Development of the Primary Sorption Pump for the SEIS Seismometer of the InSight Mission to Mars

We report on the development of a passive sorption pump, capable of maintaining high-vacuum conditions in the InSight seismometer throughout the duration of any extended mission. The adsorber material is a novel zeolite-loaded aerogel (ZLA) composite, which consists of fine zeolite particles homogeneously dispersed throughout a porous silica network. The outgassing species within the SEIS evacuated container were analyzed and the outgassing rate was estimated by different methods. The results were used to optimize the ZLA composition to adsorb the outgassing constituents, dominated by water, while minimizing the SEIS bakeout constraints. The InSight ZLA composite additionally facilitated substantial CO₂ adsorption capabilities for risk mitigation against external leaks in Mars atmosphere. To comply with the stringent particle requirements, the ZLA getters were packaged in sealed containers, open to the SEIS interior through \(1~\upmu\mbox{m}\)-size pore filters. Results from experimental validation and verification tests of the packaged getters are presented. The pressure forecast based on these data, corroborated by rudimentary in situ pressure measurements, infer SEIS operational pressures not exceeding \(10^{-5}~\mbox{mbar}\) throughout the mission.     

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 \(\geq3\mbox{--}5~\mbox{m}\) 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.     

Preliminary results of Texus 8 experiments on effects of surface tension minimum

A stable, observable liquid-gas interface was realized in an experimental cell (3 × 2 × 1 cm) under microgravity conditions. The liquid used was an aqueous 6.24 10^?3 molal solution of n-heptanol. A temperature gradient, established at the interface, resulted in the build-up of a Marangoni convection cell with the liquid flowing in an unusual direction (i.e. at the surface the liquid flowed from the cold to the hot side).The same experiment on Earth gives rise to a Marangoni cell superimposed on buoyancy cells. The Marangoni and the buoyancy cells then turn in opposite directions.     

The COS-B X-ray observations of X-ray binaries

The observational information on X-ray binaries that was collected with the 80 cm² auxiliary X-ray detector onboard the COS-B gamma-ray satellite is reviewed. The results illustrate that in the study of X-ray binaries observations of long duration are extremely effective, even when using a small instrument.     

Narrative psychological content analysis as a tool for psychological status monitoring of crews in isolated,confined and extreme settings

This paper is about a pilot application of narrative psychological content analysis in the psychological status monitoring of Crew 71 of a space analog simulation environment, the Mars Desert Research Station (MDRS). Both the method and its theoretical framework, Scientific Narrative Psychology, are original developments by Hungarian psychologists [5] (László, 2008). The software was NooJ, a multilingual linguistic development environment [11] (Silberztein, 2008). Three measures were conceptualized and assessed: emotional status, team spirit and subjective physical comfort. The results showed the patterns of these three measures on a daily basis at group level, and allowed for detecting individual differences as well. The method is adaptable to languages involved in space psychology, e.g. Russian, French and German in addition to English.     

Mercury’s Interior Structure, Rotation, and Tides

This review addresses the deep interior structure of Mercury. Mercury is thought to consist of similar chemical reservoirs (core, mantle, crust) as the other terrestrial planets, but with a relatively much larger core. Constraints on Mercury’s composition and internal structure are reviewed, and possible interior models are described. Large advances in our knowledge of Mercury’s interior are not only expected from imaging of characteristic surface features but particularly from geodetic observations of the gravity field, the rotation, and the tides of Mercury. The low-degree gravity field of Mercury gives information on the differences of the principal moments of inertia, which are a measure of the mass concentration toward the center of the planet. Mercury’s unique rotation presents several clues to the deep interior. From observations of the mean obliquity of Mercury and the low-degree gravity data, the moments of inertia can be obtained, and deviations from the mean rotation speed (librations) offer an exciting possibility to determine the moment of inertia of the mantle. Due to its proximity to the Sun, Mercury has the largest tides of the Solar System planets. Since tides are sensitive to the existence and location of liquid layers, tidal observations are ideally suited to study the physical state and size of the core of Mercury.     

Observational Overview of Young Intermediate-Mass Objects: Herbig Ae/Be Stars

Recent discoveries of planets orbiting several nearby solar-mass stars have focussed renewed attention on the frequency and evolution of planetary systems and their evolutionary precursors around both solar and intermediate (2 M/M 8) mass stars. As a result of a wealth of new observations at all wavelengths of the circumstellar material around the nearest of the young intermediate-mass stars, the so-called Herbig Ae/Be (HAeBe) stars, we are beginning to see how these systems are similar to the solar mass objects, and how they differ. A review of the recent literature is presented, including the evolutionary status of the stars, binary frequency and the star forming environment, the morphology of the circumstellar material, including the first direct detections of disks in Keplerian rotation around these objects, and mass loss and infall phenomena. Prospects for advances in this research area as a result of advances in instrumentation are reviewed.