Publications

Moses WJ, Gitelson AA, Berdnikov S, Bowles JH, Povazhnyi V, Saprygin V, Wagner EJ, Patterson KW. HICO-based NIR-Red models for estimating chlorophyll-a concentration in productive coastal waters. IEEE Geoscience and Remote Sensing Letters. 2014;11(6):1111-1115.

We present here results that demonstrate the potential of near-infrared (NIR)-red models to estimate chlorophyll- a (chl- a) concentration in coastal waters using data from the spaceborne Hyperspectral Imager for the Coastal Ocean (HICO). Since the recent demise of the MEdium Resolution Imaging Spectrometer (MERIS), the use of sensors such as HICO has become critical for coastal ocean color research. Algorithms based on two- and three-band NIR-red models, which were previously used very successfully with MERIS data, were applied to HICO images. The two- and three-band NIR-red algorithms yielded accurate estimates of chl- a concentration, with mean absolute errors that were only 10.92% and 9.58%, respectively, of the total range of chl- a concentrations measured over a period of several months in 2012 and 2013 on the Taganrog Bay in Russia. Given the uncertainties in the radiometric calibration of HICO, the results illustrate the robustness of the NIR-red algorithms and validate the radiometric, spectral, and atmospheric corrections applied to HICO data as they relate to estimating chl- a concentration in productive coastal waters. Inherent limitations due to the characteristics of the sensor and its orbit prohibit HICO from providing anywhere near the level of frequent global coverage as provided by standard multispectral ocean color sensors. Nevertheless, the results demonstrate the utility of HICO as a tool for determining water quality in select coastal areas and the cross-sensor applicability of NIR-red models and provide an indication of what could be achieved with future spaceborne hyperspectral sensors in estimating coastal water quality.

Mao XW, Pecaut MJ, Stodieck LS, Ferguson VL, Bateman TA, Bouxsein ML, Gridley DS. Biological and metabolic response in STS-135 space-flown mouse skin. Free Radical Research. 2014;48(8):890-897.

There is evidence that space flight condition-induced biological damage is associated with increased oxidative stress and extracellular matrix (ECM) remodeling. To explore possible mechanisms, changes in gene expression profiles implicated in oxidative stress and in ECM remodeling in mouse skin were examined after space flight. The metabolic effects of space flight in skin tissues were also characterized. Space Shuttle Atlantis (STS-135) was launched at the Kennedy Space Center on a 13-day mission. Female C57BL/6 mice were flown in the STS-135 using animal enclosure modules (AEMs). Within 3?5 h after landing, the mice were euthanized and skin samples were harvested for gene array analysis and metabolic biochemical assays. Many genes responsible for regulating production and metabolism of reactive oxygen species (ROS) were significantly (p < 0.05) altered in the flight group, with fold changes >1.5 compared to AEM control. For ECM profile, several genes encoding matrix and metalloproteinases involved in ECM remodeling were significantly up-/down-regulated following space flight. To characterize the metabolic effects of space flight, global biochemical profiles were evaluated. Of 332 named biochemicals, 19 differed significantly (p < 0.05) between space flight skin samples and AEM ground controls, with 12 up-regulated and 7 down-regulated including altered amino acid, carbohydrate metabolism, cell signaling, and transmethylation pathways. Collectively, the data demonstrated that space flight condition leads to a shift in biological and metabolic homeostasis as the consequence of increased regulation in cellular antioxidants, ROS production, and tissue remodeling. This indicates that astronauts may be at increased risk for pathophysiologic damage or carcinogenesis in cutaneous tissue.

Keith DJ, Schaeffer BA, Lunetta RS, Gould, Jr. RW, Rocha K, Cobb DJ. Remote sensing of selected water-quality indicators with the hyperspectral imager for the coastal ocean (HICO) sensor. International Journal of Remote Sensing. 2014;35(9):2927-2962.

The Hyperspectral Imager for the Coastal Ocean (HICO) offers the coastal environmental monitoring community an unprecedented opportunity to observe changes in coastal and estuarine water quality across a range of spatial scales not feasible with traditional field-based monitoring or existing ocean colour satellites. HICO, an Office of Naval Research-sponsored programme, is the first space-based maritime hyperspectral imaging instrument designed specifically for the coastal ocean. HICO has been operating since September 2009 from the Japanese Experiment Module ? Exposed Facility on the International Space Station (ISS). The high pixel resolution (approximately 95 m at nadir) and hyperspectral imaging capability offer a unique opportunity for characterizing a wide range of water colour constituents that could be used to assess environmental condition. In this study, we transform atmospherically corrected ISS/HICO hyperspectral imagery and derive environmental response variables routinely used for evaluating the environmental condition of coastal ecosystem resources. Using atmospherically corrected HICO imagery and a comprehensive field validation programme, three regionally specific algorithms were developed to estimate basic water-quality properties traditionally measured by monitoring agencies. Results indicated that a three-band chlorophyll a algorithm performed best (R2 = 0.62) when compared with in situ measurement data collected 2?4 hours of HICO acquisitions. Coloured dissolved organic matter (CDOM) (R2 = 0.93) and turbidity (R2 = 0.67) were also highly correlated. The distributions of these water-quality indicators were mapped for four estuaries along the northwest coast of Florida from April 2010 to May 2012. However, before the HICO sensor can be transitioned from proof-of-concept to operational status and its data applied to benefit decisions made by coastal managers, problems with vicarious calibration of the sensor need to be resolved and standardized protocols are required for atmospheric correction. Ideally, the sensor should be placed on a polar orbiting platform for greater spatial and temporal coverage as well as for image synchronization with field validation efforts.

Garcia RA, Fearns PR, McKinna LI. Detecting trend and seasonal changes in bathymetry derived from HICO imagery: A case study of Shark Bay, Western Australia. Remote Sensing of Environment. 2014;147:186-205.

The Hyperspectral Imager for the Coastal Ocean (HICO) aboard the International Space Station has offered for the first time a dedicated space-borne hyperspectral sensor specifically designed for remote sensing of the coastal environment. However, several processing steps are required to convert calibrated top-of-atmosphere radiances to the desired geophysical parameter(s). These steps add various amounts of uncertainty that can cumulatively render the geophysical parameter imprecise and potentially unusable if the objective is to analyze trends and/or seasonal variability. This research presented here has focused on: (1) atmospheric correction of HICO imagery; (2) retrieval of bathymetry using an improved implementation of a shallow water inversion algorithm; (3) propagation of uncertainty due to environmental noise through the bathymetry retrieval process; (4) issues relating to consistent geo-location of HICO imagery necessary for time series analysis, and; (5) tide height corrections of the retrieved bathymetric dataset. The underlying question of whether a temporal change in depth is detectable above uncertainty is also addressed. To this end, nine HICO images spanning November 2011 to August 2012, over the Shark Bay World Heritage Area, Western Australia, were examined. The results presented indicate that precision of the bathymetric retrievals is dependent on the shallow water inversion algorithm used. Within this study, an average of 70% of pixels for the entire HICO-derived bathymetry dataset achieved a relative uncertainty of less than ± 20%. A per-pixel t-test analysis between derived bathymetry images at successive timestamps revealed observable changes in depth to as low as 0.4 m. However, the present geolocation accuracy of HICO is relatively poor and needs further improvements before extensive time series analysis can be performed.

Mishra DR, Schaeffer BA, Keith DJ. Performance evaluation of normalized difference chlorophyll index in northern Gulf of Mexico estuaries using the Hyperspectral Imager for the Coastal Ocean. GIScience and Remote Sensing. 2014;51(2):175-198.

The Hyperspectral Imager for the Coastal Ocean (HICO) was used to derive chlorophyll-a (chl-a) based on the normalized difference chlorophyll index (NDCI) in two Gulf of Mexico coastal estuaries. Chl-a data were acquired from discrete in situ water sample analysis and above-water hyperspectral surface acquisition system (HyperSAS) remote sensing reflectance in Pensacola Bay (PB) and Choctawhatchee Bay (CB). NDCI algorithm calibrations and validations were completed on HICO data. Linear and best-fit (polynomial) calibrations performed strongly with R2 of 0.90 and 0.96, respectively. The best validation of NDCI resulted with an R2 of 0.74 and root-mean-square error (RMSE) of 1.64 µg/L. A strong spatial correspondence was observed between NDCI and chl-a, with higher NDCI associated with higher chl-a and these areas were primarily located in the northern PB and eastern CB at the river mouths. NDCI could be effectively used as a qualitative chl-a monitoring tool with a reduced need for site-specific calibration.

Cho HJ, Ogashawara I, Mishra DR, White J, Kamerosky A, Morris L, Clarke C, Simpson A, Banisakher D. Evaluating Hyperspectral Imager for the Coastal Ocean (HICO) data for seagrass mapping in Indian River Lagoon, FL. GIScience and Remote Sensing. 2014;51(2):120-138.

Differentiation between benthic habitats, particularly seagrass and macroalgae, using satellite data is complicated because of water column effects plus the presence of chlorophyll-a in both seagrass and algae that result in similar spectral patterns. Hyperspectral imager for the coastal ocean data over the Indian River Lagoon, Florida, USA, was used to develop two benthic classification models, SlopeRED and SlopeNIR. Their performance was compared with iterative self-organizing data analysis technique and spectral angle mapping classification methods. The slope models provided greater overall accuracies (63?64%) and were able to distinguish between seagrass and macroalgae substrates more accurately compared to the results obtained using the other classifications methods.

Pellicori SF, Martinex CL, Hausgen P, Wilt D. Development and testing of coatings for orbital space radiation environments. Applied Optics. 2014;53(4):A339-350.

Specific coating processes and materials were investigated in the quest to develop multilayer coatings with greater tolerance to space radiation exposure. Ultraviolet reflection (UVR) and wide-band antireflection (AR) multilayer coatings were deposited on solar cell covers and test substrates and subsequently exposed to simulated space environments and also flown on the Materials International Space Station Experiment-7 (MISSE-7) to determine their space environment stability. Functional solar cells integrated with these coatings underwent simulated UV and MISSE-7 low earth orbit flight exposure. The effects of UV, proton, and atomic oxygen exposure on coatings and on assembled solar cells as related to the implemented deposition processes and material compositions were small. The UVR/AR coatings protected flexible polymer substrate materials that are intended for future flexible multijunction cell arrays to be deployed from rolls. Progress was made toward developing stable and protective coatings for extended space-mission applications. Test results are presented.

Ryan JP, Davis CO, Tufillaro NB, Kudela RM, Gao BG. Application of the Hyperspectral Imager for the Coastal Ocean to Phytoplankton Ecology Studies in Monterey Bay, CA, USA. Remote Sensing. 2014;6(2):1007-1025.

As a demonstrator for technologies for the next generation of ocean color sensors, the Hyperspectral Imager for the Coastal Ocean (HICO) provides enhanced spatial and spectral resolution that is required to understand optically complex aquatic environments. In this study we apply HICO, along with satellite remote sensing and in situ observations, to studies of phytoplankton ecology in a dynamic coastal upwelling environment—Monterey Bay, CA, USA. From a spring 2011 study, we examine HICO-detected spatial patterns in phytoplankton optical properties along an environmental gradient defined by upwelling flow patterns and along a temporal gradient of upwelling intensification. From a fall 2011 study, we use HICO’s enhanced spatial and spectral resolution to distinguish a small-scale “red tide” bloom, and we examine bloom expansion and its supporting processes using other remote sensing and in situ data. From a spectacular HICO image of the Monterey Bay region acquired during fall of 2012, we present a suite of algorithm results for characterization of phytoplankton, and we examine the strengths, limitations, and distinctions of each algorithm in the context of the enhanced spatial and spectral resolution.

Hu X, Raja WK, An B, Tokareva O, Cebe P, Kaplan DL. Stability of silk and collagen protein materials in space. Scientific Reports. 2013;3:3428.

Collagen and silk materials, in neat forms and as silica composites, were flown for 18 months on the International Space Station [Materials International Space Station Experiment (MISSE)-6] to assess the impact of space radiation on structure and function. As natural biomaterials, the impact of the space environment on films of these proteins was investigated to understand fundamental changes in structure and function related to the future utility in materials and medicine in space environments. About 15% of the film surfaces were etched by heavy ionizing particles such as atomic oxygen, the major component of the low-Earth orbit space environment. Unexpectedly, more than 80% of the silk and collagen materials were chemically crosslinked by space radiation. These findings are critical for designing next-generation biocompatible materials for contact with living systems in space environments, where the effects of heavy ionizing particles and other cosmic radiation need to be considered.

Carruthers, Jr. CW, Gerdts C, Johnson MD, Webb P. A microfluidic, high throughput protein crystal growth method for microgravity. PLOS ONE. 201321;8(11):e82298.

The attenuation of sedimentation and convection in microgravity can sometimes decrease irregularities formed during macromolecular crystal growth. Current terrestrial protein crystal growth (PCG) capabilities are very different than those used during the Shuttle era and that are currently on the International Space Station (ISS). The focus of this experiment was to demonstrate the use of a commercial off-the-shelf, high throughput, PCG method in microgravity. Using Protein BioSolutions’ microfluidic Plug Maker™/CrystalCard™ system, we tested the ability to grow crystals of the regulator of glucose metabolism and adipogenesis: peroxisome proliferator-activated receptor gamma (apo-hPPAR-γ LBD), as well as several PCG standards. Overall, we sent 25 CrystalCards™ to the ISS, containing ~10,000 individual microgravity PCG experiments in a 3U NanoRacks NanoLab (1U = 103 cm.). After 70 days on the ISS, our samples were returned with 16 of 25 (64%) microgravity cards having crystals, compared to 12 of 25 (48%) of the ground controls. Encouragingly, there were more apo-hPPAR-γ LBD crystals in the microgravity PCG cards than the 1g controls. These positive results hope to introduce the use of the PCG standard of low sample volume and large experimental density to the microgravity environment and provide new opportunities for macromolecular samples that may crystallize poorly in standard laboratories.

Hammond TG, Stodieck LS, Birdsall HH, Becker JL, Koenig PM, Hammond JS, Gunter MA, Allen PL. Effects of microgravity on the virulence of Listeria monocytogenes, Enterococcus faecalis, Candida albicans, and Methicillin-Resistant Staphylococcus aureus. Astrobiology. 2013;13(11):1081-1090.

To evaluate effects of microgravity on virulence, we studied the ability of four common clinical pathogens—Listeria monocytogenes, methicillin-resistant Staphylococcus aureus (MRSA), Enterococcus faecalis, and Candida albicans—to kill wild type Caenorhabditis elegans (C. elegans) nematodes at the larval and adult stages. Simultaneous studies were performed utilizing spaceflight, clinorotation in a 2-D clinorotation device, and static ground controls. The feeding rate of worms for killed E. coli was unaffected by spaceflight or clinorotation. Nematodes, microbes, and growth media were separated until exposed to true or modeled microgravity, then mixed and grown for 48 h. Experiments were terminated by paraformaldehyde fixation, and optical density measurements were used to assay residual microorganisms. Spaceflight was associated with reduced virulence for Listeria, Enterococcus, MRSA, and Candida for both larval and adult C. elegans. These are the first data acquired with a direct in vivo assay system in space to demonstrate virulence. Clinorotation reproduced the effects of spaceflight in some, but not all, virulence assays: Candida and Enterococcus were less virulent for larval worms but not adult worms, whereas virulence of MRSA and Listeria were unaffected by clinorotation in tests with both adult and larval worms. We conclude that four common clinical microorganisms are all less virulent in space.

Bergstrom L, Bringmann T, Cholis I, Hooper D, Weniger C. New limits on dark matter annihilation from Alpha Magnetic Spectrometer cosmic ray positron data. Physical Review Letters. 2013;111(17):171101.

The Alpha Magnetic Spectrometer experiment onboard the International Space Station has recently provided cosmic ray electron and positron data with unprecedented precision in the range from 0.5 to 350 GeV. The observed rise in the positron fraction at energies above 10 GeV remains unexplained, with proposed solutions ranging from local pulsars to TeV-scale dark matter. Here, we make use of this high quality data to place stringent limits on dark matter with masses below ? 300 GeV, annihilating or decaying to leptonic final states, essentially independent of the origin of this rise. We significantly improve on existing constraints, in some cases by up to 2 orders of magnitude.

Braga F, Giardino C, Bassani C, Matta E, Candiani G, Strombeck N, Adamo M, Bresciani M. Assessing water quality in the northern Adriatic Sea from HICO™ data. Remote Sensing Letters. 2013;4(10):1028-1037.

This letter focuses on water-quality estimation in the northern Adriatic Sea using physically-based methods applied to image obtained with the Hyperspectral Imager for the Coastal Ocean (HICO™). Optical properties of atmosphere and water were synchronously measured to parameterise such methods. HICO™-derived maps of chlorophyll-a (chl-a) and suspended particulate matter (SPM) indicated low values, in the range of 0-3 mg m-3 and 0-4 g m-3, respectively, correlating significantly with field data (R2 = 0.71 for chl-a and R2 = 0.85 for SPM). The results, on analysis, identify clear waters in the open sea and moderately turbid waters near the coast due to river sediment discharge and organic matter from coastal lagoons. These findings support the use of HICO™ data to assess water-quality parameters in coastal zones and suggest the feasibility of integrating them with future-generation space-borne hyperspectral images.

Hammond TG, Stodieck LS, Birdsall HH, Becker JL, Koenig PM, Hammond JS, Gunter MA, Allen PL. Effects of microgravity on the virulence of Salmonella toward Caenorhabditis elegans. New Space. 2013;1(3):123-131.

To evaluate the effects of microgravity on virulence genes in Salmonella, we studied the ability of various Salmonella deletion mutants to kill wild-type Caenorhabditis elegans nematodes at the larval and adult stages. Simultaneous studies were performed utilizing spaceflight, clinorotation, and static ground controls. Nematodes, Salmonella, and growth media were separated until exposed to true or simulated microgravity, and then mixed and grown for 48?h. Experiments were terminated by paraformaldehyde fixation, and optical density measurements were used to assay residual microorganisms. Prior flight in space led to reduced virulence of wild-type Salmonella when subsequently evaluated in a ground-based virulence assay with carefully matched inocula for never-flown Salmonella controls. However, when the virulence assay was conducted in spaceflight, there was only a minimal change in the virulence of wild-type Salmonella toward C. elegans. Deletion of pipA, a gene in Salmonella pathogenicity island-5, reduced Salmonella virulence toward wild-type and Tol1-deletion L2 larvae in spaceflight but had no effect on virulence for Tol1-deletion adult worms in spaceflight. PipA-deletion Salmonella were also less virulent toward wild-type L2 larvae in clinorotation, but showed a paradoxical increased virulence toward Tol1-deletion L2 larvae in clinorotation.

Pramanik S, Mishra M. Linear stability analysis of Korteweg stresses effect on miscible viscous fingering in porous media. Physics of Fluids. 2013;25(7):074104.

Viscous fingering (VF) is an interfacial hydrodynamic instability phenomenon observed when a fluid of lower viscosity displaces a higher viscous one in a porous media. In miscible viscous fingering, the concentration gradient of the undergoing fluids is an important factor, as the viscosity of the fluids are driven by concentration. Diffusion takes place when two miscible fluids are brought in contact with each other. However, if the diffusion rate is slow enough, the concentration gradient of the two fluids remains very large during some time. Such steep concentration gradient, which mimics a surface tension type force, called the effective interfacial tension, appears in various cases such as aqua-organic, polymer-monomer miscible systems, etc. Such interfacial tension effects on miscible VF is modeled using a stress term called Korteweg stress in the Darcy's equation by coupling with the convection-diffusion equation of the concentration. The effect of the Korteweg stresses at the onset of the instability has been analyzed through a linear stability analysis using a self-similar Quasi-steady-state-approximation (SS-QSSA) in which a self-similar diffusive base state profile is considered. The quasi-steady-state analyses available in literature are compared with the present SS-QSSA method and found that the latter captures appropriately the unconditional stability criterion at an earlier diffusive time as well as in long wave approximation. The effects of various governing parameters such as log-mobility ratio, Korteweg parameters, disturbances' wave number, etc., on the onset of the instability are discussed for, (i) the two semi-infinite miscible fluid zones and (ii) VF of the miscible slice cases. The stabilizing property of the Korteweg stresses effect is observed for both of the above mentioned cases. Critical miscible slice lengths are computed to have the onset of the instability for different governing parameters with or without Korteweg stresses. These stabilizing properties of the Korteweg stresses captured in this present study are in agreement with the numerical simulations of fully nonlinear problem and the experimental observations reported in the literature.

Amin R, Lewis D, Gould, Jr. RW, Hou W, Lawson A, Ondrusek M, Arnone RB. Assessing the application of cloud-shadow atmospheric correction algorithm on HICO. IEEE Transactions on Geoscience and Remote Sensing. 2014;52(2):2646-2653.

Several ocean color earth observation satellite sensors are presently collecting daily imagery, including the Hyperspectral Imager for the Coastal Ocean (HICO). HICO has been operating aboard the International Space Station since its installation on September 24, 2009. It provides high spatial resolution hyperspectral imagery optimized for the coastal ocean. Atmospheric correction, however, still remains a challenge for this sensor, particularly in optically complex coastal waters. In this paper, we assess the application of the cloud-shadow atmospheric correction approach on HICO data and validate the results with the in situ data. We also use multiple sets of cloud, shadow, and sunlit pixels to correct a single image multiple times and intercompare the results to assess variability in the retrieved reflectance spectra. Retrieved chlorophyll values from this intercomparison are similar and also agree well with the in situ chlorophyll measurements.

Warren P, Golden A, Hanover J, Love D, Shephard F, Szewczyk NJ.  Evaluation of the fluids mixing enclosure system for life science experiments during a commercial Caenorhabditis elegans spaceflight experiment. Advances in Space Research. 2013;15(12):2241-2250.

The Student Spaceflight Experiments Program (SSEP) is a United States national science, technology, engineering, and mathematics initiative that aims to increase student interest in science by offering opportunities to perform spaceflight experiments. The experiment detailed here was selected and flown aboard the third SSEP mission and the first SSEP mission to the International Space Station (ISS). Caenorhabditis elegans is a small, transparent, self-fertilizing hermaphroditic roundworm that is commonly used in biological experiments both on Earth and in Low Earth Orbit. Past experiments have found decreased expression of mRNA for several genes whose expression can be controlled by the FOXO transcription factor DAF-16. We flew a daf-16 mutant and control worms to determine if the effects of spaceflight on C. elegans are mediated by DAF-16. The experiment used a Type Two Fluids Mixing Enclosure (FME), developed by Nanoracks LLC, and was delivered to the ISS aboard the SpaceX Dragon and returned aboard the Russian Soyuz. The short time interval between experiment selection and the flight rendered preflight experiment verification tests impossible. In addition, published research regarding the viability of the FME in life science experiments was not available. The experiment was therefore structured in such a way as to gather the needed data. Here we report that C. elegans can survive relatively short storage and activation in the FME but cannot produce viable populations for post-flight analysis on extended missions. The FME appears to support short-duration life science experiments, potentially on supply or crew exchange missions, but not on longer ISS expeditions. Additionally, the flown FME was not properly activated, reportedly due to a flaw in training procedures. We suggest that a modified transparent FME could prevent similar failures in future flight experiments.

Krasowski MJ, Prokop NF, Flatico JM, Greer LC, Jenkins PP, Neudeck PG, Chen L, Spina DC. CIB: An improved communication architecture for real-time monitoring of aerospace materials, instruments, and sensors on the ISS. The Scientific World Journal. 2013;2013(185769):12.

The Communications Interface Board (CIB) is an improved communications architecture that was demonstrated on the International Space Station (ISS). ISS communication interfaces allowing for real-time telemetry and health monitoring require a significant amount of development. The CIB simplifies the communications interface to the ISS for real-time health monitoring, telemetry, and control of resident sensors or experiments. With a simpler interface available to the telemetry bus, more sensors or experiments may be flown. The CIB accomplishes this by acting as a bridge between the ISS MIL-STD-1553 low-rate telemetry (LRT) bus and the sensors allowing for two-way command and telemetry data transfer. The CIB was designed to be highly reliable and radiation hard for an extended flight in low Earth orbit (LEO) and has been proven with over 40 months of flight operation on the outside of ISS supporting two sets of flight experiments. Since the CIB is currently operating in flight on the ISS, recent results of operations will be provided. Additionally, as a vehicle health monitoring enabling technology, an overview and results from two experiments enabled by the CIB will be provided. Future applications for vehicle health monitoring utilizing the CIB architecture will also be discussed.

Vendrame W, Pinares A. Characterizing parameters of Jatropha curcas cell cultures for microgravity studies. Advances in Space Research. 2013;51(11):2069-2074.

Jatropha (Jatropha curcas) is a tropical perennial species identified as a potential biofuel crop. The oil is of excellent quality and it has been successfully tested as biodiesel and in jet fuel mixes. However, studies on breeding and genetic improvement of jatropha are limited. Space offers a unique environment for experiments aiming at the assessment of mutations and differential gene expression of crops and in vitro cultures of plants are convenient for studies of genetic variation as affected by microgravity. However, before microgravity studies can be successfully performed, pre-flight experiments are necessary to characterize plant material and validate flight hardware environmental conditions. Such preliminary studies set the ground for subsequent spaceflight experiments. The objectives of this study were to compare the in vitro growth of cultures from three explant sources (cotyledon, leaf, and stem sections) of three jatropha accessions (Brazil, India, and Tanzania) outside and inside the petriGAP, a modified group activation pack (GAP) flight hardware to fit petri dishes. In vitro jatropha cell cultures were established in petri dishes containing a modified MS medium and maintained in a plant growth chamber at 25 ± 2 °C in the dark. Parameters evaluated were surface area of the explant tissue (A), fresh weight (FW), and dry weight (DW) for a period of 12 weeks. Growth was observed for cultures from all accessions at week 12, including subsequent plantlet regeneration. For all accessions differences in A, FW and DW were observed for inside vs. outside the PetriGAPs. Growth parameters were affected by accession (genotype), explant type, and environment. The type of explant influenced the type of cell growth and subsequent plantlet regeneration capacity. However, overall cell growth showed no abnormalities. The present study demonstrated that jatropha in vitro cell cultures are suitable for growth inside PetriGAPs for a period of 12 weeks. The parameters evaluated in this study provide the basic ground work and pre-flight assessment needed to justify a model for microgravity studies with jatropha in vitro cell cultures. Future studies should focus on results of experiments performed with jatropha in vitro cultures in microgravity.

Aguilar-Benitez M, Alberti G, Alpat B, Alvino A, Ambrosi G, et al. First result from the alpha magnetic spectrometer on the International Space Station: Precision measurement of the positron fraction in primary cosmic rays of 0.5-350 GeV. Physical Review Letters. 2013;110(14):141102.

A precision measurement by the Alpha Magnetic Spectrometer on the International Space Station of the positron fraction in primary cosmic rays in the energy range from 0.5 to 350 GeV based on 6.8 × 10 6 positron and electron events is presented. The very accurate data show that the positron fraction is steadily increasing from 10 to ? 250 GeV, but, from 20 to 250 GeV, the slope decreases by an order of magnitude. The positron fraction spectrum shows no fine structure, and the positron to electron ratio shows no observable anisotropy. Together, these features show the existence of new physical phenomena.

Nag S, Katz JG, Saenz-Otero A. Collaborative gaming and competition for CS-STEM education using SPHERES zero robotics. Acta Astronautica. 2013;83:145-174.

There is widespread investment of resources in the fields of Computer Science, Science, Technology, Engineering, Mathematics (CS-STEM) education to improve STEM interests and skills. This paper addresses the goal of revolutionizing student education using collaborative gaming and competition, both in virtual simulation environments and on real hardware in space. The concept is demonstrated using the SPHERES Zero Robotics (ZR) Program which is a robotics programming competition. The robots are miniature satellites called SPHERES—an experimental test bed developed by the MIT SSL on the International Space Station (ISS) to test navigation, formation flight and control algorithms in microgravity. The participants compete to win a technically challenging game by programming their strategies into the SPHERES satellites, completely from a web browser. The programs are demonstrated in simulation, on ground hardware and then in a final competition when an astronaut runs the student software aboard the ISS. ZR had a pilot event in 2009 with 10 High School (HS) students, a nationwide pilot tournament in 2010 with over 200 HS students from 19 US states, a summer tournament in 2010 with ∼150 middle school students and an open-registration tournament in 2011 with over 1000 HS students from USA and Europe. The influence of collaboration was investigated by (1) building new web infrastructure and an Integrated Development Environment where intensive inter-participant collaboration is possible, (2) designing and programming a game to solve a relevant formation flight problem, collaborative in nature—and (3) structuring a tournament such that inter-team collaboration is mandated. This paper introduces the ZR web tools, assesses the educational value delivered by the program using space and games and evaluates the utility of collaborative gaming within this framework. There were three types of collaborations as variables—within matches (to achieve game objectives), inter-team alliances and unstructured communication on online forums. Simulation competition scores, website usage statistics and post-competition surveys are used to evaluate educational impact and the effect of collaboration.

Bailey JF, Hargens AR, Cheng KK, Lotz JC. Post-spaceflight recovery of biomechanical properties of murine intervertebral discs. Gravitational and Space Biology. 2012;26(2):38-47.

Introduction: Prolonged exposure to microgravity during spaceflight is thought to adversely affect the human spine because of reports that disc herniation risk is increased post-spaceflight. The increased herniation risk is highest during the first post-spaceflight year, and gradually subsides thereafter. Consequently, we hypothesized that the biomechanical properties of the intervertebral disc (IVD) deteriorate during spaceflight but then recover after acclimation to normal gravity. To test this hypothesis, we compared the compressive creep properties of caudal IVDs of murine subjects that had returned from a 13-day Shuttle mission (STS-133) to those of ground-based control mice. Methods: Spaceflight (n=6) and control (n=10) groups consisted of 13-week-old, BALB/c mice (11 weeks at launch). Mice were sacrificed +1 day, +5 days, or +7 days after the landing of STS-133. Disc height was measured in situ, and compressive creep rate was fit to a fluid transport model to determine disc biomechanical properties. Results: Compared to controls, spaceflight mice had 12% lower disc height and 21% lower strain-dependence on swelling pressure. Biomechanical properties did not recover significantly over the 7-day post-flight period. Discussion: Biomechanical properties of the murine caudal IVD were diminished by spaceflight, consistent with observations that prolonged exposure to microgravity increases disc herniation risk. These properties did not recover after short-term re-acclimation to 1g loading.

Amin R, Gould, Jr. RW, Hou W, Arnone RB, Lee Z. Optical algorithm for cloud shadow detection over water. IEEE Transactions on Geoscience and Remote Sensing. 2013;51(2):732-741.

The application of ocean color product retrieval algorithms for pixels containing cloud shadows leads to erroneous results. Thus, shadows are an important scene type that should be identified and excluded from the set of clear-sky pixels. In this paper, we present an optical cloud shadow-detection technique called the Cloud Shadow Detection Index (CSDI). This approach is for homogeneous water bodies such as deep waters where shadow detection is very challenging due to the relatively small differences in the brightness values of the shadows and neighboring sunlit or some other regions. The CSDI technique is developed based on the small differences between the total radiances reaching the sensor from the shadowed and neighboring sunlit regions of similar optical properties by amplifying the differences through integrating the spectra of the two regions. The Integrated Value (IV) is then normalized by the mean of the IVs within a spatial adaptive sliding box where atmospheric and marine optical properties are assumed homogeneous. Assuming that the true color and the IV images represent accurate shadow locations, the results were visually compared. The CSDI images agree reasonably well with the corresponding true color and the IV images over open ocean. Also, the shape of the cloud shadow particularly for the isolated cloud closely follows that of the cloud, as expected, reconfirming the potential of the CSDI technique.

Chen W, Mied R, Gao BG, Wagner EJ. Surface velocities from multiple-tracer image sequences. IEEE Geoscience and Remote Sensing Letters. 2012;9(4):769-773.

We discuss a new inverse model to estimate surface velocity using an image sequence with more than one tracer. The method employs the global optimal solution technique, which covers an image scene with subarrays or tiles, within which both velocity components are specified as bilinear forms. Substitution into the tracer conservation equation for each tracer yields a system of equations for the velocity field, which is constrained to fit the image data in a least-squares sense over the entire image domain. Solution is achieved iteratively by a Gauss-Seidel method. A numerical model is used as a benchmark to examine the accuracy of this new technique. Image pairs from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments onboard the NASA Terra and Aqua spacecraft and the hyperspectral imager for the coastal ocean instrument currently onboard the International Space Station are also used to demonstrate the new inverse model with actual ocean data. The derived vector field from MODIS is then compared with the velocity field obtained by the single-tracer technique, and the results are found to be qualitatively equivalent.

Gao BG, Li R, Lucke RL, Davis CO, Bevilacqua RM, Korwan DR, Montes MJ, Bowles JH, Corson MR. Vicarious calibrations of HICO data acquired from the International Space Station. Applied Optics. 2012; 51(14):2559-2567.

The Hyperspectral Imager for the Coastal Ocean (HICO) presently onboard the International Space Station (ISS) is an imaging spectrometer designed for remote sensing of coastal waters. The instrument is not equipped with any onboard spectral and radiometric calibration devices. Here we describe vicarious calibration techniques that have been used in converting the HICO raw digital numbers to calibrated radiances. The spectral calibration is based on matching atmospheric water vapor and oxygen absorption bands and extraterrestrial solar lines. The radiometric calibration is based on comparisons between HICO and the EOS/MODIS data measured over homogeneous desert areas and on spectral reflectance properties of coral reefs and water clouds. Improvements to the present vicarious calibration techniques are possible as we gain more in-depth understanding of the HICO laboratory calibration data and the ISS HICO data in the future.