DNA survives critical entry into Earth's atmosphere

November 26, 2014
Launch of the rocket TEXUS-49 from the Esrange Space Center in Kiruna, North Sweden. Credit: Adrian Mettauer

The genetic material DNA can survive a flight through space and re-entry into the earth's atmosphere—and still pass on genetic information. A team of scientists from UZH obtained these astonishing results during an experiment on the TEXUS-49 research rocket mission.

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 from the TEXUS-49 mission. And this was not the only surprise: For the most part, the DNA salvaged was even still able to transfer genetic information to bacterial and . "This study provides experimental evidence that the DNA's genetic information is essentially capable of surviving the of space and the re-entry into Earth's dense atmosphere," says study head Professor Oliver Ullrich from the University of Zurich's Institute of Anatomy.

Spontaneous second mission

The experiment called DARE (DNA atmospheric re-entry experiment) resulted from a spontaneous idea: UZH scientists Dr. Cora Thiel and Professor Ullrich were conducting experiments on the TEXUS-49 mission to study the role of gravity in the regulation of gene expression in human cells using remote-controlled hardware inside the rocket's payload. During the mission preparations, they began to wonder whether the outer structure of the rocket might also be suitable for stability tests on so-called biosignatures. "Biosignatures are molecules that can prove the existence of past or present ," explains Dr. Thiel. And so the two UZH researchers launched a small second mission at the European rocket station Esrange in Kiruna, north of the Arctic Circle.

DNA survives the most extreme conditions

The quickly conceived additional experiment was originally supposed to be a pretest to check the stability of biomarkers during spaceflight and re-entry into the atmosphere. Dr. Thiel did not expect the results it produced: "We were completely surprised to find so much intact and functionally active DNA." The study reveals that from the DNA can essentially withstand the most extreme conditions.

Various scientists believe that DNA could certainly reach us from outer space as Earth is not insulated: in extraterrestrial material made of dust and meteorites, for instance, around 100 tons of which hits our planet every day.

Dr. Cora Thiel and Professor Oliver Ullrich salvage DNA molecules from the outer shell of the payload section of the TEXUS rocket. Credit: Adrian Mettauer

This extraordinary stability of DNA under space conditions also needs to be factored into the interpretion of results in the search for extraterrestrial life: "The results show that it is by no means unlikely that, despite all the safety precautions, ships could also carry terrestrial DNA to their landing site. We need to have this under control in the search for extraterrestrial life," points out Ullrich.

Explore further: Testing immune cells on the International Space Station

More information: Cora S. Thiel, Svantje Tauber, Andreas Schütte, Burkhard Schmitz, Harald Nuesse, Ralf Möller, 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. November 26, 2014. DOI: 10.1371/journal.pone.0112979

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aksdad
4 / 5 (1) Nov 26, 2014
It's interesting. DNA has been known to survive harsh conditions, though this experiment hardly simulates a meteor entry into earth's atmosphere. First of all, the meteor is going 10 to 70 km/s when it hits the atmosphere and starts burning intensely. The TEXUS 49 rocket was going nowhere close to that and didn't achieve anything like the heat generated by a meteor. Secondly, the meteor was traveling for millions of years or more in a deep vacuum exposed to ionizing radiation that would kill DNA.
Torbjorn_Larsson_OM
5 / 5 (1) Nov 27, 2014
@aksdad: I don't think survival of DNA is much interesting in itself. But on meteorites as transpermia vehicles, it works. A large hypervelocity impactor on a terrestrial planet will spallate away crustal material, some of which will reach escape velocity (~ half the typical impactor velocity, roughly orbital velocity of convergent trajectories). Bacteria has been shown to survive and replicate after such shocks with some percent fecundity.

In space the fragments will deep freeze, something bacteria also survive with percents of fecundity. If they are lodged in crustal cracks they are shielded from DNA breakdown while resting by a few cm of stone. Finally, a light fragment will rapidly brake to terminal velocity, with a thin melt "ash shell" and deep frozen innards, so doing no more damage than solar wind/cosmic ray damage did earlier.

The only problem is that the transfer likelihood is small (rare transfer, small bacterial populations), any indigenous life will arise quicker.

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