Potential Effects of Surface Temperature Variations and Disturbances and Thermal Convection on the Mars InSight HP<Superscript>3</Superscript> Heat-Flow Determination

The HP³ instrument on the InSight lander mission will measure subsurface temperatures and thermal conductivities from which heat flow in the upper few meters of the regolith at the landing site will be calculated. The parameter to be determined is steady-state conductive heat flow, but temperatures may have transient perturbations resulting from surface temperature changes and there could be a component of thermal convection associated with heat transport by vertical flow of atmospheric gases over the depth interval of measurement. The experiment is designed so that it should penetrate to a depth below which surface temperature perturbations are smaller than the required measurement precision by the time the measurements are made. However, if the measurements are delayed after landing, and/or the probe does not penetrate to the desired depth, corrections may be necessary for the transient perturbations. Thermal convection is calculated to be negligible, but these calculations are based on unknown physical properties of the Mars regolith. The effects of thermal convection should be apparent at shallow depths where transient thermal perturbations would be observed to deviate from conductive theory. These calculations were required during proposal review and their probability of predicting a successful measurement a prerequisite for mission approval. However, their uncertainties lies in unmeasured physical parameters of the Mars regolith.     

Evaluation of the Terrestrial Albedo Applied to Some Scientific Missions

Using the Earth albedo model and the orbital dynamics model developed as part of the First Look Project (Fast Initial In-Orbit Identification of Scientific Satellites) the terrestrial albedo is evaluated considering the orbits of some scientific missions as Gravity Probe B, MICROSCOPE and STEP. The model of the Earth albedo is based on the reflectivity data measured by NASA’s Earth Probe satellite, which is part of the TOMS project (Total Ozone Mapping Spectrometer). The reflectivity data are available daily, on line at the TOMS website, and they fluctuate because of changes in clouds and ice coverage and seasonal changes. The data resolution partitions the Earth surface into a number of cells. The incident irradiance on each cell is used to calculate total radiant flux from the cell. With the radiant flux from each cell, the irradiance at the satellite is calculated.     

Volatile Trapping in Martian Clathrates

Thermodynamic conditions suggest that clathrates might exist on Mars. Despite observations which show that the dominant condensed phases on the surface of Mars are solid carbon dioxide and water ice, clathrates have been repeatedly proposed to play an important role in the distribution and total inventory of the planet’s volatiles. Here we review the potential consequences of the presence of clathrates on Mars. We investigate how clathrates could be a potential source for the claimed existence of atmospheric methane. In this context, plausible clathrate formation processes, either in the close subsurface or at the base of the cryosphere, are reviewed. Mechanisms that would allow for methane release into the atmosphere from an existing clathrate layer are addressed as well. We also discuss the proposed relationship between clathrate formation/dissociation cycles and how potential seasonal variations influence the atmospheric abundances of argon, krypton and xenon. Moreover, we examine several Martian geomorphologic features that could have been generated by the dissociation of extended subsurface clathrate layers. Finally we investigate the future in situ measurements, as well as the theoretical and experimental improvements that will be needed to better understand the influence of clathrates on the evolution of Mars and its atmosphere.     

Educating Europe - finding the best way

The subject of space education is attracting increasing attention, but there are diverging views as to how it should be approached, as can be seen from the following two reports of Education Remote Sensing '92, a conference held in Cardiff, Wales, 28–30 June 1992.     

Radar Doppler Spectra of Turbulent Ionized Wakes

The evaluation of the double convolution integrat involved in the expression of the radar response to scattering from a turbulent ionized wake is simplified by the approximation technique presented here, so that the Doppler spectrum parameters can be explicitly expressed in terms of the wake characteristics.     

Harnessing functional food strategies for the health challenges of space travel—Fermented soy for astronaut nutrition

Astronauts face numerous health challenges during long-duration space missions, including diminished immunity, bone loss and increased risk of radiation-induced carcinogenesis. Changes in the intestinal flora of astronauts may contribute to these problems. Soy-based fermented food products could provide a nutritional strategy to help alleviate these challenges by incorporating beneficial lactic acid bacteria, while reaping the benefits of soy isoflavones. We carried out strain selection for the development of soy ferments, selecting strains of lactic acid bacteria showing the most effective growth and fermentation ability in soy milk (Streptococcus thermophilus ST5, Bifidobacterium longum R0175 and Lactobacillus helveticus R0052). Immunomodulatory bioactivity of selected ferments was assessed using an in vitro challenge system with human intestinal epithelial and macrophage cell lines, and selected ferments show the ability to down-regulate production of the pro-inflammatory cytokine interleukin-8 following challenge with tumour necrosis factor-alpha. The impact of fermentation on vitamin B1 and B6 levels and on isoflavone biotransformation to agluconic forms was also assessed, with strain variation-dependent biotransformation ability detected. Overall this suggests that probiotic bacteria can be successfully utilized to develop soy-based fermented products targeted against health problems associated with long-term space travel.     

Inflatable shape changing colonies assembling versatile smart space structures

Various plants have the ability to follow the sun with their flowers or leaves during the course of a day via a mechanism known as heliotropism. This mechanism is characterised by the introduction of pressure gradients between neighbouring motor cells in the plant?s stem, enabling the stem to bend. By adapting this bio-inspired mechanism to mechanical systems, a new class of smart structures can be created. The developed overall structure is made up of a number of cellular colonies, each consisting of a central pressure source surrounded by multiple cells. After launch, the cellular arrays are deployed in space and are either preassembled or alternatively are attached together during their release or afterwards. A central pressure source is provided by a high-pressure storage unit with an integrated valve, which provides ingress gas flow to the system; the gas is then routed through the system via a sequence of valve operations and cellular actuations, allowing for any desired shape to be achieved within the constraints of the deployed array geometry. This smart structure consists of a three dimensional adaptable cellular array with fluid controlling Micro Electromechanical Systems (MEMS) components enabling the structure to change its global shape. The proposed MEMS components include microvalves, pressure sensors, mechanical interconnect structures, and electrical routing. This paper will also give an overview of the system architecture and shows the feasibility and shape changing capabilities of the proposed design with multibody dynamic simulations. Example applications of this lightweight shape changing structure include concentrators, mirrors, and communications antennas that are able to dynamically change their focal point, as well as substructures for solar sails that are capable of steering through solar winds by altering the sails? subjected area.     

Earth–Moon libration point orbit stationkeeping: Theory,modeling, and operations

Collinear Earth–Moon libration points have emerged as locations with immediate applications. These libration point orbits are inherently unstable and must be maintained regularly which constrains operations and maneuver locations. Stationkeeping is challenging due to relatively short time scales for divergence, effects of large orbital eccentricity of the secondary body, and third-body perturbations. Using the Acceleration Reconnection and Turbulence and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) mission orbit as a platform, the fundamental behavior of the trajectories is explored using Poincaré maps in the circular restricted three-body problem. Operational stationkeeping results obtained using the Optimal Continuation Strategy are presented and compared to orbit stability information generated from mode analysis based in dynamical systems theory.