Bonnie J. Berdahl

A model of Martian surface chemistry

SummaryAlkaline earth and alkali metal superoxides and peroxides,γ-Fe2O3 and carbon suboxide polymer are proposed to be constituents of the Martian surface material. These reactive substances explain the water modified reactions and thermal behaviors of the Martian samples demonstrated by all of the Viking Biology Experiments. It is also proposed that the syntheses of these substances result mainly from electrical discharges between wind-mobilized particles at Martian pressures; plasmas are initiated and maintained by these discharges. Active species in the plasma either combine to form or react with inorganic surfaces to create the reactive constitutents.

The search for life on Mars - Viking 1976 gas changes as indicators of biological activity

Gas compositional changes in the headspace of the Viking Biology Gas Exchange Experiment can originate from biological activity as well as redox chamical reactions, sorption and desorption phenomena, acid-base reactions, and trapped gas release. Biological phenomena are differentiated from the nonbiological gas changes by their dynamical qualities, notably by the ability of the M4 medium to sustain biological activity. Medium incompatibilities, with potential microbial types in soils, are demonstrated to be ameliorated by an incubation chamber design that provides thin films of medium around particulate soil masses and salt gradients when the soil is wet from below. Two phenomena in soils, the production and consumption of hydrogen and carbon monoxide, are coupled for a newly isolatedClostridium sp. A decrease in molecular nitrogen production by denitrifying organisms in the second and subsequent incubation cycles results from competitive nitrate utilization by anaerobic organisms. All soils tested from the cold, dry desert regions of Antarctica contain predominantly aerobic organisms while only six of the twelve soils respire using nitrate under anaerobic conditions. Although dry Antarctica soils are not the best simulations of Martian anoxic conditions, their responses show that long incubation times may be needed on Mars to demonstrate biological gas change phenomena.

The chemical activities of the Viking biology experiments and the arguments for the presence of superoxides, peroxides, gamma-Fe2O3 and carbon suboxide polymer in the Martian soil

The evolution of N2, Ar, O2, and CO2 from Martian soil as a function of humidity in the Gas Exchange Experiment are correlated with the mean level of water vapor in the Martian atmosphere. All but O2 are associated with desorption. The evolution of oxygen is consistent with the presence of alkaline earth and alkali metal superoxides; and their peroxides and the gamma-Fe2O3 in the soil can account for the generation of radioactive gas in the Labeled Release Experiment. The slower evolution of CO2 from both the Gas Exchange Experiment and the Labeled Release Experiment are associated with the direct oxidation of organics by gamma-Fe2O3. The Pyrolytic Release Experiments second peak may be carbon suboxide as demonstrated by laboratory experiments. A necessary condition is that the polymer exists in the Martian soil. We ascribe the activity of the surface samples to the reaction of Martian particulates with an anhydrous CO2 atmosphere activated by uv and ionizing radiations. The surface particles are ultimately altered by exposure to small but significant amounts of water at the sites. From the working model, we have predicted the peculiar nature of the chemical entities and demonstrated that the model is justified by laboratory data. The final confirmation of this model will entail a return to Mars, but the nature and implications of this chemistry for the Martian surface is predicted to reveal even more about Mars with further simulations in the laboratory.

Deficiency of the DNA of Micrococcus radiodurans in methyladenine and methylcytosine.

Abstract Micrococcus radiodurans , an extraordinarily radiation-resistant organism, was found to have no detectable methylated bases in its DNA nor any DNA methyltransferase activity. The DNA can receive methyl groups in vitro from enzymes from heterologous sources. It thus may serve as ‘methyl-deficient’ DNA.

Carbon suboxide polymer, an explanation for the wave of darkening on Mars

The carbon suboxide thermal polymer or its irradiated product is affected by water vapor. The polymerized carbon suboxide simulates the Martian wave of darkening on an inner wall of a glass tube when humidified by passage of water vapor through the tube. The polymer is visibly darkened by the advancing vapor front. With increasing polymer thickness or water vapor concentration, or both, the wave of darkening similarly intensifies thus simulating the dark fringe in the Martian circumpolar areas. It is hypothesized that light and dark areas have polymer coatings, but light areas have small particles that scatter white light more effectively and appear brighter on the surface of Mars. It is proposed that on Mars, there is a continual lightening of the surface by particulate material settling from the atmosphere.

IMPLICATIONS OF THE HYPOHYDROUS HISTORY OF MARS

We have shown that clays, carbonates, α-Fe 2 O 3 , and Fe 3 O 4 . impart an alkaline state to aqueous solutions that govern the rate of decomposition of H 2 O 2 . In the presence of these materials singly, the production of 14 CO 2 from the oxidative decarboxylation process catalyzed by γ-Fe 2 O 3 is strongly inhibited. Because the results of the Viking Labeled Release Experiment were simulated exactly by the γ-Fe 2 O 3 /H 2 O 2 system, we conclude that these materials (clays, etc.) are not in such an abundance as to quench the peroxidase activity demonstrated on Mars. Because these materials are generally formed in an aqueous environment, we conclude that Mars has had a very long hypohydrous history.