The High Resolution Imaging Science Experiment (HiRISE) during MRO’s Primary Science Phase (PSP)

The High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO) acquired 8 terapixels of data in 9137 images of Mars between October 2006 and December 2008, covering ∼0.55% of the surface. Images are typically 5-6 km wide with 3-color coverage over the central 20% of the swath, and their scales usually range from 25 to 60 cm/pixel. Nine hundred and sixty stereo pairs were acquired and more than 50 digital terrain models (DTMs) completed; these data have led to some of the most significant science results. New methods to measure and correct distortions due to pointing jitter facilitate topographic and change-detection studies at sub-meter scales. Recent results address Noachian bedrock stratigraphy, fluvially deposited fans in craters and in or near Valles Marineris, groundwater flow in fractures and porous media, quasi-periodic layering in polar and non-polar deposits, tectonic history of west Candor Chasma, geometry of clay-rich deposits near and within Mawrth Vallis, dynamics of flood lavas in the Cerberus Palus region, evidence for pyroclastic deposits, columnar jointing in lava flows, recent collapse pits, evidence for water in well-preserved impact craters, newly discovered large rayed craters, and glacial and periglacial processes. Of particular interest are ongoing processes such as those driven by the wind, impact cratering, avalanches of dust and/or frost, relatively bright deposits on steep gullied slopes, and the dynamic seasonal processes over polar regions. HiRISE has acquired hundreds of large images of past, present and potential future landing sites and has contributed to scientific and engineering studies of those sites. Warming the focal-plane electronics prior to imaging has mitigated an instrument anomaly that produces bad data under cold operating conditions.     

The Effect of Undetected Barriers on Groundwater Drawdown and Recovery

In large-scale pumping projects, such as mine dewatering, predictions are often made about the rate of groundwater level recovery after pumping has ceased. However, these predictions may be impacted by geological uncertainty—including the presence of undetected impermeable barriers. During pumping, an impermeable barrier may be undetected if it is located beyond the maximum extent of the cone of depression; yet it may still control drawdown during the recovery phase. This has implications for regional-scale modeling and monitoring of groundwater level recovery. In this article, non-dimensional solutions are developed to show the conditions under which a barrier may be undetected during pumping but still significantly impact groundwater level recovery. The magnitude of the impact from an undetected barrier will increase as the ratio of pumping rate to aquifer transmissivity increases. The results are exemplified for a hypothetical aquifer with an unknown barrier 3 km from a pumping well. The difference in drawdown between a model with and without a barrier may be <1 m in the 10 years while pumping is occurring, but up to 50 m after pumping has ceased.     

Land expropriation in urbanizing China: an examination of negotiations and compensation

A driving force of urban development is “accumulation by dispossession” which occurs through expropriation, privatization, and commodification of land. While the macro theory is now well refined, there is still much we do not know about how the underlying processes occur and how they shape economic development and urbanization. In this study, we analyze 2009 survey data of land expropriation cases across 12 Chinese cities, and find that expropriation takes different forms leading to specific outcomes. In half the cases, local governments followed central government policies requiring them to pay standard rates of compensation, but in the other half, local governments negotiated with farmers over the terms of expropriation. In the latter scenario, farmers were more likely to receive compensation higher than the standard rate, particularly if they were embedded in local power structures, which we argue could be counteracted if all households in a rural collective negotiate one agreement rather than individual agreements. These findings move us closer to understanding why accumulation through dispossession sometimes contributes to economic growth and social development, and at other times undermines urban development leading to social instability.     

Geology and stratigraphy of King crater, lunar farside

Clementine and photographic data sets have been used to investigate the crustal stratigraphy and geology of King crater on the lunar farside (120°E, 5.5°N). Pre-existing topographic regimes or stress fields dominate many structures in the crater, which has excavated materials from depths of up to 14 km. The upper crust in the area is noritic anorthosite, grading to a more anorthositic signature with depth. A possible batholithic intrusion is also present in a 15-km-wide band, extending from the southern crater floor to at least 50 km north of King, and from near-surface levels down to at least the excavation depth of the crater. It is generally feldspathic, but is cut by mafic dykes now visible in the north wall. King also shows evidence for the presence of a cryptomare, exposed in regions of the peaks and in dark halo craters within the ejecta blanket. Localized olivine-bearing mineralogies are observed on the central peaks, suggesting isolated pockets of troctolitic mineralogies to have been present at 8- to 14-km depths. Copious volumes of crystalline melt produced from the impact event cover King’s floor to a maximum thickness of 30-60 m, and have pooled in a number of natural depressions outside of the main crater. The main pool in the pre-existing A1-Tusi crater has a minimum depth of 150 m. Domes on the crater floor are verified as nonvolcanic in origin, and did not act as a source for any of the lava-like materials in King.     

Geographic influences on sexual and reproductive health service utilization in rural Mozambique

The HIV/AIDS epidemic remains a major public health issue across the globe, and it is of particular concern in sub-Saharan Africa. Utilization of sexual and reproductive health (SRH) services can significantly impact HIV prevention, transmission, and treatment. SRH service utilization may be determined by individual characteristics, such as education and economic status, but also by the location and accessibility of health care facilities. Using population-based survey data, this study applies exploratory spatial analysis techniques to examine spatial patterns of SRH service utilization among rural married women in southern Mozambique. Clustering among those using services is found as are spatial associations, indicating significant spatial variability in the utilization of health services. The findings provide valuable insights for current and future health care program planning and configuration.     

Space Operation and Performance of Doped Germanium Photo-Conducting Detectors in the Far Infrared: Experience from the ISO LWS

The performance of the ten doped germaniumphotoconducting detectors on the Infrared SpaceObservatory Long Wavelength Spectrometer is discussed. This instrument was designed to make spectroscopicmeasurements of astronomical sources in the wavelengthrange from 43 to 198 m. It employed^* a combination of stressed and unstressed Ge:Ga detectorsand one Ge:Be detector coupled to Infrared Labs JF-4integrating amplifiers. The performance of thedetectors was affected by the ionising radiation inthe space environment. The Noise Equivalent Power ofthe detectors increased by a factor of 4 compared tothat measured during ground testing. We show thatthis was the result of reducing the operating bias,and therefore the responsivity, of the detectors andusing shorter integration ramps to alleviate theeffects of the ionising radiation impacts. ^ast ISO exhausted its helium supply on 8 April 1998.     

Dialogue, metaphors of dialogue and understandings of geography

Increasingly, human and physical geographers alike describe their research practices as involving dialogue of some kind. However, the widespread popularity of the term belies some very different understandings of its meaning and methodological implications. In this paper we reflect on these different conceptions of 'dialogical' geography as a way, first, of illustrating the broad range of understandings of research methodology now current in the discipline and, second, of identifying their implications for three long–standing controversies in the discipline: relativism and the truth of geographical knowledge, the associated dualisms between subject/object, nature/society, and realism/constructionism, and the potential for unity between human and physical geography. We argue that, while dialogue is a potentially fruitful way of understanding and practising geography, that the defence of it, like the attacks on it, is often misconceived.