WASHINGTON (AFP) - DNA molecules attached to the outside of a rocket may be able survive a trip to suborbital space and back into the Earth's atmosphere at extremely high temperatures, according to a study Wednesday.

The experiment, carried out on the TEXUS-49 rocket mission in March 2011, "showed that DNA could be recovered from all application sites on the exterior of the rocket," according to the study published in PLOS ONE journal.

The surviving molecules were still able to transfer genetic information to cells and bacteria, even after exposure to temperature as high as 1000 degrees Celsius, according to co-authors Cora Thiel and Oliver Ullrich from University of Zurich.

The authors said the experiment could be the basis for "a model for nucleic acids that could serve as biomarkers in the search for past or present extraterrestrial life."

"DNA plays an important role as a biomarker for the search of extraterrestrial signatures of life, and scientists are working to characterise and compare the influence of Earth and space conditions on DNA," the study said.

Researchers attached artificial plasmid DNA with a flourescent marker to three different spots on the rocket for the experiment, which was initially designed to test for biomarker stability during space flight and return to Earth.

Thiel and Ullrich said they were "totally surprised" by the results of the experiment, and did not think the molecules would survive the space journey.

"We never expected to recover so many intact and functional active DNA," they said.

The scientists say the results raise concerns about contaminating space crafts, landers and landing sites with DNA from Earth.

"It is not only an issue from space to Earth, it is also an issue from Earth to space and to other planets," the co-authors said.