Indigenous embedded microbial filaments, bacterial cells and other microfossils were found in the Orgueil, Ivuna (CI1), Murchison, and Bells (CM2) carbonaceous meteorites. Biominerals, biofilms, framboids, magnetite platelets, and curious elemental iron ovoids covered with minute fibrils and carbon sheaths were also found. The S-4100 Hitachi Field Emission Scanning Electron Microscope (FESEM) and Energy Dispersive X-ray Analysis (EDAX) were used for in situ investigations of freshly fractured interior meteorite surfaces. EDAX x-ray spectra shows the microfossils bear signatures of the meteorite matrix and possess elemental ratios indicating they are indigenous and not recent microbial contaminants. Many of the well-preserved biogenic remains in the meteorites are encased within carbon-rich, sometimes electron transparent, sheaths. Their size, morphology and ultra microstructure are comparable to microfossils known from the phosphorites of Khubsughul, Mongolia and to some of the living cyanobacteria and other sulfur- and sulfate-reducing bacteria known from the halophilic Microcoleus mats of Sivash Lagoon, Crimea and from Mono Lake in California.
A permanent ice covered water body, called Lake Paula, was detected in Patriot Hills in the West Antarctic and sampled for the first time ever for microbial life.
The ice sheet measured approximately 2,5m thickness and the water body has a depth of about 10m. The lake is situated near a moraine which partly ablates from snow and provides meltwater from the slopes to the lake during austral summer. These running waters which are kept liquid by the heating up of the dark soil are penetrating the lower ice cover and thus softening up the lakeside part if the ice core. It is inoculated by nutrients, active microbes and diatoms of terrestrial origin. A distinct gradient concerning bacterial numbers, biomass and production which is 10 fold at the ice-water interface compared to the exposed part is observable. Temperature sensitivity of the embedded microbes reflect the gradient as well: Bacteria isolated from the upper part showed growth optima at 10°C, the lower part at 25°C, phylogenetic properties done by 16s rDNA reveal distinct communities depending on their vertical position, some clones are similar to those retrieved in Lake Vostok ice cores.
These results offer the conclusion that even in this harsh environment like the Antarctic continent a dynamic system like microbial ice aggregates can be sustained as long as the supply of liquid water which is essential for an active bacterial metabolism is provided at least for a small time frame.
In January 2002 the Planetary Studies Foundation returned to Antarctica to conduct a systematic search for meteorites on the blue ice fields near the Pecora Escarpment. The Pecora Escarpment area was previously searched by two National Science Foundation (NSF) teams that collectively recovered 526 meteorites. The two primary goals of the PSF Antarctica 2002 expedition were to determine if a significant number of meteorites could be found in a previously searched area, and to collect ice core samples to determine the presence or absence of microbial life. Several days' fieldwork resulted in the recovery of 33 meteorites, which included one stony-iron, two achondrites, an enstatite chondrite, and the collection of numerous ice samples. One particularly intriguing question that needed to be answered concerned the possibility that microbial life present in the ice may contaminate the meteorites. Antarctica was once considered to be a pristine environment with little or no biological contamination. This concept was particularly significant to the study of carbonaceous chondrites in order to insure that the organic compounds present in the meteorite were truly extraterrestrial in origin and not a product of terrestrial contamination. The preliminary results of this study indicated that microbial life was present in every ice sample.
In January 2000, the Planetary Studies Foundation (PSF) of Algonquin, Illinois USA chose to extend its meteorite collecting efforts to the Thiel Mountains of Antartical, an area of known meteorite concentrations. The goal of this mission was to expand the previously searched blue ice areas at the Moulton Escarpment and to collect as many meteorites as possible. Two previous National Science Foundation search teams collectively recovered 36 meteorites. In five days of searching the PSF team collected 19 confirmed stone meteorites and two possible achondrites. Later evaluation and analyses of these specimens indicated that one of the original 19 stone meteorites, TIL 99002, was actually a rare achondrite and that the other two possible achondrites were not. Preliminary analyses indicate that TIL 99002 is either an acapulcoite or a lodranite, while the other two are terrestrial dacite or porphyritic andesite.
In 1998, the Patriot Hills area of the Ellsworth Mountains of Antarctica was selected by the Planetary Studies Foundation (PSF) of Algonquin, Illinois USA as a potential site for the collection of meteorites. The eight person expedition searched several sites in and around the Patriot Hills, but met with little success in finding meteorites. In January 2000, the PSF chose to continue its efforts in the Thiel Mountains, an area of known meteorite concentrations. The goal was to collect as many meteorites as possible by extending the previously searched blue ice areas at the Moulton Escarpment. Earlier search teams collectively recovered 36 meteorites. In the five days of fieldwork at the Moulton Escarpment, the PSF team collected 19 confirmed stone meteorites, and 2 possible achondrites. Upon return to Patriot Hills another small stone meteorite, consisting of 6 small fragments totalling 1.7 grams, was collected in the Morris Moraine where a 23 mg meteorite fragment was found in 1998. In addition, ice samples were collected at Patriot Hills, Thiel Mountains, and the South Pole. The presence of several micro-organisms has been identified in these samplings and will be evaluated as possible contaminants of Antarctic meteorites.
Conference Committee Involvement (2)
Instruments, Methods, and Missions for Astrobiology X
28 August 2007 | San Diego, California, United States
Instruments, Methods, and Missions for Astrobiology VIII
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