Microbial fuel cells applied to the metabolically based detection of extraterrestrial life

Since the 1970s, when the Viking spacecrafts carried out experiments to detect microbial metabolism on the surface of Mars, the search for nonspecific methods to detect life in situ has been one of the goals of astrobiology. It is usually required that a methodology detect life independently from its composition or form and that the chosen biological signature point to a feature common to all living systems, such as the presence of metabolism. In this paper, we evaluate the use of microbial fuel cells (MFCs) for the detection of microbial life in situ. MFCs are electrochemical devices originally developed as power electrical sources and can be described as fuel cells in which the anode is submerged in a medium that contains microorganisms. These microorganisms, as part of their metabolic process, oxidize organic material, releasing electrons that contribute to the electric current, which is therefore proportional to metabolic and other redox processes. We show that power and current density values measured in MFCs that use microorganism cultures or soil samples in the anode are much larger than those obtained with a medium free of microorganisms or sterilized soil samples, respectively. In particular, we found that this is true for extremophiles, which have been proposed as potential inhabitants of extraterrestrial environments. Therefore, our results show that MFCs have the potential to be used for in situ detection of microbial life.     

Some psychophysiological and behavioral aspects of adaptation to simulated autonomous Mission to Mars

“Mars-105” experiment was executed in March–July 2009 in Moscow, at the Institute for Bio-Medical Problems (IBMP) with participation of European Space Agency (ESA) to simulate some specific conditions of future piloted Mars mission. In the last 35 days of isolation, in order to simulate autonomous flight conditions, some serious restrictions were established for the crew resupply and communication with Mission Control (MC). The objective of the study was to investigate psychophysiological and behavioral aspects (communication) of adaptation during this period of “high autonomy”. We used computerized analysis of the crew written daily reports to calculate the frequencies of utilization of certain semantic units, expressing different psychological functions. To estimate the level of psycho-physiological stress, we measured the concentration of urinal cortisol once in two weeks. To investigate psycho-emotional state, we used the questionnaire SAN, estimating Mood, Activity and Health once in two weeks.During the simulation of autonomous flight, we found out the different tendencies of communicative behavior. One group of subjects demonstrated the tendency to “activation and self-government” under “high autonomy” conditions. The other subjects continued to use communicative strategy that we called “closing the communication channel”. “Active” communication strategy was accompanied by increasing in subjective scores of mood and activity. The subjects, whose communication strategy was attributed as “closing”, demonstrated the considerably lower subjective scores of mood and activity. Period of high autonomy causes specific changes in communication strategies of the isolated crew.     

A method for calculating the resistance of spacecraft design elements under the action of space debris particles

In this paper, the problems of the application and development of models of space debris when designing means of the anti-meteorite spacecraft protection are considered. The developed method enables us to calculate the resistance of design elements based on the conjugation of a modified spatial model of the distribution of space-debris particles and ballistic limit dependences for a calculated element.     

Improved Switching Converter Model Using Discrete and Averaging Techniques

The nonlinear modeling and analysis of dc-dc converters has been done by averaging and discrete-sampling techniques. The averaging technique is simple, but inaccurate, as the modulation frequencies approach the theoretical limit of one-half the switching frequency. The discrete technique is accurate even at high frequencies, but is very complex and cumbersome. An improved model is developed by combining the aforementioned techniques. This new model is easy to implement in circuit and state variable forms and is accurate to the theoretical limit.     

An Optimally Integrated Track Recovery System for Aerial Bathymetry

An airborne system has been developed for charting shallow coastal and inland waters. The primary components of this system are an aerial survey camera, a profiling laser radar, an analytical stereo plotter, and a multisensor track recovery system (TRS). The TRS comprises a gimbaled inertial navigation system and a number of auxiliary sensors which acquire redundant position and attitude information. The sensor data are combined postmission using a U-D factorized Kalman filter and modified Bryson-Frazier smoother to compute accurate estimates of the orientation parameters of the survey camera at the times of film exposure. These parameters are used to position each overlapping pair of photographs on the analytical plotter to form a stereo image and corresonding analytical stereomodel from which water depth measurements are made. Flight trial results demonstrate that the TRS can achieve radial position and attitude accuracies which exceed 1 m and 2 arcmin root mean square (rms), respectively, and that this level of performance is sufficient to enable water depth measurements to be made to an accuracy of better than 0.65 m (rms).     

Development of a gas chromatography compatible Sample Processing System (SPS) for the in-situ analysis of refractory organic matter in martian soil: preliminary results

In the frame of the 2009 Mars Science Laboratory (MSL) mission a new sample preparation system (SPS) compatible with gas chromatography–mass spectrometry (GC–MS) has been developed for the in situ analysis of complex organic molecules in the Martian soil. The goal is to detect, if they exist, some of the key compounds that play an important role in life on Earth including carboxylic acids, amino acids and nucleobases.     

Changes in vacuolation in the root apex cells of soybean seedlings in microgravity.

Changes in the vacuolation in root apex cells of soybean (Glycine max L. [Merr.]) seedlings grown in microgravity were investigated. Spaceflight and ground control seedlings were grown in the absence or presence of KMnO4 (to remove ethylene) for 6 days. After landing, in order to study of cell ultrastructure and subcellular free calcium ion distribution, seedling root apices were fixed in 2.5% (w/v) glutaraldehyde in 0.1 M cacodylate buffer and 2% (w/v) glutaraldehyde, 2.5% (w/v) formaldehyde, 2% (w/v) potassium antimonate K[Sb(OH)6] in 0.1 M K2HPO4 buffer with an osmolarity (calculated theoretically) of 0.45 and 1.26 osmol. The concentrations of ethylene in all spaceflight canisters were significantly higher than in the ground control canisters. Seedling growth was reduced in the spaceflight-exposed plants. Additionally, the spaceflight-exposed plants exhibited progressive vacuolation in the root apex cells, particularly in the columella cells, to a greater degree than the ground controls. Plasmolysis was observed in columella cells of spaceflight roots fixed in solutions with relatively high osmolarity (1.26 osmol). The appearance of plasmolysis permitted the evaluation of the water status of cells. The water potential of the spaceflight cells was higher than the surrounding fixative solution. A decrease in osmotic potential and/or an increase in turgor potential may have induced increases in cell water potential. However, the plasmolysed (i.e. non-turgid) cells implied that increases in water potential were accompanied with a decrease in osmotic potential. In such cells changes in vacuolation may have been involved to maintain turgor pressure or may have been a result of intensification of other vacuolar functions like digestion and storage.     

Computer modelling of a penetrator thermal sensor

The Philae lander is part of the Rosetta mission to investigate comet 67P/Churyumov-Gerasimenko. It will use a harpoon like device to anchor itself onto the surface. The anchor will perhaps reach depths of 1–2 m. In the anchor is a temperature sensor that will measure the boundary temperature as part of the MUPUS experiment. As the anchor attains thermal equilibrium with the comet ice it may be possible to extract the thermal properties of the surrounding ice, such as the thermal diffusivity, by using the temperature sensor data. The anchor is not an optimal shape for a thermal probe and application of analytical solutions to the heat equation is inappropriate. We prepare a numerical model to fit temperature sensor data and extract the thermal diffusivity. Penetrator probes mechanically compact the material immediately surrounding them as they enter the target. If the thermal properties, composition and dimensions of the penetrator are known, then the thermal properties of this pristine material may be recovered although this will be a challenging measurement. We report on investigations, using a numerical thermal model, to simulate a variety of scenarios that the anchor may encounter and how they will affect the measurement.     

An analysis of low-frequency component in microacceleration measurements made onboard the <Emphasis Type="Italic">Foton M-2</Emphasis> satellite

The low-frequency component is investigated in the data of measurements performed onboard the Foton M-2 satellite with the three-component accelerometer TAS-3. Investigations consisted in comparison of this component with its calculated analog found from a reconstruction of the satellite’s attitude motion. The influence of the Earth’s magnetic field on the accelerometer readings is discovered by way of spectral analysis of the functions representing the results of determining the low-frequency microacceleration by two methods. After making correction for this influence, the results obtained by these two methods coincided within a root-mean-square error of less than 10^?6 m/s².     

Comments on Stabilization of a Satellite

An expression is derived for the cost resultingfrom the stabilization of a satellite using aspecific optimal control (SOC). An exampleis given in which the optimal and SOC yieldvirtually identical costs.