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76-480: The NAI is a virtual, distributed organization that integrates astrobiology research and training programs in concert with the national and international science communities. Although NASA had explored the idea of forming an astrobiology institute in the past, when the Viking biological experiments returned negative results for life on Mars , the public lost interest and federal funds for exobiology dried up. In 1996,

152-400: A heavy, radioactive isotope of carbon. If there were photosynthetic organisms present, it was believed that they would incorporate some of the carbon as biomass through the process of carbon fixation , just as plants and cyanobacteria on earth do. After several days of incubation, the experiment removed the gases, baked the remaining soil at 650 °C (1200 °F), and collected

228-489: A trigger such as the FOM inputs. The cause of this increase in decomposition has often been attributed to an increase in microbial activity resulting from higher energy and nutrient availability released from the FOM. After the input of FOM, specialized microorganisms are believed to grow quickly and only decompose this newly added organic matter. The turnover rate of SOM in these areas is at least one order of magnitude higher than

304-856: A 0.45 micrometre filter (DOM), and that which cannot (POM). Organic matter is important in water and wastewater treatment and recycling, natural aquatic ecosystems, aquaculture, and environmental rehabilitation. It is, therefore, important to have reliable methods of detection and characterisation, for both short- and long-term monitoring. Various analytical detection methods for organic matter have existed for up to decades to describe and characterise organic matter. These include, but are not limited to: total and dissolved organic carbon, mass spectrometry , nuclear magnetic resonance (NMR) spectroscopy , infrared (IR) spectroscopy , UV-Visible spectroscopy , and fluorescence spectroscopy . Each of these methods has its advantages and limitations. The same capability of natural organic matter that helps with water retention in

380-456: A broad suite of atmospheric trace gases on Mars and help determine if their formation is of biological or geological origin. The Mars Orbiter Mission has also been attempting – since late 2014 – to detect and map methane on Mars' atmosphere. A press commentary argued that, if there was life at the Viking lander sites, it may have been killed by the exhaust from the landing rockets. That is not

456-491: A carbon dioxide atmosphere, ultraviolet light (remember: Mars lacks an ozone layer, so the surface is bathed in ultraviolet) can cause carbon dioxide to react with soils to produce various oxidizers, including highly reactive superoxides (salts containing O 2 ). When mixed with small organic molecules, superoxidizers readily oxidize them to carbon dioxide, which may account for the LR result. Superoxide chemistry can also account for

532-420: A forest, for example, leaf litter and woody materials fall to the forest floor. This is sometimes referred to as organic material. When it decays to the point in which it is no longer recognizable, it is called soil organic matter. When the organic matter has broken down into a stable substance that resists further decomposition it is called humus . Thus soil organic matter comprises all of the organic matter in

608-491: A problem for missions which land via an airbag -protected capsule, slowed by parachutes and retrorockets, and dropped from a height that allows rocket exhaust to avoid the surface. Mars Pathfinder 's Sojourner rover and the Mars Exploration Rovers each used this landing technique successfully. The Phoenix Scout lander descended to the surface with retro-rockets, however, their fuel was hydrazine , and

684-477: A robotic arm to pick up and place soil samples into sealed test containers on the craft. The two landers carried out the same tests at two places on Mars' surface, Viking 1 near the equator and Viking 2 further north. The four experiments below are presented in the order in which they were carried out by the two Viking landers. The biology team leader for the Viking program was Harold P. Klein (NASA Ames). A gas chromatograph — mass spectrometer ( GCMS )

760-437: Is a device that separates vapor components chemically via a gas chromatograph and then feeds the result into a mass spectrometer , which measures the molecular weight of each chemical. As a result, it can separate, identify, and quantify a large number of different chemicals. The GCMS (PI: Klaus Biemann , MIT) was used to analyze the components of untreated Martian soil, and particularly those components that are released as

836-535: Is common throughout the ecosystem and is cycled through decomposition processes by soil microbial communities that are crucial for nutrient availability. After degrading and reacting, it can move into soil and mainstream water via waterflow. Organic matter provides nutrition to living organisms. Organic matter acts as a buffer in aqueous solutions to maintain a neutral pH in the environment. The buffer acting component has been proposed to be relevant for neutralizing acid rain . Some organic matter not already in

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912-529: Is crucial to all ecology and to all agriculture , but it is especially emphasized in organic farming , where it is relied upon especially heavily. The priming effect is characterized by intense changes in the natural process of soil organic matter (SOM) turnover, resulting from relatively moderate intervention with the soil. The phenomenon is generally caused by either pulsed or continuous changes to inputs of fresh organic matter (FOM). Priming effects usually result in an acceleration of mineralization due to

988-606: Is found to be much different than Earth's, that would support the 1970s interpretation." Biemann has written a commentary critical of the Navarro-González and McKay paper, to which the latter have replied; the exchange was published in December 2011. In 2021 the chlorine isotope ratio on Mars was measured by the Trace Gas Orbiter and found to be almost indistinguishable from the terrestrial ratio, leaving

1064-454: Is not alone in believing otherwise. The current claim for life on Mars is grounded on old evidence reinterpreted in the light of recent developments. In 2006, scientist Rafael Navarro demonstrated that the Viking biological experiments likely lacked sensitivity to detect trace amounts of organic compounds. In a paper published in December 2010, the scientists suggest that if organics were present, they would not have been detected because when

1140-405: Is one of many organic compounds that can be synthesized without any biological activity. Organic matter is heterogeneous and very complex. Generally, organic matter, in terms of weight, is: The molecular weights of these compounds can vary drastically, depending on if they repolymerize or not, from 200 to 20,000 amu. Up to one-third of the carbon present is in aromatic compounds in which

1216-435: Is required to explain the results of the Viking biology experiments. A more detailed study was conducted in 2017 by a team of researchers including Quinn. While this study was not specifically designed to match the data from the LR experiment, it was found that hypochlorite could partially explain the control results, including the 160 °C sterilization test. The authors stated "Further experiments are planned to characterize

1292-458: The Curiosity rover. At the time, the total absence of organic material on the surface made the results of the biology experiments moot, since metabolism involving organic compounds were what those experiments were designed to detect. The general scientific community surmises that the Viking's biological tests remain inconclusive, and can be explained by purely chemical processes. Despite

1368-463: The decomposition of organic matter including its chemical properties and other environmental parameters. Metabolic capabilities of the microbial communities play a crucial role on decomposition since they are highly connected with the energy availability and processing. In terrestrial ecosystems the energy status of soil organic matter has been shown to affect microbial substrate preferences. Some organic matter pools may be energetically favorable for

1444-460: The microbial communities resulting in their fast oxidation and decomposition, in comparison with other pools where microbial degraders get less return from the energy they invest. By extension, soil microorganisms preferentially mineralize high-energy organic matter, avoiding decomposing less energetically dense organic matter. Measurements of organic matter generally measure only organic compounds or carbon , and so are only an approximation of

1520-409: The "sterilization" seen in the LR experiment." In a 2002 paper published by Joseph Miller, he speculates that recorded delays in the system's chemical reactions point to biological activity similar to the circadian rhythm previously observed in terrestrial cyanobacteria . On 12 April 2012, an international team including Levin and Patricia Ann Straat published a peer reviewed paper suggesting

1596-548: The Exobiology and Evolutionary Biology Program, $ 11 million; ASTID, $ 9 million; ASTEP, $ 5 million. As of 2018, the NAI has 10 teams including about 600 researchers distributed across ~100 institutions. It also has 13 international partner organizations. Some past and present teams are: NAI has partnership program with other international astrobiology organizations to provide collaborative opportunities for its researchers within

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1672-421: The LR experiment, no explanation involving inorganic chemistry as of 2016 is able to give satisfactory explanations of the complete data from the LR experiment, and specifically address the question of what active agent on the soil samples could be adversely affected by heating to approximately 50 °C and destroyed with long-term storage in the dark at 10 °C, as data suggest. James Lovelock argued that

1748-561: The PR results was most likely. However, in subsequent years, as the GCMS results have come increasingly under scrutiny, the pyrolytic release experiment results have again come to be viewed as possibly consistent with biological activity, although "An explanation for the apparent small synthesis of organic matter in the pyrolytic release experiment remains obscure." Organic compounds seem to be common, for example, on asteroids, meteorites, comets and

1824-458: The Viking data, either with biological or non-biological materials on Earth. While no experiment has ever precisely duplicated the Mars LR test and control results, experiments with hydrogen peroxide -saturated titanium dioxide have produced similar results. While the majority of astrobiologists still conclude that the Viking biological experiments were inconclusive or negative, Gilbert Levin

1900-516: The Viking landers heated samples of Martian soil were chloromethane and dichloromethane -- chlorine compounds interpreted at the time as likely contaminants from cleaning fluids." According to a paper authored by a team led by Rafael Navarro-González of the National Autonomous University of Mexico , "those chemicals are exactly what [their] new study found when a little perchlorate -- the surprise finding from Phoenix --

1976-468: The Viking mission would have done better to examine the Martian atmosphere than look at the soil. He theorised that all life tends to expel waste gases into the atmosphere, and as such it would be possible to theorise the existence of life on a planet by detecting an atmosphere that was not in chemical equilibrium. He concluded that there was enough information about Mars' atmosphere at that time to discount

2052-453: The Viking samples, the organic content of the Martian soil could have been as high as 0.1% and still would have produced the (false) negative result that the GCMS returned. Thus, while conventional wisdom regarding the Viking biology experiments still points to "no evidence of life", recent years have seen at least a small shift toward "inconclusive evidence"." According to a 2010 NASA press release: "The only organic chemicals identified when

2128-499: The acceleration of mineralization while a negative priming effect results in immobilization, leading to N unavailability. Although most changes have been documented in C and N pools, the priming effect can also be found in phosphorus and sulfur, as well as other nutrients. Löhnis was the first to discover the priming effect phenomenon in 1926 through his studies of green manure decomposition and its effects on legume plants in soil. He noticed that when adding fresh organic residues to

2204-536: The added water to produce oxygen and hydrogen, and with the nutrients to produce carbon dioxide (CO 2 ). Norman Horowitz was the chief of the Jet Propulsion Laboratory bioscience section for the Mariner and Viking missions from 1965 to 1976. Horowitz considered that the great versatility of the carbon atom makes it the element most likely to provide solutions, even exotic solutions, to

2280-662: The announcement of possible traces of ancient life in the Allan Hills 84001 meteorite from Mars led to new interest in the subject. At the same time, NASA developed the Origins Program , broadening its reach from exobiology to astrobiology , the study of the origin, evolution, distribution, and future of life in the universe. In 1998, $ 9 million was set aside to fund the NASA Astrobiology Institute (NAI), an interdisciplinary research effort using

2356-431: The bulk soil. Other soil treatments, besides organic matter inputs, which lead to this short-term change in turnover rates, include "input of mineral fertilizer, exudation of organic substances by roots, mere mechanical treatment of soil or its drying and rewetting." Priming effects can be either positive or negative depending on the reaction of the soil with the added substance. A positive priming effect results in

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2432-488: The by-products are larger than membrane pore sizes. This clogging problem can be treated by chlorine disinfection ( chlorination ), which can break down residual material that clogs systems. However, chlorination can form disinfection by-products . Water with organic matter can be disinfected with ozone -initiated radical reactions. The ozone (three oxygens) has powerful oxidation characteristics. It can form hydroxyl radicals (OH) when it decomposes, which will react with

2508-452: The carbon atoms form usually six-membered rings. These rings are very stable due to resonance stabilization , so they are challenging to break down. The aromatic rings are also susceptible to electrophilic and nucleophilic attacks from other electron-donating or electron-accepting material, which explains the possible polymerization to create larger molecules of organic matter. Some reactions occur with organic matter and other materials in

2584-422: The concept of the priming effect was widely disregarded until about the 1980s-1990s. The priming effect has been found in many different studies and is regarded as a common occurrence, appearing in most plant soil systems. However, the mechanisms which lead to the priming effect are more complex than originally thought, and still remain generally misunderstood. Although there is a lot of uncertainty surrounding

2660-405: The control part of the experiment as described for the PR below. The result was quite a surprise, considering the negative results of the first two tests, with a steady stream of radioactive gases being given off by the soil immediately following the first injection. The experiment was done by both Viking probes, the first using a sample from the surface exposed to sunlight and the second probe taking

2736-420: The creation of a new nomenclatural rank that classified some Viking results as ' metabolic ' and therefore representative of a new form of life. The taxonomy proposed by Crocco has not been accepted by the scientific community, and the validity of Crocco's interpretation hinged entirely on the absence of an oxidative agent in the Martian soil. According to Gilbert Levin and Patricia Ann Straat, investigators of

2812-534: The detection of "extant microbial life on Mars", based on mathematical speculation through cluster analysis of the Labeled Release experiments of the 1976 Viking Mission . The pyrolytic release ( PR ) experiment (PI: Norman Horowitz , Caltech) consisted of the use of light, water, and a carbon-containing atmosphere of carbon monoxide (CO) and carbon dioxide (CO 2 ), simulating that on Mars. The carbon-bearing gases were made with carbon-14 ( C),

2888-424: The end products of the plume (water, nitrogen, and ammonia) were not found to have affected the soils at the landing site. Natural organic matter Organic matter , organic material , or natural organic matter refers to the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have come from

2964-584: The expertise of different scientific research institutions and universities from across the country, centrally linked to Ames Research Center in Mountain View, California . Gerald Soffen former Project Scientist with the Viking program , helped coordinate the new institute. In May, NASA selected eleven science teams, each with a Principal Investigator (PI). NAI was established in July with Scott Hubbard as interim Director. Nobel laureate Baruch S. Blumberg

3040-421: The feces and remains of organisms such as plants and animals . Organic molecules can also be made by chemical reactions that do not involve life. Basic structures are created from cellulose , tannin , cutin , and lignin , along with other various proteins , lipids , and carbohydrates . Organic matter is very important in the movement of nutrients in the environment and plays a role in water retention on

3116-457: The first response, that was evidence that the activity was chemical in nature. However, a nil, or greatly diminished response, was evidence for biology. This same control was to be used for any of the three life detection experiments that showed a positive initial result. The initial assessment of results from the Viking 1 PR experiment was that "analysis of the results shows that a small but significant formation of organic matter occurred" and that

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3192-409: The gas exchange experiment is producing analogous results to those from Viking 1. Again, oxygen disappeared once the nutrient solution came into contact with the soil. Again, carbon dioxide began to appear and still continues to evolve". The labeled release ( LR ) experiment (PI: Gilbert Levin , Biospherics Inc.) gave the most promise for exobiologists . In the LR experiment, a sample of Martian soil

3268-452: The global science community. Selected, significant topics of interdisciplinary research by NAI as of 2008: Viking biological experiments In 1976 two identical Viking program landers each carried four types of biological experiments to the surface of Mars . The first successful Mars landers, Viking 1 and Viking 2 , then carried out experiments to look for biosignatures of microbial life on Mars . The landers each used

3344-577: The icy bodies orbiting the Sun, so detecting no trace of any organic compound on the surface of Mars came as a surprise. The GC-MS was definitely working, because the controls were effective and it was able to detect traces of chlorine, attributed to the cleaning solvents that had been used to sterilize it prior to launch. A reanalysis of the GC-MS data was performed in 2018, suggesting that organic compounds may actually have been detected, corroborating with data from

3420-519: The importance of this finding with respect to the results obtained by Viking as "while perchlorate is too poor an oxidizer to reproduce the LR results (under the conditions of that experiment perchlorate does not oxidize organics), it does oxidize, and thus destroy, organics at the higher temperatures used in the Viking GCMS experiment. NASA astrobiologist Chris McKay has estimated, in fact, that if Phoenix -like levels of perchlorates were present in

3496-522: The initial incubation would then produce still more radioactive gas as the dormant bacteria sprang into action to consume the new dose of food. This was not true of the Martian soil; on Mars, the second and third nutrient injections did not produce any further release of labeled gas." The 2011 edition of the same textbook noted that "Albet Yen of the Jet Propulsion Laboratory has shown that, under extremely cold and dry conditions and in

3572-402: The instrument sampled the atmosphere of the incubation chamber and used a gas chromatograph to measure the concentrations of several gases, including oxygen , CO 2 , nitrogen , hydrogen , and methane . The scientists hypothesized that metabolizing organisms would either consume or release at least one of the gases being measured. In early November 1976, it was reported that "on Viking 2,

3648-420: The interpretation of the GCMS results inconclusive. The gas exchange ( GEX ) experiment (PI: Vance Oyama , NASA Ames) looked for gases given off by an incubated soil sample by first replacing the Martian atmosphere with the inert gas helium . It applied a liquid complex of organic and inorganic nutrients and supplements to a soil sample, first with just nutrients added, then with water added too. Periodically,

3724-542: The level of once living or decomposed matter. Some definitions of organic matter likewise only consider "organic matter" to refer to only the carbon content or organic compounds and do not consider the origins or decomposition of the matter. In this sense, not all organic compounds are created by living organisms, and living organisms do not only leave behind organic material. A clam's shell, for example, while biotic , does not contain much organic carbon , so it may not be considered organic matter in this sense. Conversely, urea

3800-414: The nutrients in the soil. There are several ways to quickly increase the amount of humus. Combining compost, plant or animal materials/waste, or green manure with soil will increase the amount of humus in the soil. These three materials supply nematodes and bacteria with nutrients for them to thrive and produce more humus, which will give plants enough nutrients to survive and grow. Soil organic matter

3876-463: The positive result from the Labeled Release experiment, a general assessment is that the results seen in the four experiments are best explained by oxidative chemical reactions with the Martian soil. One of the current conclusions is that the Martian soil, being continuously exposed to UV light from the Sun (Mars has no protective ozone layer ), has built up a thin layer of a very strong oxidant . A sufficiently strong oxidizing molecule would react with

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3952-499: The positive results seen by the Labeled Release experiment (see below). A 2011 astrobiology textbook notes that this was the decisive factor due to which "For most of the Viking scientists, the final conclusion was that the Viking missions failed to detect life in the Martian soil." Experiments conducted in 2008 by the Phoenix lander discovered the presence of perchlorate in Martian soil. The 2011 astrobiology textbook discusses

4028-703: The possibility of life there. Since then, methane has been discovered in Mars ' atmosphere at 10ppb, thus reopening this debate. Although in 2013 the Curiosity rover failed to detect methane at its location in levels exceeding 1.3ppb. later in 2013 and in 2014, measurements by Curiosity did detect methane, suggesting a time-variable source. The ExoMars Trace Gas Orbiter , launched in March 2016, implements this approach and will focus on detection, characterization of spatial and temporal variation, and localization of sources for

4104-467: The problems of survival of life on other planets. However, he also considered that the conditions found on Mars were incompatible with carbon based life. In August 2008, the Phoenix lander detected perchlorate , a strong oxidizer when heated above 200 °C. This was initially thought to be the cause of a false positive LR result. However, results of experiments published in December 2010 propose that organic compounds "could have been present" in

4180-485: The process of decaying or decomposing , such as humus . A closer look at the biological material in the process of decaying reveals so-called organic compounds ( biological molecules ) in the process of breaking up (disintegrating). The main processes by which soil molecules disintegrate are by bacterial or fungal enzymatic catalysis . If bacteria or fungi were not present on Earth, the process of decomposition would have proceeded much slower. Various factors impact

4256-402: The products in a device which counted radioactivity. If any of the C had been converted to biomass, it would be vaporized during heating and the radioactivity counter would detect it as evidence for life. Should a positive response be obtained, a duplicate sample of the same soil would be heated to "sterilize" it. It would then be tested as a control and should it still show activity similar to

4332-429: The puzzling results seen when more nutrients were added to the soil in the LR experiment; because life multiplies, the amount of gas should have increased when a second or third batch of nutrients was added, but if the effect was due to a chemical being consumed in the first reaction, no new gas would be expected. Lastly, many superoxides are relatively unstable and are destroyed at elevated temperatures, also accounting for

4408-530: The question of whether Viking found organic compounds is still wide open, as alternative chemical and biological interpretations are possible. In 2013, astrobiologist Richard Quinn at the Ames Center conducted experiments in which amino acids reacting with hypochlorite, which is created when perchlorate is irradiated with gamma rays, seemed to reproduce the findings of the labeled-release experiment. He concluded that neither hydrogen peroxide nor superoxide

4484-401: The reason for the priming effect, a few undisputed facts have emerged from the collection of recent research: Recent findings suggest that the same priming effect mechanisms acting in soil systems may also be present in aquatic environments, which suggests a need for broader considerations of this phenomenon in the future. One suitable definition of organic matter is biological material in

4560-496: The reducing power of the organic compounds of the organisms. It has also been argued that the Labeled Release (LR) experiment detected so few metabolising organisms in the Martian soil, that it would have been impossible for the gas chromatograph to detect them. This view has been put forward by the designer of the LR experiment, Gilbert Levin, who believes the positive LR results are diagnostic for life on Mars. He and others have conducted ongoing experiments attempting to reproduce

4636-457: The sample from underneath a rock; both initial injections came back positive. Sterilization control tests were subsequently carried out by heating various soil samples. Samples heated for 3 hours at 160 °C gave off no radioactive gas when nutrients were injected, and samples heated for 3 hours at 50 °C exhibited a substantial reduction in radioactive gas released following nutrient injection. A sample stored at 10 °C for several months

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4712-459: The soil analyzed by both Viking 1 and 2 , since NASA's Phoenix lander in 2008 detected perchlorate, which can break down organic compounds. The study's authors found that perchlorate can destroy organics when heated and produce chloromethane and dichloromethane as byproduct, the identical chlorine compounds discovered by both Viking landers when they performed the same tests on Mars. Because perchlorate would have broken down any Martian organics,

4788-488: The soil comes from groundwater . When the groundwater saturates the soil or sediment around it, organic matter can freely move between the phases. Groundwater has its own sources of natural organic matter including: Organisms decompose into organic matter, which is then transported and recycled. Not all biomass migrates, some is rather stationary, turning only over the course of millions of years. The organic matter in soil derives from plants, animals and microorganisms. In

4864-508: The soil creates problems for current water purification methods. In water, organic matter can still bind to metal ions and minerals. The purification process does not necessarily stop these bound molecules but does not cause harm to any humans, animals, or plants. However, because of the high reactivity of organic matter, by-products that do not contain nutrients can be made. These by-products can induce biofouling , which essentially clogs water filtration systems in water purification facilities, as

4940-399: The soil exclusive of the material that has not decayed. An important property of soil organic matter is that it improves the capacity of a soil to hold water and nutrients, and allows their slow release, thereby improving the conditions for plant growth. Another advantage of humus is that it helps the soil to stick together which allows nematodes , or microscopic bacteria, to easily decay

5016-502: The soil is heated to check for organics, perchlorate destroys them rapidly producing chloromethane and dichloromethane, which is what the Viking landers found. This team also notes that this is not a proof of life but it could make a difference in how scientists look for organic biosignatures in the future. Results from the current Mars Science Laboratory mission and the under-development ExoMars program may help settle this controversy. In 2006, Mario Crocco went as far as proposing

5092-465: The soil is heated to different temperatures. It could measure molecules present at a level of a few parts per billion. The GCMS measured no significant amount of organic molecules in the Martian soil. In fact, Martian soils were found to contain less carbon than lifeless lunar soils returned by the Apollo program . This result was difficult to explain if Martian bacterial metabolism was responsible for

5168-592: The soil to create compounds never seen before. Unfortunately, it is challenging to characterize these because so little is known about natural organic matter in the first place. Research is currently being done to determine more about these new compounds and how many are being formed. Aquatic organic matter can be further divided into two components: (1) dissolved organic matter (DOM), measured as colored dissolved organic matter (CDOM) or dissolved organic carbon (DOC), and (2) particulate organic matter (POM). They are typically differentiated by that which can pass through

5244-455: The soil, it resulted in intensified mineralization by the humus N. It was not until 1953, though, that the term priming effect was given by Bingeman in his paper titled, The effect of the addition of organic material on the decomposition of an organic soil . Several other terms had been used before priming effect was coined, including priming action, added nitrogen interaction (ANI), extra N and additional N. Despite these early contributions,

5320-406: The sterilized control showed no evidence of organics, showing that the "findings could be attributed to biological activity." However, given the persistence of organic release at 90 °C, the inhibition of organics after injecting water vapor and, especially, the lack of detection of organics in the Martian soil by the GCMS experiment, the investigators concluded that a nonbiological explanation of

5396-616: The surface of the planet. Living organisms are composed of organic compounds. In life, they secrete or excrete organic material into their environment, shed body parts such as leaves and roots and after organisms die, their bodies are broken down by bacterial and fungal action. Larger molecules of organic matter can be formed from the polymerization of different parts of already broken down matter. The composition of natural organic matter depends on its origin, transformation mode, age, and existing environment, thus its bio-physicochemical functions vary with different environments. Organic matter

5472-434: The thermal stability of hypochlorite and other oxychlorine species in the context of the LR experiments." Before the discovery of the oxidizer perchlorate on Mars in 2008, some theories remained opposed to the general scientific conclusion. An investigator suggested that the biological explanation of the lack of detected organics by GC-MS could be that the oxidizing inventory of the H 2 O 2 -H 2 O solvent well exceeded

5548-442: Was added to desert soil from Chile containing organics and analyzed in the manner of the Viking tests." However, the 2010 NASA press release also noted that: "One reason the chlorinated organics found by Viking were interpreted as contaminants from Earth was that the ratio of two isotopes of chlorine in them matched the three-to-one ratio for those isotopes on Earth. The ratio for them on Mars has not been clearly determined yet. If it

5624-625: Was appointed the first Director of the institute, and served from May 15, 1999 – October 14, 2002. The NASA Astrobiology Program includes the NAI as one of four components, including the Exobiology and Evolutionary Biology Program; the Astrobiology Science and Technology Instrument Development (ASTID) Program; and the Astrobiology Science and Technology for Exploring Planets (ASTEP) Program. Program budgets for fiscal year 2008 were as follows: NAI, $ 16 million; Grants for

5700-401: Was inoculated with a drop of very dilute aqueous nutrient solution. The nutrients (7 molecules that were Miller-Urey products) were tagged with radioactive C. The air above the soil was monitored for the evolution of radioactive CO 2 (or other carbon-based ) gas as evidence that microorganisms in the soil had metabolized one or more of the nutrients. Such a result was to be followed with

5776-419: Was later tested showing significantly reduced radioactive gas release. A CNN article from 2000 noted that "Though most of his peers concluded otherwise, Levin still holds that the robot tests he coordinated on the 1976 Viking lander indicated the presence of living organisms on Mars." A 2006 astrobiology textbook noted that "With unsterilized Terrestrial samples, though, the addition of more nutrients after

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