CCISS,Vascular and BP Reg: Canadian space life science research on ISS

A comprehensive goal of the Canadian Space Agency studies (CCISS, Vascular and BP Reg) has been to investigate the efficacy of current exercise countermeasures to maintain cardiovascular and cerebrovascular health on return to Earth after up to 6-months in space. Results from the CCISS experiments revealed no significant change of in-flight heart rate during daily activities or sleep, and small, but variable between astronauts, post-flight elevation. The between astronaut differences were exaggerated during measurement of spontaneous baroreflex slope, which was reduced post-flight (P<0.05) during paced breathing with 3 astronauts having significant correlations between reduced baroreflex and reduced RR-interval (consistent with reduced fitness). Cerebrovascular autoregulation and CO₂ response were mildly impaired after flight. Some loss of in-flight fitness of astronauts in Vascular was reflected by the increase in HR at a work rate of 161±46 W of 12.3±10.5 bpm, 10.4±5.9 bpm and 13.4±5.7 bpm for early-flight, late-flight and R+1, respectively. On return to gravity, changes in resting heart rate for supine (5.9±3.5 bpm), sit (8.1±3.3 bpm) and stand (10.3±10.0 bpm) were small but variable between individuals (from −5 bpm to +20 bpm in post-flight standing) and not related to the change in exercise heart rate. In Vascular astronauts, pulse wave transit time measured to the finger tended to be reduced post-flight and carotid artery distensibility was significantly reduced (P=0.03, and n=6). The heart rate and baroreflex data suggest that some astronauts return with cardiovascular deconditioning in spite of the exercise regimes. However, greater arterial stiffness is common among all astronauts studied to date. The new CSA project, BP Reg, will monitor inflight blood pressure in an attempt to identify astronauts in greater need for countermeasures. Future research should focus on whether Vascular changes in astronauts might make them an appropriate model to study the mechanisms of arterial aging on Earth.     

InSight Mars Lander Robotics Instrument Deployment System

The InSight Mars Lander is equipped with an Instrument Deployment System (IDS) and science payload with accompanying auxiliary peripherals mounted on the Lander. The InSight science payload includes a seismometer (SEIS) and Wind and Thermal Shield (WTS), heat flow probe (Heat Flow and Physical Properties Package, HP³) and a precision tracking system (RISE) to measure the size and state of the core, mantle and crust of Mars. The InSight flight system is a close copy of the Mars Phoenix Lander and comprises a Lander, cruise stage, heatshield and backshell. The IDS comprises an Instrument Deployment Arm (IDA), scoop, five finger “claw” grapple, motor controller, arm-mounted Instrument Deployment Camera (IDC), lander-mounted Instrument Context Camera (ICC), and control software. IDS is responsible for the first precision robotic instrument placement and release of SEIS and HP³ on a planetary surface that will enable scientists to perform the first comprehensive surface-based geophysical investigation of Mars’ interior structure. This paper describes the design and operations of the Instrument Deployment Systems (IDS), a critical subsystem of the InSight Mars Lander necessary to achieve the primary scientific goals of the mission including robotic arm geology and physical properties (soil mechanics) investigations at the Landing site. In addition, we present test results of flight IDS Verification and Validation activities including thermal characterization and InSight 2017 Assembly, Test, and Launch Operations (ATLO), Deployment Scenario Test at Lockheed Martin, Denver, where all the flight payloads were successfully deployed with a balloon gravity offload fixture to compensate for Mars to Earth gravity.     

Stable iron isotopes and microbial mediation in red pigmentation of the Rosso Ammonitico (mid-late Jurassic, Verona area, Italy)

The iron (Fe) isotopic composition of 17 Jurassic limestones from the Rosso Ammonitico of Verona (Italy) have been analyzed by Multiple-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS). Such analysis allowed for the recognition of a clear iron isotopic fractionation (mean -0.8 per thousand, ranging between -1.52 to -0.06 per thousand) on a millimeter-centimeter scale between the red and grey facies of the studied formation. After gentle acid leaching, measurements of the Fe isotopic compositions gave delta(56)Fe values that were systematically lower in the red facies residues (median: -0.84 per thousand, range: -1.46 to +0.26 per thousand) compared to the grey facies residues (median: -0.08 per thousand, range: -0.34 to +0.23 per thousand). In addition, the red facies residues were characterized by a lighter delta(56)Fe signal relative to their corresponding leachates. These Fe isotopic fractionations could be a sensitive fingerprint of a biotic process; systematic isotopic differences between the red and grey facies residues, which consist of hematite and X-ray amorphous iron hydroxides, respectively, are hypothesized to have resulted from the oxidizing activity of iron bacteria and fungi in the red facies. The grey Fe isotopic data match the Fe isotopic signature of the terrestrial baseline established for igneous rocks and low-C(org) clastic sedimentary rocks. The Fe isotopic compositions of the grey laminations are consistent with the influx of detrital iron minerals and lack of microbial redox processes at the water-interface during deposition. Total Fe concentration measurements were performed by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) (confirmed by concentration estimations obtained by MC-ICP-MS analyses of microdrilled samples) on five samples, and resultant values range between 0.30% (mean) in the grey facies and 1.31% (mean) in the red facies. No correlation was observed between bulk Fe content and pigmentation or between bulk Fe content and Fe isotopic compositions. The rapid transformation of the original iron oxyhydroxides to hematite could have preserved the original isotopic composition if it had occurred at about the same temperature. This paper supports the use of Fe isotopes as sensitive tracers of biological activities recorded in old sedimentary sequences that contain microfossils of iron bacteria and fungi. However, a careful interpretation of the iron isotopic fractionation in terms of biotic versus abiotic processes requires supporting data or direct observations to characterize the biological, (geo)chemical, or physical context in relation to the geologic setting. This will become even more pertinent when Fe isotopic studies are expanded to the interplanetary realm.     

NeQuick 2 and IRI Plas VTEC predictions for low latitude and South American sector

Using vertical total electron content (VTEC) measurements obtained from GPS satellite signals the capability of the NeQuick 2 and IRI Plas models to predict VTEC over the low latitude and South American sector is analyzed. In the present work both models were used to calculate VTEC up to the height of GPS satellites. Also, comparisons between the performance of IRI Plas and IRI 2007 have been done. The data correspond to June solstice and September equinox 1999 (high solar activity) and they were obtained at nine stations. The considered latitude range extends from 18.4°N to ?64.7°N and the longitude ranges from 281.3°E to 295.9°E in the South American sector. The greatest discrepancies among model predictions and the measured VTEC are obtained at low latitudes stations placed in the equatorial anomaly region. Underestimations as strong as 40?TECU [1?TECU?=?10¹⁶?m^?2] can be observed at BOGT station for September equinox, when NeQuick2 model is used. The obtained results also show that: (a) for June solstice, in general the performance of IRI Plas for low latitude stations is better than that of NeQuick2 and, vice versa, for highest latitudes the performance of NeQuick2 is better than that of IRI Plas. For the stations TUCU and SANT both models have good performance; (b) for September equinox the performances of the models do not follow a clearly defined pattern as in the other season. However, it can be seen that for the region placed between the Northern peak and the valley of the equatorial anomaly, in general, the performance of IRI Plas is better than that of NeQuick2 for hours of maximum ionization. From TUCU to the South, the best TEC predictions are given by NeQuick2.The source of the observed deviations of the models has been explored in terms of CCIR foF2 determination in the available ionosonde stations in the region. Discrepancies can be also related to an unrealistic shape of the vertical electron density profile and or an erroneous prediction of the plasmaspheric contribution to the vertical total electron content. Moreover, the results of this study could be suggesting that in the case of NeQuick, the underestimation trend could be due to the lack of a proper plasmaspheric model in its topside representation. In contrast, the plasmaspheric model included in IRI, leads to clear overestimations of GPS derived TEC.     

Inferring Nighttime Ionospheric Parameters with the Far Ultraviolet Imager Onboard the Ionospheric Connection Explorer

The Ionospheric Connection Explorer (ICON) Far Ultraviolet (FUV) imager, ICON FUV, will measure altitude profiles of OI 135.6 nm emissions to infer nighttime ionospheric parameters. Accurate estimation of the ionospheric state requires the development of a comprehensive radiative transfer model from first principles to quantify the effects of physical processes on the production and transport of the 135.6 nm photons in the ionosphere including the mutual neutralization contribution as well as the effect of resonant scattering by atomic oxygen and pure absorption by oxygen molecules. This forward model is then used in conjunction with a constrained optimization algorithm to invert the anticipated ICON FUV line-of-sight integrated measurements. In this paper, we describe the connection between ICON FUV measurements and the nighttime ionosphere, along with the approach to inverting the measured emission profiles to derive the associated O⁺ profiles from 150–450 km in the nighttime ionosphere that directly reflect the electron density in the F-region of the ionosphere.     

Electron Physics of Asymmetric Magnetic Field Reconnection

There have been many significant advances in understanding magnetic field reconnection as a result of improved space measurements and two-dimensional computer simulations. While reviews of recent work have tended to focus on symmetric reconnection on ion and larger spatial scales, the present review will focus on asymmetric reconnection and on electron scale physics involving the reconnection site, parallel electric fields, and electron acceleration.     

The Aster project: Flight to a near-Earth asteroid

The information on the project being developed in Brazil for a flight to binary or triple near-Earth asteroid is presented. The project plans to launch a spacecraft into an orbit around the asteroid and to study the asteroid and its satellite within six months. Main attention is concentrated on the analysis of trajectories of flight to asteroids with both impulsive and low thrust in the period 2013-2020. For comparison, the characteristics of flights to the (45) Eugenia triple asteroid of the Main Belt are also given.     

Long-Term Evolution of the Martian Crust-Mantle System

Lacking plate tectonics and crustal recycling, the long-term evolution of the crust-mantle system of Mars is driven by mantle convection, partial melting, and silicate differentiation. Volcanic landforms such as lava flows, shield volcanoes, volcanic cones, pyroclastic deposits, and dikes are observed on the martian surface, and while activity was widespread during the late Noachian and Hesperian, volcanism became more and more restricted to the Tharsis and Elysium provinces in the Amazonian period. Martian igneous rocks are predominantly basaltic in composition, and remote sensing data, in-situ data, and analysis of the SNC meteorites indicate that magma source regions were located at depths between 80 and 150 km, with degrees of partial melting ranging from 5 to 15 %. Furthermore, magma storage at depth appears to be of limited importance, and secular cooling rates of 30 to 40 K?Gyr^?1 were derived from surface chemistry for the Hesperian and Amazonian periods. These estimates are in general agreement with numerical models of the thermo-chemical evolution of Mars, which predict source region depths of 100 to 200 km, degrees of partial melting between 5 and 20 %, and secular cooling rates of 40 to 50 K?Gyr^?1. In addition, these model predictions largely agree with elastic lithosphere thickness estimates derived from gravity and topography data. Major unknowns related to the evolution of the crust-mantle system are the age of the shergottites, the planet’s initial bulk mantle water content, and its average crustal thickness. Analysis of the SNC meteorites, estimates of the elastic lithosphere thickness, as well as the fact that tidal dissipation takes place in the martian mantle indicate that rheologically significant amounts of water of a few tens of ppm are still present in the interior. However, the exact amount is controversial and estimates range from only a few to more than 200 ppm. Owing to the uncertain formation age of the shergottites it is unclear whether these water contents correspond to the ancient or present mantle. It therefore remains to be investigated whether petrologically significant amounts of water of more than 100 ppm are or have been present in the deep interior. Although models suggest that about 50 % of the incompatible species (H₂O, K, Th, U) have been removed from the mantle, the amount of mantle differentiation remains uncertain because the average crustal thickness is merely constrained to within a factor of two.     

Navigational Aids and Spatial Memory Impairment: The Role of Divided Attention

Navigational aids impair spatial memory for experienced environments, but the cognitive mechanisms underlying impairment remain an open question. Recent evidence implicates divided attention, but to date no study has directly manipulated divided attention in navigational aid contexts. The present study addresses this need. Participants navigated virtual towns with aid presence and divided attention factorially crossed in a within-participants design. They then completed spatial memory assessments. Divided attention alone impaired spatial memory. Navigational aid presence impaired spatial memory when attention was undivided, replicating previous findings, but did not to a greater extent when attention was divided. These findings suggest that navigational aids divide attention sufficiently to impair spatial memory.     

Microphysics of Cosmic Plasmas: Background, Motivation and Objectives

With the maturing of space plasma research in the solar system, a more general approach to plasma physics in general, applied to cosmic plasmas, has become appropriate. There are both similarities and important differences in describing the phenomenology of space plasmas on scales from the Earth’s magnetosphere to galactic and inter-galactic scales. However, there are important aspects in common, related to the microphysics of plasma processes. This introduction to a coordinated collection of papers that address the several aspects of the microphysics of cosmic plasmas that have unifying themes sets out the scope and ambition of the broad sweep of topics covered in the volume, together with an enumeration of the detailed objectives of the coverage.