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Life From Space? (Panspermia; Lithopanspermia)

One chap (John Rummel, the planetary protection officer) (great job title!)pointed out that Louis and Wickramasinge are astrophysicists; when the biologists examined the rain back in 2001 they had no trouble identifying the red material as Trenepohlia, an algal spore.
 
eburacum said:
One chap (John Rummel, the planetary protection officer) (great job title!)pointed out that Louis and Wickramasinge are astrophysicists; when the biologists examined the rain back in 2001 they had no trouble identifying the red material as Trenepohlia, an algal spore.
Click to expand...

I know... the fact it had DNA and was identifiable will take a while to filter through to a lot of people though. There'll be 50,000 pages on the internet that won't be updated that currently support the notion that it's alien.

I guess it's one of the reasons that many scientists avoid this side of things.
 
Meteorite yields life origin clue

Hollow spheres found in a primordial meteorite could yield clues to the origin of life on Earth.
Scientists say that "bubbles" like those in the Tagish Lake meteorite may have helped along chemical processes important for the emergence of life.

The globules could also be older than our Solar System; their chemistry suggests they formed at temperatures of about -260C, near "absolute zero".

Details of the work by Nasa scientists are published in the journal Science.

Analysis of the bubbles shows they arrived on Earth in the meteorite and are not terrestrial contaminants.

These hollow spheres could have provided a protective envelope for the raw organic molecules needed for life.

Dr Lindsay Keller of Nasa's Johnson Space Center (JSC) in Houston, Texas, told BBC News that some scientists believed such structures were "a step in the right direction" to making a cell wall.

But he emphasised that the globules in Tagish Lake were in no way equivalent to a cell. The hollow spheres seem to be empty, but they do have organic molecules on their surfaces.

Mike Zolensky, a Nasa mineralogist, commented: "If, as we suspect, this type of meteorite has been falling on to Earth throughout its entire history, then the Earth was seeded with these organic globules at the same time life was first forming here."

Co-author Keiko Nakamura-Messenger of JSC told BBC News: "We reported only 26 globules in this paper, because they are small and hard to analyse. But we have seen hundreds in a small area. We can estimate that there are billions of them in this meteorite."

The ratios of different forms, or isotopes, of the elements hydrogen and nitrogen in the meteorite are very unusual, which suggests the structures did not come from Earth, say the scientists.

"The isotopic ratios in these globules show that they formed at temperatures of about -260C, near absolute zero," said co-author Scott Messenger, also from Johnson Space Center.

"The organic molecules most likely originated in the cold molecular cloud that gave birth to our Solar System, or at the outermost reaches of the early Solar System."

The Tagish Lake meteorite was collected immediately after its fall over Canada in 2000. It has been maintained in a frozen state, minimising the potential for terrestrial contamination.
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http://news.bbc.co.uk/1/hi/sci/tech/6197228.stm
 
Comets hold life chemistry clues
By Jonathan Amos
Science reporter, BBC News, San Francisco



The mission to Comet 81P/Wild-2 has changed our understanding


Enlarge Image

The idea that comets delivered the chemical "seeds" for life to the early Earth has been given a big boost.

Scientists studying the tiny grains of material recovered from Comet Wild-2 by Nasa's Stardust mission have found large, complex carbon-rich molecules.

They are of the type that could have been important precursor components of the initial reactions that gave rise to the planet's biochemistry.

The first full analysis of the Wild-2 grains is reported in Science magazine.

"Whatever it took to get life started, the more variety of molecules you had in the mix and the more they looked like the kinds of molecules that life uses now then the easier it should have been," Dr Scott Sandford from Nasa's Ames Research Center told BBC News.

The Stardust spacecraft flew past the 5km-wide icy "mud-ball" known as Comet 81P/Wild-2 in January 2004.

The probe swept up particles fizzing off the object's surface as it passed some 240km (149 miles) from the comet's core, or nucleus. These tiny grains, just a few thousandths or a millimetre in size, were then returned to Earth in a sealed capsule.

Lab clues

Distributed among the world's leading astro-labs, the specimens are giving researchers a remarkable insight into the conditions that must have existed in the earliest phases of the Solar System when planets and comets were forming.

Dr Sandford led the organics investigation; some 55 researchers in more than 30 institutions. His team sees many delicate, volatile compounds that are quite unlike those familiar in meteorites that have fallen to Earth.


See how Stardust grabbed material from Comet Wild-2


In pictures

These Wild-2 compounds lack the aromaticity, or carbon ring structures, frequently found in meteorite organics. They are very rich in oxygen and nitrogen, and they probably pre-date the existence of our Solar System.

"It's quite possible that what we're seeing is an organic population of molecules that were made when ices in the dense cloud from which our Solar System formed were irradiated by ultraviolet photons and cosmic rays," Dr Sandford explained.

"That's of interest because we know that in laboratory simulations where we irradiate ice analogues of types we know are out there, these same experiments produce a lot of organic compounds, including amino acids and a class of compounds called amphiphiles which if you put them in water will spontaneously form a membrane so that they make little cellular-like structures."

No-one knows how life originated on the cooling early Earth, but it has become a popular theory that a bombardment of comets may have deposited important chemical units for the initiating reactions.

The Stardust results, also reported here at the American Geophysical Union Fall Meeting, will give support to this idea.

Hot and cold

They will also allow researchers to "re-tune" the models they use to describe how materials were moved and mixed up in the early Solar System.

The Stardust mineral grains generally show a huge diversity, and, very surprisingly, there are materials incorporated into the samples that must have formed close in to the proto-Sun.

These include calcium-aluminium and magnesium-olivine fragments.

"They form in the hottest possible place in the Solar System, so it's quite stunning to find something like them in a body that came together in the coldest place in the Solar System," said Dr Don Brownlee from the University of Washington and who is the principal investigator, or lead scientist, on Stardust.

"There must have been some way of getting them from the new Sun to the outer fringes of the proto-planetary disc," commented Professor Monica Grady from the UK's Open University.

"There must have been major turbulence and currents and disc-wide mixing, which hadn't really been predicted."

The international team of scientists has used a wide variety of sophisticated laboratory analytical techniques to study the samples. But there is a realisation that technologies improve and some comet samples will be kept back for future study.

Just as with the Moon rocks returned by the Apollo programme, researchers are likely to be working on the Stardust samples for decades.

"The information from Stardust has been a revelation and will continue to be as we couple it with other comet data we get from Nasa's Deep Impact mission and Europe's Rosetta mission, which is coming up in seven years' time," said Professor Grady.

In the UK, scientists from the Open University, Imperial College London, the Natural History Museum and the Universities of Kent, Manchester and Glasgow have been involved in the analysis.

[email protected].


http://news.bbc.co.uk/2/hi/science/nature/5173992.stm
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Hardy bug re-opens Mars debate

Controversial claims have again emerged that Martian microbes could have established themselves here on Earth after hitching rides on meteorites.
A handful of bacteria on Earth today have the ability to survive exposure to extremely high levels of radiation that would kill other organisms.

Now, a team of scientists argues that the bugs could only have evolved this unusual ability on a planet like Mars.

The claims by a Russian-American team appear in the journal Astrobiology.

Recent discoveries of water in the permafrost on Mars and signs of subsurface water in mid-latitude regions have raised hopes that the Red Planet might host the right conditions for life.

According to one theory, impacts on the surface of the Red Planet could have thrown Martian rocks into space, which wandered the vaccum before tumbling through Earth's atmosphere and crashing down as meteorites.

If these Martian meteorites contained any life forms able to survive the journey, they might have been able to gain a foothold on our own planet, scientists speculate.

'Conan the bacterium'

The best-studied radiation-resistant microbe is Deinococcus radiodurans.

It can withstand several thousand times the lethal dose of radiation for humans, and has been nicknamed "Conan the bacterium" by microbiologists. :D

But other scientists say that radiation tolerance is a side effect of the defence mechanism bacteria such as D. radiodurans have developed to protect against dehydration.

D. radiodurans and other radiation-resistant bacteria survive because they are very efficient at repairing their DNA. But this is also useful for surviving extreme desiccation in arid environments.

The team led by Alexander Pavlov at the University of Arizona, US, rejects this alternative explanation.

"Our hypothesis of a Martian origin for radio-resistant bacteria provides an explanation for their ability to withstand ionizing radiation, a trait that appears to be of no value on Earth at any time in its history," the scientists write in Astrobiology.

The clement background levels of radiation on Earth are not thought to have changed significantly for the last four billion years.

As such, there has been no evolutionary pressure for bacteria to develop resistance to such high levels of radiation, the researchers argue.

Trained up

But the Martian permafrost, where radiation levels are 100 times higher than on Earth, could provide a plausible environment where bacteria could pick up radiation-resistant genes.

In their paper, Professor Pavlov and his colleagues outline several pieces of evidence which cast doubt on the dehydration theory.

For example, they argue there is no evidence that the degree of resistance to radiation is related to the degree of resistance to dehydration in bacteria. Instead, Pavlov and his colleagues argue that these are independent attributes.

Scientists have also carried out experiments in which they blast "ordinary" bacteria with gamma rays, allow the survivors to recover, and then repeat the process again and again. After many cycles, the bacteria develop resistance to high levels of radiation.

But bugs exposed to successive cycles of dehydration and hydration in the lab develop resistance only to desiccation, not to radiation.

Scientists who are sceptical of the group's claims have pointed out that the genome of D. radiodurans is very similar to that of "ordinary" terrestrial bacteria, arguing against an extra-terrestrial origin.

Pavlov and his colleagues say that frequent exchanges of bacteria carried on meteorites between Mars and Earth could explain this similarity.

Nasa says around 34 of the 24,000 meteorites so far found on Earth have been identified as coming from Mars.

http://news.bbc.co.uk/1/hi/sci/tech/6191197.stm
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Astrobiologist Awarded Prize

Dr. Joshua Lederberg.
by Staff Writers
Washington DC (SPX) Dec 21, 2006
Dr. Joshua Lederberg, a Nobel-winning microbiolgist whose advice helped create NASA's early biology programs, will receive the Medal of Freedom, the United States' highest civilian honor. Dr. Lederberg became interested in exobiology -- the study of life beyond Earth -- in the 1950s, as interest in exploring space began to build in the United States and other countries.
He was one of the first scientists to express concern that spacecraft from Earth might carry microbes that could contaminate the moon or other landing sites.

He co-chaired the 1964 Summer Study, sponsored by NASA and the Space Studies Board of the National Academy of Science, which outlined the rationale for searching for life on Mars and started to make the search for life beyond Earth intellectually respectable.

He was consulted frequently by NASA during the development of the Viking mission, which carried experiments designed to determine whether life could exist on Mars.

"Joshua Lederberg was one of the guiding lights behind the Viking search for life on Mars and a very close friend and trusted adviser to Jerry Soffen, Viking project scientist" said Langley Research Center senior research scientist Dr. Joel S. Levine. "Lederberg visited Langley often and was influential in promoting the importance of searching for life outside Earth -- even before that concept was fashionable."

Lederberg has remained active with NASA in the 21st century. In 2000, Baruch Blumberg, then the director of the NASA Astrobiology Institute and a Nobel Laureate himself, included Lederberg on his "Director's Science Council," which consisted of 10 members, most of which were Nobel Laureates with expertise ranging from physics to molecular biology. Dr. Lederberg continues to be affiliated with institute activities and recently served as a reviewer for the joint NAI-American Philosophical Society "Lewis and Clark Fund for Exploration and Field Research in Astrobiology."

Lederberg was born in Montclair, N.J. on May 23, 1925. He was brought up in the Washington Heights District of Upper Manhattan, New York City, where he received his education in Public School 46, Junior High School 164 and Stuyvesant High School. From 1941 to 1944 he studied at Columbia College, where he obtained his B.A. with honors in Zoology (premedical course), and from 1944 to 1946 at the College of Physicians and Surgeons of Columbia University Medical School. Here he carried out part-time research with Professor F.J. Ryan in the Department of Zoology. Subsequently, he went to the Department of Microbiology and Botany at Yale University, New Haven, Conn., as Research Fellow of the Jane Coffin Childs Fund for Medical Research and, during 1946-1947, as a graduate student with Professor E.L. Tatum. He was awarded a doctorate in 1948.

In 1947, he was appointed assistant professor of genetics at the University of Wisconsin, where he was promoted to associate professor in 1950 and professor in 1954. He organized the Department of Medical Genetics in 1957, of which he was chairman during 1957-1958.

He organized the Stanford University Medical School's Department of Genetics, which appointed him professor and executive head in 1959. Since 1962, he has been Director of the Kennedy Laboratories for Molecular Medicine at Stanford.

Lederberg was Visiting Professor of Bacteriology at the University of California, Berkeley, in 1950; and Fulbright Visiting Professor of Bacteriology at Melbourne University, Australia, in 1957. In the latter year, he was elected to the National Academy of Sciences.

Read more about Dr. Lederberg and NASA's early efforts in exobiology and the Viking program in the NASA publication "On Mars: Exploration of the Red Planet, 1958-1978."


Medal
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Dust ‘comes alive’ in space
Robert Booth

SCIENTISTS have discovered that inorganic material can take on the characteristics of living organisms in space, a development that could transform views of alien life.

An international panel from the Russian Academy of Sciences, the Max Planck institute in Germany and the University of Sydney found that galactic dust could form spontaneously into helixes and double helixes and that the inorganic creations had memory and the power to reproduce themselves.

A similar rethinking of prospective alien life is being undertaken by the National Research Council, an advisory body to the US government. It says Nasa should start a search for what it describes as “weird life” - organisms that lack DNA or other molecules found in life on Earth.

The new research, to be published this week in the New Journal of Physics, found nonorganic dust, when held in the form of plasma in zero gravity, formed the helical structures found in DNA. The particles are held together by electromagnetic forces that the scientists say could contain a code comparable to the genetic information held in organic matter. It appeared that this code could be transferred to the next generation.

Professor Greg Morfill, of the Max Planck institute of extra-terrestrial physics, said: “Going by our current narrow definitions of what life is, it qualifies.

“The question now is to see if it can evolve to become intelligent. It’s a little bit like science fiction at the moment. The potential level of complexity we are looking at is of an amoeba or a plant.

“I do not believe that the systems we are talking about are life as we know it. We need to define the criteria for what we think of as life much more clearly.”

It may be that science is starting to study territory already explored by science fiction. The television series The X-Files, for example, has featured life in the form of a silicon-based parasitic spore.

The Max Planck experiments were conducted in zero gravity conditions in Germany and on the International Space Station 200 miles above earth.

The findings have provoked speculation that the helix could be a common structure that underpins all life, organic and nonorganic.

http://www.timesonline.co.uk/tol/news/u ... 241753.ece
 
Sounds a bit like the sentient dust cloud in Fred Hoyle's The Black Cloud (
 
Did life begin on comets?
18:17 17 August 2007
NewScientist.com news service
Hazel Muir

If you buy a lottery ticket this week, what are the odds that you'll win the grand prize then get struck by lightning as you pop open the champagne? Vanishingly small, but still much higher than the odds that life on Earth first evolved on our planet, according to an ardent proponent of the notion that life came from space.
Chandra Wickramasinghe from Cardiff University, UK, has long argued the case for cometary panspermia, the idea that comets are infected with primitive life forms and delivered life to the early Earth. That would explain why life on Earth arose so quickly after our planet formed around 4.5 billion years ago.
Wickramasinghe says the case has been bolstered by NASA's Deep Impact probe, which blasted Comet Tempel 1 with a projectile in July 2005. Scientists reported seeing clay particles spewing out from the interior. Because clay needs liquid water to form, Wickramasinghe says that suggests comets once had warm, liquid interiors due to heating from radioactive isotopes.
Clay is also a favoured catalyst for converting simple organic molecules into complex biopolymers on the early Earth. Now, Wickramasinghe and his colleagues argue that the sheer volume of watery clay environments on comets makes them a far more likely site for the origin of life than our home planet.
The team estimates that the volume of these environments on the early Earth would have been about 10,000 cubic kilometres. A single 20-kilometre-wide comet could offer about a tenth of that, but when you include all the comets in the outer solar system, volume arguments alone make comets 1012 times more likely than Earth to have spawned life, they say.
What's more, watery pools on the Earth's surface would be prone to evaporation and short-lived, they argue. "But in a comet, the clay particles and liquid water are intermixed with life's building blocks for one or two million years," says Wickramasinghe.
However, the report doesn't impress comet expert Michael Mumma from NASA's Goddard Space Flight Center in Greenbelt, Maryland, US. He says the existence of clays in comets is controversial because there is no clay in the samples of Comet Wild 2 that NASA's Stardust spacecraft returned to Earth in January 2006. Nor has anyone, other than advocates of panspermia, made the case that radiogenic heating kept comet interiors liquid during the first million years of their history.

http://space.newscientist.com/article/d ... omets.html
 
Fiery rock will test whether life came from space
15:06 13 August 2007
NewScientist.com news service
David Shiga

A rock will be hurled into space on a rocket and subjected to the fiery heat of re-entry into Earth's atmosphere to test whether life could have hitched a ride from one planet to another in debris from an asteroid strike.
The rock is one of 35 experiments to fly on a European Space Agency mission called Foton M3, which is set to launch on 14 September from the Baikonur Cosmodrome in Kazakhstan.

Some scientists say life could have spread around the solar system by hitching rides inside rocks blasted from one planet or moon to another by asteroid impacts (see Earth rocks could have taken life to Titan).
Loch rockTo investigate that idea, John Parnell at the University of Aberdeen in the UK designed the experiment, which involves a 400-million-year-old rock formed from sediment at the bottom of an ancient lake in Scotland.

The fist-sized rock will be protected inside the spacecraft during launch, then uncovered when the craft re-enters the atmosphere at 8 kilometres per second.

Researchers want to see how the re-entry affects molecules in the rock that are believed to form only from the decay of living things, such as steranes and hopanes, which in this case come from algae. "The outer part might have melted or possibly disintegrated, but the interior portion might be rather better preserved," Parnell told New Scientist.

Steranes and hopanes, which are derived from cell walls, are especially promising as a possible signature of ancient life in meteorites because they stay around for so long. "Unlike things like DNA that decompose quite quickly, these have long-term stability over millions or even billions of years," Parnell says.

"This experiment is really designed to look at fossil biomarkers rather than living ones," he continues. "But the more you know about the survival of organic molecules in general, the more you can understand whether living [things] could survive as well."

The results will help determine whether there is hope of finding such signatures in meteorites from Mars. In 1996, scientists said they had found fossilised signs of ancient life in a Martian rock, though many researchers dispute the claim (see Hunting life in Martian rocks).

Jean Pierre de Vera of Heinrich Heine University in Düsseldorf, Germany, who is not involved in the experiment, says better knowledge of the biomarkers used in the experiment could also help scientists recognise signs of life on Mars and elsewhere in the solar system. "This is important for the search for recent or past life forms on other planets," he told New Scientist.

De Vera is involved in another experiment on Foton M3 that bears on the transfer of life by meteorites. Called STONE, it will expose a rock colonised by lichens to the heat of re-entry to see whether the lichens can survive.

http://space.newscientist.com/article/d ... space.html
 
When I was a wee nipper, the idea that life could have come from space was practically 'heresy' - now it seems to be the accepted thing...

Moon meteorites may hold clue to life on Earth
By Richard Gray, Science Correspondent, Sunday Telegraph
Last Updated: 12:01am BST 26/08/2007

Scientists are planning a mission to drill beneath the Moon's surface for buried meteorites that may hold clues to how life began on Earth.

British space experts are to reveal plans next month to send robotic drills to the Moon to collect cores of lunar rock.

They believe that beneath the Moon's dust-covered surface they will find the remains of meteorites that date back to the early history of the earth.

As the Moon is geologically inactive, the scientists hope to find rocks that would have been destroyed long ago by volcanoes and earthquakes on our own planet. They claim it will be possible to find a record of meteorites dating back more than 3.8 billion years, around the time that life is thought to have begun on Earth.

These preserved meteorites may hold evidence for theories that water and even the precursors of life on our own planet were carried here on asteroids. Scientists also hope they will find fragments of rock from Earth itself in the lunar crust, knocked off by meteorite bombardments, giving an insight into the planet's early history.

The European Space Agency will outline its plans to land the equipment on the Moon next month at the European Planetary Science Congress in Germany.

British scientists and oil industry executives met early this month to discuss a similar mission. The space technology company LogicaCMG, which organised the meeting, will also reveal the outcome of those talks next month.

Stuart Martin, the director of space and satellite communications at LogicaCMG, said: "Drilling on the Moon presents some unique challenges… Anchoring a rig to the surface, which is covered in a couple of yards of dust, is also something that will need to be solved."

He added: "The oil industry is keen to help as it is searching for oil in increasingly extreme environments so it wants drilling rigs that can be controlled remotely."

Scientists expect the first drilling mission to use a lightweight rig, powered by solar panels, which will drive a two-inch-wide drill into the surface. Cores obtained from the drill will be analysed on board and the results beamed back to earth.

The ESA also hopes to use small, 400lb rockets to fire samples back to the earth to be analysed.

While Dr Bernard Foing, the ESA's senior research co-ordinator, said there was "a possibility we will find prebiotic forms of life", Dr Ian Crawford, a planetary scientist at London University's Birkbeck College, added that drilling on the Moon would also provide valuable training for exploring other planets.

http://tinyurl.com/265ctx
 
When I was a wee nipper, the idea that life could have come from space was practically 'heresy' - now it seems to be the accepted thing...
Click to expand...

Well, not completely; Wickramasinge is out on a limb with his 'hot comet' ideas, but lithopanspermia is quite respectable, I think.

I have made a fictional account of some of the possibilities in this entry for Orion's Arm
http://www.orionsarm.com/science/Abiogenesis.html
in this scenario, the questions of abiogenesis, panspermia and the origin of life have been answered by an examination of thousands of extrasolar lifebearing worlds during the course of interstellar exploration.
 
Did life begin with a meteorite?
Scientists discover genetic ingredient for creation of man on rock from space
Wednesday, 18 June 2008

The building blocks of genes have been found in a meteorite, raising the prospect of life originating with the aid of extraterrestrial molecules that came from space more than 3.6 billion years ago.

Scientists have found that the meteorite contains complex organic chemicals which can be used to make self-replicating molecules that are the essential genetic ingredient of all known lifeforms – DNA and RNA.

Although organic molecules such as sugars and amino acids have been found in meteorites before, it is the first time scientists have found evidence for the existence of extraterrestrial compounds that can be used to make genes. The two substances are called uracil and xanthine and they are the precursors of the building-block molecules, known as nucleobases, that help store and transmit genetic information from one generation to the next – one of the vital signs of life.

Scientists found the two building blocks during analysis of a meteorite that fell near the Australian town of Murchison on 28 September 1969. The Murchison meteorite had already been shown to contain sugars and phosphates, two other essential ingredients of DNA and RNA.

"At the compound-class level, you have all the basic components needed to make the buildings blocks of DNA in a single meteorite," said Professor Mark Sephton of Imperial College London, who led the research team. "It's not the compete jigsaw to explain the origin of life, but it is the partial jigsaw. This discovery lends weight to the idea that the building blocks of life came from space."

The origin of life is one of science's greatest unsolved mysteries. Scientists have postulated that it must have begun with simple organic molecules that somehow gained the ability to replicate themselves in a watery environment.

The first fossilised signs of life appear in ancient terrestrial rocks dated to about 3.5 billion years ago and it is known that the Earth suffered a meteorite bombardment between 3.8 and 4.5 billion years ago.

For about 40 years scientists have speculated that these meteorites – fragments of the larger asteroids left over from the origin of the solar system – may have brought the simple organic molecules used by the first lifeforms. The latest discovery of nucleobases in the Murchison meteorite further supports the idea of an extraterrestrial source of the organic molecules necessary for genetic inheritance, said Zita Martins of Imperial College, the lead author of the study, published in the journal Earth and Planetary Science Letters.

"Early life may have adopted nucleobases from meteoritic frag- ments for use in genetic coding which enabled them to pass on successful features to subsequent generations," Dr Martins said.

The analysis of meteorites for signs of life is mired in controversy. However, it is clear that organic molecules of surprising complexity seem to be ubiquitous in space, either on asteroids orbiting the solar system or on meteorites analysed on Earth, said Professor Sephton.

"Because meteorites represent leftover materials from the formation of the solar system, key components for life – including nucleobases – could be widespread in the cosmos," he said.

So where did it all begin?

Primordial soup

First suggested by Charles Darwin and elaborated on by the US chemist Stanley Miller who in 1953 created simple organic molecules in a test-tube.

Hydrothermal vents

These sea-floor volcanic "chimneys" spew out minerals that can react in heat to create the building blocks of life.

Panspermia

The British cosmologist Fred Hoyle first proposed that extraterrestrial microbes could be carried by asteroids and deposited on passing planets.

Divine intervention

Given that Darwinian evolution can explain everything about life but its origins, some believe that the hand of God is needed.

http://www.independent.co.uk/news/scien ... 49201.html
 
Note that neither uracil nor xanthine are components of DNA, so the idea of microbes from space still has a little way to go to close the credibility gap.
 
eburacum said:
Note that neither uracil nor xanthine are components of DNA, so the idea of microbes from space still has a little way to go to close the credibility gap.
Click to expand...
The article actually said
The two substances are called uracil and xanthine and they are the precursors of the building-block molecules, known as nucleobases, that help store and transmit genetic information from one generation to the next
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And more 'so-called pre-genetic material' here:

Meteorite could hold solar clues

A rare type of meteorite that could hold clues to the birth of our Solar System has been bought by London's Natural History Museum.

The Ivuna meteorite, obtained from a US private collection, has the same chemical make-up from which the Solar System formed 4.5 billion years ago.

It landed in Tanzania in 1938 as one 705g stone, since split into samples.

Pieces from the UK sample, the largest in any public collection in the world, will be removed for study.

Most Ivuna samples are held in private collections, or by the Tanzanian government.

Ivuna's chemical make-up, which matches the Sun, is extremely rare - just nine of the 35,000 known meteorites, or 0.03%, have this solar composition.

Dr Caroline Smith, meteorite curator at the Natural History Museum (NHM), told BBC News: "These types of meteorite are very susceptible to alteration on Earth. Changes in humidity, for example, can change their composition.

"But this meteorite is important as it fell relatively recently and has been kept under nitrogen in a sealed environment for the last two or three decades.

"It's a particularly important specimen to science because it's been so well preserved. We're all incredibly excited about it because it's so pristine."

Monica Grady, professor of planetary sciences at the Open University in Milton Keynes, commented: "This is fantastic for the UK's meteorite experts. This material represents the crumbs from the foundation of the Solar System. It's an unbelievable opportunity to study it in close-up.

"The museum has been very bold in acquiring it."

One question that Ivuna could help answer is how the chemical building blocks for life came to Earth.

Important components of so-called pre-genetic material, the amino acids b-alanine and glycine, were found in Ivuna in a 2001 study.

Last week, scientists at Imperial College London confirmed that a meteorite called Murchison contained extra-terrestrial molecules that were the precursors to DNA and RNA.

In addition to being used for research, Ivuna will be a star specimen in a new meteorites gallery, which the NHM is planning for the near future.

"The plan is to take the meteorite to Nasa's Johnson Space Center in Houston, where we'll have a 20g piece taken off and that will be sub-divided into two 10g pieces," Dr Smith explained.

"One piece will be put to one side. The other will be divided into 200mg allocations - less than the size of your fingernail - for researchers to study."

http://news.bbc.co.uk/1/hi/sci/tech/7464583.stm
 
Rynner said:
The article actually said
Quote:
The two substances are called uracil and xanthine and they are the precursors of the building-block molecules, known as nucleobases, that help store and transmit genetic information from one generation to the next
Click to expand...
Yes, but that suggests to me that organic precursors of nucleic acids may be raining down out if the sky, rather than whole microbes as Chandra Wickramasinghe suggests.

These materials may not have had a role to play in abiogenesis on our planet, although it seems quite plausible that they did. However the idea that microbes, germs, diseases, or whole organisms of any sort originate within comets and are carried from world to world and star to star by them seems as unlikely as ever.
 
Life from Venus blown to Earth?

Life on Venus could be blown to Earth by powerful winds, scientists claim.

Previous research has considered the possibility of micro organisms existing in Venus's atmosphere despite extreme temperatures on its surface.

But two scientists at the Cardiff Centre for Astrobiology say microbes from Venus could actually be blown into the Earth's atmosphere by solar winds.

Their findings follow analysis of data from the European Space Agency's Venus Express probe, launched in 2005.

Prof Chandra Wickramasinghe and Dr Janaki Wickramasinghe claim Venus's clouds contain chemicals that are consistent with the presence of micro organisms.

VENUS FACTS

Distance from Sun: 108,200,000km
Diameter: 12,103km
Year length: 224.7 Earth days
Atmosphere: 96% carbon dioxide, 3% nitrogen
Moons: 0
Missions: Between 1961 and 1989 the US and USSR launched more than 30 spacecraft towards Venus
Brightness: Venus is the brightest object in the sky apart from the Sun and Moon

They suggest that under certain conditions, these microbes from high in Venus's atmosphere could be blown into the Earth's atmosphere.

This process would only take days or weeks.

But the Sun, Earth and Venus must be suitably aligned, which last happened in 2004 and will not happen again until 2012. :shock: 8)

Prof Wickramasinghe said: "Venus and Earth have often been referred to as sisters because of their geological similarities.

"Our research proposes that the two sisters may be biologically interconnected as well."

The work has been published online in a new paper in the Astrophysics and Space Science journal.

But Prof Fred Taylor, a planetary scientist at Oxford University, said he was sceptical about the research.

"The idea of life on Venus, particularly the clouds where the temperature and pressure are similar to the Earth, has been floated around for a while but is not really very likely," he said.

He added that it was "most unlikely" anyway that microbes from Venus could be transferred to the Earth's atmosphere by solar winds.

The Venus Express probe, launched in November 2005, is orbiting the planet to study its atmosphere.

Scientists hope to learn how Venus, which is similar to Earth in size, mass and composition, evolved so differently over the last 4.6 billion years.

The mission was the first to be sent to the planet in 15 years.

http://news.bbc.co.uk/1/hi/wales/south_east/7525390.stm
 
Interstellar 'slowball' could have carried seeds of life

COULD a star in a distant solar system have thrown the life's building blocks our way?

Previous studies into whether material could travel between solar systems predicted that such an exchange would be unlikely, because the speed matter would need to be travelling at to escape one star would mean it was moving too fast to be caught by another.

Now Edward Belbruno and colleagues at Princeton University have shown that planetary systems in young, densely packed star clusters could throw out rocks at a slower pace. They showed that for rocks in certain orbital positions, the gravitational pull of the central star is equal to the pull of other stars in the cluster. This sends the rocks into chaotic orbits that eventually allow them to wander off at about 0.1 kilometres per second - slow enough for other stars to catch them (http://arxiv.org/abs/0808.3268).

The team estimates that up to 1018 individual rocks could leave such a system in the first 100 million years of a cluster's life, before the stars drifted too far apart. They believe these rocks could have carried basic biological components like amino acids.

Related Articles

Fiery rock will test whether life came from space
http://www.newscientist.com/article.ns?id=dn12469
13 August 2007

Spacewalking microbes may reveal life's origin
http://www.newscientist.com/article.ns?id=dn13684
15 April 2008

Did life begin on comets?
http://www.newscientist.com/article.ns?id=dn12506
17 August 2007

Weblinks

Amaya Moro Martin, Princeton
http://www.astro.princeton.edu/~amaya/

Edward Belbruno
http://www.edbelbruno.com

From issue 2672 of New Scientist magazine, 04 September 2008, page 21
Slowball
Click to expand...
 
Meteorite experiment deals blow to 'bugs from space' theory

A novel experiment has dealt a setback to a theory that life on Earth was kickstarted by bacteria that hitched a ride on space rocks.

The 'pan-spermia' hypothesis is that cells were transported to the infant Earth on rocks that were bumped off other planets or even came from another star system.

The theory gained a boost in 1996, when a group of US scientists proposed that a famous meteorite found in Antarctica may have held traces of fossilised bacteria that once lived on Mars.

Seeking to find out more, European scientists have devised "artificial meteorites" to see what happens when rocks bearing fossil traces and living bacteria are exposed to the fiery heat of entering Earth's atmosphere.

In research set to to be unveiled, they attached small two-centimetre thick rocks to the unmanned Russian Foton M3 capsule that was launched in September 2007 and returned to Earth 12 days later.

The samples were embedded on the capsule's heat shield, which reached a peak velocity of 7.6 kilometres per second (27,200 kms per hour) during the controlled descent.

One sample comprised a 3.5 billion year-old piece of sedimentary rock from Pilbara, that contained carbonaceous microfossils.

The other was a piece of sedimentary lake rock from the Scotland's Orkney Islands containing chemical traces of past organisms.

The back of both rocks was smeared with a living bacterium called Chroococcidiopsis - a hardy, primitive species that lives on the underside of stones in the desert, surviving on tiny droplets of moisture.

Some scientists have considered it or its relative to be a good candidate for a Martian germ.

Recovered and analysed after the return, the Pilbara sample was found to be covered with a creamy-white fusion crust about half a millimetre thick but, underneath, its microfossils were intact.

The Orkney samples lost nearly a third of its mass, but otherwise survived, as did its biomolecules.

But there was bad news for the Chroococcidiopsis.

The bugs were burnt to a crisp, although their carbonised outline remained intact.

"The STONE-6 experiment suggests that, if Martian sedimentary meteorites carry traces of past life, these traces could be safely transported to Earth," said investigator Frances Westall, of the Centre of Molecular Biophysics in Orleans, France, in a press release.

"However, the results are more problematic when applied to pan-spermia.

"STONE-6 showed at least two centimetres of rock is not sufficient to protect the organisms during the [atmospheric] entry."

The study was scheduled to be presented on Thursday (local time) at the European Planetary Science Congress in Munster in west Germany.

So far 39 meteorites have been found on Earth that have been attributed to a Martian origin through their chemical signature.

The notion is that they were knocked off the planet in the distant past by an asteroid impact, then wandered in space before landing here.

But all these meteorites are of basalt, or volcanic origin.

None of them are sedimentary, which is a term for rocks that are laid down in beds or strata as a result of wind, water or gravity.

This has perplexed scientists, as there is abundant evidence for sediments on the red planet.

The outcome of the STONE-6 experiment, though, shows that Martian sedimentary rocks could survive entry through Earth's atmosphere.

The Foton capsule generated temperatures of around 1,700 degrees Celsius, although its speed was somewhat slower than that of a meteorite.

Meteorites normally attain a velocity of 12-15 kms per second depending on their angle of descent.

A third piece of rock, a control sample of basalt, was lost during the descent.
Click to expand...

ABC News
 
I'm not at all sure that embedding stones in the heat shield of a fairly massive re-entry vehicle is a fair simulation of how similar 'free-flying' stones would behave.

Free-flying stones would probably decelerate more quickly, and be more able to radiate away some of the heat generated. My guess is that these two factors would result in the stones being less thoroughly 'cooked' than the embedded ones.

Most meteorites arrive on Earth still almost as cold as space itself, as there is not enough time for the heat of re-entry to conduct into the interior.
 
Sun's siblings may have seeded Earth life
by Rachel Courtland

ETLife

Enlarge image
A cluster of newborn stars might share life-bearing rocks between them. (Image: ESA and NASA) An international team of researchers has identified a novel place to look for life: on planets that orbit the Sun's stellar siblings.

Most of the stars in the Milky Way got their start in clouds of dust and gas that eventually formed clusters of stars. If our Sun started life in such a scenario, the cluster would most likely have drifted apart after a few hundred million of years.

But that might have been enough time for life to travel between the rocky debris surrounding each nascent star, according to a study led by astronomer Mauri Valtonen at the Turku University in Finland.

Rock-smashing experiments have suggested that microbes could certainly survive a massive crash that sandwiches them in debris and jettisons them into space.

And a recent study by Edward Belbruno and colleagues at Princeton University showed that planets in densely packed star clusters could throw out as many as 1018 rocks in the first 100 million years or so, at speeds slow enough for other stars to capture them.

The new research suggests that microbes from other planetary systems, if they existed, could very well have hitched a ride in such rocks – as long as the rocks were large enough to protect the organisms from cosmic rays and the heat of impact. If the Sun was born in a cluster, there would have been time for around 100 life-bearing rocks to be captured by our star before the cluster drifted apart, the researchers say.

Belbruno notes one reservation about the result: rocks moving slowly enough to be captured by other stars will take tens of millions of years to reach their neighbours. It is unknown whether microbes can survive that long in interstellar space, he points out.

Nevertheless, Valtonen's result means we might improve our chances of finding something similar to terrestrial life if we can track down the Sun's former siblings.

Finding such stars may be possible with the European Space Agency's Gaia telescope, set to launch in 2011. The orbiting satellite will measure the proper motion of roughly a billion stars. That should allow astronomers to backtrack the star's positions to where they sat billions of years ago.

The study will be published in an upcoming issue of The Astrophysical Journal.

Related Articles

'All-seeing' telescope could take us back in time
http://www.newscientist.com/article.ns? ... 926752.100
24 September 2008

Interstellar 'slowball' could have carried seeds of life
http://www.newscientist.com/article.ns? ... 926725.400
04 September 2008

Biggest space camera will map Milky Way
http://www.newscientist.com/article.ns?id=dn7511
13 June 2005

Weblinks
Gaia, ESA
http://gaia.esa.int/science-e/www/area/ ... fareaid=26

The study on arXiv pre-press server
http://arxiv.org/abs/0809.0378
Click to expand...
 
Number of alien worlds quantified

Intelligent civilisations are out there and there could be thousands of them, according to an Edinburgh scientist.

The discovery of more than 330 planets outside our solar system in recent years has helped refine the number of life forms that are likely to exist.

The current research estimates that there are at least 361 intelligent civilisations in our Galaxy and possibly as many as 38,000.

The work is reported in the International Journal of Astrobiology.

Even with the higher of the two estimates, however, it is not very likely that contact could be established with alien worlds.

While researchers often come up with overall estimates of the likelihood of intelligent life in the universe, it is a process fraught with guesswork; recent guesses put the number anywhere between a million and less than one.

"It's a process of quantifying our ignorance," said Duncan Forgan, the University of Edinburgh researcher who carried out the work.

In his new approach, Mr Forgan simulated a galaxy much like our own, allowing it to develop solar systems based on what is now known from the existence of so-called exoplanets in our galactic neighbourhood.

These simulated alien worlds were then subjected to a number of different scenarios.

The first assumed that it is difficult for life to be formed but easy for it to evolve, and suggested there were 361 intelligent civilisations in the galaxy.

A second scenario assumed life was easily formed but struggled to develop intelligence. Under these conditions, 31,513 other forms of life were estimated to exist.

The final scenario examined the possibility that life could be passed from one planet to another during asteroid collisions - a popular theory for how life arose here on Earth.

That approach gave a result of some 37,964 intelligent civilisations in existence.

While far-flung planets may reduce uncertainty in how many Earth-like planets there are, some variables in the estimate will remain guesses.

For example, the time from a planet's formation to the first sparks of life, or from there to the first intelligent civilisations, are large variables in the overall estimate.

For those, Mr Forgan says, we will have to continue to assume Earth is an average case.

"It is important to realise that the picture we've built up is still incomplete," said Mr Forgan.

"Even if alien life forms do exist, we may not necessarily be able to make contact with them, and we have no idea what form they would take.

"Life on other planets may be as varied as life on Earth and we cannot predict what intelligent life on other planets would look like or how they might behave."

http://news.bbc.co.uk/1/hi/sci/tech/7870562.stm
 
Clues To A Secret Of Life Found In Meteorite Dust
http://www.sciencedaily.com/releases/20 ... 153047.htm

Artist's concept of asteroids delivering amino acids to Earth. The jagged white line at the bottom of the image is the actual data from the analysis of the Murchison meteorite. The two largest peaks are the amounts of right-handed and left-handed versions of the amino acid isovaline. Note that the highest of these two peaks is the amount of left-handed isovaline, revealing an excess of the left-handed variety in the meteorite. (Credit: NASA/Mary Pat Hrybyk-Keith)

ScienceDaily (Mar. 18, 2009) — NASA scientists analyzing the dust of meteorites have discovered new clues to a long-standing mystery about how life works on its most basic, molecular level.

"We found more support for the idea that biological molecules, like amino acids, created in space and brought to Earth by meteorite impacts help explain why life is left-handed," said Dr. Daniel Glavin of NASA's Goddard Space Flight Center in Greenbelt, Md. "By that I mean why all known life uses only left-handed versions of amino acids to build proteins." Glavin is lead author of a paper on this research appearing in the Proceedings of the National Academy of Sciences March 16.

Proteins are the workhorse molecules of life, used in everything from structures like hair to enzymes, the catalysts that speed up or regulate chemical reactions. Just as the 26 letters of the alphabet are arranged in limitless combinations to make words, life uses 20 different amino acids in a huge variety of arrangements to build millions of different proteins. Amino acid molecules can be built in two ways that are mirror images of each other, like your hands. Although life based on right-handed amino acids would presumably work fine, "you can't mix them," says Dr. Jason Dworkin of NASA Goddard, co-author of the study. "If you do, life turns to something resembling scrambled eggs -- it's a mess. Since life doesn't work with a mixture of left-handed and right-handed amino acids, the mystery is: how did life decide -- what made life choose left-handed amino acids over right-handed ones?"

Over the last four years, the team carefully analyzed samples of meteorites with an abundance of carbon, called carbonaceous chondrites. The researchers looked for the amino acid isovaline and discovered that three types of carbonaceous meteorites had more of the left-handed version than the right-handed variety – as much as a record 18 percent more in the often-studied Murchison meteorite. "Finding more left-handed isovaline in a variety of meteorites supports the theory that amino acids brought to the early Earth by asteroids and comets contributed to the origin of only left-handed based protein life on Earth," said Glavin.

All amino acids can switch from left-handed to right, or the reverse, by chemical reactions energized with radiation or temperature, according to the team. The scientists looked for isovaline because it has the ability to preserve its handedness for billions of years, and it is extremely rarely used by life, so its presence in meteorites is unlikely to be from contamination by terrestrial life. "The meteorites we studied are from before Earth formed, over 4.5 billion years ago," said Glavin. "We believe the same process that created extra left-handed isovaline would have created more left-handed versions of the other amino acids found in these meteorites, but the bias toward left-handed versions has been mostly erased after all this time."

The team's discovery validates and extends the research first reported a decade ago by Drs. John Cronin and Sandra Pizzarello of Arizona State University, who were first to discover excess isovaline in the Murchison meteorite, believed to be a piece of an asteroid. "We used a different technique to find the excess, and discovered it for the first time in the Orgueil meteorite, which belongs to another meteorite group believed to be from an extinct comet," said Glavin.

The team also found a pattern to the excess. Different types of meteorites had different amounts of water, as determined by the clays and water-bearing minerals found in the meteorites. The team discovered meteorites with more water also had greater amounts of left-handed isovaline. "This gives us a hint that the creation of extra left-handed amino acids had something to do with alteration by water," said Dworkin. "Since there are many ways to make extra left-handed amino acids, this discovery considerably narrows down the search."

If the bias toward left-handedness originated in space, it makes the search for extraterrestrial life in our solar system more difficult, while also making its origin a bit more likely, according to the team.

"If we find life anywhere else in our solar system, it will probably be microscopic, since microbes can survive in extreme environments," said Dworkin. "One of the biggest problems in determining if microscopic life is truly extra-terrestrial is making sure the sample wasn't contaminated by microbes brought from Earth. If we find the life is based on right-handed amino acids, then we know for sure it isn't from Earth. However, if the bias toward left-handed amino acids began in space, it likely extends across the solar system, so any life we may find on Mars, for example, will also be left-handed. On the other hand, if there is a mechanism to choose handedness before life emerges, it is one less problem prebiotic chemistry has to solve before making life. If it was solved for Earth, it probably has been solved for the other places in our solar system where the recipe for life might exist, such as beneath the surface of Mars, or in potential oceans under the icy crust of Europa and Enceladus, or on Titan."

The research was funded by the NASA Astrobiology Institute, the NASA Cosmochemistry program, and the NASA Astrobiology: Exobiology, and Evolutionary Biology program.


--------------------------------------------------------------------------------

Journal reference:

Daniel P. Glavin and Jason P. Dworkin. Enrichment of the amino acid L-isovaline by aqueous alteration on CI and CM meteorite parent bodies. Proceedings of the National Academy of Sciences, 2009; DOI: 10.1073/pnas.0811618106
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Life on earth may have started 4.4billion years ago, according to asteroid study
Life on earth may have started significantly earlier than previously thought, according to a study of an asteroid bombardment 3.9 billion years ago.
Last Updated: 8:44PM BST 20 May 2009

Underground microbes survived the multiple impacts, which only scorched part of the planet's surface and went on to thrive as water temperatures increased, scientists found.

This helped life's emergence and early diversification, according to researchers who have modelled how the Earth's crust changed during this time.

Although many believe the bombardment, which is believed to have lasted for up to 200 million years, would have sterilised Earth, the new study shows it would have melted only a fraction of it and that microbes could well have survived in underground habitats, insulated from the destruction.

Dr Oleg Abramov, of Colorado University, said the findings suggest the microbes could date back to well before the asteroid storm.

"These new results push back the possible beginnings of life on Earth to well before the bombardment period 3.9 billion years ago.

"It opens up the possibility that life emerged as far back as 4.4 billion years ago, about the time the first oceans are thought to have formed."

The researchers, whose findings are published in Nature, used data from Apollo moon rocks, impact records from the moon, Mars and Mercury, and previous theoretical studies to build three-dimensional computer models that replicate the bombardment.

The 3-D models allowed them to monitor temperatures beneath individual craters to assess heating and cooling of the crust following large impacts in order to evaluate habitability.

The study indicated that less than 25 percent of Earth's crust would have melted during such a bombardment.

http://www.telegraph.co.uk/scienceandte ... study.html
 
Found: first amino acid on a comet
23:59 17 August 2009 by Maggie McKee

An amino acid has been found on a comet for the first time, a new analysis of samples from NASA's Stardust mission reveals. The discovery confirms that some of the building blocks of life were delivered to the early Earth from space.

Amino acids are crucial to life because they form the basis of proteins, the molecules that run cells. The acids form when organic, carbon-containing compounds and water are zapped with a source of energy, such as photons – a process that can take place on Earth or in space.

Previously, researchers have found amino acids in space rocks that fell to Earth as meteorites, and tentative evidence for the compounds has been detected in interstellar space. Now, an amino acid called glycine has been definitively traced to an icy comet for the first time.

"It's not necessarily surprising, but it's very satisfying to find it there because it hasn't been observed before," says Jamie Elsila of NASA's Goddard Space Flight Center, lead author of the new study. "It's been looked for [on comets] spectroscopically with telescopes but the content seems so low you can't see it that way."

Raw materials
Comets and asteroids are thought to have bombarded the Earth early in its history, and the new discovery suggests they carried amino acids with them.

"We are interested in understanding what was on the early Earth when life got started," Elsila told New Scientist. "We don't know how life got started ... but this adds to our knowledge of the ingredient pool."

Jonathan Lunine of the University of Arizona agrees. "Life had to get started with raw materials," he told New Scientist. "This provides another source [of those materials]."

The amino acid was found in samples returned to Earth by NASA's Stardust mission, which flew by Comet Wild 2 in 2004 to capture particles shed by the 5-kilometre object.

etc...

http://www.newscientist.com/article/dn1 ... ef=dn17628
 
The Cell, a BBC series, is interesting viewing.

The last episode looks at the origin of life:

http://www.bbc.co.uk/iplayer/episode/b0 ... k_of_Life/
The Cell - 3. The Spark of Life

In a three-part series, Dr Adam Rutherford tells the extraordinary story of the scientific quest to discover the secrets of the cell and of life itself. Every living thing is made of cells, microscopic building blocks of almost unimaginable power and complexity.

The final part reveals how our knowledge of cells has brought us to the brink of one of the most important moments in history. Scientists are close to repeating what has happened only once in four billion years - the creation of a new life form.

Broadcast on:BBC Four, 12:20am Thursday 27th August 2009
Duration: 60 minutes
Available until: 9:59pm Wednesday 2nd September 2009
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Also reveals recent new results from Stanley Miller's 1950 experiments with the 'primordial soup', and also looks at amino acids found in ancient meteorites (about 33 min. into the prog).
 
Professor's alien life 'seed' theory claimed
http://news.bbc.co.uk/2/hi/uk_news/wale ... 491398.stm

Interstellar dust cloud
The remains of living matter have been found in interstellar dust clouds

New evidence from astrobiology "overwhelmingly" supports the view that life was seeded from outside Earth, a scientist has claimed.

Prof Chandra Wickramasinghe of Cardiff University says the first microbes were deposited on Earth 3,800m years ago.

The astrobiologist has helped developed the panspermia theory which suggests an extra-terrestrial origin for life.

He argues for a cycle of life as microbes find their way into comets and "multiply and seed other planets".

In the article, published in the International Journal of Astrobiology, Monday, he argues humans and indeed all life on Earth is of alien origin, brought onto the planet by comets hitting the planet.

Prof Wickramasinghe, of Cardiff University's centre for astrobiology, says there is a cyclical transfer process of life from planet to planet.

He believes comets hit planets and push living organic matter out into space, some of which survives and in turn gets transferred to developing planetary systems over a timescale of millions and millions of years, seeding life on the newly formed planets.


Chandra Wickramasinghe Image: BBC
Interstellar clouds appear to be the graveyard of life not its cradle
Professor Chandra Wickramasinge

He accepts this model still does not explain how life actually began in the first place, but says there is no hard evidence to support the theory that life only began in a "primordial soup" on Earth, or other places.

Over the past three decades research has shown that large swathes of the Milky Way are strewn with gigantic dust clouds full of organic molecules, which some people have argued shows life emerging independently from new in these clouds.

In his paper, he says recent interpretation of spectra readings from the organic molecules found in interstellar clouds has indicated that they are in fact the remains of bacteria which has been broken down, rather than being built up.

"Interstellar clouds appear to be the graveyard of life not its cradle," he said.

"Each time a new planetary system forms a few surviving microbes find their way into comets. These then multiply and seed other planets," he said.

He adds: "We are thus part of a connected chain of being that extends over a large volume of the cosmos. Evidence is pointing inexorably in this direction."

The professor and his late colleague Sir Fred Hoyle championed the panspermia theory from the 1960s.
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Meteorites may have kick-started life on Earth
Meteorites that bombarded Earth four billion years ago could have kick-started life rather than wiping it out, a study shows.
Published: 12:01PM GMT 10 Mar 2010

Microbes are believed to have survived the massive barrage of impacts by taking refuge deep underground - and actually thrived on the temperatures generated.

Previously scientists thought that nothing could have survived the 'heavy bombardment', but now researchers believe it could have even been beneficial to certain organisms.

The earliest physical evidence of life on Earth in the shape of fossils only dates back to 3.8 billion years.

But the new research suggests it began hundreds of thousands of years before this - and could yield new clues about primitive life on Mars.

Professor John Parnell's team found minerals in a crater on Devon Island, a wilderness in the Canadian High Arctic, had been deposited by a type of microbe which likes heat - and is capable of withstanding temperatures close to boiling point.

He said: "The mineral containing the microbe is pyrite - otherwise known as fool's gold - and pyrite likes sulphur of which there is plenty on the surface of Mars.

"So these microbes known as hyperthermophiles may have existed on Mars when the planet was much warmer than it is now."

Scientists had believed that life on Earth could not have survived the bombardment.

But hyperthermophiles had colonised all of the Haughton Crater - over 12 miles across and at least 200 metres below the Earth's surface indicating that they would have been able to live deep underground in the darkness known as the 'deep biosphere'.

Prof Parnell, of Aberdeen University, said: "When the Earth was young, over four billion years ago it was repeatedly hit by large meteorites which would have shocked and melted the planet's surface.

"Up until now scientists have imagined that primitive life would not have been able to withstand this pummelling.

"But our analysis of the mineral told us that this ancient microbe could have been able to survive meteorite bombardment through a combination of living underground and reinvading the surface rock while it was still very hot.

"So the asteroid bombardment may well have led to these primitive lifeforms flourishing rather than wiping them out.

"Our findings add to a growing body of evidence that there is much life on our planet that lives deep below out of sight and that this is where early life on Earth may have started.

"Similar meteorite craters with similar minerals occur on Mars, and this work highlights an approach that could help us look for evidence of life there."

The research is published in this month's Geology.

http://www.telegraph.co.uk/science/spac ... Earth.html
 
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