Mysterious long, red fingers beckon from the depths of Pavilion Lake, B.C.
Are they life forms? An international team of researchers that includes NASA astronaut Michael Gernhardt and former Canadian astronaut Dave Williams wants to answer that question, and in the process help in the search for life on Mars.
The unique growths, first photographed by a remotely operated vehicle three years ago, are called microbialites and are home to a thriving population of various kinds of bacteria. The researchers are trying to determine whether bacteria built the structures.
That, says Greg Slater of McMaster University in Hamilton, is where the Martian connection comes in.
The microbialites are made of limestone, a form of carbonate. Many planetary scientists believe Mars should be rich in carbonates, although so far, none have been found.
If scientists can prove the hypothesis that bacteria built the microbialites, and if fossils of similar structures are found on Mars, then researchers will know that bacteria once lived on the Red Planet, Dr. Slater says.
Recreational divers have long been interested in what they call freshwater corals in Pavilion Lake, about a five-hour drive north of Vancouver.
In the late 1990s, a team that included researchers from B.C.'s Simon Fraser University and NASA's Ames Research Center in California decided to have a look. They reported in the journal Nature the discovery of microbialites in 2000.
Some of the domed structures looked like giant cauliflower and were more than three metres high. They also resembled rare fossils dating back to the Earth's early Cambrian period. This made them unique, and a possible window on the past.
"They are very fragile. They crumble easily to the touch, but they have solidity to them. They are like a rock, a very porous rock," said Darlene Lim, a Canadian astrobiologist who works at the Ames centre and began studying Pavilion Lake in 2004.
Similar, although more damaged microbialites were found in nearby Kelly Lake. Then, in 2005, a remotely operated vehicle took photos of even stranger-looking structures in the deepest part of Pavilion Lake, about 50 metres below the surface.
The pictures suggest the deep-water microbialites are different from the ones found in the lake's shallow waters.
"They look distinctly reddish," Dr. Slater said. They also have finger-like pro- trusions.
To get down to 50 metres, or roughly 160 feet, the researchers have to use submersibles; it is too difficult and dangerous for them to dive.
Scientists from the University of British Columbia, NASA and McMaster have been trained to use the one-person vehicles, which are equipped with a manipulator arm and a basket.
Starting late in June, they will begin descending to take pictures and collect samples. They will also map all the different shapes and sizes of microbialites in the lake. They want to figure out how various factors, such as light, affect how the structures grow.
Dr. Williams retired as an active astronaut earlier this year and joined McMaster's faculty of medicine.
He and Dr. Gernhardt are also "aquanauts," who have spent weeks in an underwater laboratory called Aquarius, which is about six kilometres off Key Largo in the Florida Keys National Marine Sanctuary.
There are a lot of similarities to working in space and underwater.
And it's not a stretch, Dr. Williams said, to think that strange growths in a Canadian lake might lead to discoveries on Mars.
"I don't think it is far-fetched," he said.
