2800 year old frozen microbes revived

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2,800-year-old frozen microbes revived

Antarctic discovery adds to hopes for life on Mars

By Robert Roy Britt

SPACE.COM

Dec. 16 — Within ice that covers a salty, liquid Antarctic lake scientists have found and revived microbes that were at least 2,800 years old. The discovery points to probable life within the underground lake and suggests the sort of ecosystem that might exist on Mars.

THE ANCIENT MICROBES were in a state of suspended metabolism, similar to dormancy, said study team member John Priscu of Montana State University.

“They’re in a frozen state,” Priscu said in a telephone interview. “They’ll come back to life if you add water.”

Priscu and his colleagues camped out on the ice above 2.5-mile-long (5-kilometer) Lake Vida for about two weeks back in 1996. They drilled down about 50 feet (15 meters) to collect the aged bacteria. They were just reaching the briny slush of the lake, said to be seven times saltier than the ocean and able to remain liquid even at temperatures lower than -10 Celsius (14 degrees Fahrenheit).

“It was hard drilling,” Priscu said. “It was 40 below. It was a real tough job. The next step was to get to the brine.”

However, to prevent contaminating the pristine lake, the drilling system was back-pressured with de-ionized water. Seals began to fail, and the system started to leak. The researchers were forced to stop.

Priscu thinks the lake holds live organisms. Life has been found in similar salty conditions, such as the Great Salt Lake and the Dead Sea. And his lab work shows organisms can thrive in the frigid temperatures presumed for Lake Vida. His team has frozen blocks of organisms to -15 Celsius and kept them alive.

CONFIDENCE FOR LIFE ON MARS

Further, he said similar pockets of ice or briny water on Mars almost surely hold life, or at least signs of it. Other researchers are typically more reserved about their speculation of possible life on Mars. But Priscu has seen the living, up close, in the harshest conditions our own planet has to offer.

Critters called cyanobacteria dominate life at these extremes. Another Antarctic lake, called Vostok, has been under similar study and organisms have been found in the ice above it. And several research teams have examined cyanobacteria in easier-to-reach pockets of polar ice. The creatures are innovative enough to generate their own sunscreen — a handy ability to have on Mars, where radiation is harsher than on Earth.

The Lake Vida creatures are unique for their age, determined by the age of ice in which they were embedded. Other similar studies have involved ice that is frequently replenished and not as old.

Frozen polar regions on Mars might contain organisms similar to those Priscu and his colleagues have been studying over the years, he said. Or deep underground pockets of ice — or even water — could support them. In Priscu’s mind, the question of finding life on Mars is only whether it will be crawling around or hung in a sort of natural ice museum.

“It’s either extinct or extant,” he said, alliteratively ruling out the possibility of coming up entirely empty in the search for past or present life on the Red Planet.

JUST THAW THEM OUT

He said data his team has collected suggest bacteria and their DNA can remain viable for up to a million years. Ice is a good preservative, he said. Add a little water — which even in a deep freeze can occur in layers where frictional energy melts ice for brief periods — and organisms might maintain and repair their blueprints for life for many millions of years.

“If they’re frozen [on Mars] and younger than 1 million years,” Priscu said, “give them some water and they probably would come back.”

The research, funded by the National Science Foundation and NASA, is reported in the this week’s issue of the Proceedings of the National Academy of Sciences. Peter Doran of the University of Illinois at Chicago is the lead author of the paper.

When the study began, the scientists had thought Lake Vida might be a frozen chunk of ice, like other known “lakes” in the region. But the ice cores, along with ground-penetrating radar and long-term temperature data, revealed that Vida has a thick, light-blocking ice cover, vast amounts of ancient organic material and sediment, and the liquid zone underneath.

“Mars is believed to have a water rich past, and if life developed, a Lake Vida-type ecosystem may have been the final niche for life on Mars before the water bodies froze solid,” Doran said in a statement.