Failure to find life on Earth bad news for Mars hunters

Can not finding signs of life at a place on Earth that closely resembles the area on Red Planet a bad news for those trying to find life on the Martian surface? Yes, say researchers, suggesting that the failure to find active microbes in the coldest Antarctic soils on Earth has implications for search for life on Mars.

Jackie Goordial, post-doctoral fellow at McGill University in Montreal, Canada, has spent the past four years looking for signs of active microbial life in permafrost soil taken from University Valley in Antarctica where extremely cold and dry conditions have persisted for over 150,000 years.

The reason that scientists are looking for life in this area is that it is thought to be the place on Earth that most closely resembles the permafrost found in the northern polar region of Mars at the Phoenix landing site.

The research team carried out several tests, both in the field (where they failed to find evidence of carbon dioxide or methane - a gas used by all living things - in the soil) and then back in the lab at McGill University.

The tests, however, failed to show any signs of active life.

"I have been trying to cheer her up by telling her that not finding life is important too," said Lyle Whyte, Goordial's supervisor, in a paper appeared in The ISME Journal.

However, "it is hard for both of us to believe that we may have reached a cold and arid threshold where even microbial life cannot actively exist," Whyte noted.

University Valley is one of the coldest, oldest and driest places on Earth. "We couldn't detect any microbial activity within these samples," Whyte pointed out.

According to Goordial, they don't know if there is activity beyond their limits of detection.

"If conditions are too cold and dry to support active microbial life on an analogous climate on Earth, then the colder dryer conditions in the near surface permafrost on Mars are unlikely to contain life," the authors added.

"Additionally, if we cannot detect activity on Earth, in an environment which is teeming with microorganisms, it will be extremely unlikely and difficult to detect such activity on Mars," Whyte continued.

On a positive note, however, the researchers add that this suggests that any microorganisms that may be transported to Mars from Earth by mistake are unlikely to be able to survive on the Martian surface, something that is of current concern for planetary protection.