© 2014 Peter Free
Citation — to study
Cora S. Thiel, Svantje Tauber, Andreas Schütte, Burkhard Schmitz, Harald Nuesse, Ralf Moeller, and Oliver Ullrich, Functional Activity of Plasmid DNA after Entry into the Atmosphere of Earth Investigated by a New Biomarker Stability Assay for Ballistic Spaceflight Experiments, PLoS ONE 9(11): e112979, DOI:10.1371/journal.pone.0112979 (26 November 2014)
Citation — to press release
University of Zurich, DNA survives critical entry into Earth’s atmosphere, Mediadesk – University of Zurich (26 November 2014)
Playing with “what if” yields a surprising result
While preparing an experiment to see how gravitational changes affect gene expression from DNA carried inside the payload of a sounding (research) rocket, the research team wondered what might happen if they put some of the plasmid DNA at various locations on the outside of the suborbital rocket.
From the press release:
Applied to the outer shell of the payload section of a rocket using pipettes, small, double-stranded DNA molecules flew into space from Earth and back again.
After the launch, space flight, re-entry into Earth’s atmosphere and landing, the so-called plasmid DNA molecules were still found on all the application points on the rocket . . . .
For the most part, the DNA salvaged was even still able to transfer genetic information to bacterial and connective tissue cells.
“This study provides experimental evidence that the DNA’s genetic information is essentially capable of surviving the extreme conditions of space and the re-entry into Earth’s dense atmosphere,” says study head Professor Oliver Ullrich . . . .
“The results show that it is by no means unlikely that, despite all the safety precautions, space ships could also carry terrestrial DNA to their landing site. We need to have this under control in the search for extraterrestrial life.”
© 2014 University of Zurich, DNA survives critical entry into Earth’s atmosphere, Mediadesk – University of Zurich (26 November 2014) (extracts)
As quantified in the paper’s abstract:
[A]rtificial plasmid DNA carrying a fluorescent marker . . . and an antibiotic resistance cassette (kanamycin/neomycin) was attached on different positions of rocket exterior;
(i) circular every 90 degree on the outer surface concentrical of the payload,
(ii) in the grooves of screw heads located in between the surface application sites,
(iii) on the surface of the bottom side of the payload.
Temperature measurements showed two major peaks at 118 and 130°C during the 780 seconds lasting flight on the inside of the recovery module, while outer gas temperatures of more than 1000°C were estimated on the sample application locations.
Subsequent analyses showed that DNA could be recovered from all application sites with a maximum of 53% in the grooves of the screw heads.
We could further show that up to 35% of DNA retained its full biological function, i.e., mediating antibiotic resistance in bacteria and fluorescent marker expression in eukariotic cells.
© 2014 Cora S. Thiel, Svantje Tauber, Andreas Schütte, Burkhard Schmitz, Harald Nuesse, Ralf Moeller, and Oliver Ullrich, Functional Activity of Plasmid DNA after Entry into the Atmosphere of Earth Investigated by a New Biomarker Stability Assay for Ballistic Spaceflight Experiments, PLoS ONE 9(11): e112979, DOI:10.1371/journal.pone.0112979 (26 November 2014) (extracts, underlines added)
These findings would be still more persuasive, if they are replicated after (for example) 6 months of an orbital mission and its subsequent reentry.
Keep in mind, also, that external temperatures (during reentry) are estimates.
The moral? — A treasure trove for science fiction writers
If (as it seems) it is possible to carry Earth’s contaminating DNA outward into space — then — external origin DNA-like material could conceivably make it through our atmosphere to contaminate or populate the Earth.
What fun — and all from a clever research team playing around with a seemingly low probability idea.