A Pre-Landing Assessment of Regolith Properties at the InSight Landing Site

This article discusses relevant physical properties of the regolith at the Mars InSight landing site as understood prior to landing of the spacecraft. InSight will land in the northern lowland plains of Mars, close to the equator, where the regolith is estimated to be ≥3--5 m thick. These investigations of physical properties have relied on data collected from Mars orbital measurements, previously collected lander and rover data, results of studies of data and samples from Apollo lunar missions, laboratory measurements on regolith simulants, and theoretical studies. The investigations include changes in properties with depth and temperature. Mechanical properties investigated include density, grain-size distribution, cohesion, and angle of internal friction. Thermophysical properties include thermal inertia, surface emissivity and albedo, thermal conductivity and diffusivity, and specific heat. Regolith elastic properties not only include parameters that control seismic wave velocities in the immediate vicinity of the Insight lander but also coupling of the lander and other potential noise sources to the InSight broadband seismometer. The related properties include Poisson’s ratio, P- and S-wave velocities, Young’s modulus, and seismic attenuation. Finally, mass diffusivity was investigated to estimate gas movements in the regolith driven by atmospheric pressure changes. Physical properties presented here are all to some degree speculative. However, they form a basis for interpretation of the early data to be returned from the InSight mission.Additional co-authors: Nick Teanby and Sharon Keda

Macrosocial determinants of population health in the context of globalization

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/55738/1/florey_globalization_2007.pd

Determination of Melanterite-Rozenite and Chalcanthite-Bonattite Equilibria by Humidity Measurements at 0.1 MPa

Melanterite (FeSO4•7H2O)-rozenite (FeSO4•4H2O) and chalcanthite (CuSO4•5H2O)-bonattite (CuSO4•3H2O) equilibria were determined by humidity measurements at 0.1 MPa. Two methods were used; one is the gas-flow-cell method (between 21 and 98 °C), and the other is the humidity buffer method (between 21 and 70 °C). The first method has a larger temperature uncertainty even though it is more efficient. With the aid of humidity buffers, which correspond to a series of saturated binary salt solutions, the second method yields reliable results as demonstrated by very tight reversals along each humidity buffer. These results are consistent with those obtained by the first method, and also with the solubility data reported in the literature. Thermodynamic analysis of these data yields values of 29.231 ± 0.025 and 22.593 ± 0.040 kJ/mol for standard Gibbs free energy of reaction at 298.15 K and 0.1 MPa for melanterite-rozenite and chalcanthite-bonattite equilibria, respectively. The methods used in this study hold great potential for unraveling the thermodynamic properties of sulfate salts involved in dehydration reactions at near ambient conditions

On The Entropy Of Glaucophane Na2Mg3Al2Si8O22(Oh)2

The heat capacity of glaucophane from the Sesia-Lanza region of Italy having the approximate composition (Na1.93Ca0.05Fe0.02) (Mg2.60Fe0.41) (Al1.83 Fe0.15Cr0.01) (Si7.92Al0.08)O22(OH)2 was measured by adiabatic calorimetry between 4.6 and 359.4 K. After correcting the C(p)0 data to values for ideal glaucophane, Na2Mg3Al2Si8O22(OH)2 the third-law entropy S(298)0-S(0)0 was calculated to be 541.2 +/- 3.0 J.mol-1.K-1. Our value for S(298)0 - S(0)0 is 12.0 J.mol-1.K-1 (2.2%) smaller than the value of Likhoydov et al. (1982), 553.2 +/- 3.0, is within 6.2 J.mol-1.K-1 of the value estimated by Holland (1988), and agrees remarkably well with the value calculated by Gillet et al. (1989) from spectroscopic data, 539 J.mol-1.K-1

Modeling The Thermal Extraction Of Water Ice From Regolith

Modeling has been developed to support the development of volatile extraction technologies for the Moon, Mars, asteroids, or other bodies. This type of modeling capability is important to avoid the high cost of multiple test campaigns in simulated lunar conditions as the hardware design is iterated. The modeling uses the Crank-Nicholson algorithm applied in a two dimensional (2D) axisymmetric (extendable to 3D) finite difference formalism. It uses soil thermal parameters developed from Apollo soil measurements with adaptations for asteroid regolith. Simulations show that it successfully replicates thermal measurements on the surfaces of asteroids and the Moon and helps interpret those measurements to provide insight into the subsurface properties of those bodies. The 2D simulations have provided insight into the cooling of a lunar drill bit and provide a method to determine the original subsurface temperature despite the presence of the warm bit

Negative spatial association between lymphatic filariasis and malaria in West Africa.

Objective To determine the relationship between human lymphatic filariasis, caused by Wuchereria bancrofti, and falciparum malaria, which are co-endemic throughout West Africa. Methods We used geographical information systems and spatial statistics to examine the prevalence of lymphatic filariasis in relation to malaria prevalence, mosquito species distributions, vegetation and climate. Results A negative spatial association between W. bancrofti and falciparum malaria prevalence exists. Interspecies competition between parasites, seasonality, differences in the distribution and vector competence of Anopheles vectors, agricultural practices and insecticide resistance may be factors driving current (and potentially future) spatial distributions. Conclusion Further investigating these factors will become crucial as large-scale lymphatic filariasis and malaria control programmes are implemented in West Africa that may influence the epidemiology of both diseases

Negative Spatial Association Between Lymphatic Filariasis and Malaria in Africa

Human lymphatic filariasis (LF), caused by Wuchereria bancrofti, is a disabling parasitic disease endemic throughout sub-Saharan Africa. A detailed inter-country study in West Africa using a grid sampling technique for the rapid assessment of LF distribution has demonstrated that W. bancrofti prevalence varies considerably throughout Benin, Burkina Faso, Ghana and Togo. Here we show, using geographic information systems (GIS) and spatial statistics that a robust negative association between LF and malaria prevalence exists. This is a surprising finding, given that in rural West Africa both diseases are transmitted by mosquitoes of the Anopheles gambiae complex. A key factor distinguishing the two disease epidemiologies may be the different distributions and vector competence of the An. gambiae cytoforms. Alternatively interspecies competition between the parasites, with W. bancrofti being more dominant where malaria transmission is more seasonal, may drive the spatial distributions. Differentiating between the various hypotheses may become crucial as large-scale LF and malaria control programmes are implemented in West Africa that may impact on the epidemiology of both diseases.