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ASTROBIOLOGY

Microbial cells found in outer spaceResults showing that living organismnscould comefrom outerspaceput intoquestion the theory of the originof life on Earth.RichardButler reports.

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Did life arise rom above orbelow the tropopause?Life from outer space is no longer simply inthe realm of science fiction. A group of inter-national scientists claim to have discoveredliving matter in the Earth's outer atmosphere.Air samples collected over tropical Indiashow, what appears to be, microbial cells ataltitudes that suggest they don't come fromthe Earth. Members of the group say thatthese cells could only be present in the outeratmosphere if they were delivered there fromspace. Furthermore, they claim this is evi-dence that matter from space could beresponsible for life on Earth.One of the key researchers, ChandraWickramasinghe, professor of astrobiologyat Cardiff University, UK,claims that the discovery 'The amcprovides 'unambiguousevidence for the presence materialof .. . living cells . . . wellabove the tropopause, betweenabove which no air from ellsperlower down would.normal- C -ly be transported.' Wickramasinghe, alongwith his colleague Sir Fred Hoyle, has been along-time advocate of the panspermia theory,that life arrived on Earth from space, as

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support this theory. However, some of thereport's more far-reaching claims are beingviewed with uncertainty by others working inthe field.The samples were taken using collectionequipment attached to a balloon and flown upto 41km over Hyderabad in central India.Samples were taken at various heights.Because of the risk of contamination, allsampling was performed under stringentlyaseptic conditions. The collected sampleswere examined under a microscope, usingdyes that fluoresce only when absorbed byliving cells. The group discovered quantitiesof both viable and non-viable cells. Based onthe concentration ofritof cells collected, thescientists calculateddilected was that the Earthreceives around one70 and 1000 third of a tonne ofre of air' biomaterial from, ~~~space each day.

Jason Dworkin, a researcher at NASA'sAmes Research Centre, is sceptical: 'These[results] are based on photomicrographsonly. I would very much like to see an inde-

of genetic material to allow further researchMuch of the concern stems froWickramasinghe's statements about air ncirculating upwards from below ttropopause, a wide gap between the Earthinner atmosphere, troposphere and oustratosphere. Laura Iraci, also from Ames,incredulous. 'As an atmospheric chemisttake issue with Wickramasinghe's statemethat air below the tropopause is not transpoed up to the stratosphere. This is incorrecFor example .. . chlorofluorocarbons, whihave sources only at the surface of the Ear[are found] in the stratosphere,' sexplained.While Dworkin is interested to learn whtype of cells the group has collected, hestill sceptical: 'Only if the biology of thecritters puts them at the very base, or onseparate branch, of the tree of life and if thappear viable after exposure to space condtions, or their biochemistry is unlike any t'air below the tropopauseis not transported up tothe stratosphere'

restrial organism, would I consider thembe extraterrestrial.'Wickramasinghe, however, seeundaunted by these doubts. 'The amountmaterial collected was between 100 and 10cells per litre of air, it would either have toan incredible fluke in the point that we sapled, or there are cells living at that heighhe said. While he accepts that some contions would result in heavy matter beitransported beyond the tropopause, the disbution pattern found by his group, wincreasing quantities of cells at greaheights, is not consistent with them comfrom the surface.'The clumps we found, between 10 a20iim size, would fall out [back to the sface] in three to four months. He sugge'the odds of these cells coming from lift-[from the surface] is very remote.'The group should soon be able to answsome of Dworkin's concerns, as they inteto conduct PCR amplification on the sampto find out more about the cells' propertand, it is hoped, origin.Despite widespread doubts, Wickramsinghe sees the research as compelling edence for the panspermia theory that himsand Hoyle have supported for the pastyears. 'If you accept this as a valid res

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COPYRIGHT INFORMATION

TITLE: Microbial cells found in outer space

SOURCE: Chemistry & Industry no16 Ag 20 2001

WN: 0123203923002

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