An analytical representation of non-gyrotropic distributions and related space applications

Clear signature of non-gyrotropic energetic electron distributions was found by ISEE 1 and ISEE 2 spacecrafts just upstream of the Earth's bow shock and recently detected by in situ observations of the WIND plasma experiment. On the other hand, the appearance of non-gyrotropic ion velocity distributions is well established in the magnetotail providing evidence of magnetic reconnection processes. Motivated by these findings we introduce an analytical representation of non-Maxwellian/non-gyrotropic distribution functions, accurately fitting the characteristics of observations, where Maxwellians are recovered as special case of these highly general velocity space distributions. In particular, the analytical distribution function model can serve as basis of detailed wave-particle interaction analysis and of studies of the physical background of the evolution of both, non-gyrotropic electron and ion distributions, which is discussed for various space plasma environments.     

The use of the National Research Council of Canada's Falcon 20 research aircraft as a terrestrial analogue space environment (TASE) for space surgery research: Challenges and suggested solutions

Emergency surgery will be needed to prevent death if humans are used to explore beyond low earth's orbit. Laparoscopic surgery (LS) is envisioned as a less invasive option for space, but will induce further stresses and complicate logistical requirements. Thus, further study into the technology and physiology of LS in weightlessness is required. We recently utilized the National Research Council of Canada's Flight Research Laboratory's Falcon 20 aircraft as a terrestrial analogue space environment (TASE) for space surgery research. The Falcon 20 had never been used for this purpose nor had the involved teams collaborated previously. There were many process challenges including the lack of antecedent surgical studies on this aircraft, a requirement for multiple disciplines who were unfamiliar and geographically distant from each other, flight performance limitations with the Falcon 20, complex animal care requirements, requirements for prototypical in-flight life-support surgical suites, financial limitations, and a need to use non-flight hardened technologies. Stepwise suggested solutions to these challenges are outlined as guidelines for future investigators intending similar research. Overall, the Falcon 20 TASE, backed by the flight resources, especially the design and fabrication capabilities of the NRC-FRL, provide investigators with a versatile and responsive opportunity to pursue research into advanced medical techniques that will be needed to save lives during space exploration.     

Advances in numerical modeling of astrophysical and space plasmas

Plasma science is rich in distinguishable scales ranging from the atomic to the galactic to the meta-galactic, i.e., themesoscale. Thus plasma science has an important contribution to make in understanding the connection between microscopic and macroscopic phenomena. Plasma is a system composed of a large number of particles which interact primarily, but not exclusively, through the electromagnetic field. The problem of understanding the linkages and couplings in multi-scale processes is a frontier problem of modern science involving fields as diverse as plasma phenomena in the laboratory to galactic dynamics.Unlike the first three states of matter, plasma, often called the fourth state of matter, involves the mesoscale and its interdisciplinary founding have drawn upon various subfields of physics including engineering, astronomy, and chemistry. Basic plasma research is now posed to provide, with major developments in instrumentation and large-scale computational resources, fundamental insights into the properties of matter on scales ranging from the atomic to the galactic. In all cases, these are treated as mesoscale systems. Thus, basic plasma research, when applied to the study of astrophysical and space plasmas, recognizes that the behavior of the near-earth plasma environment may depend to some extent on the behavior of the stellar plasma, that may in turn be governed by galactic plasmas. However, unlike laboratory plasmas, astrophysical plasmas will forever be inaccessible to in situ observation. The inability to test concepts and theories of large-scale plasmas leaves only virtual testing as a means to understand the universe. Advances in in computer technology and the capability of performing physics first principles, fully three-dimensional, particle-in-cell simulations, are making virtual testing a viable alternative to verify our predictions about the far universe.The first part of this paper explores the dynamical and fluid properties of the plasma state, plasma kinetics, and the radiation emitted from plasmas. The second part of this paper outlines the formulation for the particle-in-cell simulation of astrophysical plasmas and advances in simulational techniques and algorithms, as-well-as the advances that may be expected as the computational resource grows to petaflop speed/memory capabilities.Dedicated to the memories of Hannes Alfvén and Oscar Buneman; Founders of the Subject.     

On the application of magnetic methods for the characterisation of space weathering products

Space weathering is now commonly accepted to modify the optical and magnetic properties of airless body regoliths throughout the Solar System. Although the precise formation processes are not well understood, the presence of ubiquitous sub-microscopic metallic iron (SMFe) grains in lunar soils and corresponding spectral analyses have explained both the unique optical and magnetic properties of such soils. More recently, a variety of ion irradiation, laser melting and vaporisation and impact experiments have been shown to reproduce these effects in the laboratory. Such experiments are crucial to the study of the formation of SMFe under controlled conditions. To date, more emphasis has been placed on optical analyses of laboratory samples, as these address directly the mineralogical interpretation of remote sensing data. However, the magnetic analyses performed on the Apollo and Luna samples have provided useful qualitative and quantitative evaluation of regolith metallic iron content. These techniques are reviewed here, demonstrated on pulsed laser irradiated olivine powder, and their utility for determining the quantity and size distribution of this metallic iron discussed. Ferromagnetic resonance, multi-frequency magnetic susceptibility, vibrating sample magnetometry and thermomagnetic measurements were carried out. Each showed trends expected for the conversion of paramagnetic Fe²⁺ in olivine to fine-grained Fe⁰, with some grains in the superparamagnetic size range. Although evidence for superparamagnetic iron was found, the quantity of sub-microscopic metallic iron produced in these experiments proved insufficient to make conclusive measurements of either the quantity or size distribution of this iron. Improvements to both the experimental and analytical procedures are discussed to better enable such measurements in the future.     

Experimental study of the sublimation of ice through an unconsolidated clay layer: Implications for the stability of ice on Mars and the possible diurnal variations in atmospheric water

We have studied the sublimation of ice and water vapor transport through various thicknesses of clay (<63 μm grain size). We experimentally demonstrate that both adsorption and diffusion strongly affect the transport of water, and that the processes of diffusion and adsorption can be separately quantified once the system comes to a steady state. At shallow depths of clay, water vapor transport is determined by diffusion through both the atmosphere and the clay layer, whereas at greater depth the rate of sublimation of the ice is governed only by diffusion through the clay. Using two different models, we determine the diffusion coefficient for water vapor through unconsolidated clay layer to be 1.08±0.04×¹⁰⁻⁴ and . We also determined the adsorption isotherms for the clay layer, which follow the Langmuir theory at low water vapor pressure (<100 Pa, where a monolayer of water molecules forms on the surface of the clay) and the BET theory at higher pressure (where multiple water layers form). From our analysis of both types of isotherms we determined the adsorption constants to be and c=30±10, respectively, and specific surface areas of 1.10±0.2×¹⁰⁵ and , respectively. Finally, we report a theoretical kinetic model for the simultaneous diffusion and adsorption from which we determine adsorption kinetic constants according to the Langmuir theory of and . If the martian regolith possesses diffusive properties similar to those of the unconsolidated montmorillonite soil we investigated here, it would not represent a significant barrier to the sublimation of subsurface ice. However, at the low subsurface temperatures of high latitude (180 K on average), ice could survive from the last glaciation period (about 300 to 400,000 years ago). Higher subsurface temperatures in the equatorial regions would prevent long-timescale survival of ice in the shallow subsurface. In agreement with previous work, we show that adsorption of water by a clay regolith could provide a significant reservoir of subsurface water and it might account for the purported diurnal cycle in the water content of the atmosphere.     

Notes on applications of General Relativity in free space

Varying the step, at which Lorentz signature is introduced in the scheme of applications of general relativity outside the material distribution, new solutions can be obtained. The interpretations of these solutions can be achieved if the field equations R_μv = 0 are written in a wider space than the Riemannian one. A counter example is given in favour of this claim.     

Use of multi-point analysis and modelling to address cross-scale coupling in space plasmas: Lessons from Cluster

The properties of plasmas (in space) are fundamentally governed by both ‘cross-scale’ coupling and comparative temporal behaviour operating over the micro-, meso-, and (MHD-) fluid regimes: for example, under conditions of turbulence, during magnetic reconnection and in shocks and other plasma boundaries. These themes map to a number of related and overlapping, phenomena, where known phenomena play different roles in each theme. Detailed understanding of fundamental plasma processes therefore requires analysis of both theoretical models (to distinguish the collisionless from the collisional regimes) and multi-scale measurements (suitable to address issues of stationarity). In particular, the investigation of phenomena requires analysis techniques which can distinguish and quantify temporal behaviour and the multi-scale spatial behaviour. The analysis of existing, multi-point data sets has led to a number of data co-ordination methods, such as the four spacecraft analysis tools developed for cluster, and we consider examples here. Advanced analysis concepts may be investigated with suitable considerations of measurement quality:adequate sampling of phenomena (for example, to extract the necessary information on the mechanisms operating) requires suitable spacecraft configurations and directly relates to the measurement quality achievable. A particular issue is how to resolve temporal behaviour across the spatial regimes, so that the data set is suitably coordinated. With the addition of theoretical modelling (in the context of particular phenomena) both the space and laboratory plasma regimes may be compared and we give an example of nonlinear wave coupling across spatial scales in this context.     

Raman spectroscopic detection of key biomarkers of cyanobacteria and lichen symbiosis in extreme Antarctic habitats: Evaluation for Mars Lander missions

With proposals that micro-miniaturised Raman spectrometers could soon be part of a suite of analytical instrumentation on the surface of Mars, it is critically important to examine the spectral information that could be forthcoming from attempts to determine key molecular biosignatures under the hostile conditions of extra-terrestrial planetary exploration. Current approaches include the analysis of genuine martian geological material in the form of the SNC class meteorites, the formulation of simulated martian regoliths and the examination of putative martian terrestrial analogues; the latter provide the basis of this paper in the form of Antarctic extremophile habitats. In particular, specimens of epilithic, chasmolithic and endolithic lichen and cyanobacterial colonies sampled along a progressively worsening transect towards a “limits of life” situation, beyond which survival of organisms becomes impossible, provide what is arguably the best terrestrial proving-ground for prototype Raman spectrometers for martian exploration. Here, we report the results of experiments on these extant Antarctic extremophile colonies using a range of Raman excitation wavelengths and experimental conditions and also include a compilation of molecular spectral biosignatures, which may be considered as a suitable database for recognition of bioorganic modification of geological strata.     

Thinned simulations of extremely energetic showers in dense media for radio applications

This paper presents our results for full 3-D simulations of very-high to ultra-high energy electromagnetic cascades – and the associated coherent Cherenkov radiation – as might be produced by high-energy neutrino interactions in dense media. Using “thinning” techniques, we develop an algorithm based on the existing “ZHS” code, and demonstrate that the new “ZHS-thinned” code can produce fast and accurate results for showers up to . Using ZHS-thinned, we develop new parameterisations for the radiation from showers in ice, salt, and the lunar regolith, with a separate treatment of the megaregolith (deep regolith). Our parameterisations include for the first time a method to simulate fluctuations in shower length induced by the LPM effect. Our results, which avoid the pit-falls of scaling simulations from lower energies, allow improved calculations of the detection probability for experiments searching for high-energy neutrinos using the radio technique.     

Elastic collisions in ion irradiation experiments: A mechanism for space weathering of silicates

Ion irradiation experiments have been performed on silicates (bulk samples) rich of olivine, pyroxene, and serpentine to simulate the effects of space weathering induced on asteroids by solar wind ions. We have used different ions (H⁺, He⁺, Ar⁺, Ar²⁺) having different energies (from 60 to 400 keV) to weather the samples, probed by Raman spectroscopy and UV-vis-NIR reflectance spectroscopy. All the irradiated materials have shown reddening and darkening of reflectance spectra in the 0.25-2.7 μm spectral range. We have found that the increase of the spectral slope of the continuum across the 1-μm band is strongly related with the number of displacements caused by colliding ions because of elastic collisions with the target nuclei. The spectral slopes have been compared, at increasing ion fluence, with those from irradiated Epinal meteorite. We show that formation of nuclear displacements by solar wind ion irradiation is a physical mechanism that reddens the asteroidal surfaces on a time-scale lower than 10⁶ years.     

A strain-based porosity model for use in hydrocode simulations of impacts and implications for transient crater growth in porous targets

Numerical modelling of impact cratering has reached a high degree of sophistication; however, the treatment of porous materials still poses a large problem in hydrocode calculations. We present a novel approach for dealing with porous compaction in numerical modelling of impact crater formation. In contrast to previous attempts (e.g., P-alpha model, snowplow model), our model accounts for the collapse of pore space by assuming that the compaction function depends upon volumetric strain rather than pressure. Our new ?-alpha model requires only four input parameters and each has a physical meaning. The model is simple and intuitive and shows good agreement with a wide variety of experimental data, ranging from static compaction tests to highly dynamic impact experiments. Our major objective in developing the model is to investigate the effect of porosity and internal friction on transient crater formation. We present preliminary numerical model results that suggest that both porosity and internal friction play an important role in limiting crater growth over a large range in gravity-scaled source size.     

Evaluation of cell lysis procedures and use of a micro fluidic system for an automated DNA-based cell identification in interplanetary missions

A Modular Assay System for Solar System Exploration (MASSE) is being developed to include sample handling, pre-treatment, separation and analysis of biological target compounds by both DNA and protein microarrays. To better design sensitive and accurate initial upstream sample handling of the MASSE instrument, experiments investigating the sensitivity and potential extraction bias of commercially available DNA extraction kits between classes of environmentally relevant prokaryotes such as gram-negative bacteria (Escherichia coli), gram-positive bacteria (Bacillus megatarium), and Archaea (Haloarcula marismortui) were performed. For extractions of both planktonic cultures and spiked Mars simulated regolith, FTA^® paper demonstrated the highest sensitivity, with detection as low as 1×10¹ cells and 3.3×10² cells, respectively. In addition to the highest sensitivity, custom modified application of FTA^® paper extraction protocol is the simplest in terms of incorporation into MASSE and displayed little bias in sensitivity with respect to prokaryotic cell type. The implementation of FTA paper for environmental microbiology investigations appears to be a viable and effective option potentially negating the need for other pre-concentration steps such as filtration and negating concerns regarding extraction efficiency of cells. In addition to investigations on useful technology for upstream sample handling in MASSE, we have also evaluated the potential for μTAS to be employed in the MASSE instrument by employing proprietary lab-on-a-chip development technology to investigate the potential for microfluidic cell lysis of different prokaryotic cells employing both chemical and biological lysis agents. Real-time bright-field microscopy and quantitative PMT detection indicated that that gram positive, gram negative and archaeal cells were effectively lyzed in a few seconds using the microfluidic chip protocol developed. This included employing a lysis buffer with components including lysozyme, Protease, Proteinase K, Tween-20 and TritonX-100. The effectiveness of antibiotics and other chemical lysis agents were also screened and demonstrated partial effectiveness on all three cell types. This work demonstrates a step wise approach to evaluating the efficacy and sensitivity of commercial macro-scale technology and state-of-the-art developmental microfluidic technology under consideration for incorporation into the remotely operated MASSE instrument currently under development at the Carnegie Institution of Washington.     

The analysis of indexed astronomical time series –VII. Simultaneous use of times of maxima and minima to test for period changes in long-period variables

A statistical model is formulated that enables one to analyse jointly the times between maxima and minima in the light curves of monoperiodic pulsating stars. It is shown that the combination of both sets of data into one leads to analyses that are more sensitive. Illustrative applications to the American Association of Variable Star Observers data for a number of long-period variables demonstrate the usefulness of the approach.     

Motion in the field of a rotationally symmetric potential: Exact use of an approximate equation for the derivative of the field of directions along the normal to a trajectory

The previously derived equation (Agekyan 1974) for the derivative ?f/?n of the field of directions along the normal to a trajectory is approximate, because differentiating along the normal takes the point out of the orbit and changes the third integral of motion. However, on the envelope of the trajectory, i.e., on the contour of an orbit or a fold, ?f/?n undergoes a discontinuity of the second kind. Many authors have used this property to find points of the contours of orbits and folds. Although the integrable equation is approximate, the envelope points are determined accurately.