Life Confirmed At Extreme Depths

SEWilco writes "A few years ago the life forms around deep-ocean thermal vents were a surprise. Now ancient bacteria alive in rock 2 miles down have been found. The story is in the San Francisco Chronicle. It is also at Nature.Com, but that server is already rejecting connects. Other bacteria survived frozen in the pressures of an ocean 100 miles deep. This increases the known limits of where life can exist on any planet. Thomas Gold undoubtedly is not surprised at hot, deep bacteria living on hydrogen."

Comments

100 miles deep?? Explained!

[KarMannJRO]

OK, before we all jump on that "ocean 100 miles deep" claim (as I was about to do), here's the actual quote from the article:

Other bacteria, frozen into chunks of ice in a Washington laboratory, have thrived inside a high-pressure container and went right on reproducing after they were exposed to pressures equivalent to life at the bottom of an ocean 100 miles deep.

So they aren't really claiming to have found oceans 100 miles deep.

Here's the text if the link is down:

[nekdut]

American Geophysical Union Meeting,
San Francisco, December, 2002

Goldmine yields clues for life on Mars
Radioactive bacteria live deep in the Earth - and maybe elsewhere.
9 December 2002
TOM CLARKE

Mine dwelling bacteria may be similar to the first life on Earth
© GettyImages

There are tiny creatures living off radiation in ancient pockets of water several kilometres beneath the Earth's surface, say researchers.

The microbes seem to have been isolated for hundreds of millions of years. Similar conditions might exist beneath the surface of Mars.

"Anywhere you have a crust with uranium and water in it, you have the potential for life," microbiologist Tullis Onstott, of Princeton University, New Jersey, told this week's American Geophysical Union in San Francisco.

As you go deeper, the chemicals essential for normal life - organic matter and oxygen - disappear. And you get crushed and cooked, as temperature and pressure rise.

Microbes have been found a kilometre or so beneath the Earth's surface before. But cost and contamination with shallower bugs have hindered scientists looking deeper for life.

Working with miners in the world's deepest holes - 3.5 kilometre-deep South African goldmines - Onstott and his colleagues found hot water rich in bacteria.

The water is loaded with dissolved hydrogen gas, at a concentration up to a hundred million times higher than normal. Radioactive isotopes in the water show that the gas could only have formed by radioactive energy from surrounding uranium deposits splitting the water into hydrogen and oxygen, argues Onstott.

Researchers had speculated that bacteria might make hydrogen in this way, but it has never been seen before. "It's a completely novel system for supporting life," says John Baross, who studies deep-sea bacteria at the University of Washington in Seattle.

The mine-dwelling bacteria are hard to grow in the lab. Genetic evidence suggests that some of the microbes are related to a species called Pyrococcus abyssi, which lives in hot, deep-sea vents.

These bacteria are thought to be similar to the first life on Earth. They use hydrogen and sulphur to survive without oxygen.

Other genetic sequences of microbes in the mine water are unlike those of any other species. Onstott says that he would not be surprised if the mine contained new species with new types of metabolism.

Radioactive dating by Onstott's colleagues suggests that some pockets of mine water have been isolated for several hundred million years. "The dinosaurs came and went while this water has been down there," he says.

If the microbes can be grown and their workings probed, they should provide new insights into primitive life, Baross adds.

Missions to Mars could look for life by sniffing for hydrogen seeping up from deep in the planet's crust, says Onstott. Mars has some water and uranium, although less than Earth.

© Nature News Service / Macmillan Magazines Ltd 2002

Chemosynthesis resources

[JUNIS KANUNI]

Great Breakdown of Chemosynthesis.
Quick image summary of chemosynthesis for the bored.

Re:Um, the Mariana Trench? 24 miles deep?

[DaveAtFraud]

Here's the pertinent quote from ExtremeScience:

Challenger Deep got its name from the British survey ship Challenger II, which pinpointed the deep water off the Marianas Islands in 1951. Then in 1960, the US Navy sent the Trieste (a submersible - a mini-submarine designed to go really deep) down into the depths of the Marianas trench to see just how far they would go. They touched bottom at 35,813 feet. That means, while they were parked on the bottom in the bathyscaphe, there were almost seven miles of water over their heads!

The complete write up is here. The Mariana Trench is a fairly large subduction feature; the Challenger Deep being the deepest point.

BTW, 35,813 / 5,280 = 6.7827 miles (which would be somewhat shy of 24).