Clouds and Earth Radiant Energy System (CERES), a review: Past,present and future

The Clouds and Earth Radiant Energy System (CERES) project’s objectives are to measure the reflected solar radiance (shortwave) and Earth-emitted (longwave) radiances and from these measurements to compute the shortwave and longwave radiation fluxes at the top of the atmosphere (TOA) and the surface and radiation divergence within the atmosphere. The fluxes at TOA are to be retrieved to an accuracy of 2%. Improved bidirectional reflectance distribution functions (BRDFs) have been developed to compute the fluxes at TOA from the measured radiances with errors reduced from ERBE by a factor of two or more. Instruments aboard the Terra and Aqua spacecraft provide sampling at four local times. In order to further reduce temporal sampling errors, data are used from the geostationary meteorological satellites to account for changes of scenes between observations by the CERES radiometers.     

Telemetry,telecommand and safety sub-systems for scientific ballooning from Hyderabad

Highly sophisticated balloon-borne scientific payloads have stringent requirement on the telemetry and command system. The development and fabrication of the on-board TT&C package for telemetry, tracking, command, safety and ranging for these experiments is done in-house at the National Balloon Facility (NBF) at Hyderabad. In the last few years, we have made major improvements both in the ground station and the on-board sub-systems, thereby improving the data quality, data handling speed and the general flight control along with aviation safety. The new system has telemetry data rate up to 1 Mbps. A reduction in weight, power and cost of the reengineered on-board integrated package has also lead to the ease of operation during field tests prior to launch and at remote recovery sites. In this paper, we describe the details of the new control package, its flight performance and our plans for portable S-band telemetry and telecommand system to cater to the balloon flights from Antarctic station and long duration balloon flights.     

Satellite and ground detection of very dense smoke clouds produced on the islands of the Paraná river delta that affected a large region in Central Argentina

Intense fires were produced on the Paraná river delta islands, Argentina, during most part of 2008, by a combination of an exceptionally dry period and the farmers’ use of a fire land-cleaning technique. In April 2008, those fires significantly affected the nearby regions and their inhabitants, from Rosario city to Buenos Aires mega-city. In this work we present satellite as well as ground Aerosol Optical Depth (AOD) at 550 nm data obtained during the propagation of pollution clouds to the central zone of Argentina. The highest value (1.18) was registered at Buenos Aires by atmospheric remote sensing, using the satellite instrument MODIS/Terra on April 18th 2008 at 10:35 local time (= UT − 3 h). On the same day, ground air quality detectors also measured in this city the highest Total Suspended Particle (TSP) value of the month, 2.02 mg/m³. The AOD(550) daily variation at Rosario Astronomical Observatory, which is located near the Paraná riverside, was derived by combining solar ultraviolet erythemal irradiance data (measured with a YES biometre) with model calculations. On April 25th 2008, from 12:00 to 15:30 local time, a rather high and constant AOD(550) value was registered, with a mean value of (0.90 ± 0.21). Cities located on the side of the Rosario–Buenos Aires highway (San Nicolás, Baradero and San Pedro) were also affected, showing a mean AOD(550) between the Rosario and Buenos Aires values. The particulate matter was collected with gridded samplers placed on the Paraná river islands as well as at the Rosario Observatory. They were analysed with a Scanning Electron Microscope (SEM) and mainly showed a biological origin. Even if normally large particles travel small distances from the source, organic aerosol in the range of 40–100 μm and complex asymmetric structures were registered several kilometres away from the aerosol sources on the islands. Another event of intense UV index attenuation (98.6%) occurred on September 18th 2008, due to very dense smoke clouds that extended over the Rosario area for several hours. The clouds were driven away from the fires by East–northeast and East–southeast winds. The minimum value of this index measured around noon allows to derive a maximum AOD(550)_max = (3.65 ± 0.90) at 12:45 local time. Soot clouds extended over the Paraná river, transporting Burned Biomass Debris (BBD) that deposited on Rosario. In particular, burned leaves and small branches with dimensions of 1–20 cm were collected. The mean (BBD) particles deposited on the ground from 7:00 to 19:00 local time were (0.92 ± 0.20) BBD/(m² h).     

Analysis of nonstationary heating and cooling of a thermomagnetic engine gadolinium working element

The paper presents the results of calculating nonstatitionary heat exchange between a heattransfer agent (water) and a gadolinium working element of the thermomagnetic engine with the use of ANSYS 13.0 certified software. Recommendations for designing the thermomagnetic engine working elements are given based on the analysis of calculation results.     

Aircraft engine health management via stochastic modelling of flight data interrelations

A novel engine health management (EHM) scheme is introduced. It uses flight-level, instead of thermodynamic, data to cost-effectively augment the onboard EHM redundancy. For a nominal healthy aircraft, fault-sensitive interrelations among flight data are globally modelled inside a flight regime via Constant-Coefficient Pooled Nonlinear AutoRegressive with eXogenous (CCP-NARX) excitation representations. Single or sequential engine faults perturb these interrelations. Statistically evaluating the perturbation-induced effects draws reliable conclusions on the engine?s health. Validation and comparisons with Kalman filter-based alternatives are made throughout the regime under various operational conditions.     

The Magnetic Electron Ion Spectrometer (MagEIS) Instruments Aboard the Radiation Belt Storm Probes (RBSP) Spacecraft

This paper describes the Magnetic Electron Ion Spectrometer (MagEIS) instruments aboard the RBSP spacecraft from an instrumentation and engineering point of view. There are four magnetic spectrometers aboard each of the two spacecraft, one low-energy unit (20–240 keV), two medium-energy units (80–1200 keV), and a high-energy unit (800–4800 keV). The high unit also contains a proton telescope (55 keV–20 MeV). The magnetic spectrometers focus electrons within a selected energy pass band upon a focal plane of several silicon detectors where pulse-height analysis is used to determine if the energy of the incident electron is appropriate for the electron momentum selected by the magnet. Thus each event is a two-parameter analysis, an approach leading to a greatly reduced background. The physics of these instruments are described in detail followed by the engineering implementation. The data outputs are described, and examples of the calibration results and early flight data presented.     

Characterization of Kalman filter residuals in the presence ofmismodeling

The mean and covariance of a Kalman filter residual are computed for specific cases in which the Kalman filter model differs from a linear model that accurately represents the true system (the truth model). Multiple model adaptive estimation (MMAE) uses a bank of Kalman filters, each with a different internal model, and a hypothesis testing algorithm that uses the residuals from this bank of Kalman filters to estimate the true system model. At most, only one Kalman filter model will exactly match the truth model and will produce a residual whose mean and standard deviation have already been analyzed. All of the other filters use internal models that mismodel the true system. We compute the effects of a mismodeled input matrix, output matrix, and state transition matrix on these residuals. The computed mean and covariance are compared with simulation results of flight control failures that correspond to mismodeled input matrices and output matrices     

Solid organic matter in the atmosphere and on the surface of outer Solar System bodies.

Many bodies in the outer Solar System display the presence of low albedo materials. These materials, evident on the surface of asteroids, comets, Kuiper Belt objects and their intermediate evolutionary step, Centaurs, are related to macromolecular carbon bearing materials such as polycyclic aromatic hydrocarbons and organic materials such as methanol and related light hydrocarbons, embedded in a dark, refractory, photoprocessed matrix. Many planetary rings and satellites around the outer gaseous planets display such component materials. One example, Saturn's largest satellite, Titan, whose atmosphere is comprised of around 90% molecular nitrogen N2 and less than 10% methane CH4, displays this kind of low reflectivity material in its atmospheric haze. These materials were first recorded during the Voyager 1 and 2 flybys of Titan and showed up as an optically thick pinkish orange haze layer. These materials are broadly classified into a chemical group whose laboratory analogs are termed "tholins", after the Greek word for "muddy". Their analogs are produced in the laboratory via the irradiation of gas mixtures and ice mixtures by radiation simulating Solar ultraviolet (UV) photons or keV charged particles simulating particles trapped in Saturn's magnetosphere. Fair analogs of Titan tholin are produced by bombarding a 9:1 mixture of N2:CH4 with charged particles and its match to observations of both the spectrum and scattering properties of the Titan haze is very good over a wide range of wavelengths. In this paper, we describe the historical background of laboratory research on this kind of organic matter and how our laboratory investigations of Titan tholin compare. We comment on the probable existence of polycyclic aromatic hydrocarbons in the Titan Haze and how biological and nonbiological racemic amino acids produced from the acid hydrolysis of Titan tholins make these complex organic compounds prime candidates in the evolution of terrestrial life and extraterrestrial life in our own Solar System and beyond. Finally, we also compare the spectrum and scattering properties of our resulting tholin mixtures with those observed on Centaur 5145 Pholus and the dark hemisphere of Saturn's satellite Iapetus in order to demonstrate the widespread distribution of similar organics throughout the Solar System.     

Survival of amino acids in micrometeorites during atmospheric entry

The delivery of amino acids by micrometeorites to the early Earth during the period of heavy bombardment could have been a significant source of the Earth's prebiotic amino acid inventory provided that these organic compounds survived atmospheric entry heating. To investigate the sublimation of amino acids from a micrometeorite analog at elevated temperature, grains from the CM-type carbonaceous chondrite Murchison were heated to 550 degrees C inside a glass sublimation apparatus (SA) under reduced pressure. The sublimed residue that had collected on the cold finger of the SA after heating was analyzed for amino acids by HPLC. We found that when the temperature of the meteorite reached approximately 150 degrees C, a large fraction of the amino acid glycine had vaporized from the meteorite, recondensed onto the end of the SA cold finger, and survived as the rest of the grains heated to 550 degrees C. alpha-Aminoisobutryic acid and isovaline, which are two of the most abundant non-protein amino acids in Murchison, did not sublime from the meteorite and were completely destroyed during the heating experiment. Our experimental results suggest that sublimation of glycine present in micrometeorite grains may provide a way for this amino acid to survive atmospheric entry heating at temperatures > 550 degrees C; all other amino acids apparently are destroyed.     

Brines in seepage channels as eluants for subsurface relict biomolecules on Mars?

Water, vital for life, not only maintains the integrity of structural and metabolic biomolecules, it also transports them in solution or colloidal suspension. Any flow of water through a dormant or fossilized microbial community elutes molecules that are potentially recognizable as biomarkers. We hypothesize that the surface seepage channels emanating from crater walls and cliffs in Mars Orbiter Camera images results from fluvial erosion of the regolith as low-temperature hypersaline brines. We propose that, if such flows passed through extensive subsurface catchments containing buried and fossilized remains of microbial communities from the wet Hesperian period of early Mars (approximately 3.5 Ga ago), they would have eluted and concentrated relict biomolecules and delivered them to the surface. Life-supporting low-temperature hypersaline brines in Antarctic desert habitats provide a terrestrial analog for such a scenario. As in the Antarctic, salts would likely have accumulated in water-filled depressions on Mars by seasonal influx and evaporation. Liquid water in the Antarctic cold desert analogs occurs at -80 degrees C in the interstices of shallow hypersaline soils and at -50 degrees C in salt-saturated ponds. Similarly, hypersaline brines on Mars could have freezing points depressed below -50 degrees C. The presence of hypersaline brines on Mars would have extended the amount of time during which life might have evolved. Phototrophic communities are especially important for the search for life because the distinctive structures and longevity of their pigments make excellent biomarkers. The surface seepage channels are therefore not only of geomorphological significance, but also provide potential repositories for biomolecules that could be accessed by landers.