, used two airplanes to
create "stereoscopic" images of the meteors. Ground-based instruments
were used, as well.
In one striking image (see the click-to-enlarge animation) they
followed a meteor that exploded into what scientists call a fireball.
The trail left by the fireball contained what the researchers called
the "fingerprint of complex organic matter."
The fingerprint involves higher-than-expected concentrations of carbon
monoxide and carbon compounds that seemed to develop as the meteor
interacted with Earth's atmosphere.
Jenniskens and his colleagues caution that more work needs to be done
to confirm these findings.
Heat created by the meteors' race through the atmosphere sets up an
environment conducive to combining substances to form new compounds,
Jenniskens explained in an interview. He suggests, therefore, that
comets could have supplied basic chemicals that were lacking on early
The whole recipe might have gotten mixed in the air, he said, before
settling on the planet and getting down to the business of breathing.
Changing picture of meteors
Jenniskens and Michael Wilson, of the University of California, San
Francisco, also found evidence that the light we see from a meteor
comes not from the head of the meteor, but from the wake.
This wake is similar to the one created by a boat. In this analogy, the
boat plows the water, but the energy goes into the wake. With a meteor,
it means that the heat energy does not destroy the molecules in the
"The findings were somewhat surprising because it indicates that the
process that gives rise to the light we see from a meteor is more
complex than simple heating of the air through collision with
the 'head' of the meteor," Wilson said. "The temperature associated
with the light is much cooler."
Jenniskens said that the temperature of the wake, 4,300 degrees Kelvin
(7,200 degrees Fahrenheit, or 3,982 degrees Celsius), is just right for
breaking bonds in carbon monoxide, from which other life-seeding carbon
compounds can form.
One view of how life began on Earth
Wickramasinghe, director of the Cardiff Centre for Astrobiology,
described his view of the most likely scenario for how life began on
Earth, using the new findings as a springboard for a more controversial
"Comets are the breeding sites for cosmic bacteria," he explained. "In
the early history of the solar system comets picked up enough viable
microbes from interstellar space to incubate them in their warm watery
A million years later, the bacteria exhausted the comet's heat source,
were freeze dried, and became dormant. Then, as the comet approached
the Sun, some of its material was blown off into space.
"It is these ready-formed bacterial particles that entered the Earth
for the first time 4 billion years ago and established the ancient
Kingdom of Archaea, for which we have evidence in the geological
Other researchers are warming to the idea of panspermia, but remain
"This idea that the evolution of life has been tied to space is one
that has been growing stronger and stronger," said Benjamin Weiss, a
Caltech researcher. Weiss led a recent study of a Mars meteorite found
in Antarctica, discovering that the space rock remained cool enough to
have supported the transfer of microbial life.
"But until someone actually finds evidence that life has come from
space -- not just evidence that such an event is highly likely --
panspermia is still going to be just a hypothesis, and rightly so,"
Jenniskens and his colleagues will not conduct such thorough research
of this year's Leonids, but they hope to be back at it in 2001.
Meanwhile, NASA will loft a weather balloon toward the stratosphere on
Saturday to record the sights and sounds of the 2000 Leonid meteor
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