MARSBUGS: The Electronic Exobiology Newsletter Volume 3, Number 8, 8 August, 1996. Editors: David Thomas, Department of Biological Sciences, University of Idaho, Moscow, ID, 83844-3051, USA, thoma457@uidaho.edu. Julian Hiscox, Microbiology Department, BBRB 17, Room 361, University of Alabama at Birmingham, Birmingham, AL 35294-2170, USA, Julian_hiscox@micro.microbio.uab.edu. MARSBUGS is published on a weekly to quarterly basis as warranted by the number of articles and announcements. Copyright of this compilation exists with the editors, except for specific articles, in which instance copyright exists with the author/authors. E-mail subscriptions are free, and may be obtained by contacting either of the editors. Contributions are welcome, and should be submitted to either of the two editors. Contributions should include a short biographical statement about the author(s) along with the author(s)' correspondence address. Subscribers are advised to make appropriate inquiries before joining societies, ordering goods etc. Back issues may be obtained via anonymous FTP at: ftp.uidaho.edu/pub/mmbb/marsbugs. The purpose of this newsletter is to provide a channel of information for scientists, educators and other persons interested in exobiology and related fields. This newsletter is not intended to replace peer-reviewed journals, but to supplement them. We, the editors, envision MARSBUGS as a medium in which people can informally present ideas for investigation, questions about exobiology, and announcements of upcoming events. Exobiology is still a relatively young field, and new ideas may come out of the most unexpected places. Subjects may include, but are not limited to: exobiology proper (life on other planets), the search for extraterrestrial intelligence (SETI), ecopoeisis/terraformation, Earth from space, planetary biology, primordial evolution, space physiology, biological life support systems, and human habitation of space and other planets. ----------------------------------------------------------------- INDEX 1) Editors' note. 2) SIGNS OF PAST LIFE ON MARS? ORGANIC COMPOUNDS AND POSSIBLE BIOLOGICAL FEATURES FOUND IN MARTIAN METEORITE American Association for the Advancement of Science 3) METEORITE YIELDS EVIDENCE OF PRIMITIVE LIFE ON EARLY MARS NASA release 96-160 4) SEARCH FOR PAST LIFE ON MARS: POSSIBLE RELIC BIOGENIC ACTIVITY IN MARTIAN METEORITE ALH84001 5) MARS METEORITE IMAGES AVAILABLE VIA THE INTERNET NASA release I96-6 6) PHOTOGRAPHS OF THE POSSIBLE ANCIENT MARTIAN ORGANISMS ----------------------------------------------------------------- EDITORS' NOTE The past few days have presented us with some very exciting information. Several agencies have released information concerning the possible martian microfossils. We have tried to provide you, the readers, with all of this information, even though much of it is repetition. We highly suggest reading the upcoming issue of Science in order to get the story straight from the researchers involved. ----------------------------------------------------------------- SIGNS OF PAST LIFE ON MARS? ORGANIC COMPOUNDS AND POSSIBLE BIOLOGICAL FEATURES FOUND IN MARTIAN METEORITE (Featured in 16 August 1996 Science) American Association for the Advancement of Science News Release Ever since scientists learned that water once flowed on Mars, they've wondered whether life might also have flourished on the apparently now-dead planet. In the 16 August issue of Science, McKay et al report the first identification of organic compounds in a Martian meteorite. The authors further suggest that these compounds, in conjunction with a number of other mineralogical features observed in the rock, may be evidence of ancient Martian microorganisms. The paper's authors are David S. McKay and Everett K. Gibson, Jr., of NASA's Johnson Space Center in Houston, TX; Kathie L. Thomas-Keprta of Lockheed Martin in Houston, TX; Hojatollah Vali of McGill University in Montreal, Quebec; Christopher S. Romanek of the University of Georgia's Savannah River Ecology Laboratory in Aiken, SC; and Simon J. Clemett, Xavier D. F. Chllier, Claude R. Maechlin, and Richard N. Zare of Stanford University in Stanford, CA. Organic (complex, carbon-based) molecules are the requisite building blocks of life on Earth. The authors looked for signs of such molecules and other mineralogical and textural indications of past life within the pore space and fractures of meteorite Allan Hills 84001 (ALH84001), one of only 12 meteorites identified as having come from Mars. ALH84001 is the oldest of the Martian dozen, having crystallized from molten rock about 4.5 billion years ago, early in the planet's evolution, and it is the only Martian meteorite to contain significant carbonate minerals. (The carbonates formed sometime after the rock, perhaps about 3.6 billion years ago.) About 15 million years ago, a major asteroid impact on Mars threw ALH84001 into space, where it eventually fell onto an ice field in Antarctica about 13,000 years ago. ALH84001, which shows little evidence of terrestrial weathering, was discovered by meteorite-hunting scientists in 1984 and only recently identified at Martian. ALH84001 is riven with tiny fractures resulting primarily from impacts that occurred while the rock was on Mars. The secondary carbonates formed along with some of these fractures. The Science authors prepared thin sample sections that included these pre-existing fractures, and found on their surfaces a clear and distinct distribution of polycyclic aromatic hydrocarbons (PAHs), organic molecules containing multiple connected rings of carbon atoms--the first organic molecules ever seen in a Martian rock. A variety of contamination checks and control experiments indicated that the organic material was indigenous to the rock and was not the result of terrestrial contamination. For example, the authors noted that the concentration of PAHs increases inward, whereas terrestrial contamination likely would have resulted in more PAHs on the exterior of the rock. The big question is: where did the PAHs come from? It is thought that PAHs can form one of two ways: non-biologically, during early star formation; or biologically, through the activity of bacteria or other living organisms, or their degradation (fossilization). On Earth, PAHs are abundant as fossil molecules in ancient sedimentary rocks, coal and petroleum, the result of chemical changes that occurred to the remains of dead marine plankton and early plant life. They also occur during partial combustion, such as when a candle burns or food is grilled. To address the origin of these PAHs, the authors examined the chemistry, mineralogy, and texture of carbonates associated with PAHs in the Martian meteorite. Under the transmission electron microscope, the carbonate globules were seen to contain fine- grained magnetite and iron-sulfide particles. From these and other analyses, the authors developed a list of observations about the carbonates and PAHs that, taken individually, could be explained by non-biological means. However, as they write in their Science article, "when considered collectively ... we conclude that [these phenomena] are evidence for primitive life on early Mars." Some of their observations are as follows: * The higher concentrations of PAHs were found associated with the carbonates. * The carbonates formed within the rock fissures, about 3.6 billion years ago, and are younger than the rock itself. * The magnetite and iron-sulfide particles inside the carbonate globules are chemically, structurally and morphologically similar to magnetosome particles produced by bacteria on Earth. * High-resolution scanning electron microscopy revealed on the surface of the carbonates small (100 nanometers) ovoids and elongated features. Similar textures have been found on the surface of calcite concretions grown from Pleistocene groundwater in southern Italy, which have been interpreted as representing nanobacteria. * Some earlier reports had suggested that the temperature at which the ALH84001 carbonates formed was as high as 700 degrees C--much too hot for any kind of life. However, the isotopic composition of the carbonates, and the new data on the magnetite and iron-sulfide particles, imply a temperature range of 0 to 80 degrees C, cool enough for life. * The magnetite--a mineral that contains some ferric (Fe3+) iron, perhaps indicating formation by oxidation (the addition of oxygen)--and iron sulfide--a mineral that can be formed by reduction (the loss of oxygen)--were found in close proximity in the Martian meteorite. On Earth, closely associated mineralogical features involving both oxidation and reduction are characteristic of biological activity. Science is the official journal of the American Association for the Advancement of Science (AAAS) in Washington, DC, the world's largest general science organization. ----------------------------------------------------------------- METEORITE YIELDS EVIDENCE OF PRIMITIVE LIFE ON EARLY MARS NASA release 96-160 A NASA research team of scientists at the Johnson Space Center (JSC), Houston, TX, and at Stanford University, Palo Alto, CA, has found evidence that strongly suggests primitive life may have existed on Mars more than 3.6 billion years ago. The NASA-funded team found the first organic molecules thought to be of Martian origin; several mineral features characteristic of biological activity; and possible microscopic fossils of primitive, bacteria-like organisms inside of an ancient Martian rock that fell to Earth as a meteorite. This array of indirect evidence of past life will be reported in the August 16 issue of the journal Science, presenting the investigation to the scientific community at large for further study. The two-year investigation was co- led by JSC planetary scientists Dr. David McKay, Dr. Everett Gibson and Kathie Thomas-Keprta of Lockheed-Martin, with the major collaboration of a Stanford team headed by Professor of Chemistry Dr. Richard Zare, as well as six other NASA and university research partners. "There is not any one finding that leads us to believe that this is evidence of past life on Mars. Rather, it is a combination of many things that we have found," McKay said. "They include Stanford's detection of an apparently unique pattern of organic molecules, carbon compounds that are the basis of life. We also found several unusual mineral phases that are known products of primitive microscopic organisms on Earth. Structures that could be microscopic fossils seem to support all of this. The relationship of all of these things in terms of location--within a few hundred thousandths of an inch of one another--is the most compelling evidence." "It is very difficult to prove life existed 3.6 billion years ago on Earth, let alone on Mars," Zare said. "The existing standard of proof, which we think we have met, includes having an accurately dated sample that contains native microfossils, mineralogical features characteristic of life, and evidence of complex organic chemistry." "For two years, we have applied state-of-the-art technology to perform these analyses, and we believe we have found quite reasonable evidence of past life on Mars," Gibson added. "We don't claim that we have conclusively proven it. We are putting this evidence out to the scientific community for other investigators to verify, enhance, attack--disprove if they can -- as part of the scientific process. Then, within a year or two, we hope to resolve the question one way or the other." "What we have found to be the most reasonable interpretation is of such radical nature that it will only be accepted or rejected after other groups either confirm our findings or overturn them," McKay added. The igneous rock in the 4.2-pound, potato-sized meteorite has been age-dated to about 4.5 billion years, the period when the planet Mars formed. The rock is believed to have originated underneath the Martian surface and to have been extensively fractured by impacts as meteorites bombarded the planets in the early inner solar system. Between 3.6 billion and 4 billion years ago, a time when it is generally thought that the planet was warmer and wetter, water is believed to have penetrated fractures in the subsurface rock, possibly forming an underground water system. Since the water was saturated with carbon dioxide from the Martian atmosphere, carbonate minerals were deposited in the fractures. The team's findings indicate living organisms also may have assisted in the formation of the carbonate, and some remains of the microscopic organisms may have become fossilized, in a fashion similar to the formation of fossils in limestone on Earth. Then, 16 million years ago, a huge comet or asteroid struck Mars, ejecting a piece of the rock from its subsurface location with enough force to escape the planet. For millions of years, the chunk of rock floated through space. It encountered Earth's atmosphere 13,000 years ago and fell in Antarctica as a meteorite. It is in the tiny globs of carbonate that the researchers found a number of features that can be interpreted as suggesting past life. Stanford researchers found easily detectable amounts of organic molecules called polycyclic aromatic hydrocarbons (PAHs) concentrated in the vicinity of the carbonate. Researchers at JSC found mineral compounds commonly associated with microscopic organisms and the possible microscopic fossil structures. The largest of the possible fossils are less than 1/100 the diameter of a human hair, and most are about 1/1000 the diameter of a human hair--small enough that it would take about a thousand laid end-to-end to span the dot at the end of this sentence. Some are egg-shaped while others are tubular. In appearance and size, the structures are strikingly similar to microscopic fossils of the tiniest bacteria found on Earth. The meteorite, called ALH84001, was found in 1984 in Allan Hills ice field, Antarctica, by an annual expedition of the National Science Foundation's Antarctic Meteorite Program. It was preserved for study in JSC's Meteorite Processing Laboratory and its possible Martian origin was not recognized until 1993. It is one of only 12 meteorites identified so far that match the unique Martian chemistry measured by the Viking spacecraft that landed on Mars in 1976. ALH84001 is by far the oldest of the 12 Martian meteorites, more than three times as old as any other. Many of the team's findings were made possible only because of very recent technological advances in high- resolution scanning electron microscopy and laser mass spectrometry. Only a few years ago, many of the features that they report were undetectable. Although past studies of this meteorite and others of Martian origin failed to detect evidence of past life, they were generally performed using lower levels of magnification, without the benefit of the technology used in this research. The recent discovery of extremely small bacteria on Earth, called nanobacteria, prompted the team to perform this work at a much finer scale than past efforts. The nine authors of the Science report include McKay, Gibson and Thomas-Keprta of JSC; Christopher Romanek, formerly a National Research Council post-doctoral fellow at JSC who is now a staff scientist at the Savannah River Ecology Laboratory at the University of Georgia; Hojatollah Vali, a National Research Council post-doctoral fellow at JSC and a staff scientist at McGill University, Montreal, Quebec, Canada; and Zare, graduate students Simon J. Clemett and Claude R. Maechling and post- doctoral student Xavier Chillier of the Stanford University Department of Chemistry. The team of researchers includes a wide variety of expertise, including microbiology, mineralogy, analytical techniques, geochemistry and organic chemistry, and the analysis crossed all of these disciplines. Further details on the findings presented in the Science article include: * Researchers at Stanford University used a dual laser mass spectrometer--the most sensitive instrument of its type in the world--to look for the presence of the common family of organic molecules called PAHs. When microorganisms die, the complex organic molecules that they contain frequently degrade into PAHs. PAHs are often associated with ancient sedimentary rocks, coals and petroleum on Earth and can be common air pollutants. Not only did the scientists find PAHs in easily detectable amounts in ALH84001, but they found that these molecules were concentrated in the vicinity of the carbonate globules. This finding appears consistent with the proposition that they are a result of the fossilization process. In addition, the unique composition of the meteorite's PAHs is consistent with what the scientists expect from the fossilization of very primitive microorganisms. On Earth, PAHs virtually always occur in thousands of forms, but, in the meteorite, they are dominated by only about a half-dozen different compounds. The simplicity of this mixture, combined with the lack of light-weight PAHs like naphthalene, also differs substantially from that of PAHs previously measured in non- Martian meteorites. * The team found unusual compounds--iron sulfides and magnetite-- that can be produced by anaerobic bacteria and other microscopic organisms on Earth. The compounds were found in locations directly associated with the fossil-like structures and carbonate globules in the meteorite. Extreme conditions--conditions very unlikely to have been encountered by the meteorite--would have been required to produce these compounds in close proximity to one another if life were not involved. The carbonate also contained tiny grains of magnetite that are almost identical to magnetic fossil remnants often left by certain bacteria found on Earth. Other minerals commonly associated with biological activity on Earth were found in the carbonate as well. * The formation of the carbonate or fossils by living organisms while the meteorite was in the Antarctic was deemed unlikely for several reasons. The carbonate was age dated using a parent- daughter isotope method and found to be 3.6 billion years old, and the organic molecules were first detected well within the ancient carbonate. In addition, the team analyzed representative samples of other meteorites from Antarctica and found no evidence of fossil-like structures, organic molecules or possible biologically produced compounds and minerals similar to those in the ALH84001 meteorite. The composition and location of PAHs organic molecules found in the meteorite also appeared to confirm that the possible evidence of life was extraterrestrial. No PAHs were found in the meteorite's exterior crust, but the concentration of PAHs increased in the meteorite's interior to levels higher than ever found in Antarctica. Higher concentrations of PAHs would have likely been found on the exterior of the meteorite, decreasing toward the interior, if the organic molecules are the result of contamination of the meteorite on Earth. Additional information may be obtained at 1 p.m. EDT via the Internet at http://www.jsc.nasa.gov/pao/flash/ ----------------------------------------------------------------- SEARCH FOR PAST LIFE ON MARS: POSSIBLE RELIC BIOGENIC ACTIVITY IN MARTIAN METEORITE ALH84001 David S. McKay, Everett K. Gibson, Kathie L. Thomas-Keprta, Hojatollah Vail, Christopher S. Romanek, Simon J. Clement, Xavier D. F. Chillier, Claude R. Maechling, and Richard N. Zare. [This message was passed along the internet, author unknown, and is of interest to the current debate about the possible origin and evolution of life on Mars. If we are infringing upon someone's copyright, it is not our intention to do so, and we apologize.] ALH84001 is a martian meteorite, a coarse-grained orthopyroxene containing relatively large amounts of carbonate, with a crystallization age of 4.5 Gyr. Carbonate globules within fractures in the rock are dated at 3.6 Gyr. Fractionation of carbon has taken place to enhance C-13 consistent with terrestrial biogenic process (but other processes not excluded). PAHs also appear on interior fracture surfaces in excess of 1 ppm. They present extensive tests and discussion to show that they are confident that these are all indigenous to the meteorite and do not represent contamination. Mass spec studies show these PAHs are complex not simple and suggest (to the authors) a biogenic source. They then discuss TEM studies of the Fe/S fraction in the meteorite. Nanometer sized magnetite and Fe- sulfide phases are associated with Mg-Fe-rich carbonate. These observed structures and concentrations can be explained by either inorganic or biogenic processes. However, they argue that the range of conditions (pH) for inorganic precipitation is unlikely to have occurred on Mars, whereas biogenic processes seem to offer a more natural explanation for the detailed structures observed, and they are apparently similar to terrestrial magnetofossils (remains of bacterial magnetosomes). SEM studies of carbonate globules are then discussed (typically ovoid and 100 nm across). Origin of the ovoids and other observed textures is unclear, but they may be related to terrestrial microfossils, or they may be erosional features due to partial dissolution of the carbonate. They do not believe these structures result from contamination. They suggest possible microbiological activity for both the ovoid carbonate structures and the Fe-sulfides. On the basis of a number of circumstantial arguments, they "interpret that the carbonate globules have a biogenic origin and were likely formed at low temperatures". (The temperature of formation of the carbonates in this meteorite has been controversial). "It is possible that all of the described features can be explained by inorganic processes, but these explanations appear to require restricted conditions." The evidence consistent with life includes: (1) penetration of the igneous rock by fluid leading to possible organic deposits of minerals along veins (2) formation of the carbonate globules much later than the formation of the rock itself, (3) SEM and TEM images of the globules that resemble terrestrial biogenic structures, (4) magnetite and iron sulfide particles that could have been formed biogenically. The authors feel that the cumulative effect of these points is to provide "evidence for primitive life on early Mars" ----------------------------------------------------------------- MARS METEORITE IMAGES AVAILABLE VIA THE INTERNET NASA release I96-6 Photographs that support today's briefing at which a team of NASA and Stanford scientists will discuss their findings showing strong circumstantial evidence of possible early Martian life, including microfossil remains found in a Martian meteorite, are available via the Internet. Real time audio of today's briefing also will be available from these sites. The Internet World Wide Web URLs are: http://www.jsc.nasa.gov/pao/flash http://cu-ames.arc.nasa.gov/marslife http://rsd.gsfc.nasa.gov/marslife ----------------------------------------------------------------- PHOTOGRAPHS OF THE POSSIBLE ANCIENT MARTIAN ORGANISMS from the Marslife web page: http://cu-ames.arc.nasa.gov/. [Due to the nature of Marsbugs' format, the photos cannot be easily e-mailed. However, printable copies of Marsbugs (MS-Word for Windows format), with the photos included, are available via anonymous FTP at ftp.uidaho.edu/pub/mmbb/marsbugs.] A NASA research team of scientists at the Johnson Space Center and at Stanford University has found evidence that strongly suggests primitive life may have existed on Mars more than 3.6 billion years ago. The NASA-funded team found the first organic molecules thought to be of Martian origin; several mineral features characteristic of biological activity; and possible microscopic fossils of primitive, bacteria-like organisms inside of an ancient Martian rock that fell to Earth as a meteorite. This array of indirect evidence of past life will be reported in the Aug. 16 issue of the journal Science, presenting the investigation to the scientific community at large to reach a future consensus that will either confirm or deny the team's conclusion. Below is the photographic evidence for this discovery. S96-12301 (JPG; TIF) - In the center of this electron microscope image of a small chip from a meteorite are several tiny structures that are possible microscopic fossils of primitive, bacteria-like organisms that may have lived on Mars more than 3.6 billion years ago. A two-year investigation by a NASA research team found organic molecules, mineral features characteristic of biological activity and possible microscopic fossils such as these inside of an ancient Martian rock that fell to Earth as a meteorite. The largest possible fossils are less than 1/100th the diameter of a human hair in size while most are ten times smaller. S96-12299 (JPG; TIF) - This electron microscope image is a close- up of the center part of photo number S96-12301. While the exact nature of these tube-like structures is not known, one interpretation is that they may be microscopic fossils of primitive, bacteria-like organisms that may have lived on Mars more than 3.6 billion years ago. A two-year investigation by a NASA research team found organic molecules, mineral features characteristic of biological activity and possible microscopic fossils such as these inside of an ancient Martian rock that fell to Earth as a meteorite. The largest possible fossils are less than 1/100th the diameter of a human hair in size while most are ten times smaller. S96-12298 (JPG; TIF) - This electron microscope image shows extremely tiny tubular structures that are possible microscopic fossils of bacteria-like organisms that may have lived on Mars more than 3.6 billion years ago. A two-year investigation by a NASA research team found organic molecules, mineral features characteristic of biological activity and possible microscopic fossils such as these inside of an ancient Martian rock that fell to Earth as a meteorite. The largest possible fossils are less than 1/100th the diameter of a human hair in size while most are ten times smaller. The fossil-like structures were found in carbonate minerals formed along pre-existing fractures in the meteorite in a fashion similar to the way fossils occur in limestone on Earth, although on a microscopic scale. S96-12297 (JPG; TIF) - This electron microscope image shows egg- shaped structures, some of which may be possible microscopic fossils of Martian origin as discussed by NASA research published in the Aug. 16, 1996, issue of the journal Science. A two-year investigation found organic molecules, mineral features characteristic of biological activity and possible microscopic fossils such as these inside of an ancient Martian rock that fell to Earth as a meteorite. The largest possible fossils are less than 1/100th the diameter of a human hair in size while most are ten times smaller. S96-12300 (JPG; TIF) - This electron microscope image shows tubular structures of likely Martian origin. These structures are very similar in size and shape to extremely tiny microfossils found in some Earth rocks. This photograph is part of a report by a NASA research team published in the Aug. 16, 1996, issue of the journal Science. A two-year investigation by the team found organic molecules, mineral features characteristic of biological activity and possible microscopic fossils such as these inside of an ancient Martian rock that fell to Earth as a meteorite. The largest possible fossils are less than 1/100th the diameter of a human hair in size while most are ten times smaller. S96-12609 (JPG; TIF) & S96-12610 (JPG; TIF) - This high-resolution scanning electron microscope image shows an unusual tube-like structural form that is less than 1/100th the width of a human hair in size found in meteorite ALH84001, a meteorite believed to be of Martian origin. Although this structure is not part of the research published in the Aug. 16 issue of the journal Science, it is located in a similar carbonate glob in the meteorite. This structure will be the subject of future investigations that could confirm whether or not it is fossil evidence of primitive life on Mars 3.6 billion years ago. S94-032549 (JPG; TIF) - This 4.5 billion-year-old rock, labeled meteorite ALH84001, is believed to have once been a part of Mars and to contain fossil evidence that primitive life may have existed on Mars more than 3.6 billion years ago. The rock is a portion of a meteorite that was dislodged from Mars by a huge impact about 16 million years ago and that fell to Earth in Antarctica 13,000 years ago. The meteorite was found in Allan Hills ice field, Antarctica, by an annual expedition of the National Science Foundation's Antarctic Meteorite Program in 1984. It is preserved for study at the Johnson Space Center's Meteorite Processing Laboratory in Houston. S95-00690 (JPG; TIF) - This photograph shows orange-colored carbonate mineral globules found in a meteorite, called ALH84001, believed to have once been a part of Mars. These carbonate minerals in the meteorite are believed to have been formed on Mars more than 3.6 billion years ago. Their structure and chemistry suggest that they may have been formed with the assistance of primitive, bacteria-like living organisms. A two- year investigation by a NASA research team found organic molecules, mineral features characteristic of biological activity and possible microscopic fossils inside of carbonate minerals such as these in the meteorite. Curator: Annie Platoff Responsible NASA Official: Kelly Humphries Page Originator: Johnson Space Center Page Provider: Ames Research Center ----------------------------------------------------------------- End Marsbugs Vol. 3, No. 8.