Thriving Antarctic bacteria yield hope
for extraterrestrial life
Oregon State University
Friday June 26, 1998
CORVALLIS, Ore. - Bacterial colonies are thriving underneath ice on one
of the coldest, driest deserts on Earth, researchers have discovered, in
conditions that might compare to those on Mars or Europa and provide
insights for life forms that could be found elsewhere in our solar system.
The study will be reported Friday in the journal Science.
This study was conducted on ice-covered lakes in the McMurdo Dry
Valleys of Antarctica, which has an average annual temperature about 68
degrees below zero and gets less than four inches of precipitation a year.
But in that frigid, arid environment, scientists at Oregon State University
and four other institutions found liquid water pockets embedded about six
feet deep in solid ice, where a combination of sediments, water and solar
radiation during long summer days supports a viable population of bacteria.
"This is a very barren environment with virtually nothing we usually
associate with living organisms," said Stephen Giovannoni, an associate
professor of microbiology at Oregon State University. "But these
photosynthetic cyanobacteria are alive, self-sufficient, and growing.
They're able to live through the harsh freeze-thaw cycle of the seasons, fix
nitrogen and release oxygen as they make carbohydrates from water and
carbon dioxide."
"They have their own little world there we knew nothing about."
The nutritional requirements of these life forms are minimal, Giovannoni
said - a little light, water, carbon dioxide, phosphate, nitrate and other
minerals. But in fact the primitive life processes they are undertaking are
quite similar to those that first formed the oxygen-rich atmosphere of Earth
and made higher life forms possible.
And in the study, the researchers cite two locations where they feel
conditions may exist that are similar to those found in barren Antarctica -
Mars, and a large moon of Jupiter, Europa.
"It's been suggested that Mars is too dry and cold for life to exist,"
Giovannoni said. "But it's also known that both Mars and Europa have
frozen water on or near their surfaces. We speculate that in conditions
similar to those we observed in Antarctica, it would be a distinct possibility
that similar life forms exist on Mars or Europa."
While Mars may have had extensive liquid water at one time, the
researchers say in their report, it rapidly cooled and ice would have
become, as it is today, the dominant form of water on Mars' surface. A
search for fossil evidence of the most recent life on Mars' surface could
be based on life within ice, they said.
The process of life formation is still largely unknown and very complex,
Giovannoni said.
"Any cell, even a very basic cell such as those found in bacteria, is a very
complicated thing," he said. "But experiments have shown you can get
fairly complicated molecules and amino acids from the interaction of basic
chemicals and electricity."
Giovannoni has studied bacteria all over the Earth, from the basalt rocks of
deep sea floors to Antarctic ice cores, Yellowstone National Park hot
springs and the bacterial plankton of Oregon's Crater Lake. Researchers
continue to be amazed, he said, at how little is known about microbes, how
few have actually been described, how they function and their ecological
interaction with the rest of the world.
"Recent advances in molecular biology now allow us to identify these
unknown organisms, and what we're learning is the world is full of bacteria
we know virtually nothing about," he said. "I could probably isolate a new,
previously unknown bacterium from the sole of your shoe."
Past research has been held back by lack of funding, Giovannoni said, as
agencies seemed unsure that studies of bacteria, their evolution or behavior
had any practical value. But new applications of bacterial research in
understanding the global carbon cycle, creating new antibiotics or enzymes
for industrial use have raised increasing interest, he said.
And the search for life elsewhere in the universe might first be successful,
he said, when bacteria such as those being identified in Antarctica are one
day found on Mars.
Mars Study
A NASA instrument to measure the gas composition of the upper
atmosphere of Mars and hardware to support a radio science experiment
will fly on a Japanese spacecraft known as Planet-B. The Neutral Mass
Spectrometer (NMS) instrument and Ultra Stable Oscillator are
scheduled for launch aboard Planet-B on July 3, 1998, from the
Kagoshima Space Center on Kyushu Island, Japan.
The radio science hardware was built by the Johns Hopkins University
Applied Physics Laboratory in Laurel, MD, under contract to NASA.
The ultra-precise signals generated by the oscillator serve as a very
accurate clock to enable analysis of the Martian atmosphere and to help
guide the spacecraft as it orbits the red planet.
Planet-B is designed to perform long-term studies of the upper Martian
atmosphere and ionosphere, and its interaction with the solar wind.
Launch of Planet-B is scheduled for 2:12 p.m. EDT on July 3. After
launch, the Planet-B spacecraft will be placed into Earth orbit and will
use two swingbys past the Moon to establish conditions for a final
trajectory to Mars.
Once the spacecraft reaches Mars, which is now scheduled for Oct. 11,
1999, it will be placed into a highly elliptical or "egg- shaped" orbit
stretching from 93-186 miles (150-300 kilometers) to about 17,000
miles (27,300 kilometers) above the surface. The low-altitude portion of
the orbit will be used for remote sensing of the lower atmosphere and
surface, and for direct measurements of upper atmosphere and
ionosphere. The more distant parts of the orbit will allow instruments to
probe the ions and neutral gas escaping from Mars, which interact with
the charged-particle "wind" blowing outward from the Sun. Ionization of
the upper atmospheric gas by solar radiation produces the
charged-particle atmosphere (ionosphere) that acts as an obstacle to the
solar wind.