DNA smeared on the side of a space rocket survived a trip into space and re-entry, tantalisingly hinting that the recipe for life on Earth, or even life itself, could hop between worlds.
Zurich University scientist Cora Thiel and her colleagues had planned originally to test only the effects of microgravity on DNA by sending up some samples aboard a Texas-49 rocket. But, as the team prepared for the launch of their cargo skywards, they also decided to apply some DNA to the outside surface of the rocket to see whether any would survive the brief cruise into space.
Samples of one form of bacterial DNA, called plasmids, containing the genetic instructions for a glowing green protein and an antibiotic resistance gene, were painted onto the outer body of the rocket in several places and also applied to the grooves in the screw heads securing the rocket's skin.
After blast-off, the rocket accelerated at up to 17g to reach an altitude of 268 kilometres above the Earth. The total flight time was 780 seconds, of which 378 seconds were spent weightless. Sensors inside the rocket showed that the surface during launch and recovery reached temperatures of up to 120 degrees Celsius.
When the rocket returned to Earth, swabs taken from the DNA test sites were tested for the integrity of the DNA by adding it to bacteria and to see if any began to glow. Surprisingly, despite the harsh conditions experienced by the DNA en-route, up to 53% of the material recovered from the screw heads was viable and functional.
The results have considerable implications for what's dubbed "planetary protection". The study, published in PLoS One this week, shows that DNA can remain stable and functional during even very high-speed, high "g" and high-temperature flight conditions.
For this reason, when we send spacecraft and probes to explore distant worlds, careful attention needs to be paid to ensure that pristine alien environments are not contaminated by Earth-originating biological materials. These precautions are taken to a great extent, but there's clearly little room for complacency.