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  • 251.
    Nilsson, Hans
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Slapak, Rikard
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Barghouthi, I.A.
    Department of Physics, Al-Quds University, Jerusalem.
    Eriksson, A.I.
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    André, M.
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Hot and cold ion outflow: Spatial distribution of ion heating2012In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 117Article in journal (Refereed)
    Abstract [en]

    Ions apparently emanating from the same source, the ionospheric polar cap, can either end up as energized to keV energies in the high-altitude cusp/mantle, or appear as cold ions in the magnetotail lobes. We use Cluster observations of ions and wave electric fields to study the spatial variation of ion heating in the cusp/mantle and polar cap. The average flow direction in a simplified cylindrical coordinate system is used to show approximate average ion flight trajectories, and discuss the temperatures, fluxes and wave activity along some typical trajectories. It is found that it is suitable to distinguish between cusp, central and nightside polar cap ion outflow trajectories, though O+ heating is mainly a function of altitude. Furthermore we use typical cold ion parallel velocities and the observed average perpendicular drift to obtain average cold ion flight trajectories. The data show that the cusp is the main source of oxygen ion outflow, whereas a polar cap source would be consistent with our average outflow paths for cold ions observed in the lobes. A majority of the cusp O+ flux is sufficiently accelerated to escape into interplanetary space. A scenario with significant oxygen ion heating in regions with strong magnetosheath origin ion fluxes, cold proton plasma dominating at altitudes below about 8 RE in the polar cap, and most of the cusp oxygen outflow overcoming gravity and flowing out in the cusp and mantle is consistent with our observations.

  • 252.
    Nilsson, Hans
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Wieser, Gabriella Stenberg
    Swedish Institute of Space Physics.
    Behar, Etienne
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Wedlund, Cyril Simon
    Aalto University, School of Electrical Engineering, Department of Radio Science and Engineering.
    Gunell, Herbert
    Belgian Institute for Space Aeronomy, Brussels.
    Yamauchi, Masatoshi
    Swedish Institute of Space Physics.
    Lundin, Rickard
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Barabash, Stas
    Swedish Institute of Space Physics.
    Wieser, Martin
    Swedish Institute of Space Physics.
    Carr, Chris
    Imperial College London.
    Cupido, Emanuele
    Imperial College London.
    Burch, James L.
    Southwest Research Institute, 6220 Culebra Road, San Antonio.
    Fedorov, Andrei
    Institut de Recherche en Astrophysique et Planetologie, Toulouse.
    Savaud, Jean-André
    Institut de Recherche en Astrophysique et Planetologie, Toulouse.
    Koskinen, Hannu
    Department of Physics, University of Helsinki.
    Kallio, Esa
    Aalto University, School of Electrical Engineering, Department of Radio Science and Engineering.
    Lebreton, Jean-Pierre
    Laboratoire de Physique et Chimie de l’Environnement et de l’Espace (LPC2E).
    Eriksson, Anders
    Swedish Institute of Space Physics, Ångström Laboratory.
    Edberg, Niklas
    Swedish Institute of Space Physics, Ångström Laboratory.
    Goldstein, Raymond
    Belgian Institute for Space Aeronomy, Brussels.
    Henri, Pierre
    Laboratoire de Physique et Chimie de l’Environnement et de l’Espace (LPC2E).
    Coenders, Christoph
    Technische Universität–Braunschweig, Institute for Geophysics and Extraterrestrial Physics.
    Mokashi, Prachet
    Southwest Research Institute, 6220 Culebra Road, San Antonio.
    Nemeth, Zoltan
    Wigner Research Centre for Physics, 1121 Konkoly Thege Street 29-33, Budapest.
    Richter, Ingo
    Technische Universität–Braunschweig, Institute for Geophysics and Extraterrestrial Physics.
    Rubin, Martin
    Physikalisches Institut, University of Bern.
    Birth of a comet magnetosphere: A spring of water ions2015In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 347, no 6220, aaa0571Article in journal (Refereed)
    Abstract [en]

    The Rosetta mission shall accompany comet 67P/Churyumov-Gerasimenko from a heliocentric distance of >3.6 astronomical units through perihelion passage at 1.25 astronomical units, spanning low and maximum activity levels. Initially, the solar wind permeates the thin comet atmosphere formed from sublimation, until the size and plasma pressure of the ionized atmosphere define its boundaries: A magnetosphere is born. Using the Rosetta Plasma Consortium ion composition analyzer, we trace the evolution from the first detection of water ions to when the atmosphere begins repelling the solar wind (~3.3 astronomical units), and we report the spatial structure of this early interaction. The near-comet water population comprises accelerated ions (

  • 253.
    Nilsson, Hans
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Wieser, Gabriella Stenberg
    Swedish Institute of Space Physics.
    Behar, Etienne
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Wedlund, Cyril Simon
    Aalto University, School of Electrical Engineering, Department of Radio Science and Engineering.
    Kallio, Esa
    Finnish Meteorological Institute, Aalto University, School of Electrical Engineering, Department of Radio Science and Engineering.
    Gunell, Herbert
    Swedish Institute of Space Physics / Institutet för rymdfysik , Belgian Institute for Space Aeronomy, Brussels.
    Edberg, N.J.T.
    Swedish Institute of Space Physics, Uppsala.
    Eriksson, Anders
    Swedish Institute of Space Physics, Ångström Laboratory.
    Yamauchi, Masatoshi
    Swedish Institute of Space Physics.
    Koenders, Christoph
    Institut für Geophysik und Extraterrestrische Physik, Technische Universität Braunschweig.
    Wieser, Martin
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Lundin, Rickard
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Barabash, Stas
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Mandt, Kathleen E.
    Space Science and Engineering Division, Southwest Research Institute (SwRI).
    Burch, James L.
    Southwest Research Institute, 6220 Culebra Road, San Antonio.
    Goldstein, Raymond M.
    Space Science and Engineering Division, Southwest Research Institute (SwRI).
    Mokashi, Prachet
    Southwest Research Institute, 6220 Culebra Road, San Antonio.
    Carr, Chris
    Imperial College London.
    Cupido, Emanuele
    Imperial College London.
    Fox, P.T.
    Imperial College London.
    Szego, Karoly
    Wigner Research Centre for Physics, 1121 Konkoly Thege Street 29-33, Budapest.
    Nemeth, Zoltan
    Wigner Research Centre for Physics, 1121 Konkoly Thege Street 29-33, Budapest.
    Fedorov, Andrei
    Institut de Recherche en Astrophysique et Planetologie, Toulouse.
    Sauvaud, J.A.
    Institut de Recherche en Astrophysique et Planetologie, Toulouse.
    Koskinen, Hannu
    Department of Physics, University of Helsinki.
    Geiger, B.
    Rosetta Science Ground Segment, Science and Robotic Exploration (SRE-OOR).
    Evolution of the ion environment of comet 67P/Churyumov-Gerasimenko2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 583, A20Article in journal (Refereed)
    Abstract [en]

    Context. The Rosetta spacecraft is escorting comet 67P/Churyumov-Gerasimenko from a heliocentric distance of >3.6 AU, where the comet activity was low, until perihelion at 1.24 AU. Initially, the solar wind permeates the thin comet atmosphere formed from sublimation. Aims. Using the Rosetta Plasma Consortium Ion Composition Analyzer (RPC-ICA), we study the gradual evolution of the comet ion environment, from the first detectable traces of water ions to the stage where cometary water ions accelerated to about 1 keV energy are abundant. We compare ion fluxes of solar wind and cometary origin. Methods. RPC-ICA is an ion mass spectrometer measuring ions of solar wind and cometary origins in the 10 eV-40 keV energy range. Results. We show how the flux of accelerated water ions with energies above 120 eV increases between 3.6 and 2.0 AU. The 24 h average increases by 4 orders of magnitude, mainly because high-flux periods become more common. The water ion energy spectra also become broader with time. This may indicate a larger and more uniform source region. At 2.0 AU the accelerated water ion flux is frequently of the same order as the solar wind proton flux. Water ions of 120 eV-few keV energy may thus constitute a significant part of the ions sputtering the nucleus surface. The ion density and mass in the comet vicinity is dominated by ions of cometary origin. The solar wind is deflected and the energy spectra broadened compared to an undisturbed solar wind.

  • 254. Norberg, O.
    et al.
    Puccio, W.
    Olsen, J.
    Barabash, Stas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Andersson, L.
    Winningham, J.D.
    Jonsson, U.
    Luleå tekniska universitet.
    Eriksson, Magnus
    Munin: a student nanosatellite for space weather information1999In: Microsatellites as research tools: Proceedings of COSPAR Colloquium on Microsatellites as Research Tools held in Tainan, Taiwan, 14-17 December 1997 / edited by Fei-Bin Hsiao., Elsevier, 1999Conference paper (Refereed)
  • 255.
    Nordström, T.
    et al.
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Stenberg, G.
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Nilsson, Hans
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Barabash, Stas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Zhang, T.L.
    Austrian Academy of Sciences, Space Research Institute, Graz.
    Venus ion outflow estimates at solar minimum: Influence of reference frames and disturbed solar wind conditions2013In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 118, no 6, 3592-3601 p.Article in journal (Refereed)
    Abstract [en]

    Recent estimates of ion escape rates from Venus, based on ASPERA-4 data, differ by more than a factor of 4. Whereas the ASPERA-4 instrument provides state-of-the art observations, the limited field of view of the instrument and the strongly limited geographical coverage of the spacecraft orbit means that significant assumptions must be used in the interpretation of the data. We complement previous studies by using a method of average distribution functions to obtain as good statistics as possible while taking the limited field of view into account. We use more than 3 years of data, more than any of the previous studies, and investigate how the choice of a geographical reference frame or a solar wind electric field oriented reference frame affects the results. We find that the choice of reference frame cannot explain the difference between the previously published reports. Our results, based on a larger data set, fall in between the previous studies. Our conclusion is that the difference between previous studies is caused by the large variability of ion outflow at Venus. It matters significantly for the end result which data are selected and which time period is used. The average escape rates were found to be 5.2±1.0×1024 s−1for heavy ions (m/q ≥16) and 14±2.6×1024 s−1for protons. We also discuss the spatial distribution of the planetary ion outflow in the solar wind electric field reference frame.

  • 256.
    Perez, Javier Roldán
    et al.
    Department of Physics, Systems Engineering and Signal Theory, University of Alicante.
    Pomares, J.
    Department of Physics, Systems Engineering and Signal Theory, University of Alicante.
    Emami, Reza
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Image-based control of satellite-mounted robot manipulators2016In: Proceedings of 2016 7th International Conference on Mechanical and Aerospace Engineering, ICMAE 2016: London, United Kingdom, 18-20 July 2016, Piscataway, NU: IEEE Communications Society, 2016, 346-351 p., 7549564Conference paper (Refereed)
    Abstract [en]

    Robot manipulators have multiple uses and are especially useful when dealing with complex manipulation tasks in unstructured environments. This paper presents a direct image-based controller for performing the guidance of a free-floating robot manipulator. A camera is attached to the end-effector of the manipulator and the robot is attached to a base satellite. The proposed direct image-based control strategy computes the torque to be applied to the joints, and takes into account the system's kinematics and dynamics model. The operation is such that the base is completely free and floating in space with no attitude control, and thus freely reacting to the movements of the robot manipulator attached to it. The main objective is to track a desired trajectory in the image space with respect to an observed object in space. The proposed control strategy optimizes the motor commands with respect to a specified metric. The controller is applied to direct visual control of a four-degree-of-freedom robot manipulator.

  • 257.
    Pietranera, Luca
    et al.
    University of Manchester, School of Physics and Astronomy.
    Buehler, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Calisse, Paolo
    University of Cardiff, School of Physics and Astronomy.
    Emde, Claudia
    Deutsches Zentrum fuer Luft- und Raumfahrt (DLR) Institut fuer Physik der Atmosphaere, Oberpfaffenhofen.
    Hayton, Darren
    University of Cardiff, School of Physics and Astronomy.
    John, Viju Oommen
    University of Miami, Rosenstiel School of Marine and Atmospheric Sciences, Miami.
    Maffei, Bruno
    University of Manchester, School of Physics and Astronomy.
    Piccirillo, Lucio
    University of Manchester, School of Physics and Astronomy.
    Pisano, Giampaolo
    University of Manchester, School of Physics and Astronomy.
    Savini, Giorgio
    University of Cardiff, School of Physics and Astronomy.
    Sreerekha, T. R.
    Met Office Hadley Centre, Exeter.
    Observing cosmic microwave background polarisation through ice2007In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 376, no 2, 645-650 p.Article in journal (Refereed)
    Abstract [en]

    Ice crystal clouds in the upper troposphere can generate polarization signals at the μK level. This signal can seriously affect very sensitive ground-based searches for E and B modes of cosmic microwave background polarization. In this paper, we estimate this effect within the ...

  • 258.
    Pomares, Jorge
    et al.
    University of Alicante.
    Felicetti, Leonard
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Pérez, Javier
    University of Alicante.
    Emami, Reza
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Space Mechatronics group, University of Toronto, Institute for Aerospace Studies.
    Concurrent Image-based Visual Servoing with Adaptive Zooming for Non-cooperative Rendezvous Maneuvers2017In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948Article in journal (Refereed)
    Abstract [en]

    An image-based servo controller for the guidance of a spacecraft during non-cooperative rendezvous is presented in this paper. The controller directly utilizes the visual features from image frames of a target spacecraft for computing both attitude and orbital maneuvers concurrently. The utilization of adaptive optics, such as zooming cameras, is also addressed through developing an invariant-image servo controller. The controller allows for performing rendezvous maneuvers independently from the adjustments of the camera focal length, improving the performance and versatility of maneuvers. The stability of the proposed control scheme is proven analytically in the invariant space, and its viability is explored through numerical simulations.

  • 259.
    Pope, Charles
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Calibration and Uncertainty Analysis of a Spacecraft Attitude Determination Test Stand2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Experimental testing of attitude determination systems still plays an important role, despite increasing use of simulations. Testing provides a means to numerically quantify system performance, give confidence in the models and methods, and also discover and compensate for unexpected behaviours and interactions with the attitude determination system. The usefulness of the test results is dependent on an understanding of the uncertainties that contribute to the attitude error. With this understanding, the significance of the results can be assessed, and efforts to reduce attitude errors can be directed appropriately. The work of this thesis is to gain a quantitative understanding of the uncertainties that impact the attitude error of low cost spinning spacecraft using COTS camera (as Sun sensor) and MEMS magnetometer. The sensors were calibrated and the uncertainties in these calibrations were quantified, then propagated through the Triad method to uncertainties in the attitude. It was found that most systematic errors were reduced to negligible levels, except those due to timing latencies. Attitude errors achieved in the laboratory with the experimental setup were around 0.14 degrees (3σ) using either the Triad, q-method or Extended Kalman Filter with a gyro for dynamic model replacement. The errors in laboratory were dominated by magnetometer noise. Furthermore, correlated systematic errors had the effect of reducing the attitude error calculated in the laboratory. For an equivalent Sun-mag geometry in orbit, simulation showed that total attitude error would be of the order of 0.77 degrees (3σ). An uncertainty contribution analysis revealed this error was dominated by uncertainties in the inertial magnetic field model. Uncertainties in knowledge of the inertial Sun model, sensor calibration, sensor alignment and sensor noise were shown to be insignificant in comparison.

  • 260.
    Poppe, A.R.
    et al.
    Space Science Laboratory, University of California, Berkeley.
    Fatemi, Shahab
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Halekas, J.S.
    Space Science Laboratory, University of California, Berkeley.
    Holmström, Mats
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Delory, G.T.
    Space Science Laboratory, University of California, Berkeley.
    ARTEMIS observations of extreme diamagnetic fields in the lunar wake2014In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 41, no 11, 3766-3773 p.Article in journal (Refereed)
    Abstract [en]

    We present two Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun ( ARTEMIS) observations of diamagnetic fields in the lunar wake at strengths exceeding twice the ambient magnetic field during high plasma beta conditions. The first observation was 350 km from the lunar surface while the Moon was located in the terrestrial magnetosheath with elevated particle temperatures. The second observation was in the solar wind ranging from 500 to 2000 km downstream, with a relatively low magnetic field strength of approximately 1.6 nT. In both cases, the plasma beta exceeded 10. We discuss the observations and compare the data to hybrid plasma simulations in order to validate the model under such extreme conditions and to elucidate the global structure of the lunar wake during these observations. The extreme nature of the diamagnetic field in the lunar wake provides an important end-member test case for theoretical and modeling studies of the various plasma processes operating in the lunar wake.

  • 261.
    Potrivitu, George-Cristian
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. University Toulouse III Paul Sabatier France.
    Low–voltage External Discharge Plasma Thruster and Hollow Cathodes Plasma Plume Diagnostics Utilising Electrostatic Probes and Retarding Potential Analyser2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The present thesis is the result of a research period at the Institute of Space and Astronautical Science of the Japanese Aerospace Exploration Agency, ISAS/JAXA within Funaki Laboratory of the Department of Space Flight Systems that followed the path of plume plasma diagnostics for space electric propulsion drives. During the experimental studies two high-current hollow cathodes and an innovative prototype of a low-voltage fully external discharge plasma thruster (XPT) had their plasma plumes diagnosed using electrostatic probes and retarding potential analyser (RPA).

    A Hall thruster and hollow cathode plume is defined as an unmagnetised quasi-neutral plasma which is mainly formed of neutral particles, electrons, singly and doubly charged ions. Plasma diagnostic techniques provide information through practical observations in order to fully understand the dynamics of the aforementioned plume components, the physical processes taking place within the plume and their effects on the spacecraft, for instance. Mastering these aspects of the plasma plume of space electric propulsion drives bolster the design processes, leading to highly efficient devices.

    Firstly, the introduction provides insights on the fundamental principles of hollow cathodes and Hall thrusters and a brief presentation of the plasma diagnostic techniques used during the research: single and double Langmuir probes, emissive probes and retarding potential analyser. Then, the fundamental plume diagnostics principles are depicted in an exhaustive way, departing from classical plasma kinetic theory, energy distribution functions and ending with an overview on the theory of charge collection by cylindrical probes. Subsequently, peculiarities of various analysis techniques are exposed for the Langmuir probes, emissive probes and RPA, with an emphasis on their strengths and demerits.

    The experimental setups for the cathodes and XPT plume diagnostic procedures are then outlined. The experimental logic, setup and electrical diagrams as well as a presentation of each probe design and manufacturing details are extensively discussed.

    The hollow cathodes experimental results are exposed with a discourse that aims of overviewing the difference between the various data analysis methods applied for the raw data. A discussion ensued based on the results in order to effectively identify mechanisms that produced the observed plasma parameters distributions.

    For the first time, the plume of a fully external discharge plasma thruster was diagnosed utilising double Langmuir probes.  The thesis highlights the main results obtained for the XPT far-field plume plasma diagnostics. The experimental findings for both thruster centreline positions and 2D plume maps for several axial distances away from the anode plate offer a ground basis for future measurements, a comparison term and a database to support ongoing computational codes. The results are discussed and related to the thruster performances data obtained during previous experiments.

    The thesis includes consistency analyses between the experimental data and the numerical simulation results and the uncertainties in measured plasma parameters associated with each data analysis procedure are evaluated for each data set. Last, the conclusions underline the main aspects of the research and further work on the previously mentioned plasma diagnostic techniques for hollow cathodes and XPT is suggested. 

  • 262.
    Rijal, Samundra
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Case Study: Conceptual Ground Station Design for N66 Connect AB2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As the communication deficit in the Arctic region is enormous especially above 75 [Deg] N latitude, the concern and opportunity of providing reliable & efficient connectivity in the Arctic region has beenduly noted & understood by N66 Connect AB (N66). This case study documents a comprehensive research which implements system engineering approach for establishment of a Ground Station (GS) at Svalbard, Norway with sole focus of connecting the inaccessible geographical region lying in the Arctic with rest of the world. Several GS system & subsystem are studied and comparative analysis is made on how the communication can be established with the N66 Connect AB (N66)’s potential clients and its satellites that are to be deployed in September, 2018.The case study resulted in analysis of several risks involved during development & operation of the GS,the hardware, software & operational architecture, the features of GS’s system capable of meeting N66’s objectives and the market potential of the service after GS operations.

  • 263.
    Rydberg, Bengt
    et al.
    Chalmers University of Technology, Department of Radio and Space Science, Gothenburg.
    Eriksson, Patrick
    Chalmers University of Technology, Department of Radio and Space Science, Gothenburg.
    Buehler, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Prediction of cloud ice signatures in submillimeter emission spectra by means of ground-based radar and in-situ microphysical data2007In: Quarterly Journal of the Royal Meteorological Society, ISSN 0035-9009, E-ISSN 1477-870X, Vol. 133, no Suppl.2, 151-162 p.Article in journal (Refereed)
    Abstract [en]

    Submillimetre down-looking radiometry is a promising technique for global measurements of cloud ice properties. There exist no observation data of sufficient size that can be used for detailed pre-launch studies of such an instrument and other means must be found to obtain data to optimise the instrument design and similar tasks. Several aspects of the observations make traditional retrieval methods not suitable and nonlinear multidimensional regression techniques (e.g. Bayesian Monte Carlo integration and neural networks) must be applied. Such methods are based on a retrieval database and to be successful the database must mimic relevant real conditions closely. A method to generate such databases of high quality is described here. Correct vertical distributions of cloud ice are obtained by basic data from ground-based radars. Cloud ice particle microphysical properties are generated randomly where statistical parameters are selected to mimic in situ measurement data closely. Atmospheric background fields from ECMWF are perturbed to account for variation on sub-grid scales. All these data, together with sensor characteristics, are fed into a state-of-the-art radiative transfer simulator (ARTS). The method was validated by a successful comparison with AMSU data.

  • 264.
    Rydberg, Bengt
    et al.
    Chalmers University of Technology, Department of Radio and Space Science, Gothenburg.
    Eriksson, Patrick
    Chalmers University of Technology, Department of Radio and Space Science, Gothenburg.
    Buehler, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Murtagh, Donal
    Chalmers University of Technology, Department of Radio and Space Science, Gothenburg.
    Non-Gaussian Bayesian retrieval of tropical upper tropospheric cloud ice and water vapour from Odin-SMR measurements2009In: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, Vol. 2, no 2, 621-637 p.Article in journal (Refereed)
    Abstract [en]

    Improved Odin-SMR retrievals of upper tropospheric water are presented. The new retrieval algorithm retrieves humidity and cloud ice mass simultaneously and takes into account of cloud inhomogeneities. Both these aspects are introduced for microwave limb sounding inversions for the first time. A Bayesian methodology is applied allowing for a formally correct treatment of non-unique retrieval problems involving non-Gaussian statistics. Cloud structure information from CloudSat is incorporated into the retrieval algorithm. This removes a major limitation of earlier inversion methods where uniform cloud layers were assumed and caused a systematic retrieval error. The core part ofthe retrieval technique is the generation of a database that must closely represent real conditions. Good agreement with Odin-SMR observations indicates that this requirement is met. The retrieval precision is determined to be about 5–17% RHi and 65% for humidity and cloud ice mass, respectively.For both quantities, the vertical resolution is about 5 km and the best retrieval performance is found between 11 and 15 km. New data show a significantly improved agreement with CloudSat cloud ice mass retrievals, at the same time consistency with the Aura MLS humidity results is maintained. The basics of the approach presented can be applied for all passive cloud observations and should be of broad interest. The results can also be taken as a demonstration of the potential of down-looking sub-mm radiometry for global measurements of cloud ice properties.

  • 265.
    Rüfenacht, R.
    et al.
    Institute of Applied Physics, University of Bern.
    Murk, A.
    Institute of Applied Physics, University of Bern.
    Kämpfer, N.
    Institute of Applied Physics, University of Bern.
    Eriksson, P.
    Chalmers University of Technology, Department of Earth and Space Sciences.
    Buehler, S. A.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Division of Space Technology, SRT, Luleä University of Technology.
    Middle-atmospheric zonal and meridional wind profiles from polar, tropical and midlatitudes with the ground-based microwave Doppler wind radiometer WIRA2014In: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, Vol. 7, 4491-4505 p.Article in journal (Refereed)
    Abstract [en]

    WIRA is a ground-based microwave Doppler spectroradiometer specifically designed for the measurement of profiles of horizontal wind in the upper stratosphere and lower mesosphere region where no other continuously running measurement technique exists. A proof of principle has been delivered in a previous publication. A technical upgrade including a new high-frequency amplifier and sideband filter has improved the signal to noise ratio by a factor of 2.4. Since this upgrade the full horizontal wind field comprising zonal and meridional wind profiles is continuously measured. A completely new retrieval based on optimal estimation has been set up. Its characteristics are detailed in the present paper. Since the start of the routine operation of the first prototype in September 2010, WIRA has been measuring at four different locations at polar, mid- and tropical latitudes (67°22′ N/26°38′ E, 46°57′ N/7°26′ E, 43°56′ N/5°43′ E and 21°04′ S/55°23′ E) for time periods between 5.5 and 11 months. The data presented in this paper are daily average wind profiles with typical uncertainties and resolutions of 10 to 20 m s−1 and 10 to 16 km, respectively. A comparison between the data series from WIRA and European Centre for Medium-Range Weather Forecasts (ECMWF) model data revealed agreement within 10% in the stratospheric zonal wind. The meridional wind profiles agree within their error bars over the entire sensitive altitude range of WIRA. However, significant differences in the mesospheric zonal wind speed of up to 50% have been found.

  • 266.
    Rüfenacht, R.
    et al.
    Institute of Applied Physics, University of Bern.
    Murk, A.
    Institute of Applied Physics, University of Bern.
    Kämpfer, N.
    Institute of Applied Physics, University of Bern.
    Eriksson, P.
    Chalmers University of Technology, Department of Earth and Space Sciences.
    Buehler, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Middle-atmospheric zonal and meridional wind profiles from polar, tropical and midlatitudes with the ground-based microwave Doppler wind radiometer WIRA2014In: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, Vol. 7, 7717-7752 p.Article in journal (Refereed)
    Abstract [en]

    WIRA is a ground-based microwave Doppler spectro radiometer specifically designed for the measurement of profiles of horizontal wind in the upper stratosphere and lower mesosphere region where no other continuously running measurement technique exists. A proof of principle has been delivered in a previous publication. Since a technical upgrade which improved the signal to noise ratio by a factor of 2.4 the full horizontal wind field comprising zonal and meridional wind profiles is continuously measured. A completely new retrieval based on optimal estimation has been set up. Its characteristics are detailed in the present paper.Since the start of the routine operation of the first prototype in September 2010, WIRA has been measuring at four different locations at polar, mid and tropical latitudes for time periods between 5.5 and 11 months. A comparison between the data series from WIRA and ECMWF model data revealed agreement within 10% in the stratospheric zonal wind. The meridional wind profiles agree within their error bars over the entire sensitive altitude range of WIRA. However, significant differences in the mesospheric zonal wind speed of up to 40% have been found.

  • 267.
    Sadeghi, Soheil
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Emami, Reza
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Multi-spacecraft Studies of the Auroral Acceleration Region: From Cluster to Nanosatellites2017In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 59, no 5, 1173-1188 p.Article in journal (Refereed)
    Abstract [en]

    This paper discusses the utilization of multiple Cubesats in various formations for studies in the auroral acceleration region. The focus is on the quasi-static properties, spatio-temporal features, electric potential structures, field-aligned currents, and their relationships, all of which are fundamentally important for an understanding of the magnetosphere-ionosphere coupling. It is argued that a multitude of nanosatellites can address some of the relevant outstanding questions in a broader range of spatial, temporal, and geometrical features, with higher redundancy and data consistency, potentially resulting in a shorter mission period and a higher chance of mission success. A number of mission concepts consisting of a cluster of 6 to 12 Cubesats with their specific onboard payloads are suggested for such missions over a period of as short as two months.

  • 268.
    Sam, Lydia
    et al.
    Department of Environmental Science, Sharda University.
    Bhardwaj, Anshuman
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Sinha, Vinay S.P.
    Department of Natural Resources, TERI University.
    Joshi, Pawan Kumar Umar
    Department of Natural Resources, TERI University.
    Kumar, Rajesh C.
    Department of Environmental Science, School of Basic Sciences and Research, Sharda University, Greater Noida.
    Use of Geospatial Tools to Prioritize Zones of Hydro-Energy Potential in Glaciated Himalayan Terrain2016In: Journal of the Indian Society of Remote Sensing, ISSN 0255-660X, Vol. 44, no 3, 409-420 p.Article in journal (Refereed)
    Abstract [en]

    Sustainable development of the Himalayan region is directly linked to optimal utilization of available renewable resources. There is a need to first select the zones suitable for hydropower sites, and then to focus on them only; as purely field-based surveying of rugged mountainous regions for hydropower generation requires too much of time and effort. We used geospatial tools to identify suitable sites for hydropower generation. A Geographic Information System (GIS)-based tool called Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) was used for computing annual runoff volume using watershed-wise topography and biophysical variables. The zones suitable for hydropower generation were then identified based on calculated hydropower energy using derived runoff volumes and hydraulic head. The model accuracy was checked using well established efficiency criteria: coefficient of determination (R2 = 0.98), RMSE-observations standard deviation ratio (RSR), Percent bias (PBIAS) and Nash–Sutcliffe efficiency (NSE). For all these parameters, the model was found to be performing satisfactorily.

  • 269.
    Sato, T.O.
    et al.
    Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama.
    Sagawa, H.
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    Kreyling, D.
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    Manabe, T.
    Osaka Prefecture University, Naka, Sakai.
    Ochiai, S.
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    Kikuchi, K.
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    Baron, P.
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    Mendrok, Jana
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Urban, J.
    Chalmers University of Technology, Department of Earth and Space Sciences.
    Murtagh, D.
    Chalmers University of Technology, Department of Earth and Space Sciences.
    Yasui, M.
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    Kasai, Y.
    Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama.
    Strato-mesospheric ClO observations by SMILES: error analysis and diurnal variation2012In: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, Vol. 5, no 11, 2809-2825 p.Article in journal (Refereed)
    Abstract [en]

    Chlorine monoxide (ClO) is the key species for anthropogenic ozone losses in the middle atmosphere. We observed ClO diurnal variations using the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on the International Space Station, which has a non-sun-synchronous orbit. This includes the first global observations of the ClO diurnal variation from the stratosphere up to the mesosphere. The observation of mesospheric ClO was possible due to 10–20 times better signal-to-noise (S/N) ratio of the spectra than those of past or ongoing microwave/submillimeter-wave limb-emission sounders. We performed a quantitative error analysis for the strato- and mesospheric ClO from the Level-2 research (L2r) product version 2.1.5 taking into account all possible contributions of errors, i.e. errors due to spectrum noise, smoothing, and uncertainties in radiative transfer model and instrument functions. The SMILES L2r v2.1.5 ClO data are useful over the range from 0.01 and 100 hPa with a total error estimate of 10–30 pptv (about 10%) with averaging 100 profiles. The SMILES ClO vertical resolution is 3–5 km and 5–8 km for the stratosphere and mesosphere, respectively. The SMILES observations reproduced the diurnal variation of stratospheric ClO, with peak values at midday, observed previously by the Microwave Limb Sounder on the Upper Atmosphere Research Satellite (UARS/MLS). Mesospheric ClO demonstrated an opposite diurnal behavior, with nighttime values being larger than daytime values. A ClO enhancement of about 100 pptv was observed at 0.02 to 0.01 hPa (about 70–80 km) for 50° N–65° N from January–February 2010. The performance of SMILES ClO observations opens up new opportunities to investigate ClO up to the mesopause.

  • 270.
    Schilling, Klaus
    et al.
    Julius-Maximilians Universität Würzburg, Informatik VII: Robotics & Telematics.
    Barabash, Victoria
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    SpaceMaster: An International, Interdisciplinary Master in Space Science and Technology2017Conference paper (Other academic)
    Abstract [en]

    The significant demand for aerospace engineers led 2005 to the foundation of the interdisciplinary program "SpaceMaster" by six European Universities. It was established in the European elite-program "Erasmus Mundus" to train talented young people in the challenging subject of space science and technology. The universities cooperate and contribute their special expertise to the courses in order to cover the broad interdisciplinary area of spacecraft design and space environment. In particular system design techniques are emphasized, which are of interest for a broad spectrum of industrial applications well beyond aerospace.

    The international dimension of this space education is reflected in the distribution of places for education: 1

    st semester in Würzburg (Germany), 2nd semester in Kiruna (Sweden), second year according to the desired specialization in one of the six partner European Universities. The successful students will receive double diploma from the two European Universities, where most credits were received. The student population is also very international: typically from about 600 applications 50 students are selected, half of them from Europe, the other half from outside Europe.

    The students are able to follow the more scientific tracks on space physics with an emphasis on instrumentation and astronomy, or atmospheric and planetary physics. The engineering tracks emphasize the design of spacecraft and mission realization. Here specifically the design of CanSats and educational CubeSats is used to complement the lectures by practical implementation aspects. For more than 10 years, the SpaceMaster-alumni encounter excellent career perspectives in industry, space agencies and research institutes.

    In this contribution the international university cooperation, the contents of the curriculum, as well as the specific challenges and acquired experiences in this international program are addressed.

  • 271.
    Schillings, Audrey
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Swedish Institute of Space Physics, Kiruna.
    Nilsson, Hans
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Swedish Institute of Space Physics, Kiruna.
    Slapak, Rikard
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Yamauchi, Masatoshi
    Swedish Institute of Space Physics, Kiruna.
    Westerberg, Lars-Göran
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Relative outflow enhancements during majorgeomagnetic storms: Cluster observations2017In: Annals of Geophysics, ISSN 1593-5213, E-ISSN 2037-416XArticle in journal (Refereed)
  • 272.
    Schillings, Audrey
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Slapak, Rikard
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Nilsson, Hans
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Yamauchi, Masatoshi
    Swedish Institute of Space Physics, Kiruna.
    Westerberg, Lars-Göran
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Atmospheric loss during major geomagnetic storms: Cluster observations2017Conference paper (Refereed)
  • 273.
    Schreier, Franz
    et al.
    DLR — German Aerospace Center, Remote Sensing Technology Institute, Oberpfaffenhofen.
    García, Sebastián Gimeno
    DLR — German Aerospace Center, Remote Sensing Technology Institute, Oberpfaffenhofen.
    Hedelt, Pascal
    DLR — German Aerospace Center, Remote Sensing Technology Institute, Oberpfaffenhofen.
    Hess, Michael
    DLR — German Aerospace Center, Remote Sensing Technology Institute, Oberpfaffenhofen.
    Mendrok, Jana
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Vasquez, Mayte
    DLR — German Aerospace Center, Remote Sensing Technology Institute, Oberpfaffenhofen.
    Xu, Jian
    DLR — German Aerospace Center, Remote Sensing Technology Institute, Oberpfaffenhofen.
    GARLIC - a general purpose atmospheric radiative transfer line-by-line infrared-microwave code: Implementation and evaluation2014In: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 137, 29-50 p.Article in journal (Refereed)
    Abstract [en]

    A suite of programs for high resolution infrared-microwave atmospheric radiative transfer modeling has been developed with emphasis on efficient and reliable numerical algorithms and a modular approach appropriate for simulation and/or retrieval in a variety of applications. The Generic Atmospheric Radiation Line-by-line Infrared Code — GARLIC — is suitable for arbitrary observation geometry, instrumental field–of–view, and line shape. The core of GARLIC's subroutines constitutes the basis of forward models used to implement inversion codes to retrieve atmospheric state parameters from limb and nadir sounding instruments.This paper briefly introduces the physical and mathematical basics of GARLIC and its descendants and continues with an in-depth presentation of various implementation aspects: An optimized Voigt function algorithm combined with a two-grid approach is used to accelerate the line-by-line modeling of molecular cross sections; various quadrature methods are implemented to evaluate the Schwarzschild and Beer integrals; and Jacobians, i.e. derivatives with respect to the unknowns of the atmospheric inverse problem, are implemented by means of automatic differentiation. For an assessment of GARLIC's performance, a comparison of the quadrature methods for solution of the path integral is provided. Verification and validation are demonstrated using intercomparisons with other line-by-line codes and comparisons of synthetic spectra with spectra observed on Earth and from Venus.

  • 274.
    Schreier, Franz
    et al.
    DLR, Remote Sensing Technology Institute, 82234 Oberpfaffenhofen.
    Garcia, S. Gimeno
    DLR, Remote Sensing Technology Institute, 82234 Oberpfaffenhofen.
    Milz, Mathias
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Kottayil, Ajil
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Höpfner, Michael
    Karlsruhe Institute of Technology.
    Clarmann, Thomas von
    Karlsruhe Institute of Technology.
    Stiller, Gabriele P.
    Karlsruhe Institute of Technology.
    Intercomparison of three microwave/infrared high resolution line-by-line radiative transfer codes2013In: International Radiation Symposium: Radiation Processes in the Atmosphere and Ocean, IRS 2012, Berlin, Germany; 6 August 2012-10 August 2012, 2013, 119-122 p.Conference paper (Refereed)
    Abstract [en]

    An intercomparison of three line-by-line (lbl) codes developed independently for atmospheric sounding - ARTS, GARLIC, and KOPRA - has been performed for a thermal infrared nadir sounding application assuming a HIRS-like (High resolution Infrared Radiation Sounder) setup. Radiances for the HIRS infrared channels and a set of 42 atmospheric profiles from the "Garand dataset" have been computed. Results of this intercomparison and a discussion of reasons of the observed differences are presented

  • 275.
    Schwenzer, S.P.
    et al.
    Department of Physical Sciences, CEPSAR, Open University, Milton Keynes.
    Bridges, J.C.
    Space Research Centre, Department of Physics and Astronomy, University of Leicester.
    Leveille, R.
    Canadian Space Agency, St-Hubert.
    Wiens, R.C.
    Space Remote Sensing, Los Alamos National Laboratory, Los Alamos.
    Mangold, N.
    Laboratoire Planétologie et Géodynamique de Nantes, LPGN/CNRS and Université de Nantes.
    McAdam, A.
    NASA Goddard Space Flight Center.
    Conrad, P.
    NASA Goddard Space Flight Center.
    Kelley, S.P.
    Department of Physical Sciences, CEPSAR, Open University, Milton Keynes.
    Westall, F.
    Centre de Biophysique Moléculaire, CNRS, Orléans.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Instituto Andaluz de Cienccias de la Tierra (CSIC-UGR), Grenada.
    Zorzano, M.-P.
    Centro de Astrobiologia, INTA-CSIC, Madrid.
    Fluids, evaporation and precipitates at Gale Crater, Mars2015Conference paper (Refereed)
  • 276.
    Schwenzer, Susanne P.
    et al.
    CEPSAR, Open University, Milton Keynes, Department of Physical Sciences, CEPSAR, Open University, Milton Keynes, Open University, Milton Keynes, Department of Physical Science, The Open University, Walton Hall, Milton Keynes.
    Bridges, John C.
    Space Research Centre, University of Leicester, Space Research Centre, Department of Physics and Astronomy, University of Leicester, University of Leicester.
    Wiens, Roger C.
    Los Alamos National Laboratory, Space Remote Sensing, Los Alamos National Laboratory, Los Alamos, International Space and Response Division, Los Alamos National Laboratory.
    Conrad, Pamela G.
    Planetary Environments Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, NASA Goddard Space Flight Center, Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, Maryland, Solar System Exploration Division, Goddard Space Flight Center, National Aeronautics and Space Administration, Greenbelt, Maryland, NASA Goddard Space Flight Center, Greenbelt, Maryland.
    Kelley, S.P.
    Department of Physical Sciences, CEPSAR, Open University, Milton Keynes.
    Leveille, R.
    Canadian Space Agency, St-Hubert.
    Mangold, Nicolas
    Laboratoire Planétologie et Géodynamique de Nantes, LPGN/CNRS and Université de Nantes, Laboratorie de Planetologie et Geodynamique de Nantes, Laboratoire Planétologie et Géodynamique, LPGNantes, CNRS UMR 6112, Université de Nantes, LPGN, CNRS, UMR 6112, Université Nantes, CNRS- UMR 6112, Laboratoire de Planétologie et Géodynamique, Université de Nantes.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    McAdam, Amy C.
    Planetary Environments Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, Maryland, NASA Goddard Space Flight Center, Solar System Exploration Division, Goddard Space Flight Center, National Aeronautics and Space Administration, Greenbelt, Maryland.
    Newsom, Horton E.
    Institute of Meteoritics, University of New Mexico, Albuquerque, Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, University of New Mexico, Albuquerque, Institute of Meteoritics, Department of Earth and Planetary Sciences, Albuquerque, New Mexico.
    Mier, Maria-Paz Zorzano
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Rapin, W.
    Institut de Recherche en Astrophysique et Planetologie, Toulouse.
    Spray, John G.
    Planetary and Space Science Centre, University of New Brunswick, Fredericton.
    Treiman, A.H.
    Lunar and Planetary Institute, Houston.
    Westall, F.
    Centre de Biophysique Moléculaire, CNRS, Orléans.
    Fairen, Alberto G.
    Centro de Astrobiologia, Madrid.
    Meslin, Pierre-Yves
    Institut de Recherche en Astrophysique et Planetologie, Toulouse, IRAP, CNRS/UPS, Toulouse, Université Toulouse III - Paul Sabatier, Toulouse, Université de Toulouse, UPS-OMP, IRAP.
    Fluids during diagenesis and sulfate vein formation in sediments at Gale crater, Mars2016In: Meteoritics and Planetary Science, ISSN 1086-9379, E-ISSN 1945-5100, Vol. 51, no 11, 2175-2202 p.Article in journal (Refereed)
    Abstract [en]

    We model the fluids involved in the alteration processes recorded in the Sheepbed Member mudstones of Yellowknife Bay (YKB), Gale crater, Mars, as revealed by the Mars Science Laboratory Curiosity rover investigations. We compare the Gale crater waters with fluids modeled for shergottites, nakhlites, and the ancient meteorite ALH 84001, as well as rocks analyzed by the Mars Exploration rovers, and with terrestrial ground and surface waters. The aqueous solution present during sediment alteration associated with phyllosilicate formation at Gale was high in Na, K, and Si; had low Mg, Fe, and Al concentrations—relative to terrestrial groundwaters such as the Deccan Traps and other modeled Mars fluids; and had near neutral to alkaline pH. Ca and S species were present in the 10−3 to 10−2 concentration range. A fluid local to Gale crater strata produced the alteration products observed by Curiosity and subsequent evaporation of this groundwater-type fluid formed impure sulfate- and silica-rich deposits—veins or horizons. In a second, separate stage of alteration, partial dissolution of this sulfate-rich layer in Yellowknife Bay, or beyond, led to the pure sulfate veins observed in YKB. This scenario is analogous to similar processes identified at a terrestrial site in Triassic sediments with gypsum veins of the Mercia Mudstone Group in Watchet Bay, UK.

  • 277.
    Shaik Fareedh, Junaidh
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Design, Fabrication and Modelling of Three Axis Floating Satellite Simulator2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Floating Satellite (FloatSat) system project which has been developed at the ‘Department of Aerospace Information Technology - University of Würzburg’ is used to test, develop and implement various attitude control algorithms and strategies for small satellites [1]. The FloatSat project is designed to operate on a Frictionless air bearing surface that works with compressed air flowing distributed on a hemisphere. This hemisphere is used to replicate the space environment required for a satellite to perform its attitude control, solar panel deployment and payload mission, the FloatSat basically consist of 1 axis control and stabilization with reaction wheel. Taking FloatSat to the next level, the aim of the Thesis is to Design, Fabricate and Model a three-axis controllable FloatSat that can be contained in a Sphere for free rotation and movement. The best feature of FloatSat is that they are plug & play, easily accessible and compact size; retaining all these features in the design and extending the functionality of the product proves to be challenging. Furthermore, in the thesis it will be explained in detail about the various design consideration and selection of most feasible method on producing the final product. After the preliminary research for the design characteristics it was clear that the new FloatSat will be equipped with a controllable center of gravity mechanism that will provide balancing in any desired orientation. To obtain this feature three controllable moving masses are to be used in each axis of reaction wheel position. With Three reaction wheels and three moving masses to be equipped in the FloatSat the design challenges were high as considering the Sphere diameter is only 198mm.

    The various successful 3 axis satellite simulators are either huge or they are constrained in any one of the axis where it is positioned. On doing literature research it became clear that the sphere configuration with the given size has never been documented with promising results. It makes this thesis work to be first of its kind to perform 3 Axis FloatSat stabilization in a sphere of 198mm diameter. The FloatSat components include microcontroller STM32F4, Wi-Fi module for communication, three reaction wheel motors, three axial moving mass motor, Lithium Polymer batteries and motor controllers. 

  • 278.
    Shekhar, Mayank
    et al.
    Birbal Sahni Institute of Palaeosciences, Lucknow, India.
    Bhardwaj, Anshuman
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Singh, Shaktiman
    Institut für Kartographie, Technische Universität Dresden.
    Ranhotra, Parminder S.
    Birbal Sahni Institute of Palaeosciences, Lucknow, India.
    Bhattacharyya, Amalava
    Birbal Sahni Institute of Palaeosciences, Lucknow, India.
    Pal, Ashish K.
    Birbal Sahni Institute of Palaeosciences, Lucknow, India.
    Roy, Ipsita
    Birbal Sahni Institute of Palaeosciences, Lucknow, India.
    Martín-Torres, F. Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Zorzano Mier, María-Paz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Himalayan glaciers experienced significant mass loss during later phases of little ice age2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, 10305Article in journal (Refereed)
    Abstract [en]

    To date, there is a gap in the data about the state and mass balance of glaciers in the climate-sensitive subtropical regions during the Little Ice Age (LIA). Here, based on an unprecedented tree-ring sampling coverage, we present the longest reconstructed mass balance record for the Western Himalayan glaciers, dating to 1615. Our results confirm that the later phase of LIA was substantially briefer and weaker in the Himalaya than in the Arctic and subarctic regions. Furthermore, analysis of the time-series of the mass-balance against other time-series shows clear evidence of the existence of (i) a significant glacial decay and a significantly weaker magnitude of glaciation during the latter half of the LIA; (ii) a weak regional mass balance dependence on either the El Niño-Southern Oscillation (ENSO) or the Total Solar Irradiance (TSI) taken in isolation, but a considerable combined influence of both of them during the LIA; and (iii) in addition to anthropogenic climate change, the strong effect from the increased yearly concurrence of extremely high TSI with El Niño over the past five decades, resulting in severe glacial mass loss. The generated mass balance time-series can serve as a source of reliable reconstructed data to the scientific community.

  • 279.
    Shematovich, V.I.
    et al.
    Institute of Astronomy, Russian Academy of Sciences, Moscow.
    Bisikalo, D.V.
    Institute of Astronomy, Russian Academy of Sciences, Moscow.
    Stenberg, G.
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Barabash, Stas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Dieval, Catherine
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Gérard, J-C
    LPAP, Université de Liège.
    He2+ transport in the Martian upper atmosphere with an induced magnetic field2013In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 118, no 3, 1231-1242 p.Article in journal (Refereed)
    Abstract [en]

    Solar wind helium may be a significant source of neutral helium in the Martian atmosphere. The precipitating particles also transfer mass, energy, and momentum. To investigate the transport of He2+ in the upper atmosphere of Mars, we have applied the direct simulation Monte Carlo method to solve the kinetic equation. We calculate the upward He, He+, and He2+ fluxes, resulting from energy spectra of the downgoing He2+ observed below 500 km altitude by the Analyzer of Space Plasmas and Energetic Atoms 3 instrument onboard Mars Express. The particle flux of the downward moving He2+ ions was 1–2 × 106 cm–2 s–1, and the energy flux is equal to 9–10 × 10–3 erg cm–2 s–1. The calculations of the upward flux have been made for the Martian atmosphere during solar minimum. It was found, that if the induced magnetic field is not introduced in the simulations the precipitating He2+ ions are not backscattered at all by the Martian upper atmosphere. If we include a 20 nT horizontal magnetic field, a typical field measured by Mars Global Surveyor in the altitude range of 85–500 km, we find that up to 30%–40% of the energy flux of the precipitating He2+ ions is backscattered depending on the velocity distribution of the precipitating particles. We thus conclude that the induced magnetic field plays a crucial role in the transport of charged particles in the upper atmosphere of Mars and, therefore, that it determines the energy deposition of the solar wind.

  • 280.
    Siderud, Emelie
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Upgrading a groundbased 142 GHz microwave radiometer to higher sensitivity2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The accuracy of ozone measurements in the middle atmosphere is of great importance when determining its diurnal variation. A high time resolution of the measured data is desirable and depends on the sensitivity of the receiver used to detect the ozone. This thesis aims to improve the sensitivity of a groundbased 142 GHz microwave radiometer used for measuring atmospheric ozone data. This is done by replacing the previous receiver components with a series of new components and arranging them in different setups for comparison purposes. Mechanics and wiring were changed in order to install the setups along with changes in the optics. Each test setup could be implemented as a first step towards improving the sensitivity of the radiometer. The result show that the optics contribute with an unexpected addition of noise to the measurements and hence the overall performance and improvement of the radiometer could not be determined. Suggestions are made for further work which include improving the optics and performing cryo-measurements.

  • 281.
    Singh, Shaktiman
    et al.
    Department of Environmental Science, School of Basic Sciences and Research, Sharda University, Greater Noida.
    Kumar, Rajesh
    Department of Environmental Science, School of Basic Sciences and Research, Sharda University, Greater Noida.
    Bhardwaj, Anshuman
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Sam, Lydia
    Department of Environmental Science, Sharda University, Department of Environmental Science, School of Basic Sciences and Research, Sharda University, Greater Noida.
    Shekhar, Mayank
    Birbal Sahni Institute of Palaeobotany, Lucknow.
    Singh, Atar
    Department of Environmental Science, School of Basic Sciences and Research, Sharda University, Greater Noida.
    Kumar, Ramesh
    Department of Environmental Science, School of Basic Sciences and Research, Sharda University, Greater Noida.
    Gupta, Akhilesh
    Department of Science and Technology, Technology Bhavan, New Delhi.
    Changing climate and glacio-hydrology in Indian Himalayan Region: a review2016In: Wiley Interdisciplinary Reviews: Climate Change, ISSN 1757-7780, E-ISSN 1757-7799, Vol. 7, no 3, 393-410 p.Article in journal (Refereed)
    Abstract [en]

    This study presents a comprehensive review of the published literature on the evidences of a changing climate in the Indian Himalayan Region (IHR) and its impacts on the glacio-hydrology of the region. The IHR serves as an important source of fresh water for the densely populated areas downstream. It is evident from the available studies that temperature is significantly increasing in all parts of the IHR, whereas precipitation is not indicative of any particular spatiotemporal trend. Glacio-hydrological proxies for changing climate, such as, terminus and areal changes of the glaciers, glacier mass balance, and streamflow in downstream areas, highlight changes more evidently in recent decades. On an average, studies have predicted an increase in temperature and precipitation in the region, along with increase in streamflow of major rivers. Such trends are already apparent in some sub-basins of the western IHR. The region is particularly vulnerable to changing climate as it is highly dependent on snow and glacier melt run-off to meet its freshwater demands. We present a systematic review of key papers dealing with changing temperature, precipitation, glaciers, and streamflow in the IHR. We discuss these interdisciplinary themes in relation to each other, in order to establish the present and future impacts of climatic, glaciological, and hydrological changes in the region.

  • 282.
    Slapak, Rikard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Gunell, H.
    Belgian Institute for Space Aeronomy, Avenue Circulaire, Brussels.
    Hamrin, Maria
    Department of Physics, Umeå University.
    Observations of multiharmonic ion-cyclotron waves due to inverse ion-cyclotron damping in the northern magnetospheric cusp2017In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 44, no 1, 22-29 p.Article in journal (Refereed)
    Abstract [en]

    We present a case study of inverse ion-cyclotron damping taking place in the northern terrestrial magnetospheric cusp, exciting waves at the ion-cyclotron frequency and its harmonics. The ion-cyclotron waves are primarily seen as peaks in the magnetic-field spectral densities. The corresponding peaks in the electric-field spectral densities are not as profound, suggesting a background electric field noise or other processes of wave generation causing the electric spectral densities to smoothen out more compared to the magnetic counterpart. The required condition for inverse ion-cyclotron damping is a velocity shear in the magnetic field-aligned ion-bulk flow, and this condition is often naturally met for magnetosheath influx in the northern magnetospheric cusp, just as in the presented case. We note that some ion-cyclotron wave activity is present in a few similar shear events in the southern cusp, which indicates that other mechanisms generating ion-cyclotron waves may also be present during such conditions.

  • 283.
    Slapak, Rikard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Hamrin, Maria
    Department of Physics, Umeä University.
    Pitkänen, Timo
    Department of Physics, Umeä University.
    Yamauchi, Masatoshi
    Swedish Institute of Space Physics, Kiruna.
    Nilsson, Hans
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Karlsson, Tomas
    Space and Plasma Physics, School of Electrical Engineering, Royal Institute of Technology, Stockholm.
    Schillings, Audrey
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Quantification of the total ion transport in the near-Earth plasma sheet2017In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 35, no 4, 869-877 p.Article in journal (Refereed)
    Abstract [en]

    Recent studies strongly suggest that a majority of the observed O+ cusp outflows will eventually escape into the solar wind, rather than be transported to the plasma sheet. Therefore, an investigation of plasma sheet flows will add to these studies and give a more complete picture of magnetospheric ion dynamics. Specifically, it will provide a greater understanding of atmospheric loss. We have used Cluster spacecraft 4 to quantify the H+ and O+ total transports in the near-Earth plasma sheet, using data covering 2001-2005. The results show that both H+ and O+ have earthward net fluxes of the orders of 1026 and 1024 s -1, respectively. The O+ plasma sheet return flux is 1 order of magnitude smaller than the O+ outflows observed in the cusps, strengthening the view that most ionospheric O+ outflows do escape. The H+ return flux is approximately the same as the ionospheric outflow, suggesting a stable budget of H+ in the magnetosphere. However, low-energy H+, not detectable by the ion spectrometer, is not considered in our study, leaving the complete magnetospheric H+ circulation an open question. Studying tailward flows separately reveals a total tailward O+ flux of about 0. 5 × 1025 s -1, which can be considered as a lower limit of the nightside auroral region O+ outflow. Lower velocity flows ( < 100kms -1) contribute most to the total transports, whereas the high-velocity flows contribute very little, suggesting that bursty bulk flows are not dominant in plasma sheet mass transport.

  • 284.
    Slapak, Rikard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Nilsson, Hans
    Swedish Institute of Space Physics, Kiruna.
    Schillings, Audrey
    Swedish Institute of Space Physics, Kiruna.
    Yamauchi, Masatoshi
    Swedish Institute of Space Physics, Kiruna.
    Westerberg, Lars-Göran
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Dandouras, Iannis
    CNSR, Institut de Recherche en Astrophysique et Planetologie, Toulouse.
    Atmospheric outflow from the terrestrial magnetosphere: implications forescape on evolutionary time scales2017Conference paper (Refereed)
  • 285.
    Slapak, Rikard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Nilsson, Hans
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Westerberg, Lars-Göran
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    A statistical study on O+ flux in the dayside magnetosheath2013In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 31, 1005-1010 p.Article in journal (Refereed)
    Abstract [en]

    Studies on terrestrial oxygen ion (O+) escape into the interplanetary space have considered a number of different escape paths. Recent observations however suggest a yet insufficiently investigated additional escape route for hot O+: along open magnetic field lines in the high altitude cusp and mantle. Here we present a statistical study on O+ flux in the high-latitude dayside magnetosheath. The O+ is generally seen relatively close to the magnetopause, consistent with observations of O+ flowing primarily tangentially to the magnetopause. We estimate the total escape flux in this region to be ~ 7 × 1024 s−1, implying this escape route to significantly contribute to the overall total O+ loss into interplanetary space.

  • 286.
    Slapak, Rikard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Nilsson, Hans
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Westerberg, Lars-Göran
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Eriksson, Anders
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Observations of oxygen ions in the dayside magnetosheath associated with southward IMF2012In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 117Article in journal (Refereed)
    Abstract [en]

    We present a case study of high energy oxygen ions (O+) observed in the dayside terrestrial magnetosheath, in the southern hemisphere. It is shown that the presence of O+ is strongly correlated to the IMF direction: O+ is observed only for Bz<0. Three satellites observe O$^+ immediately at both sides of the magnetopause and about 2 RE outside the magnetopause. These conditions indicate escape along open magnetic field lines. We show that if outflowing O+ is heated and accelerated sufficiently in the cusp, it takes 15-20 minutes for it to reach the magnetopause, allowing the ions to escape along newly opened field lines on the dayside. Earlier studies show evidence of strong heating and high velocities in the cusp and mantle at high altitudes, strengthening our interpretation. The observed magnetosheath O+ fluxes are of the same order as measured in the ionospheric upflow, which indicates that this loss mechanism is significant when it takes place.

  • 287.
    Slapak, Rikard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Nilsson, Hans
    Westerberg, Lars-Göran
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Larsson, Richard
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    O+ transport in the dayside magnetosheath and its dependence on the IMF direction2015In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 33, 301-307 p.Article in journal (Refereed)
    Abstract [en]

    Recent studies have shown that the escape of oxygen ions (O+) into the magnetosheath along open magnetic field lines from the terrestrial cusp and mantle is significant. We present a study of how O+ transport in the dayside magnetosheath depends on the interplanetary magnetic field (IMF) direction. There are clear asymmetries in the O+ flows for southward and northward IMF. The asymmetries can be understood in terms of the different magnetic topologies that arise due to differences in the location of the reconnection site, which depends on the IMF direction. During southward IMF, most of the observed magnetosheath O+ is transported downstream. In contrast, for northward IMF we observe O+ flowing both downstream and equatorward towards the opposite hemisphere. We observe evidence of dual-lobe reconnection occasionally taking place during strong northward IMF conditions, a mechanism that may trap O+ and bring it back into the magnetosphere. Its effect on the overall escape is however small: we estimate the upper limit of trapped O+ to be 5%, a small number considering that ion flux calculations are rough estimates. The total O+ escape flux is higher by about a factor of 2 during times of southward IMF, in agreement with earlier studies of O+ cusp outflow.

  • 288.
    Slapak, Rikard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Schillings, Audrey
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Nilsson, Hans
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Yamauchi, Masatoshi
    Swedish Institute of Space Physics, Kiruna.
    Westerberg, Lars-Göran
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Atmospheric loss from the dayside open polar region and its dependence on geomagnetic activity: Implications for atmospheric escape on evolutionary time scales2017In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 35, no 3, 721-731 p.Article in journal (Refereed)
  • 289.
    Smith, M.D.
    et al.
    NASA Goddard Space Flight Center, Greenbelt.
    Zorzano Mier, Maria-Paz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Lemmon, Mark T.
    Department of Atmospheric Sciences , Texas A&M University.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Mendaza de Cal, Maria Teresa
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Aerosol optical depth as observed by the Mars Science Laboratory REMS UV photodiodes2017Conference paper (Other academic)
  • 290.
    Smith, Michael D.
    et al.
    NASA Goddard Space Flight Center.
    Mier, Maria-Paz Zorzano
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Lemmon, Mark T.
    Department of Atmospheric Sciences, Texas A&M University, Texas A&M University, College Station.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Cal, Maria Teresa Mendaza de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Aerosol optical depth as observed by the Mars Science Laboratory REMS UV photodiodes2016In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 280, 234-248 p.Article in journal (Refereed)
    Abstract [en]

    Systematic observations taken by the REMS UV photodiodes on a daily basis throughout the landed Mars Science Laboratory mission provide a highly useful tool for characterizing aerosols above Gale Crater. Radiative transfer modeling is used to model the approximately 1.75 Mars Years of observations taken to date taking into account multiple scattering from aerosols and the extended field of view of the REMS UV photodiodes. The retrievals show in detail the annual cycle of aerosol optical depth, which is punctuated with numerous short timescale events of increased optical depth. Dust deposition onto the photodiodes is accounted for by comparison with aerosol optical depth derived from direct imaging of the Sun by Mastcam. The effect of dust on the photodiodes is noticeable, but does not dominate the signal. Cleaning of dust from the photodiodes was observed in the season around Ls=270°, but not during other seasons. Systematic deviations in the residuals from the retrieval fit are indicative of changes in aerosol effective particle size, with larger particles present during periods of increased optical depth. This seasonal dependence of aerosol particle size is expected as dust activity injects larger particles into the air, while larger aerosols settle out of the atmosphere more quickly leading to a smaller average particle size over time.

  • 291.
    Soria-Salinas, Álvaro
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Wittman, Philipp
    Luleå tekniska universitet.
    Zorzano Mier, Maria-Paz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Wind Retrieval Measurements for the Mars Surface Exploration2016Conference paper (Other academic)
    Abstract [en]

    We present a novel method to quantify the heat transfer coefficient h at the near environment of a spacecraft operating under Mars surface atmospheric conditions. As part of the scientific instruments of the ExoMars 2018 Surface Platform, the HABIT (HabitAbility: Brines, Irradiance and Temperature) instrument will be operating on Mars surface in order to establish the habitability of the landing site. By resolving the energy balance equation in temperatures over the three HABIT Air Temperature Sensor (ATS), we will retrieve the fluid temperature Tf and the known as m-parameter directly related with the heat transfer coefficient and sensitive to variations in wind density and velocity field

  • 292.
    Soria-Salinas, Álvaro
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Zorzano Mier, Maria-Paz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Convective Heat Transfer at the Martian Boundary Layer, Measurement and Model2016Conference paper (Other academic)
  • 293.
    Soria-Salinas, Álvaro
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Zorzano Mier, Maria-Paz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Thermal and Heat Transfer Studies Using the HABIT Instrument on the ExoMars 2018 Surface Platform2016Conference paper (Other academic)
  • 294.
    Soria-Salinas, Álvaro
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Zorzano Mier, Maria-Paz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Feiccabrino, James
    Department of Water Resources Engineering., Lund University.
    Convective Heat Transfer Measurements at the Martian Surface2015Conference paper (Other academic)
  • 295.
    Soria-Salinas, Álvaro
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Zorzano Mier, Maria-Paz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Sánchez-García-Casarrubios, J.
    Department of Signal and Telecommunication Theory, Universidad Autónoma de Madrid.
    Pérez-Díaz, J-L
    Department of Signal and Telecommunication Theory, Universidad Autónoma de Madrid.
    Vakkada Ramachandran, Abhilash
    Luleå tekniska universitet.
    A Xenon Mass Gauging through Heat Transfer Modeling for Electric Propulsion Thrusters2017In: World Academy of Science, Engineering and Technology: An International Journal of Science, Engineering and Technology, ISSN 2010-376X, E-ISSN 2070-3740, Vol. 11, no 1, 94-105 p.Article in journal (Refereed)
    Abstract [en]

    The current state-of-the-art methods of mass gauging of Electric Propulsion (EP) propellants in microgravity conditions rely on external measurements that are taken at the surface of the tank. The tanks are operated under a constant thermal duty cycle to store the propellant within a pre-defined temperature and pressure range. We demonstrate using computational fluid dynamics (CFD) simulations that the heat-transfer within the pressurized propellant generates temperature and density anisotropies. This challenges the standard mass gauging methods that rely on the use of time changing skin-temperatures and pressures. We observe that the domes of the tanks are prone to be overheated, and that a long time after the heaters of the thermal cycle are switched off, the system reaches a quasi-equilibrium state with a more uniform density. We propose a new gauging method, which we call the Improved PVT method, based on universal physics and thermodynamics principles, existing TRL-9 technology and telemetry data. This method only uses as inputs the temperature and pressure readings of sensors externally attached to the tank. These sensors can operate during the nominal thermal duty cycle. The improved PVT method shows little sensitivity to the pressure sensor drifts which are critical towards the end-of-life of the missions, as well as little sensitivity to systematic temperature errors. The retrieval method has been validated experimentally with CO2 in gas and fluid state in a chamber that operates up to 82 bar within a nominal thermal cycle of 38 °C to 42 °C. The mass gauging error is shown to be lower than 1% the mass at the beginning of life, assuming an initial tank load at 100 bar. In particular, for a pressure of about 70 bar, just below the critical pressure of CO2, the error of the mass gauging in gas phase goes down to 0.1% and for 77 bar, just above the critical point, the error of the mass gauging of the liquid phase is 0.6% of initial tank load. This gauging method improves by a factor of 8 the accuracy of the standard PVT retrievals using look-up tables with tabulated data from the National Institute of Standards and Technology.

  • 296.
    Sreerekha, T.R.
    et al.
    Universität Bremen.
    Buehler, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Development of an RT model for frequencies between 200 and 1000 GHz2007Report (Other academic)
  • 297.
    Sreerekha, T.R.
    et al.
    UK Met Office, Exeter.
    Buehler, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    O'Keeffe, U
    UK Met Office, Exeter.
    Doherty, A
    UK Met Office, Exeter.
    Emde, C.
    German Aerospace Center, DLR, Oberpfaffenhofen.
    John, V.O.
    RSMAS, University of Miami.
    A strong ice cloud event as seen by a microwave satellite sensor: simulations and observations2008In: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 109, no 9, 1705-1718 p.Article in journal (Refereed)
    Abstract [en]

    In this article, brightness temperatures observed by channels of the Advanced Microwave Sounding Unit-B (AMSU-B) instrument are compared to those simulated by a radiative transfer model, which can take into account the multiple scattering due to ice particles by using a discrete ordinate iterative solution method. The input fields, namely, the pressure, temperature, humidity, and cloud water content are taken from the short range forecast from the Met Office mesoscale model (UKMES). The comparison was made for a case study on the 25 January 2002 when a frontal system associated with significant cloud was present over the UK. It is demonstrated that liquid clouds have maximum impact on channel 16 of AMSU whereas ice clouds have maximum impact on channel 20. The main uncertainty for simulating microwave radiances is the assumptions about microphysical properties, such as size distribution, shape and orientation of the cloud particles, which are not known in the mesoscale model. The article examines the impact of these parameters on the cloud signal. The polarisation signal due to oriented ice particles at these frequencies is also discussed.

  • 298.
    Stern, J.C.
    et al.
    NASA Goddard Space Flight Center.
    Sutter, B.
    Jacobs Technology, NASA Johnson Space Center.
    McKay, C.P.
    NASA Ames Research Center, Moffett Field.
    Navarro-González, R.
    Universidad Nacional Autónoma de México.
    Freissinet, C.
    NASA Goddard Space Flight Center.
    Conrad, P.G.
    NASA Goddard Space Flight Center.
    Mahaffy, P.R.
    NASA Goddard Space Flight Center.
    Archer, P.D.
    Jacobs Technology, NASA Johnson Space Center.
    Ming, D.W.
    NASA Johnson Space Center, Houston.
    Niles, P.B.
    NASA Johnson Space Center, Houston.
    Zorzano, M.-P.
    Centro de Astrobiologia, INTA-CSIC, Madrid.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Instituto Andaluz de Cienccias de la Tierra (CSIC-UGR), Grenada.
    The nitrate/perchlorate ratio on Mars as an indicator for habitability2015Conference paper (Refereed)
  • 299.
    Stern, Jennifer C.
    et al.
    Solar System Exploration Division, Goddard Space Flight Center, National Aeronautics and Space Administration, Greenbelt, Maryland.
    Sutter, Brad
    Jacobs Technology, Inc., Johnson Space Center, National Aeronautics and Space Administration, Houston, Texas.
    Freissinet, Caroline
    NASA Postdoctoral Program, Goddard Space Flight Center, National Aeronautics and Space Administration, Greenbelt, Maryland.
    Navarro-González, Rafael
    Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico D.F..
    McKay, Christopher P.
    Exobiology Branch, Ames Research Center, National Aeronautics and Space Administration, Moffett Field, Kalifornien.
    Jr., P. Douglas Archer
    Jacobs Technology, Inc., Johnson Space Center, National Aeronautics and Space Administration, Houston, Texas.
    Buch, Arnaud
    Laboratoire de Genie de Procedes et Materiaux, Ecole Centrale Paris, Chatenay-Malabry.
    Brunner, Anna E.
    Solar System Exploration Division, Goddard Space Flight Center, National Aeronautics and Space Administration, Greenbelt, Maryland.
    Coll, Patrice
    Laboratoire Interuniversitaire des Systèmes Atmosphériques, Université Paris-Est Créteil, Université Paris Diderot and CNRS, Créteil.
    Eigenbrode, Jennifer L.
    Solar System Exploration Division, Goddard Space Flight Center, National Aeronautics and Space Administration, Greenbelt, Maryland.
    Fairen, Alberto G.
    Centro de Astrobiologia, Madrid.
    Franz, Heather B.
    Solar System Exploration Division, Goddard Space Flight Center, National Aeronautics and Space Administration, Greenbelt, Maryland.
    Glavin, Daniel P.
    Solar System Exploration Division, Goddard Space Flight Center, National Aeronautics and Space Administration, Greenbelt, Maryland.
    Kashyap, Srishti
    Solar System Exploration Division, Goddard Space Flight Center, National Aeronautics and Space Administration, Greenbelt, Maryland.
    McAdam, Amy C.
    Solar System Exploration Division, Goddard Space Flight Center, National Aeronautics and Space Administration, Greenbelt, Maryland.
    Ming, Douglas W.
    Astromaterials Research and Exploration Science Directorate, Johnson Space Center, National Aeronautics and Space Administration, Houston, Texas.
    Steele, Andrew
    Geophysical Laboratory, Carnegie Institution of Washington, Washington D.C..
    Szopa, Cyril
    Laboratoire Atmosphères, Milieux et Observations Spatiales, Université Pierre et Marie Curie, Université Versailles Saint-Quentin and CNRS, Paris.
    Wray, James J.
    School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Zorzano, Maria-Paz
    Centro de Astrobiologia, Madrid.
    Conrad, Pamela G.
    Solar System Exploration Division, Goddard Space Flight Center, National Aeronautics and Space Administration, Greenbelt, Maryland.
    Mahaffy, Paul R.
    Solar System Exploration Division, Goddard Space Flight Center, National Aeronautics and Space Administration, Greenbelt, Maryland.
    Evidence for indigenous nitrogen in sedimentary and aeolian deposits from the Curiosity rover investigations at Gale crater, Mars2015In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 112, no 14, 4245-4250 p., 6Article in journal (Refereed)
    Abstract [en]

    The Sample Analysis at Mars (SAM) investigation on the Mars Science Laboratory (MSL) Curiosity rover has detected oxidized nitrogen-bearing compounds during pyrolysis of scooped aeolian sediments and drilled sedimentary deposits within Gale crater. Total N concentrations ranged from 20 to 250 nmol N per sample. After subtraction of known N sources in SAM, our results support the equivalent of 110–300 ppm of nitrate in the Rocknest (RN) aeolian samples, and 70–260 and 330–1,100 ppm nitrate in John Klein (JK) and Cumberland (CB) mudstone deposits, respectively. Discovery of indigenous martian nitrogen in Mars surface materials has important implications for habitability and, specifically, for the potential evolution of a nitrogen cycle at some point in martian history. The detection of nitrate in both wind-drifted fines (RN) and in mudstone (JK, CB) is likely a result of N2 fixation to nitrate generated by thermal shock from impact or volcanic plume lightning on ancient Mars. Fixed nitrogen could have facilitated the development of a primitive nitrogen cycle on the surface of ancient Mars, potentially providing a biochemically accessible source of nitrogen.

  • 300.
    Stiller, G.P.
    et al.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Clarmann, T. von
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Höpfner, M.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Glatthor, N.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Grabowski, U.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Kellmann, S.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Kleinert, A.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Linden, A.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Milz, Mathias
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Reddmann, T.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Steck, T.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Fischer, H.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Funke, B.
    Instituto de Astrofísica de Andalucía CSIC, Granada.
    López-Puertas, M.
    Instituto de Astrofísica de Andalucía CSIC, Granada.
    Engel, A.
    Institut für Atmosphäre und Umwelt, J. W. Goethe Universität Frankfurt am Main, Frankfurt.
    Global distribution of mean age of stratospheric air from MIPAS SF6 measurements2008In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 8, no 3, 677-695 p.Article in journal (Refereed)
    Abstract [en]

    Global distributions of profiles of sulphur hexafluoride (SF6) have been retrieved from limb emission spectra recorded by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat covering the period September 2002 to March 2004. Individual SF6 profiles have a precision of 0.5 pptv below 25 km altitude and a vertical resolution of 4–6 km up to 35 km altitude. These data have been validated versus in situ observations obtained during balloon flights of a cryogenic whole-air sampler. For the tropical troposphere a trend of 0.230±0.008 pptv/yr has been derived from the MIPAS data, which is in excellent agreement with the trend from ground-based flask and in situ measurements from the National Oceanic and Atmospheric Administration Earth System Research Laboratory, Global Monitoring Division. For the data set currently available, based on at least three days of data per month, monthly 5° latitude mean values have a 1σ standard error of 1%. From the global SF6 distributions, global daily and monthly distributions of the apparent mean age of air are inferred by application of the tropical tropospheric trend derived from MIPAS data. The inferred mean ages are provided for the full globe up to 90° N/S, and have a 1σ standard error of 0.25 yr. They range between 0 (near the tropical tropopause) and 7 years (except for situations of mesospheric intrusions) and agree well with earlier observations. The seasonal variation of the mean age of stratospheric air indicates episodes of severe intrusion of mesospheric air during each Northern and Southern polar winter observed, long-lasting remnants of old, subsided polar winter air over the spring and summer poles, and a rather short period of mixing with midlatitude air and/or upward transport during fall in October/November (NH) and April/May (SH), respectively, with small latitudinal gradients, immediately before the new polar vortex starts to form. The mean age distributions further confirm that SF6 is destroyed in the mesosphere to a considerable degree. Model calculations with the Karlsruhe simulation model of the middle atmosphere (KASIMA) chemical transport model agree well with observed global distributions of the mean age only if the SF6 sink reactions in the mesosphere are included in the model.

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