Planetary science and exploration in the deep subsurface: results from the MINAR Program, Boulby Mine, UK

The subsurface exploration of other planetary bodies can be used to unravel their geological history and assess their habitability. On Mars in particular, present-day habitable conditions may be restricted to the subsurface. Using a deep subsurface mine, we carried out a program of extraterrestrial analog research – MINe Analog Research (MINAR). MINAR aims to carry out the scientific study of the deep subsurface and test instrumentation designed for planetary surface exploration by investigating deep subsurface geology, whilst establishing the potential this technology has to be transferred into the mining industry. An integrated multi-instrument suite was used to investigate samples of representative evaporite minerals from a subsurface Permian evaporite sequence, in particular to assess mineral and elemental variations which provide small-scale regions of enhanced habitability. The instruments used were the Panoramic Camera emulator, Close-Up Imager, Raman spectrometer, Small Planetary Linear Impulse Tool, Ultrasonic drill and handheld X-ray diffraction (XRD). We present science results from the analog research and show that these instruments can be used to investigate in situ the geological context and mineralogical variations of a deep subsurface environment, and thus habitability, from millimetre to metre scales. We also show that these instruments are complementary. For example, the identification of primary evaporite minerals such as NaCl and KCl, which are difficult to detect by portable Raman spectrometers, can be accomplished with XRD. By contrast, Raman is highly effective at locating and detecting mineral inclusions in primary evaporite minerals. MINAR demonstrates the effective use of a deep subsurface environment for planetary instrument development, understanding the habitability of extreme deep subsurface environments on Earth and other planetary bodies, and advancing the use of space technology in economic mining

Convectively driven transport in temperate lakes

Penetrative convection in the surface layer of a midsize temperate lake (5 km2) was investigated in both summer and winter using a conductivity-temperature-depth (CTD) logger mounted on an autonomous underwater vehicle (AUV) flown repeatedly along horizontal transects at selected depths. In summer, the epilimnion cooled differentially during a calm evening (240 and 297 W m-2 on the east and west sides of the lake, respectively). These cooling rates agree well with the average net heat flux of 270 W m-2 estimated from meteorological data. Density currents were driven by this differential cooling. In winter, CTD profiles during a sunny day showed four distinct thermal layers beneath the ice (∼50 cm thick), consistent with radiative penetrative convection: a stratified diffusive layer just beneath the ice (top 1.6 m); a well-mixed convective layer (that deepens at 1.14 m d -1 and warms at 0.015°C d-1 during the observation period); an entrainment layer (1.5 m thick); and a weakly stratified quiescent layer (to bottom). AUV transects, flown at constant depths in each layer, revealed a 150-m wide region displaying evidence of penetrative convection, surrounded by regions with negligible heat changes. These high-resolution, horizontal CTD measurements provided insight into previously unresolved physical dynamics of the well-mixed layer of a temperate lake in quasi-shear-free conditions that would have been difficult to quantify during summer months and impossible under winter ice cover without the use of an AUV platform. © 2008, by the American Society of Limnology and Oceanography, Inc

A cyclonic gyre in an ice-covered lake

Observations of a cyclonic gyre in an ice-covered, midsize (, 5 km2), temperate lake are presented. Horizontal and vertical measurements of temperature and electrical conductivity measurements were collected using a conductivity–temperature–depth logger mounted on an autonomous underwater vehicle and additional instrumentation. These measurements revealed a cylindrical density anomaly with a radius of , 110 m extending from the surface to , 14 m depth. The observed radius is smaller than the internal Rossby radius of deformation (, 200 m), which suggests a cyclogeostrophic balance between centripetal, Coriolis, and pressure forces. The maximum azimuthal velocity, calculated assuming this balance, was , 2.1 cm s21 at 6–8 m depth. The Rossby number associated with this velocity was 1.7; this is consistent with the cyclogeostrophic assumption (i.e., Rossby number . 1) and nearly twice that of similar under-ice eddies in the Arctic Ocean. The estimated Ekman spindown timescale is 1.5–15 d, but despite this, the gyre appeared to be relatively unchanged over 6 d of field observations. This persistence implies the gyre was forced over the course of the field study; however, the source of the forcing is unknown. Horizontal temperature transects at and below the bottom of the gyre revealed coherent temperature fluctuations suggestive of vertical transport associated with the gyre

Multiplatform ocean exploration: Insights from the NEEMO space analog mission

Since the beginning of space exploration, methods and protocols of exploration have been developed using space analogs on Earth to reduce research costs, develop safe deployment/retrieval protocols, and ready astronauts for hostile environments in less threatening settings. Space analogs are required as much as ever today as astronauts and scientists develop new tools and techniques for exploration, while working to address evolving mission objectives from low-earth orbit to deepspace exploration. This study examines coordinated human and robotic exploration at the Aquarius Underwater Habitat off of the coast of Key Largo, Florida, in support of the NEEMO 15 (NASA Extreme Environment Mission Operations) program. The exploration scheme presented in this work fuses (1) robotic precursormissions as a means of remote sensing data collection; (2) crowdsourcing to process immense amounts of data to identify key targets of interest that might be missed in the tight cycle of mission operations; and (3) human exploration to examine locations directly up close and collect physical samples that require involved sampling techniques. Autonomous underwater vehicles (AUVs) and single-person submersibles, called DeepWorkersâ„¢, were used as underwater analogs of robotic systems currently being used and human-operated vehicles (HOVs) proposed for use on a Near Earth Asteroid (NEA), the Moon, or Mars. In addition to operational lessons learned for space exploration that are directly applicable to ocean exploration, ocean floor mapping provides new levels of detail of benthic habitat critical for coral reef monitoring and management. Opportunistic (onsite adaptive) data sampling also took place by placing self-recording instrumentation onto each of the DeepWorkers, increasing the collection of scientific information during the submersible missions and contributing to mission planning for optimal and efficient use of expensive assets

Csk-homologous kinase (Chk) is an efficient inhibitor of Src-family kinases but a poor catalyst of phosphorylation of their C-terminal regulatory tyrosine

BACKGROUND: C-terminal Src kinase (Csk) and Csk-homologous kinase (Chk) are the major endogenous inhibitors of Src-family kinases (SFKs). They employ two mechanisms to inhibit SFKs. First, they phosphorylate the C-terminal tail tyrosine which stabilizes SFKs in a closed inactive conformation by engaging the SH2 domain in cis. Second, they employ a non-catalytic inhibitory mechanism involving direct binding of Csk and Chk to the active forms of SFKs that is independent of phosphorylation of their C-terminal tail. Csk and Chk are co-expressed in many cell types. Contributions of the two mechanisms towards the inhibitory activity of Csk and Chk are not fully clear. Furthermore, the determinants in Csk and Chk governing their inhibition of SFKs by the non-catalytic inhibitory mechanism are yet to be defined. METHODS: We determined the contributions of the two mechanisms towards the inhibitory activity of Csk and Chk both in vitro and in transduced colorectal cancer cells. Specifically, we assayed the catalytic activities of Csk and Chk in phosphorylating a specific peptide substrate and a recombinant SFK member Src. We employed surface plasmon resonance spectroscopy to measure the kinetic parameters of binding of Csk, Chk and their mutants to a constitutively active mutant of the SFK member Hck. Finally, we determined the effects of expression of recombinant Chk on anchorage-independent growth and SFK catalytic activity in Chk-deficient colorectal cancer cells. RESULTS: Our results revealed Csk as a robust enzyme catalysing phosphorylation of the C-terminal tail tyrosine of SFKs but a weak non-catalytic inhibitor of SFKs. In contrast, Chk is a poor catalyst of SFK tail phosphorylation but binds SFKs with high affinity, enabling it to efficiently inhibit SFKs with the non-catalytic inhibitory mechanism both in vitro and in transduced colorectal cancer cells. Further analyses mapped some of the determinants governing this non-catalytic inhibitory mechanism of Chk to its kinase domain. CONCLUSIONS: SFKs are activated by different upstream signals to adopt multiple active conformations in cells. SFKs adopting these conformations can effectively be constrained by the two complementary inhibitory mechanisms of Csk and Chk. Furthermore, the lack of this non-catalytic inhibitory mechanism accounts for SFK overactivation in the Chk-deficient colorectal cancer cells

Performance evaluation of underwater platforms in the context of space exploration

Robotic platforms are essential for future human planetary and lunar exploration as they can operate in more extreme environments with a greater endurance than human explorers. In this era of space exploration, a terrestrial analog that can be used for development of the coordination between manned and robotic vehicles will optimize the scientific return of future missions while concurrently minimizing the downtime of both human explorers and robotic platforms. This work presents the use of underwater exploratory robots – autonomous underwater vehicles (AUV), remotely operated vehicles (ROV), and manned submersibles – as analogues for mixed human–robot exploration of space. Subaqueous settings present diverse challenges for navigation, operation and recovery that require the development of an exploration model of a similar complexity as required for space exploration. To capitalize on the strengths of both robotic and human explorers this work presents lessons learnt with respect to the fields of human–robotic interface (HRI) and operator training. These are then used in the development of mission evaluation tools: (1) a task efficiency index (TEI), (2) performance metrics, and (3) exploration metrics. Although these independent evaluations were useful for specific missions, further refinement will be required to fully evaluate the strengths and capabilities of multiple platforms in a human–robotic exploration campaign in order to take advantage of unforeseen science opportunities in remote settings

Limnology of Pavilion Lake, B. C., Canada - Characterization of a microbialite forming environment

The objectives of this study are two-fold: (1) to describe and quantify the seasonal physical and chemical limnological properties of Pavilion Lake, a microbialite-rich lake in British Columbia, Canada, and (2) to gain a broader limnological context of Pavilion Lake by examining the limnology and hydrology of the lakes and groundwater systems in the area (∼30 km radius). Pavilion Lake is a dimictic lake with annual ice-cover. It is a hard water (mean CaCO 3 = 181.8 mg L -1), ultra-oligotrophic (mean Total Phosphorus [TP] = 3.3 μg L -1) lake, that is groundwater fed most likely through diffuse, low velocity local and regional sources. Principal Components Analysis (PCA) separated Pavilion Lake from the other groundwater, stream and lake samples along a conductivity and pH gradient on Axis 1 (λ 1 =0.392), and a nutrient (Total Nitrogen [TN], TP) and K +, Mg 2+, Si gradient on the second axis (λ 2 = 0.160). Pavilion Lake has the lowest Ca 2+ and TP concentrations, and the highest Na + concentrations and optical transmissivity amongst all sampled sites. Furthermore, the lake is characterized by low sedimentation rates. These characteristics are potentially important factors in supporting the past and on-going development of microbialites within the lake. Our study provides a limnochemical reference to consider in the conceptualization of ideal environments supporting large-scale microbialites. © E. Schweizerbart'sche Verlagsbuchhandlung 2009