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Marsbugs: The Electronic Astrobiology Newsletter, Volume 12, Number 28, 19 August 2005
Marsbugs: The Electronic Astrobiology Newsletter
Volume 12, Number 28, 19 August 2005
Editor/Publisher: David J. Thomas, Ph.D., Science Division, LyonCollege, Batesville, Arkansas72503-2317, USA.
Marsbugs is published on a weekly to monthly basis as warranted by the number of articles and announcements. Copyright of this compilation exists with the editor, but individual authors retain the copyright of specific articles. Opinions expressed in this newsletter are those of the authors, and are not necessarily endorsed by the editor or by LyonCollege. E-mail subscriptions are free, and may be obtained by contacting the editor. Information concerning the scope of this newsletter, subscription formats and availability of back-issues is available at The editor does not condone "spamming" of subscribers. Readers would appreciate it if others would not send unsolicited e-mail using the Marsbugs mailing lists. Persons who have information that may be of interest to subscribers of Marsbugs should send that information to the editor.
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Marsbugs: The Electronic Astrobiology Newsletter, Volume 12, Number 28, 19 August 2005
Articles and News
Page 1EXTREMOPHILES: NOT SO EXTREME?
By Seth Shostak
Page 1EARTH'S SURFACE TRANSFORMED BY MASSIVE ASTEROIDS
AustralianNationalUniversity release
Page 2PROZAC FOR PLANTS
By Karen Miller
Page 3MODEL GIVES CLEARER IDEA OF HOW OXYGEN CAME TO DOMINATE EARTH'S ATMOSPHERE
University of Washington release
Page 3METEOR IMPACTS: LIFE'S JUMP STARTER?
Geological Society of America release
Page 4MARS ON EARTH: AS SIMPLE AS A WALK IN THE PARK
By Leonard David
Page 4FREEZE-DRIED MATS OF MICROBES AWAKEN IN ANTARCTIC STREAM BED, SAYS CU STUDY
University of Colorado at Boulder release
Page 5CARNEGIE MELLON ROVER HEADS TO ATACAMA DESERT IN CHILE FOR FINAL MISSION IN THREE-YEAR SEARCH FOR LIFE
CarnegieMellonUniversity release
Page 6UCSD DISCOVERY SUGGESTS "PROTOSUN" WAS SHINING DURING FORMATION OF FIRST MATTER IN SOLAR SYSTEM
University of California at San Diego release
Page 7EIGHTH INTERNATIONAL MARS SOCIETY CONVENTION A GREAT SUCCESS
Mars Society release
Page 8INTELLIGENT DESIGN AND EVOLUTION AT THE WHITE HOUSE
By Edna DeVore
Page 8TINY MICROBE HAS HUGE ROLE IN OCEAN LIFE, EARTH'S CARBON CYCLE
By David Stauth
Page 9THE ENDS OF THE EARTH
By Pamela Conrad
Announcements
Page 10SJI CALLS FOR PAPERS, REVIEWERS AND EDITORIAL BOARD MEMBERS
By Neil Armand
Mission Reports
Page 11CASSINI FLIES BY SATURN'S TORTURED MOON MIMAS
NASA/JPL image advisory 2005-129
Page 11MARS EXPLORATION ROVERS UPDATE
NASA/JPL release
Page 12MARS EXPRESS RADAR COLLECTS FIRST SURFACE DATA
ESA release 38-2005
Page 13MARS GLOBAL SURVEYOR IMAGES
NASA/JPL/MSSS release
Page 13MARS RECONNAISSANCE ORBITER UPDATES
Multiple agencies' releases
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Marsbugs: The Electronic Astrobiology Newsletter, Volume 12, Number 28, 19 August 2005
1
Marsbugs: The Electronic Astrobiology Newsletter, Volume 12, Number 28, 19 August 2005
EXTREMOPHILES: NOT SO EXTREME?
By Seth Shostak
From Space.com
4 August 2005
Many of them are tiny, all of them are tough, and they could be your most distant ancestors. True to their name (which is a Greco-Latin combo for "someone who loves extremes"), extremophiles can batten and fatten in conditions that humans—and most other species—would consider off limits. The first of these sturdy organisms to be discovered, a thermophile, was found in the late 1960s in YellowstoneNational Park, hanging out in one of the hot springs. It was a bacterium with a name bigger than itself: Thermus aquaticus (literally, "warm bath water dweller." Species names are often surprisingly prosaic once you translate them.)
Thermus aquaticus not only withstood, but thrived, in temperatures above 160°F. For comparison, try turning on the hot water tap at home, and let it run. It will scald your hand, but the temperature won't exceed 140°F. This is observational proof that you are not a thermophile.
Read the full article at
EARTH'S SURFACE TRANSFORMED BY MASSIVE ASTEROIDS
AustralianNationalUniversity release
5 August 2005
A cluster of at least three asteroids between 20 and 50 kilometers across colliding with Earth over 3.2 billion years ago caused a massive change in the structure and composition of the earth's surface, according to new research by ANU earth scientists. According to Dr. Andrew Glikson and Mr. John Vickers from the Department of Earth and Marine Sciences at ANU, the impact of these asteroids triggered major earthquakes, faulting, volcanic eruption and deep-seated magmatic activity and interrupted the evolution of parts of the Earth's crust. The research extends the original discovery of extraterrestrial impact deposits, discovered in South Africa by two US scientists, D. R. Lowe and G. R. Byerly, identifying their effects in the Pilbara region in Western Australia.
"Our findings are further evidence that the seismic aftershocks of these massive impacts resulted in the abrupt termination of an over 300 million years-long evolutionary stage dominated by basaltic volcanic activity and protracted accretion of granitic plutons,"Dr. Glikson said.
The identification of impact ejecta—materials ejected by the hitting asteroid—is based on unique minerals and chemical and isotopic compositions indicative of extraterrestrial origin, including iridium anomalies. The impact ejecta from the Barberton region in the eastern Transvaal indicate the formation of impact craters several hundred kilometers in diameter in oceanic regions of the earth, analogous to the lunar maria basins (large dark impressions on the surface of the moon). The seismic effects of the impacts included vertical block movements, exposure of deep-seated granites and onset of continental conditions on parts of the earth surface. In the Pilbara, the formation of fault escarpments and fault troughs is represented by collapse of blocks up to 250-metres wide and 150-meters high, buried canyons and a major volcanic episode 3240 million years ago.
"The precise coincidence of the faulting and igneous activity with the impact deposits, coupled with the sharp break between basaltic crust and continental formations, throws a new light on the role of asteroid impacts in terrestrial evolution,"Dr. Glikson said.
Preliminary indications suggest that at about the same time the Moon was also affected by asteroid impacts and by resurgent volcanic activity. Dr. Glikson and Mr. Vickers will continue to investigate the extent and effects of large asteroid impacts by studying early terrains in other parts of the world, including India and Canada.
Contact:
Amanda Morgan
Media Liaison
Phone: 02 6125 5575 or 0416 249 245
E-mail:
Read the original news release at
An additional articleon this subject is available at
PROZAC FOR PLANTS
By Karen Miller
From NASA Science News
5 August 2005
Anxiety can be a good thing. It alerts you that something may be wrong, that danger may be close. It helps initiate signals that get you ready to act. But, while an occasional bit of anxiety can save your life, constant anxiety causes great harm. The hormones that yank your body to high alert also damage your brain, your immune system and more if they flood through your body all the time.
Plants don't get anxious in the same way that humans do. But they do suffer from stress, and they deal with it in much the same way. They produce a chemical signal—superoxide (O2-)—that puts the rest of the plant on high alert. Superoxide, however, is toxic; too much of it will end up harming the plant. This could be a problem for plants on Mars.
According to the Vision for Space Exploration, humans will visit and explore Mars in the decades ahead. Inevitably, they'll want to take plants with them. Plants provide food, oxygen, companionship and a patch of green far from home. On Mars, plants would have to tolerate conditions that usually cause them a great deal of stress—severe cold, drought, low air pressure, soils that they didn't evolve for. But plant physiologist Wendy Boss and microbiologist Amy Grunden of North CarolinaStateUniversity believe they can develop plants that can live in these conditions. Their work is supported by the NASA Institute for Advanced Concepts.
Mars, photographed by the Viking Orbiters.
Stress management is key. Oddly, there are already Earth creatures that thrive in Mars-like conditions. They're not plants, though. They're some of Earth's earliest life forms—ancient microbes that live at the bottom of the ocean, or deep within Arctic ice. Boss and Grunden hope to produce Mars-friendly plants by borrowing genes from these extreme-loving microbes. And the first genes they're taking are those that will strengthen the plants' ability to deal with stress.
Ordinary plants already possess a way to detoxify superoxide, but the researchers believe that a microbe known as Pyrococcus furiosus uses one that may work better. P. furiosus lives in a superheated vent at the bottom of the ocean, but periodically it gets spewed out into cold sea water. So, unlike the detoxification pathways in plants, the ones in P. furiosus function over an astonishing 100+ degree Celsius range in temperature. That's a swing that could match what plants experience in a greenhouse on Mars.
Left: Pyrococcus furiosus, photographed by Henry Aldrich of the University of Florida. Right: Genetically engineered plants growing in Boss and Grunden's lab.
The researchers have already introduced a P. furiosus gene into a small, fast-growing plant known as Arabidopsis. "We have our first little seedlings," says Boss. "We'll grow them up and collect seeds to produce a second and then a third generation." In about one and a half to two years, they hope to have plants that each have two copies of the new genes. At that point they'll be able to study how the genes perform: whether they produce functional enzymes, whether they do indeed help the plant survive, or whether they hurt it in some way, instead.
Eventually, they hope to pluck genes from other extremophile microbes—genes that will enable the plants to withstand drought, cold, low air pressure, and so on. The goal, of course, is not to develop plants that can merely survive martian conditions. To be truly useful, the plants will need to thrive: to produce crops, to recycle wastes, and so on. "What you want in a greenhouse on Mars," says Boss, "is something that will grow and be robust in a marginal environment."
In stressful conditions, notes Grunden, plants often partially shut down. They stop growing and reproducing, and instead focus their efforts on staying alive—and nothing more. By inserting microbial genes into the plants, Boss and Grunden hope to change that. "By using genes from other sources," explains Grunden, "you're tricking the plant, because it can't regulate those genes the way it would regulate its own. We're hoping to [short-circuit] the plant's ability to shut down its own metabolism in response to stress."
If Boss and Grunden are successful, their work could make a huge difference to humans living in marginal environments here on Earth. In many third-world countries, says Boss, "extending the crop a week or two when the drought comes could give you the final harvest you need to last through winter. If we could increase drought resistance, or cold tolerance, and extend the growing season, that could make a big difference in the lives of a lot of people."
Their project is a long-term one, emphasize the scientists. "It'll be a year and a half before we actually have [the first gene] in a plant that we can test," points out Grunden. It'll be even longer before there's a cold- and drought-loving tomato plant on Mars—or even in North Dakota. But Grunden and Boss remain convinced they will succeed.
"There's a treasure trove of extremophiles out there," says Grunden. "So if one doesn't work, you can just go on to the next organism that produces a slightly different variant of what you want."
"Amy's right," agrees Boss. "It is a treasure trove. And it's just so exciting."
Read the original article at
MODEL GIVES CLEARER IDEA OF HOW OXYGEN CAME TO DOMINATE EARTH'S ATMOSPHERE
University of Washington release
8 August 2005
A number of hypotheses have been used to explain how free oxygen first accumulated in Earth's atmosphere some 2.4 billion years ago, but a full understanding has proven elusive. Now a new model offers plausible scenarios for how oxygen came to dominate the atmosphere, and why it took at least 300 million years after bacterial photosynthesis started producing oxygen in large quantities.
The big reason for the long delay was that processes such as volcanic gas production acted as sinks to consume free oxygen before it reached levels high enough to take over the atmosphere, said Mark Claire, a University of Washington doctoral student in astronomy and astrobiology. Free oxygen would combine with gases in a volcanic plume to form new compounds, and that process proved to be a significant oxygen sink, he said. Another sink was iron delivered to the Earth's outer crust by bombardment from space. Free oxygen was consumed as it oxidized, or rusted, the metal.
But Claire said that just changing the model to reflect different iron content in the outer crust makes a huge difference in when the model shows free oxygen filling the atmosphere. Increasing the actual iron content fivefold would have delayed oxygenation by more than 1 billion years, while cutting iron to one-fifth the actual level would have allowed oxygenation to happen more than 1 billion years earlier.
"We were fairly surprised that we could push the transition a billion years in either direction, because those levels of iron in the outer crust are certainly plausible given the chaotic nature of how Earth formed," he said.
Claire and colleagues David Catling, a UW affiliate professor in atmospheric sciences, and Kevin Zahnle of the National Aeronautics and Space Administration's Ames Research Center in California will discuss their model tomorrow (August 9) in Calgary, Alberta, during the Geological Society of America's Earth System Processes 2 meeting.
Earth's oxygen supply originated with cyanobacteria, tiny water-dwelling organisms that survive by photosynthesis. In that process, the bacteria convert carbon dioxide and water into organic carbon and free oxygen. But Claire noted that on the early Earth, free oxygen would quickly combine with an abundant element, hydrogen or carbon for instance, to form other compounds, and so free oxygen did not build up in the atmosphere very readily. Methane, a combination of carbon and hydrogen, became a dominant atmospheric gas.
With a sun much fainter and cooler than today, methane buildup warmed the planet to the point that life could survive. But methane was so abundant that it filled the upper reaches of the atmosphere, where such compounds are very rare today. There, ultraviolet exposure caused the methane to decompose and its freed hydrogen escaped into space, Claire said. The loss of hydrogen atoms to space allowed increasingly greater amounts of free oxygen to oxidize the crust. Over time, that slowly diminished the amount of hydrogen released from the crust by the combination of pressure and temperature that formed the rocks in the crust.
"About 2.4 billion years ago, the long-term geologic sources of oxygen outweighed the sinks in a somewhat permanent fashion," Claire said. "Escaping to space is the only permanent escape that we envision for the hydrogen, and that drove the planet to a higher oxygen level."
The model developed by Claire, Catling and Zahnle indicates that as hydrogen atoms stripped from methane escaped into space, greenhouse conditions caused by the methane blanket quickly collapsed. Earth's average temperature likely cooled by about 30 degrees Celsius, or 54 degrees Fahrenheit, and oxygen was able to dominate the atmosphere because there was no longer an overabundance of hydrogen to consume the oxygen.
The work is funded by NASA's Astrobiology Institute and the National Science Foundation's Integrative Graduate Education and Research Traineeship program, both of which foster research to understand life in the universe by examining the limits of life on Earth.
"There is interest in this work not just to know how an oxygen atmosphere came about on Earth but to look for oxygen signatures for other Earth-like planets," Claire said.
Contact:
Mark Claire
Phone: 206-616-4549
E-mail:
Read the original news release at
Additional articles on this subject are available at:
METEOR IMPACTS: LIFE'S JUMP STARTER?
Geological Society of America release
8 August 2005
Meteor impacts are generally regarded as monstrous killers and one of the causes of mass extinctions throughout the history of life. But there is a chance the heavy bombardment of Earth by meteors during the planet's youth actually spurred early life on our planet, say Canadian geologists. A study of the Haughton Impact Crater on Devon Island, in the Canadian Arctic, has revealed some very life-friendly features at ground zero. These include hydrothermal systems, blasted rocks that are easier for microbes to inhabit, plus the cozy, protected basin created by the crater itself. If true, impact craters could represent some of the best sites to look for signs of past or present life on Mars and other planets. A presentation on the biological effects of impacts is scheduled for Monday, 8 August, at Earth System Processes 2, a meeting co-convened by the Geological Society of America and Geological Association of Canada this week in Calgary, Alberta, Canada.
The idea that meteor impacts could benefit or even create conditions suitable for the beginning of early life struck Canadian Space Agency geologist Gordon Osinski while he and colleagues were conducting a geological survey of the 24-kilometer (15-mile) diameter Haughton Crater. Along the rim of the crater they noticed what looked like fossilized hydrothermal pipes, a few meters in diameter. "That set the bells ringing about possible biological implications," said Osinski. Hydrothermal systems are thought by many people to be the favourable places for life to evolve."