A sophisticated lander for scientific exploration of Mars: scientific objectives and implementation of the Mars-96 Small Station

A mission to Mars including two Small Stations, two Penetrators and an Orbiter was launched at Baikonur, Kazakhstan, on 16 November 1996. This was called the Mars-96 mission. The Small Stations were expected to land in September 1997 (Ls approximately 178 degrees), nominally to Amazonis-Arcadia region on locations (33 N, 169.4 W) and (37.6 N, 161.9 W). The fourth stage of the Mars-96 launcher malfunctioned and hence the mission was lost. However, the state of the art concept of the Small Station can be applied to future Martian lander missions. Also, from the manufacturing and performance point of view, the Mars-96 Small Station could be built as such at low cost, and be fairly easily accommodated on almost any forthcoming Martian mission. This is primarily due to the very simple interface between the Small Station and the spacecraft. The Small Station is a sophisticated piece of equipment. With the total available power of approximately 400 mW the Station successfully supports an ambitious scientific program. The Station accommodates a panoramic camera, an alpha-proton-x-ray spectrometer, a seismometer, a magnetometer, an oxidant instrument, equipment for meteorological observations, and sensors for atmospheric measurement during the descent phase, including images taken by a descent phase camera. The total mass of the Small Station with payload on the Martian surface, including the airbags, is only 32 kg. Lander observations on the surface of Mars combined with data from Orbiter instruments will shed light on the contemporary Mars and its evolution. As in the Mars-96 mission, specific science goals could be exploration of the interior and surface of Mars, investigation of the structure and dynamics of the atmosphere, the role of water and other materials containing volatiles and in situ studies of the atmospheric boundary layer processes. To achieve the scientific goals of the mission the lander should carry a versatile set of instruments. The Small Station accommodates devices for atmospheric measurements, geophysical and geochemical studies of the Martian surface and interior, and cameras for descent phase and panoramic views. These instruments would be able to contribute remarkably to the process of solving some of the scientific puzzles of Mars.     

Modelling and assessment of hydrological changes in a developing urban catchment

Urbanization strongly changes natural catchment by increasing impervious coverage and by creating a need for efficient drainage systems. Such land cover changes lead to more rapid hydrological response to storms and change distribution of peak and low flows. This study aims to explore and assess how gradual hydrological changes occur during urban development from rural area to a medium‐density residential catchment. The Stormwater Management Model (SWMM) is utilized to simulate a series of scenarios in a same developing urban catchment. Sub‐hourly hydro‐meteorological data in warm season is used to calibrate and validate the model in the fully developed catchment in 2006. The validated model is then applied to other cases in development stage and runoff management scenarios. Based on the simulations and observations, three key problems are solved: (1) how catchment hydrology changes with land cover change, (2) how urban development changes pre‐development flows, and (3) how stormwater management techniques affect catchment hydrology. The results show that the low‐frequency flow rates had remarkably increased from 2004 to 2006 along with the increase of impervious areas. Urbanization in the residential catchment expands the runoff contributing area, accelerates hydrological response, raises peak flows in an order of magnitude of over 10, and more than doubles the total runoff volume. The effects of several LID controls on runoff hydrograph were simulated, and the techniques were able to reduce flows towards the pre‐development levels. However, the partly restored flow regime was still clearly changed in comparison to the pre‐development flow conditions. Copyright © 2014 John Wiley & Sons, Ltd.     

Stormwater quality during residential construction activities: influential variables

Research on the water quality of urban runoff has so far focussed on the post‐development phase of urban catchments, whereas water quality in developing areas under construction has remained less understood. The construction phase, however, may constitute a considerable source of diffuse pollution in urban areas. This study investigated the mechanisms affecting water quality in residential areas during the construction and post‐construction phases. Water quality (suspended solids, total phosphorus, total nitrogen and chemical oxygen demand) and runoff were monitored over a period of 5 years in three catchments located in the city of Espoo in Southern Finland. The catchments included an urbanizing area under construction and low‐density and high‐density residential areas. The water quality was quantified in terms of event mean concentrations and loads. The key influential variables explaining the water quality in a multiple linear regression analysis included hydrological variables (event volume and intensity), antecedent conditions and a variable describing the ongoing construction projects. Construction activities in the developing catchment had a profound impact on water quality. Inclusion of the variables describing activities, such as earth moving works, paving, house construction and temporary wastewater discharges, was necessary to explain water quality variations in the developing catchment. The importance of antecedent conditions as an explanatory variable depended on the site and the pollutant in question. Copyright © 2015 John Wiley & Sons, Ltd.     

Biological Assessment of Eastern Oysters (Crassostrea virginica) Inhabiting Reef,Mangrove, Seawall,and Restoration Substrates

The eastern oyster, Crassostrea virginica, plays an essential functional role in many estuarine ecosystems on the east and Gulf coasts of the USA. Oysters form biogenic reefs but also live on alternative intertidal substrates such as artificial surfaces and mangrove prop roots. The hypothesis tested in this study was that non-reef-dwelling oysters (i.e., those inhabiting mangrove, seawall, or restoration substrates) were similar to their reef-dwelling counterparts based upon a suite of biological parameters. The study was carried out at six sites in three zones in Tampa Bay on the west coast of Florida using monthly samples collected from October 2008–September 2009. The timing of gametogenesis and spawning, fecundity, and juvenile recruitment were the same for oysters in all four habitats. Oyster size (measured as shell height), density, and Perkinsus marinus infection intensity and prevalence varied among habitats. This study indicates that oysters on mangroves, seawalls, and oyster restoration substrates contribute larvae, habitats for other species, and likely other ecosystem benefits similar to those of intertidal oyster reefs in Tampa Bay. Oysters from alternative intertidal substrates should be included in any system wide studies of oyster abundance, clearance rates, and the provision of alternate habitats, especially in highly developed estuaries.     

Spatial characterization of environmental gradients in a coastal lagoon, Chincoteague Bay

Spatial patterns of environmental processes are intrinsic yet complex components of estuaries. Spatial characterization of environmental gradients is a necessary step to better understand and classify estuarine environments. A geographic information system is developed to analyze the major abiotic environmental processes, to evaluate accuracy and spatial uncertainty, and to analyze potential zonation within the choked coastal lagoon of Chincoteague Bay in Maryland and Virginia, USA. Spatially extensive grid-based models of environmental gradients are constructed from existing geospatial and environmental databases, including tidal prism, bathymetry, salinity, wave exposure, and Secchi disk depth. Integration of wetland boundaries and bathymetric data provide for full basin analysis of flushing and tidal prism. Multivariate Principal Components Analysis demonstrates the covariation among gradients and provides an empirical approach to mapping multidimensional zones within the lagoon. The project documents the development of an estuarine geographic information system that can be used to analyze and compare estuarine environments and provide data for environmental decision making.     

Mineralogy,chemistry, and noble gas contents of Adzhi-Bogdo– an LL3–6 chondritic breccia with L-chondritic and granitoidal clasts

Abstract— Adzhi-Bogdo is an ordinary chondrite regolith breccia (LL3–6) which fell on 1949 October 30 in Gobi Altay, Mongolia. The rock consists of submm- to cm-sized fragments embedded in a fine-grained clastic matrix. The polymict breccia contains various types of clasts, some of which must be of foreign origin. Components of the breccia include chondrules, melt rock clasts (some of which are K-rich), highly recrystallized rock fragments (“granulites”), breccia clasts, pyroxene-rich fragments with achondritic textures, and alkali-granitoids. The composition of olivine in most fragments is in the range of LL-chondrites. However, olivine in some components has significantly lower fayalite contents, characteristic of L-chondrites. The bulk meteorite is very weakly shocked (S2). Based on the bulk chemical composition, Adzhi-Bogdo is an ordinary chondrite. The concentrations of Fe and Ni are somewhat intermediate between L- and LL-chondrites. The contents of solar gases indicate that Adzhi-Bogdo is a regolith breccia. Most of the solar He and probably a part of the solar Ne of Adzhi-Bogdo has been lost. It is suggested that Adzhi-Bogdo experienced an (impact-induced) thermal event early in its history, because most of the radiogenic ⁴⁰Ar is retained.     

The Beagle 2 environmental sensors: science goals and instrument description

A suite of instruments on the Beagle 2 Mars lander was designed and built in order to investigate the environmental conditions at the landing site. The sensor suite was capable of measuring air temperature at two heights, surface level pressure, wind speed and direction, saltated particle momentum, UV flux (diffuse and direct at five wavelengths), the total accumulated radiation dose and investigating the nature of the oxidising environment. The scientific goals of the instruments are discussed within the context of current understanding of the environmental conditions on Mars, and the instruments themselves are described in detail. Beagle 2 landed on Mars in late 2003, as part of the ESA Mars Express mission. The expected lifetime of the lander on the surface was 180 sols, with a landing site in Isidis Planitia, but has not responded to attempts to contact it, and has now been declared lost. The Environmental Sensor Suite (ESS) was intended to monitor and characterise the current local meteorological parameters, investigating specific areas of scientific interest raised from previous missions, most notably dust transport and transient phenomena, and additionally to add context to the conditions that any possible martian micro-organisms would have to face. The design of the instrument suite was strongly influenced by mass limitations, with eight sensor subsystems having a total mass of approximately 100 g. Although Beagle 2 has been now declared lost, the scientific goals of an Environmental Sensors Suite still remain a valid target for any future astrobiology orientated missions.     

Cordierite III: the site occupation and concentration of Fe3+

Cordierite has the ideal formula (Mg,Fe)₂Al₄Si₅O₁₈ ^.x(H₂O,CO₂), but it must contain some Fe³⁺ to account for its blue color and strong pleochroism. The site occupation and concentration of Fe³⁺ in two Mg-rich natural cordierites have been investigated by EPR and ⁵⁷Fe Mössbauer spectroscopy. In addition, powder IR spectroscopy, X-ray diffraction, and TEM examination were used to characterize the samples. Single-crystal and powder EPR spectra indicate that Fe³⁺ is located on T₁1 in natural cordierites and not in the channels. The amount in Mg-rich cordierites is very small with an upper limit set by Mössbauer spectroscopy giving less than 0.004 cations per formula unit (pfu). Fe³⁺ in cordierite can, therefore, be considered insignificant for most petrologic calculations. Heat-treating cordierite in air at 1,000?°C for 2?days causes an oxidation and/or loss of Fe²⁺ on T₁1, together with an expulsion of Na⁺ from the channels, whereas heating at the Fe–FeO buffer produces little Fe³⁺ in cordierite. Heating at 1,000?°C removes all class I H₂O, but small amounts of class II H₂O remain as shown by the IR measurements. No evidence for channel Fe²⁺ or Fe³⁺ in the heat-treated samples was found. The blue color in cordierite arises from a broad absorption band (E//b and weaker with E//a) around 18,000?cm^?1 originating from charge-transfer between Fe²⁺ in the octahedron and Fe³⁺ in the edge-shared T₁1 tetrahedron. It therefore appears that all natural cordierites contain some tetrahedral Fe³⁺. The brown color of samples heated in air may be due to the formation of very small amounts of submicroscopic magnetite and possibly hematite. These inclusions in cordierite can only be identified through TEM study.     

4D GPS water vapor tomography: new parameterized approaches

Water vapor is a key variable in numerical weather prediction, as it plays an important role in atmospheric processes. Nonetheless, the distribution of water vapor in the atmosphere is observed with a coarse resolution in time and space compared to the resolution of numerical weather models. GPS water vapor tomography is one of the promising methods to improve the resolution of water vapor measurements. This paper presents new parameterized approaches for the determination of water vapor distribution in the troposphere by GPS. We present the methods and give first results validating the approaches. The parameterization of voxels (volumetric pixels) by trilinear and spline functions in ellipsoidal coordinates are introduced in this study. The evolution in time of the refractivity field is modeled by a Kalman filter with a temporal resolution of 30 s, which corresponds to the available GPS-data rate. The algorithms are tested with simulated and with real data from more than 40 permanent GPS receiver stations in Switzerland and adjoining regions covering alpine areas. The investigations show the potential of the new parameterized approaches to yield superior results compared to the non parametric classical one. The accuracy of the tomographic result is quantified by the inter-quartile range (IQR), which is decreased by 10–20% with the new approaches. Further, parameterized voxel solutions have a substantially smaller maximal error than the non parameterized ones. Simulations show a limited ability to resolve vertical structures above the top station of the network with GPS tomography.