Frozen Life
American and Russian scientists hope to find evidence in the deep ice layers of Antarctica that fungi, bacteria and even diatoms can survive on frozen celestial bodies within the solar system. "We can assume that previous asteroid impacts on Earth ejected soil, rocks and seawater containing terrestrial microorganisms into space, and that they may have reached other parts of the solar system in this way," explains Richard Hoover from the NASA Space Center in Marshall. Hoover is an X-ray astronomer, also internationally known for his work on diatoms (diatoms), who firmly believes that microorganisms can remain viable in ice for long periods of time. He and his colleague S. S. Abyzov of the Russian Academy of Sciences examined samples taken at the Vostok station, which is about 1000 kilometers from the South Pole.
"Recent studies show that the extreme conditions in the cosmic environment do not preclude the possibility that microorganisms in anabiotic states [dormant states] could exist in interplanetary space," explained Abyzov.
Belief in the existence of life beyond Earth has now been reinforced as NASA released new images and data of Jupiter's largest moon, Europa. The new results suggest the presence of slush and possibly liquid water near the surface. This reinforces the exciting possibility that Europe could harbor life.
In recent years, discoveries on Earth have shown that life can thrive or be sustained in "hostile" conditions: from volcanic vents deep in oceanic trenches, through 400,000-year-old ice, to more than five million years old Siberian permafrost.
1975 Abyzov at Vostok Station discovered bacteria, fungi, diatoms and other microorganisms carried by winds from low latitudes to Antarctica. The number of organisms frozen in layers of ice at different depths and thus of different ages changes with significant changes in the Earth's climate. The ice also serves as a time capsule, storing patterns of life for up to 500,000 years. This makes it possible to study how the genetic material changed over the centuries.
Abyzov examined his samples with NASA's Environmental Scanning Electron Microscope (ESEM), a relatively new instrument used in Marshall to analyze how materials fatigue and break. It was originally developed to study biological samples in their natural environment without the need to overlay them with gold to make them visible. And this is ideal for samples contained in ice. The device also uses an X-ray grid to analyze the sample for its chemical element composition, an important step in deciding whether the object should be considered organic.
The wide range of life forms from fungi, algae and bacteria to diatoms found by the scientists in the ice included specimens with exotic appearances. "We found some really bizarre things -- things we've never seen before," says Hoover. The objects have imaginative names based on fleeting similarities. Hoover expects that once he and Abyzov study the illustrations carefully, most will fall into the already known categories of microorganisms. "We're exploring a new world," says Hoover. "Until we have a ton more experience, we're going to see brand new things all the time first."
"It's going to be a long and challenging job to identify and classify everything that's in the ice," says Hoover. Then it will be possible to classify organisms like Klingon's forehead, a wrinkled object reminiscent of a Star Trek creature. For now, some objects only have nicknames until Hoover, Abyzov and their colleagues analyzed the exciting images and identified the microscopic beasts from the frozen underworld.
The ice containing these finds is up to 400,000 years old, depending on the depth. Russian scientists from the St. Petersburg Mining Institute developed a drilling technique that can be used to take samples from ice cores without contaminating them. They have been working at Vostok Station since 1974, recovering material from even greater depths.
The first samples examined are from a depth of 386 meters to 1249 meters, ice from a depth of 3610 meters is on its way from Vostok to the Russia Institute of Microbiology of the Russian Academy of Sciences in Moscow. According to Abyzov, part of it will be taken to Marshall later in the year.
1996 the existence of a lake was proven with seismological and other instruments. Lake Vostok is covered by a 3710 meter thick layer of ice and could be "Image" 500 000 to a million years. Since this discovery, drilling has proceeded at a slow pace while working methods are developed to keep the lake clean. Nobody has seen or sampled this lake before - the deepest sample is from a depth of 100 meters above the water surface - nor is it known why it is liquid. So far this is a scientific curiosity. alt="
The lake is 48 km by 224 km - about the size of Lake Ontario - and is 484 meters deep. New data point to a 50 meter thick layer of sediment at the bottom. Lake Vostok provides a good model for conditions on the moon Europa.
Meanwhile, ice samples from the strata above the pristine lake surface are attracting the interest of the scientific world. As early as the 1970s, Abyzov discovered - and in some cases resurrected - microorganisms in what common sense assumed to be sterile. Now, the discovery of mud and ice on the moon Europa, the high probability of water on early Mars, and our own moon are leading scientists to reconsider the possibility of life anywhere in the universe.
In the ice samples, the scientists found a lot of atmospheric dust and debris and possibly some cosmic dust. "There are some dust particles with unusual spectra," says Hoover, "that might be cosmic dust particles." The ESEM can identify a single point on the sample and scan it with X-rays to determine the elements present. The ratio of materials found in some dust particles does not correspond to the ratios that are expected in terrestrial dust grains.
Mickey Mouse and other colonies of small microbes have an unusual appearance. They are flaky, white objects, one micron in size, resembling cotton balls. Hoover discovered that "these little coccoid bodies are covered with an incredibly fibrous structure." The filaments appear to be between 30 and 40 nanometers in size (which is roughly one tenth the wavelength of visible light).
"It's hard for me to say what it is," says Abyzov, "but I'm inclined to think it's biological." Hoover says, "There are all sorts of microorganisms in ice, some that have already been identified as cyanobacteria, bacteria, fungi, spores, pollen grains and diatoms, but some that aren't identifiable as anything we've seen before." In Hoover's opinion, many of the organisms will turn out to be already known. It's just that they look different under the ESEM because it shows details that aren't visible under other microscopes. Familiar objects are small parts of sponges and feathers and fragments of diatoms. The scientists also found some large cyanobacteria with attached nanobacteria.
"What obviously happens when microorganisms are frozen is that they stop metabolism and go into an anabiotic state," explains Hoover. Anabiotic means alive but inactive - like a temporary lifelessness. Russian scientists have managed to revive and cultivate bacteria, yeast, fungi and other microbes found in the ice.
"One of the really exciting finds was that many of the cyanobacteria from 1243 meters were high in antimony," says Hoover. The X-ray spectrum shows carbon, oxygen, zinc, silicon, aluminum and potassium, elements also commonly associated with life. But it also shows exceptionally high levels of antimony, a toxic heavy metal.
ESEM operator Gregory Jerman showed that metal content varies with depth. In some layers, the microorganisms contained large amounts of antimony, while in others zinc predominated.
With more than 150 ESEM images and about as many spectra, Hoover and Abyzov will head to the Jet Propulsion Laboratory in Pasadena, California. There, Ken Nealson will attempt to obtain genetic material from the microorganisms.
