It may sound like the first chapter of a Quatermass thriller, but scientists from the University of Zurich (UZH) have discovered that DNA can survive not only a flight through space, but also re-entry into the Earth's atmosphere and still remain active. The findings are based on suborbital rocket flights and could have considerable impact on questions about the origins of life on Earth and the problems of terrestrial space probes contaminating other planets.
The UZH findings are based on the DARE (DNA atmospheric re-entry experiment) carried by the TEXUS-49 research sounding rocket launched from the European rocket station Esrange in Kiruna, Sweden, north of the Arctic Circle. Researchers used pipettes to apply samples of artificial DNA plasmids marked with a fluorescent marker and an antibiotic resistance cassette on various areas of the rocket's casing, including the outer and bottom surfaces of the payload and in the grooves of the screwheads.
According the UZH, during the flight the plasmids not only encountered the conditions of space, but also re-entry temperatures of up to 1,000⁰ C (1,800⁰ F). Despite this punishment, the DNA was recovered from the rocket casing, including 53 percent of the sample in the screwheads.
UZH says that the team expected to find signs of biomarkers in the samples. That is, remnants of organic materials that in other circumstances would indicate the presence of life. What they actually found was that the DNA was intact and functionally active, and still able to transfer genetic information to bacterial and connective tissue cells.
The implications are considerable. For one thing, it raises questions about the origins of life on Earth, since it indicates that microbes could have arrived on our planet hitchhiking on meteors. More Immediately, it draws into question the sterilization procedures used on space probes sent to Mars and other worlds that may now prove to be insufficient to prevent contamination. The UZH experiment could also mean that any life found on other planets may be the result of living matter blown off the Earth in some primordial age.
The UZH findings were published in PLOS One.
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