For decades, scientists assumed that Antarctica‘s Lake Vida was entirely frozen — and devoid of life. But Peter Doran suspected there might be liquid water — and even life — at the bottom of the lake.
Peter Doran is an Earth scientist at the University of Illinois at Chicago.
In 1996, he sampled the thick layer of ice covering Antarctica‘s enormous Lake Vida. He found microbes that were over 3,000 years old — and still alive. Doran is planning a return to Antarctica in November, 2004. He wants to break the icy seal on the lake and sample the salty brine and sediment underneath. But breaking the ice seal might contaminate this ancient lake…
Peter Doran: … and we’re going back with a very clean and very sterile approach and we’re going to be sure now that when we find life down in this lake — if we find life — that it’s going to be life that is actually living down there and not something we introduced.
Antaractica is the closest earthly analog to the cold, desert planet Mars. So Lake Vida might help in the search for signs of life on Mars. Doran says that so far, on Earth, wherever there’s water, scientists have found life.
Peter Doran: . . . in Lake Vida, we have a very salty system that’s very cold and it’s dark down there. . . If there’s no life there, it will be just as interesting to find out why. What caused it to not want to live there? So it would be great to find something living there — but it would be just as great to not find something living down there.
Links for more information:
- Peter Doran also heads up a National Science Foundation Long Term Ecological Research Project in Antarctica. Check out the LTER McMurdo Dry Valleys project here.
- The LTER Network is a listing of the LTER projects nationwide
- Astrobiology on the Web – Life in Extreme Environments
- How NASA approaches the search for life on Mars: The Exobiology Strategy
- A fun site on microbes from the American Society for Microbiology
- A picture of one radiation-tolerant bacteria that’s a good candidate for living on another planet (NASA)
- An Astronomy Picture of the Day with a close-up of Jupiter’s moon, Europa
- A website chock full of information about all kinds of extremophiles (Wayne’s Word)
- An interesting article on extremophiles (Astrobioogy.com)
More excerpts from interviews with Peter Doran:
Lake Vida is an enormous, super-salty lake sealed under more than 19 meters — or 60 feet — of ice.
Lake Vida‘s ice cap is filled with sediment, and essentially blocks light from reaching the brine underneath. So any microbes living in the brine are going to have to tolerate dark, freezing (14¡ F) water that’s seven times saltier than the ocean. Doran says: (Tape 1, 10:49) “We don’t expect to find large numbers of organisms living down there. It’s all going to be microbial life, it’s going to be hard to detect. So we want to make sure we don’t put anything down ourselves, and we also want to make sure we don’t contaminate this lake with things from the surface that perhaps would want to live down there although I find it hard to imagine anything would want to live down there!”
But if they don’t find life in the brine below, that’s an interesting find, too because it puts a limit on the parameters necessary for life. So far, every extreme environment on earth that supports water also supports life, from Yellowstone hot springs to high-pressure steam vents on the bottom of the ocean. If the Doran team doesn’t find anything living in the brine of Lake Vida: (Tape 1, 27:37) “It’s an interesting find as well, it sort of puts a limit on where we can find life, where life can exist. Everywhere on earth now where we find water, pretty much, we find life, and so we’re sort of setting up what are the bounds, what are the exceptions to that rule, and if Lake Vida is one, that tells us something.”
Doran and his team are working with engineers at NASA’s Jet Propulsion Lab to develop a remote-controlled gopher that can core through 19 meters of ice, one half meter at a time, collecting samples as it goes. The big challenge is adapting the gopher from drilling in rock to drilling in ice. As the gopher heats up, it will melt the ice it is drilling, and has the potential to either wreck the ice samples or freeze itself into the hole as it drills. Doran and his team recently met with JPL engineers to discuss the numerous challenges they’ve got to overcome. They plan to field test the gopher on a glacier in the continental US sometime next fall . After drilling through the ice, the scientists want to use the gopher to take samples from the brine, and then cores from the sediment at the bottom of the frozen lake. He says:
“When you hear (the gopher) operate, it’s almost like a little jackhammer. And it’s got a tip that’s a metal tube that’s fairly small diameter. You place it on the surface of whatever you’re interested in, and then it will vibrate at very high frequencies. And it will vibrate itself down into the rock or the ice or whatever you’re dealing with. So as it goes down, it’ll be cutting a circle around the ice it’s going through, and keeping that core of ice inside of itself until we pull it up. So we’ll have to be doing that a half-meter at a time, essentially. We’ll go down, collect the half-meter of ice, pull it up to the surface, collect the ice, go back down get the next half meter, pull it up. And when we get down to the water, essentially at that point it just acts like a weight on the end of a tube, and we’ll suck up sample or pump up sample, we haven’t decided which yet.”
All this, while perched in a tent on top of the frozen lake, in 20 degree weather and 24 hours of sunlight!
Once the device reaches the bottom, “It’ll act like a coring device again like it was in the ice and it will core into that sediment, which we think is actually going to be more like a crust of salt. The lake is so hypersaline, it’s so salty, that probably you’ve got a lot of precipitation of salt, just like table salt, it’ll be like a hard rock salt, and the device will become quite useful again because it’ll be able to just core through that and collect that salt core and bring it up to the surface.”
“We’ll be doing some straight sort of incubation type experiments, where we’re looking for productivity, evidence of actual metabolism of this life in a lab environment. So we’ll bring samples up and then run some experiments on them. See if things are actually living or not. And then our final thing is we want to look at the sediments on the bottom of the lake, on the bottom of this brine, because in any lake, the sediments contain a history of the evolution of that lake, all the things that grow in that lake eventually die and settle to the bottom, so if we can get a core of sediment as long as possible, then we’ll have a record perhaps for the past thousand years or ten thousand years of the history of that lake and how it evolved into the lake that it is today.”
“We want to make sure if we find life down there that it’s life that was actually living there, not something we took down on our instrument. So we’re going back in 2004 with a completely clean (you know) essentially surgically aseptic approach to sample life in this brine, and (uh) we’re doing it with something called an ultrasonic gopher, which is a device that’s originally designed to go onto planetary rovers, for instance a rover going to mars and drilling into rocks and things like that, but we’re modifying it to work in ice.”
“[If we can find life wanting to live in such a hostile environment, it can pretty much live anywhere, and I think the possibilities of it evolving and living elsewhere off of this planet are pretty, (pretty) good … Life is like a fungus I like to say, it wants to grow anywhere. And if we can show that on earth, I think it’s pretty plausible that it can happen elsewhere.”
“… the tool that we’ll be using when we go back is called an ultrasonic gopher. And it’s actually a coring or drilling device that vibrates at very high frequencies and will hammer its way down into the ice and you don’t even have to put pressure on it, it just rides down by itself. And it’s designed to work on planetary rovers for instance something going to mars. And that’s what we’re doing — is a planetary analog. We’re testing it out in Antarctica to see how well it works there as sort of a test for going to mars. This thing is really amazing. It will drill through rock without any effort. It hasn’t been tested in ice yet. We’re going to be the first ones to use it in ice and we have to redesign it for ice. Ice is actually harder to drill than rock, believe it or not because as this thing drills, it gets warm, so you start melting the ice and you may have freezing problems — so these are things we have to test out in the lab and overcome before we go down and test it in the field.”
“Well obviously the rover and the drill can only go to modern mars. But there’s evidence for a lot of water on mars in the past. And that’s what Antarctica is good for is what the environment might have been like in the past. But also there’s evidence of liquid water in the last million years on mars. And for water to survive anywhere near the surface, it probably is very very salty, because it needs to have a depressed freezing temperature, so it melts at some point. So there may be some ice in the shallow surface and there maybe even some very salty water in the shallow subsurface of mars –so this is kind of a test of going through a combination of ice and sediment and salty water as a modern rover might encounter drilling several meters into the ground on mars”
Life so far seems to be following a rule that wherever you find water you find life — on this planet. And that includes, we find life deep in the Earth in the — there’s a deep biosphere where there’s life deep in rocks and it’s only there because there’s water — even a little amount of water in the ground — and we have life. And just about anywhere you find water including in the Arctic, in the Antarctic, on ice sheets — life exists. So we’re trying to figure out what the limits are for that rule. For instance, in our system, in Lake Vida, we have a very salty system that’s cold and dark down there. And is that enough to push life over the edge? Is that enough to extinguish it and it says well I don’t want to live here, I’ll choose somewhere else?