DNA surprise: Biomolecules can survive space trip and fiery trip back to Earth

In a surprising discovery, scientists announced this week that unprotected samples of DNA – the genetic building blocks of all life – can actually survive a trip into space, including the fiery re-entry back through the Earth’s atmosphere.

Double-stranded DNA molecules were dissolved in a solution and then applied to the surface of a rocket before launch. To the researchers’ amazement, the DNA made it back intact and alive – still able to pass on its genetic information to bacterial and tissue cells back in the laboratory.

DNA samples were exposed for approximately 400 seconds to space above 100 kilometres and for about 200 seconds to temperatures above 100 C, according to the new study published in the journal PLOS ONE.

While the samples were applied to various parts of the rocket, small fractions of DNA that was directly applied to the exposed surfaces on the side of the rocket survived, where conditions are harshest and temperatures temporarily heated up to 100 C. Analysis showed that up to 53% of DNA recovered after being exposed to space and re-entry stresses was functional.

“We were totally surprised,” said co-author Oliver Ullrich from the University of Zurich. “In discussions with our colleagues during the development of our experiment, no one could imagine that there would be any remains of the applied DNA after the flight.

“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.”

While the authors believe this is the first experiment to directly test DNA in space, this is not the first to show that life can survive the most extreme conditions. There is documentation that even primitive microbial life can survive these extreme conditions.

Bacteria was demonstrated to survive re-entry and impact of the space shuttle Columbia back in 2003 when the orbiter disintegrated above Texas as it re-entered Earth’s atmosphere.

Contamination of Worlds

Implications of DNA surviving in space and the fiery re-entry through our planet’s thick atmosphere could have deep implications in our understanding of life’s origins. Could DNA samples travel across interplanetary space, seeding planets with the building blocks of life?

Authors point out that meteorites have been found containing organic compounds, and that 100 tons of these space stones and dust particles hit our planet every day. Now this finding could not only help shape our search for extraterrestrial life, but also our own exploration of the cosmos.

What worries researchers is the possibility of DNA and other biomolecules accidentally hitchhiking on the space probes we send to explore other planets. This has been an issue NASA has been taking seriously for decades with its planetary missions and has a strict protocol in place.

Cosmic cross-contamination of other worlds may be a reality, especially in places like Mars or the moons of Jupiter and Saturn, where we are keen on seeking signs of life. The researchers therefore suggest that when spacecrafts are being sterilized, that DNA survivability should be considered as well.

“DNA attached on a spacecraft have the potential to contaminate other celestial bodies, making it difficult to determine whether a life form existed on another planet or was introduced there by own spacecraft,” Ullrich said.

“Decontamination of spacecrafts – as part of standard planetary protection procedures – is aiming to prevent forward contamination of other planets. In this context, maybe artificial test-DNA could be also considered as an internal biomarker for decontamination efficiency.”