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  • 251.
    Mendaza de Cal, Maria Teresa
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Blanco-Ávalos, J.J.
    Universidad Alcalá de Henares (UAH) Dpto. Física y Matemáticas, Campus Científico-Tecnológico (Externo) Alcalá de Henares (Madrid).
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Instituto Andaluz de Ciencias de la Tierra (UGR-CSIC), Avenida de las Palmeras 4, Armilla, Granada, Spain.
    Interplanetary Coronal Mass Ejection effects on thermospheric density as inferred from International Space Station orbital data2017In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 60, no 10, p. 2233-2251Article in journal (Refereed)
    Abstract [en]

    The solar activity induces long term and short term periodical variations in the dynamics and composition of Earth’s atmosphere. The Sun also shows non periodical (i.e., impulsive) activity that reaches the planets orbiting around it. In particular, Interplanetary Coronal Mass Ejections (ICMEs) reach Earth and interact with its magnetosphere and upper neutral atmosphere. Nevertheless, the interaction with the upper atmosphere is not well characterized because of the absence of regular and dedicated in situ measurements at high altitudes; thus, current descriptions of the thermosphere are based on semi empirical models.

    In this paper, we present the total neutral mass densities of the thermosphere retrieved from the orbital data of the International Space Station (ISS) using the General Perturbation Method, and we applied these densities to routinely compiled trajectories of the ISS in low Earth orbit (LEO). These data are explicitly independent of any atmospheric model. Our density values are consistent with atmospheric models, which demonstrates that our method is reliable for the inference of thermospheric density. We have inferred the thermospheric total neutral density response to impulsive solar activity forcing from 2001 to the end of 2006 and determined how solar events affect this response. Our results reveal that the ISS orbital parameters can be used to infer the thermospheric density and analyze solar effects on the thermosphere.

  • 252.
    Mendrok, Jana
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Buehler, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Eriksson, Patrick
    Chalmers University of Technology.
    PERRIN, Agnes
    LISA, CNRS.
    HARTOGH, Paul
    Max-Planck-Institut für Solar System Research.
    REZAC, Ladislav
    Max-Planck-Institut für Solar System Research.
    Lemke, Oliver
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    ARTS+ - A toolbox for microwave atmospheric radiative transfer in solar system planets2013Conference paper (Other academic)
    Abstract [en]

    Microwave and (sub)millimetre-wave frequencies have long been of interest for remote sensing of the Earth and space objects. They suffer less from interference by small particles (dust, clouds), hence penetrate deeper into atmospheres revealing their deeper structures hidden to shorter wavelengths, and possess characteristic line absorption features of many gaseous species, which are of interest for the understanding of atmospheric chemistry and dynamics.Models simulating radiative transfer and wave propagation (RT/WP) have been developed by many institutions. Most of them are designed for a particular, narrow region of the electromagnetic spectrum, certain instrument types or missions, and specific atmospheric conditions. In particular, they are usually set up for a specific planetary body. This high level of specialisation allows for accurate modelling results. However, it also limits the flexibility of those models and comparability between them.For various applications there is a demand on easy and quick calculations of propagation characteristics, like feasibility estimates of missions proposed to space agencies and performance estimates of radiocommunication links between satellites or orbiter and lander.Within an ESA study we have developed a toolbox for microwave RT/WP in planetary atmospheres. The toolbox consists of the RT/WP model and a data package. The RT/WP model is a largely revised and extended version of ARTS, a sophisticated, flexible RT model for Earth atmosphere (3D spherical geometry, diverse absorption models, scattering, polarization, Jacobians). Focus has been on creating a consistent, physics-based model. Several features have been added (radio link and cloud radar modes, zeeman splitting, doppler shifts). A new spectroscopic approach has been implemented considering effects of a range of broadening/pressure-shifting/refracting species, a corresponding spectroscopic line catalogue designed and prepared. At the current state, the data package contains atmospheric and surface data for Earth and the planets Venus, Mars, and Jupiter, but is easily extendable.We will illustrate the capabilities of the toolbox introducing several example cases and presenting results from the toolbox validation.

  • 253.
    Mendrok, Jana
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Wu, Dong L.
    Jet Propulsion Laboratory.
    Buehler, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Jimenez, Carlos
    Observatoire de Paris.
    Kasai, Yasuko
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    Sub-millimeter wave radiometer for observation of cloud ice: a proposal for Japanese mission2009In: Sensors, Systems, and Next-Generation Satellites XIII: 31 August - 3 September 2009, Berlin, Germany / [ed] Roland Meynart, Bellingham, Wash: SPIE - International Society for Optical Engineering, 2009Conference paper (Refereed)
    Abstract [en]

    Ice clouds play an important role in the energy budget of the atmosphere as well as in the hydrological cycle. Currently cloud ice is one of the largest remaining uncertainties in climate models. Large discrepancies arise from different assumptions on ice cloud properties, in particular on microphysics, which are not sufficiently constrained by measurements. Passive sub-millimeter wave (SMM) techniques have the potential of providing direct information on ice content and particle sizes with daily global coverage. Here we introduce a concept for a compact 2-receiver SMM sensor and demonstrate its capabilities on measurements of ice content, mean particle size, and cloud altitude.

  • 254.
    Mihalikova, Maria
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Mesoscale processes in the polar atmosphere: radar remote sensing, balloon-borne in situ measurements and modelling2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mesoscale processes (atmospheric phenomena with horizontal scales ranging from a few tens to several hundred kilometres and lasting from a few tens of minutes to a few days) have the potential to influence the chemical composition of the troposphere. Tropopause folds and mountain waves are two important types of mesoscale processes. Concentrations and gradients of trace gases like ozone (O3) can be influenced by these processes. Tropopause folds bring ozone-rich stratospheric air to lower altitudes. Mountain waves and turbulence associated with them influence O3 gradients in the troposphere. Tropospheric O3 is a toxic pollutant and a short-lived greenhouse gas with an influence on the lifetime of many other trace gases. Understanding of its long-term development and budgets are important. For this, better understanding, generalization and representation of mesoscale processes are necessary. Observations made by the 52MHz wind-profiler radar ESRAD (ESrange RADar) and the 54.5MHz wind-profiler radar MARA (Movable Atmospheric Radar for Antarctica) served as the basis for this study. ESRAD is located close to Kiruna in arctic Sweden and has been in operation since July 1996. This is a site with frequent mountain wave activity. By analysis of ESRAD and sonde data we have studied vertical mixing and turbulence associated with mountain waves. An attempt was made to show the influence of these processes on relaxation of the O3 gradient in the lower troposphere. Additional balloon-borne in situ measurements of vertical profiles of atmospheric characteristics (temperature, humidity, O3 mixing ratio) complement the radar measurements and aid in correct identification and improved understanding of the observed processes as well as of the radar backscatter signal itself. MARA was operated at the Swedish summer station Wasa (73°S, 13.5°W) during austral summer 2010/2011 and at the Norwegian year-round station Troll (72°S, 2.5°E) nonstop since December 2011. During its operation at the Wasa station, ozonesonde measurements were successfully undertaken during the passage of a tropopause fold. These provided validity to the radar measurements and proved them to be a useful tool for tropopause fold studies, for the first time at Antarctic latitudes. Data gathered at the Troll station exhibit signs of an annual cycle of tropopause folds with winter maximum and summer minimum in their occurrence rate which is similar to the observed behaviour in the northern hemisphere. Comparisons with ECMWF (European Centre for Medium-Range Weather Forecasts) model data and the WRF model (Advanced Research and Weather Forecasting) show that higher resolution models such as WRF are needed for more adequate representation of these processes. High resolution models can in return serve as a basis for studies of areas that are not at all or only partially covered by measurement networks, as well as for global studies. Thus they can provide useful information about atmospheric transport and the state of trace gases like O3.

  • 255.
    Mihalikova, Maria
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Kirkwood, Sheila
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Tropopause fold occurrence rates over the Antarctic station Troll (72 degrees S, 2.5 degrees E)2013In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 31, no 4, p. 591-598Article in journal (Refereed)
    Abstract [en]

    One of the important mechanisms of stratosphere-troposphere exchange, which brings ozone-rich stratospheric air to low altitudes in extratropical regions, is transport related to tropopause folds. The climatology of folds has been studied at high latitudes of the Northern Hemisphere with the help of radars and global models. Global models supply information about fold occurrence rates at high latitudes of the Southern Hemisphere as well, but so far comparisons with direct measurements are rare. The Moveable Atmospheric Radar for Antarctica (MARA), a 54.5 MHz wind-profiler radar, has been operated at the Norwegian year-round station Troll, Antarctica (72 degrees S, 2.5 degrees E) since December 2011. Frequent tropopause fold signatures have been observed. In this study, based on MARA observations, an occurrence rate statistics of tropopause folds from December 2011 until November 2012 has been made, and radar data have been compared with the analysis from the European Center for Medium-Range Weather Forecasting (ECMWF). The fold occurrence rates exhibit an annual cycle with winter maximum and summer minimum and suggest significantly higher occurrence rates for the given location than those obtained previously by global model studies.

  • 256.
    Mihalikova, Maria
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Kirkwood, Sheila
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Vertical mixing in the lower troposphere by mountain waves over Arctic Scandinavia2011In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 11, p. 31475-31493Article in journal (Refereed)
    Abstract [en]

    Measurements made by ozonesondes and by a 52 MHz wind-profiling radar during February and March 1997 are studied. The radar is located at Esrange, near Kiruna in Arctic Sweden, on the eastern flank of the Scandinavian mountains. Daily ozonesondes were launched from the same site. The radar vertical and horizontal wind measurements are used to identify times when mountain waves were present. Mean vertical gradients in ozone mixing ratio in the lower troposphere are determined in conditions with mountain waves present and when they were absent. Back-trajectories were calculated so that only air-masses with their origin to the west of the mountains were included in the final averages. The vertical gradient in ozone mixing ratio is found to be about twice as steep outside wave conditions as it is during mountain waves. This suggests a very high rate of vertical mixing, with an average eddy diffusivity of order 5000 m2 s−1. This is consistent with an earlier estimate of the occurrence rate of complete mixing by wave breaking over the mountain range.

  • 257.
    Mihalikova, Maria
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Kirkwood, Sheila
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Arnault, J.
    Polar Atmospheric Research, Swedish Institute of Space Physics, Box 812, 98128, Kiruna.
    Mikhaylova, D.
    Polar Atmospheric Research, Swedish Institute of Space Physics, Box 812, 98128, Kiruna.
    Observation of a tropopause fold by MARA VHF wind-profiler radar and ozonesonde at Wasa, Antarctica: Comparison with ECMWF analysis and a WRF model simulation2012In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 30, no 9, p. 1411-1421Article in journal (Refereed)
    Abstract [en]

    Tropopause folds are one of the mechanisms of stratosphere-troposphere exchange, which can bring ozone rich stratospheric air to low altitudes in the extra-tropical regions. They have been widely studied at northern mid-or high latitudes, but so far almost no studies have been made at mid-or high southern latitudes. The Moveable Atmospheric Radar for Antarctica (MARA), a 54.5 MHz wind-profiler radar, has operated at the Swedish summer station Wasa, Antarctica (73° S, 13.5° W) during austral summer seasons from 2007 to 2011 and has observed on several occasions signatures similar to those caused by tropopause folds at comparable Arctic latitudes. Here a case study is presented of one of these events when an ozonesonde successfully sampled the fold. Analysis from European Center for Medium Range Weather Forecasting (ECMWF) is used to study the circumstances surrounding the event, and as boundary co

  • 258.
    Millán, L.
    et al.
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Read, W.
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Kasai, Y.
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    Lambert, A.
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Livesey, N.
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Mendrok, Jana
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Sagawa, H.
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    Sano, T.
    Japanese Aerospace Exploration Agency, Cho-fu, Tokyo.
    Shiotani, M.
    Kyoto University.
    Wu, D.L.
    NASA Goddard Space Flight Center.
    SMILES ice cloud products2013In: Journal of Geophysical Research: Atmospheres, ISSN 2169-8996, Vol. 118, no 12, p. 6468-6477Article in journal (Refereed)
    Abstract [en]

    Upper tropospheric water vapor and clouds play an important role in Earth's climate, but knowledge of them, in particular diurnal variation in deep convective clouds, is limited. An essential variable to understand them is cloud ice water content. The Japanese Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on board the International Space Station (ISS) samples the atmosphere at different local times allowing the study of diurnal variability of atmospheric parameters. We describe a new ice cloud data set consisting of partial Ice Water Path and Ice Water Content. Preliminary comparisons with EOS-MLS, CloudSat-CPR and CALIOP-CALIPSO are presented. Then, the diurnal variation over land and over open ocean for partial ice water path is reported. Over land, a pronounced diurnal variation peaking strongly in the afternoon/early evening was found. Over the open ocean, little temporal dependence was encountered. This data set is publicly available for download in HDF5 format.

  • 259.
    Milz, Mathias
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Study on forest fire detection with satellite data2013Report (Other academic)
  • 260. Milz, Mathias
    et al.
    Buehler, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    John, V.O.
    Met Office Hadley Centre, Exeter.
    Comparison of AIRS and AMSU-B monthly mean estimates of upper tropospheric humidity2009In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 36, no L10804Article in journal (Refereed)
    Abstract [en]

    Satellite-borne measurements provide valuable information on the global distribution of upper tropospheric humidity (UTH), which represents the mean relative humidity in a layer approximately enclosed by the atmospheric pressure levels 500 and 200 hPa. Monthly mean distributions of microwave observations of UTH obtained from the Advanced Microwave Sounding Unit-B (AMSU-B) and the Humidity Sounder for Brazil (HSB) are compared to infrared observations of UTH from the Atmospheric Infrared Sounder (AIRS). All data sets for January 2003 show distributions as expected from climatologies. Data of AIRS and AMSU-B averaged on 1.5° × 1.5° lat-lon bins for January 2003 show good overall agreement. However, with 2.7%RH AIRS shows an unexpected wet mean bias, especially for regions where the influence of clouds is small or cloud affected measurements are excluded for both sensors. In regions where AIRS is sensitive to cloud affected measurements but not AMSU-B, the bias is reduced and partly negative.

  • 261.
    Milz, Mathias
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Buehler, Stefan
    John, V.O.
    Comparison of UTH Measurements from Satellite-Borne IR and MW Sensors2008Conference paper (Other academic)
  • 262.
    Milz, Mathias
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Clarmann, T. von
    Forschungszentrum Karlsruhe.
    Bernath, P.
    University of York, Department of Chemistry.
    Boone, C.
    University of Waterloo, Deptment of Chemistry, Waterloo.
    Buehler, Stefan
    Chauhan, S.
    Forschungszentrum Karlsruhe.
    Deuber, B.
    University of Bern, Institute of Applied Physics, Atmospheric Research Group.
    Feist, D.G.
    Max-Planck-Institut für Biogeochemie, Jena.
    Funke, B.
    Instituto de Astrofísica de Andalucía CSIC, Granada.
    Glatthor, N.
    Forschungszentrum Karlsruhe.
    Grabowski, U.
    Forschungszentrum Karlsruhe.
    Griesfeller, A.
    CNRS, UVSQ, LATMOS, Verrieres Le Buisson.
    Haefele, A.
    University of Bern, Institute of Applied Physics, Atmospheric Research Group.
    Höpfner, M.
    Forschungszentrum Karlsruhe.
    Kämpfer, N.
    University of Bern, Institute of Applied Physics, Atmospheric Research Group.
    Kellmann, S.
    Forschungszentrum Karlsruhe.
    Linden, A.
    Forschungszentrum Karlsruhe.
    Müller, S.
    University of Bern, Institute of Applied Physics, Atmospheric Research Group.
    Nakajima, H.
    National Institute for Environmental Studies, Tsukuba.
    Oelhaf, H.
    Forschungszentrum Karlsruhe.
    Remsberg, E.
    NASA, Langley Research Centre, Scientific Directorate.
    Rohs, S.
    Forschungszentrum Julich.
    Russell, J.M.
    Hampton University, Department of Physics.
    Schiller, C.
    Forschungszentrum Julich.
    Sugita, T.
    National Institute for Environmental Studies, Tsukuba.
    Zhang, G.
    Forschungszentrum Karlsruhe.
    Validation of water vapour profiles (version 13) retrieved by the IMK/IAA scientific retrieval processor based on full resolution spectra measured by MIPAS on board Envisat2009In: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, no 2, p. 379-399Article in journal (Refereed)
    Abstract [en]

    Vertical profiles of stratospheric water vapour measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) with the full resolution mode between September 2002 and March 2004 and retrieved with the IMK/IAA scientific retrieval processor were compared to a number of independent measurements in order to estimate the bias and to validate the existing precision estimates of the MIPAS data. The estimated precision for MIPAS is 5 to 10% in the stratosphere, depending on altitude, latitude, and season. The independent instruments were: the Halogen Occultation Experiment (HALOE), the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS), the Improved Limb Atmospheric Spectrometer-II (ILAS-II), the Polar Ozone and Aerosol Measurement (POAM III) instrument, the Middle Atmospheric Water Vapour Radiometer (MIAWARA), the Michelson Interferometer for Passive Atmospheric Sounding, balloon-borne version (MIPAS-B), the Airborne Microwave Stratospheric Observing System(AMSOS), the Fluorescent Stratospheric Hygrometer for Balloon (FLASH-B), the NOAA frostpoint hygrometer, and the Fast In Situ Hygrometer (FISH). For the in-situ measurements and the ground based, air- and balloon borne remote sensing instruments, the measurements are restricted to central and northern Europe. The comparisons to satellite-borne instruments are predominantly at mid- to high latitudes on both hemispheres. In the stratosphere there is no clear indicationof a bias in MIPAS data, because the independent measurements in some cases are drier and in some cases are moister than the MIPAS measurements. Compared to the infrared measurements of MIPAS, measurements in the ultraviolet and visible have a tendency to be high, whereas microwave measurements have a tendency to be low. Theresults of chi2-based precision validation are somewhat controversial among the comparison estimates. However, for comparison instruments whose error budget also includes errors due to uncertainties in spectrally interfering species and where good coincidences were found, the chi2 values found are in the expected range or even below. This suggests that there is no evidence of systematically underestimated MIPAS random errors.

  • 263.
    Molina, Antonio
    et al.
    Centro de Astrobiología (INTA-CSIC), 28850 Torrejón de Ardoz, Madrid. Spain.
    López, Iván
    Universidad Rey Juan Carlos, 28933 Móstoles, Madrid. Spain.
    Prieto-Ballesteros, Olga
    Centro de Astrobiología (INTA-CSIC), 28850 Torrejón de Ardoz, Madrid. Spain.
    Fernández-Remolar, David
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. British Geological Survey, Nicker Hill, Keyworth NG12 5GG. United Kingdom.
    Ángel de Pablo, Miguel
    Universidad de Alcalá, 28871 Alcalá de Henares, Madrid. Spain.
    Gómez, Felipe
    Centro de Astrobiología (INTA-CSIC), 28850 Torrejón de Ardoz, Madrid.
    Coogoon Valles, western Arabia Terra: Hydrological evolution of a complex Martian channel system2017In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 293, p. 27-44Article in journal (Refereed)
    Abstract [en]

    Coogoon Valles is an intricate fluvial system, and its main channel was formed during the Noachian period through the erosion of the clay-bearing basement of the Western Arabia Terra. This region is characterized by a thinner crust compared to the rest of the highlands and by the occurrence of massive phyllosilicate-bearing materials. The origin of this region is still under discussion. Its surface has been exposed to a large-scale volcanism, and several episodes of extensive denudation were primarily controlled by fluvial activity. In this regard, the study of the oldest channels in Arabia Terra is crucial for understanding the global geological evolution of early Mars. The reactivation of the hydrological system by sapping followed by aeolian erosion had reshaped the channel, as well as exposed ancient materials and landforms. The examination of the bed deposits suggests an old episode of detrital sedimentation covering the Noachian basement followed by an erosive event that formed the current Coogoon Valles configuration. A complex system of deltas and alluvial fans is situated at the termination of this channel, which has been proposed as a landing site for the upcoming ExoMars and Mars 2020 missions.

  • 264.
    Moore, Casey A.
    et al.
    Centre for Research in Earth and Space Sciences, York University, Earth and Space Sciences, Toronto.
    Moores, John E.
    York University, Toronto, Centre for Research in Earth and Space Sciences, York University, Earth and Space Sciences, Toronto.
    Lemmon, Mark T.
    Texas A&M University, College Station.
    Rafkin, Scot C.R.
    Southwest Research Institute, Boulder.
    Francis, Raymond
    University of Western Ontario, Centre for Planetary Science and Exploration, University of Western Ontario, London.
    Pla-Garcia, Jorge
    Centro de Astrobiologia, INTA-CSIC, Madrid.
    Haberle, Robert
    Ames Research Centre, NASA Ames Research Center, Moffett Field.
    Zorzano, María-Paz
    Centro de Astrobiologia, INTA-CSIC, Madrid , Instituto Nacional de Técnica Aeroespacial, Madrid, Centro de Astrobiologia, Madrid, Centro de Astrobiología (CSIC-INTA), Madrid.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Burton, John R.
    Centre for Research in Earth and Space Sciences, York University, Earth and Space Sciences, Toronto.
    A Full Martian Year of Line-of-Sight Extinction within Gale Crater, Mars as Acquired by the MSL Navcam through sol 9002016In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 264, p. 102-108Article in journal (Refereed)
    Abstract [en]

    We report on line-of-sight extinction in northern Gale Crater, Mars as seen by the Mars Science Laboratory (MSL) rover, Curiosity from sol 100 to sol 900; a little more than an entire martian year. Navcam images oriented due north, which show the distant crater rim, the near ground and the sky allow the extinction due to dust within the crater to be determined. This line-of sight extinction is compared to a complementary dataset of column extinctions derived from Mastcam. The line-of-sight extinction within the crater is less than the column extinction for the majority of the martian year. This implies that the relatively low mixing ratio of dust within the crater as compared to the atmosphere above the crater rim persists through most of the year. This suggests relatively little mixing between the atmosphere above the crater and the atmosphere inside the crater and suggests that northern Gale Crater is a net sink of dust in the current era. The data does however show a yearly convergence of the line-of-sight extinction and the column-averaged extinction around Ls = 270° – 290°. This suggests that air above the crater mixes with air in the crater at this time, as predicted by mesoscale models. Matching line-of-sight and column extinction values are also seen around Ls ≈ 135°, a season that has only been observed once in this dataset, this is particularly interesting as the Rover Environmental Monitoring Station onboard Curiosity reports increased convective boundary layer heights in the same season.

  • 265.
    Moores, John E.
    et al.
    York University, Toronto.
    Lemmon, Mark T.
    Texas A&M University, College Station.
    Rafkin, Scot C R
    Southwest Research Institute, San Antonio, Texas.
    Francis, Raymond
    University of Western Ontario.
    Pla-Garcia, Jorge
    Centro de Astrobiologia, INTA-CSIC, Madrid.
    Juárez, Manuel De La Torre
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Bean, Keri
    Texas A&M University.
    Kass, David
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Haberle, Robert
    Ames Research Centre.
    Newman, Claire .E.
    Ashima Research, Pasadena.
    Mischna, Michael A.
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Vasavada, Ashwin R.
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Rennó, Nilton
    University of Michigan.
    Bell, Jim
    Arizona State University.
    III, Fred .J. Calef
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Cantor, Bruce
    Malin Space Science Systems.
    McConnochie, Timothy H.
    Department of Astronomy, University of Maryland, College Park.
    Harri, Ari-Matti
    Finnish Meteorological Institute.
    Genzer, Maria
    Finnish Meteorological Institute.
    Wong, Michael
    University of Michigan.
    Smith, Michael D.
    NASA Goddard Space Flight Center.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Zorzano, María-Paz
    Centro de Astrobiologia, INTA-CSIC, Madrid , Instituto Nacional de Técnica Aeroespacial, Madrid.
    Kemppainen, Osku
    Finnish Meteorological Institute.
    McCullough, Emily
    University of Western Ontario.
    Atmospheric movies acquired at the Mars Science Laboratory landing site: Cloud Morphology, Frequency and Significance to the Gale Crater Water Cycle and Phoenix Mission Results2015In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 55, no 9, p. 2217-2238Article in journal (Refereed)
    Abstract [en]

    We report on the first 360 sols (LS 150° to 5°), representing just over half a Martian year, of atmospheric monitoring movies acquired using the NavCam imager from the Mars Science Laboratory (MSL) Rover Curiosity. Such movies reveal faint clouds that are difficult to discern in single images. The data set acquired was divided into two different classifications depending upon the orientation and intent of the observation. Up to sol 360, 73 Zenith Movies and 79 Supra-Horizon Movies have been acquired and time-variable features could be discerned in 25 of each. The data set from MSL is compared to similar observations made by the Surface Stereo Imager (SSI) onboard the Phoenix Lander and suggests a much drier environment at Gale Crater (4.6°S) during this season than was observed in Green Valley (68.2°N) as would be expected based on latitude and the global water cycle. The optical depth of the variable component of clouds seen in images with features are up to 0.047 ± 0.009 with a granularity to the features observed which averages 3.8 degrees. MCS also observes clouds during the same period of comparable optical depth at 30 and 50 km that would suggest a cloud spacing of 2.0 to 3.3 km. Multiple motions visible in atmospheric movies support the presence of two distinct layers of clouds. At Gale Crater, these clouds are likely caused by atmospheric waves given the regular spacing of features observed in many Zenith movies and decreased spacing towards the horizon in sunset movies consistent with clouds forming at a constant elevation. Reanalysis of Phoenix data in the light of the NavCam equatorial dataset suggests that clouds may have been more frequent in the earlier portion of the Phoenix mission than was previously thought.

  • 266.
    Moradi, Isaac
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Quality control of global solar radiation using sunshine duration hours2009In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 34, no 1, p. 1-6Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to develop a new and automatic method for controlling the quality of daily global solar radiation, Gd, using sunshine duration hours. The new method has three levels of tests: first, Gd is compared against daily extraterrestrial radiation that is received on a horizontal surface (0.03×God≤Gdod); second, Gd should only exceed by a small amount of the daily clear sky irradiation that is observed under highly transparent clear skies (Gd<1.1Gcd); and third, the method uses a series of persistence checks that utilize the relation between daily global solar radiation and relative sunshine duration hours. The method is capable of identifying systematic and non-systematic errors and its ability has been shown in three different climates including semi-arid, coastal humid and very arid climates.

  • 267.
    Moradi, Isaac
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Alijani, Bohloul
    Department of Geography, Tarbiat Moalem University, Tehran.
    Muller, Richard
    German National Meteorological Service (DWD), Climate Monitoring Satellite Application Facility (CM-SAF), Offenbach.
    Kamali, Gholam Ali
    Atmospheric Sciences and Meteorological Research Center, Tehran.
    Evaluation of the Heliosat-II method using daily irradiation data for four stations in Iran2009In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 83, no 2, p. 150-156Article in journal (Refereed)
    Abstract [en]

    Efficient use of solar radiation needs detailed knowledge of its spatial and temporal variations. Such information can be achieved using interpolating measured irradiance by ground stations. But more reliable results can be obtained by processing geostationary satellite images. Heliosat is an algorithm which has been developed to estimate global horizontal irradiance at ground level from images taken in the visible band by the Meteosat satellites. The aim of this study was to evaluate the Heliosat-II model by using daily global solar irradiation data measured at the four radiometric stations in Iran as well as Meteosat-5 images which are recorded by a spacecraft over 63°E. Mean RMSD% and MBD% for all stations were 11.7% and 1.9%, respectively. The mean values of intercept, slope and correlation coefficient were 0.82 (kWhm-2), 1.05 and 0.93, respectively. Seasonally, the maximum RMSD occurs in autumn (22.1%) and the minimum is experienced in spring (8.4%). This accuracy is a great achievement for producing a high quality solar radiation atlas in a country such as Iran with very sparse radiometric network and frequently unreliable measured irradiation data.

  • 268.
    Moradi, Isaac
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Buehler, Stefan
    John, Viju
    Met Office Hadley Centre, Exeter.
    Eliasson, Salomon
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Comparing upper tropospheric humidity data from microwave satellite instruments and tropical radiosondes2010In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 115, no 24, article id D24310Article in journal (Refereed)
    Abstract [en]

    Atmospheric humidity plays an important role in the Earth's climate. Microwave satellite data provide valuable humidity observations in the upper troposphere with global coverage. In this study, we compare upper tropospheric humidity (UTH) retrieved from the Advanced Microwave Sounding Unit (AMSU-B) and the Microwave Humidity Sounder (MHS) against radiosonde data measured at four of the central facilities of the Atmospheric Radiation Measurement (ARM) program. The Atmospheric Radiative Transfer Simulator (ARTS) was used to simulate satellite brightness temperatures from the radiosonde profiles. Strong ice clouds were filtered out, as their influence on microwave measurements leads to incorrect UTH values. Day and night radiosonde profiles were analyzed separately, to take into account the radiosonde radiation bias. The comparison between radiosonde and satellite is most meaningful for data in cloud free, night time conditions, and with a time difference of less than 2 hours. We found good agreement between the two data sets. The satellite data are slightly moister than the radiosonde data, with a mean difference of 1-2.3 %RH, depending on the radiosonde site. Monthly gridded data were also compared, and showed slightly larger mean difference of up to 3.3 %RH, which can be explained by sampling issues.

  • 269. Moradi, Isaac
    et al.
    Buehler, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    John, Viju O.
    Met Office Hadley Centre, Exeter.
    Comparing upper tropospheric humidity from microwave satellite instruments and IGRA radiosonde data2010In: 11th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment, MicroRad, New York: IEEE Communications Society, 2010, p. 146-151Conference paper (Refereed)
    Abstract [en]

    In this study, Advanced Microwave Sounding Unit (AMSU-B) and Microwave Humidity Sounder (MHS) observations are compared to radiosonde data from the Integrated Global Radiosonde Archive (IGRA) dataset. This comparison can be used to evaluate the overall quality of the radiosonde data. Microwave satellite data are influenced by thick ice clouds and radiosonde data show a day-time radiation dry bias. Therefore, we used night-time cloud-free data of the year 2009 for the comparison. Overall, radiosonde data from the former Soviet Union were up to 30 %RH moister than satellite data and the the rest of the world were up to 6 %RH drier than satellite data.

  • 270. Moradi, Isaac
    et al.
    Buehler, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    John, V.O.
    Met Office Hadley Centre, Exeter.
    Reale, A.
    STAR, National Environmental Satellite, Data, and Information Service.
    Ferraro, R.R.
    STAR, National Environmental Satellite, Data, and Information Service.
    Evaluating instrumental inhomogeneities in global radiosonde upper tropospheric humidity data using microwave satellite data2013In: IEEE Transactions on Geoscience and Remote Sensing, ISSN 0196-2892, E-ISSN 1558-0644, Vol. 51, no 6, p. 3615-3624Article in journal (Refereed)
    Abstract [en]

    In this paper, the overall quality of the water vapor profiles of global operational radiosonde data for the period 2000-2009 is investigated using upper tropospheric humidity (UTH) retrieved from microwave satellite data. Overall, the nighttime radiosonde data showed a dry bias (-5% to-15%) over Europe, Australia, and New Zealand and systematically moist bias (greater than 30%) over China and the former Soviet Union. The nighttime sonde data from the U.S. and Canada showed a bias between-10% and 20%. Most stations indicated a daytime radiation dry bias, except for a few stations from the U.S. and the former Soviet Union. A sensorwise comparison showed a large nighttime wet bias for the Russian (MRZ-3A and MARS) and Chinese GZZ-2 sensors, a relatively small nighttime wet bias for the U.S. Sippican and VIZ-B2 sensors, and a nighttime dry bias for the Chinese GTS1, Vaisala (RS80-A, RS80-H, RS90, RS92K, and RS92-SGP), and the U.S. VIZ-MKII sensors. All sensors had a daytime radiation dry bias, except for the Russian MRZ-3A sensor that had a daytime radiation wet bias that could be because of the daytime radiation bias correction. Because of the large differences between different radiosonde sensors, it is essential for UTH studies to only use the data measured using a single type of sensor at any given station.

  • 271.
    Moyano-Cambero, Carles E.
    et al.
    Institute of Space Sciences (IEEC-CSIC), Campus UAB, Carrer de Can Magrans.
    Trigo-Rodríguez, Josep M.
    Institute of Space Sciences (IEEC-CSIC), Campus UAB, Carrer de Can Magrans.
    Benito, M. Isabel
    Departamento de Estratigrafía-IGEO, Facultad de Ciencias Geológicas, Universidad Complutense de Madrid-CSIC.
    Alonso-Azcárate, Jacinto
    Fac. de Ciencias Ambientales y Bioquímica, Universidad de Castilla-La Mancha.
    Lee, Martin R.
    School of Geographical and Earth Sciences, University of Glasgow.
    Mestres, Narcís
    Institut de Cìencia de Materials de Barcelona (ICMAB-CSIC) .
    Martínez-Jiménez, Marina
    Institute of Space Sciences (IEEC-CSIC), Campus UAB, Carrer de Can Magrans.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Fraxedas, Jordi
    Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and the Barcelona Institute of Science and Technology, Campus UAB.
    Petrographic and geochemical evidence for multiphase formation of carbonates in the Martian orthopyroxenite Allan Hills 840012017In: Meteoritics and Planetary Science, ISSN 1086-9379, E-ISSN 1945-5100, Vol. 52, no 6, p. 1030-1047Article in journal (Refereed)
    Abstract [en]

    Martian meteorites can provide valuable information about past environmental conditions on Mars. Allan Hills 84001 formed more than 4 Gyr ago, and owing to its age and long exposure to the Martian environment, and this meteorite has features that may record early processes. These features include a highly fractured texture, gases trapped during one or more impact events or during formation of the rock, and spherical Fe-Mg-Ca carbonates. In this study, we have concentrated on providing new insights into the context of these carbonates using a range of techniques to explore whether they record multiple precipitation and shock events. The petrographic features and compositional properties of these carbonates indicate that at least two pulses of Mg- and Fe-rich solutions saturated the rock. Those two generations of carbonates can be distinguished by a very sharp change in compositions, from being rich in Mg and poor in Fe and Mn, to being poor in Mg and rich in Fe and Mn. Between these two generations of carbonate is evidence for fracturing and local corrosion

  • 272.
    Muller, S.C.
    et al.
    University of Bern.
    Kämpfer, N.
    University of Bern.
    Feist, D.G.
    Max-Planck-Institut for Biogeochemistry, Jena.
    Haefele, A.
    University of Bern.
    Milz, Mathias
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Sitnikov, N.
    Central Aerological Observatory, Moscow Region.
    Schiller, C.
    Forschungszentrum Jülich GmbH, Jülich.
    Kiemle, C.
    DLR-Institut für Physik der Atmosphäre, Oberpfaffenhofen.
    Urban, J.
    Chalmers University of Technology.
    Validation of stratospheric water vapour measurements from the airborne microwave radiometer AMSOS2008In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 8, no 12, p. 3169-3183Article in journal (Refereed)
    Abstract [en]

    We present the validation of a water vapour dataset obtained by the Airborne Microwave Stratospheric Observing System AMSOS, a passive microwave radiometer operating at 183 GHz. Vertical profiles are retrieved from spectra by an optimal estimation method. The useful vertical range lies in the upper troposphere up to the mesosphere with an altitude resolution of 8 to 16 km and a horizontal resolution of about 57 km. Flight campaigns were performed once a year from 1998 to 2006 measuring the latitudinal distribution of water vapour from the tropics to the polar regions. The obtained profiles show clearly the main features of stratospheric water vapour in all latitudinal regions. Data are validated against a set of instruments comprising satellite, ground-based, airborne remote sensing and in-situ instruments. It appears that AMSOS profiles have a dry bias of 0 to ĝ€"20%, when compared to satellite experiments. Also a comparison between AMSOS and in-situ hygrosondes FISH and FLASH have been performed. A matching in the short overlap region in the upper troposphere of the lidar measurements from the DIAL

  • 273.
    Muralidharan, Vijay
    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.
    Concurrent rendezvous control of underactuated spacecraft2017In: Acta Astronautica, ISSN 0094-5765, E-ISSN 1879-2030, Vol. 138, p. 28-42Article in journal (Refereed)
    Abstract [en]

    The concurrent control of spacecraft equipped with one-axis unilateral thruster and three-axis attitude actuator is considered in this paper. The proposed control law utilizes attitude control channels along with the single thrust force concurrently, for three-dimensional trajectory tracking and rendezvous with a target object. The concurrent controller also achieves orbital transfer to low Earth orbits with long range separation. To demonstrate the orbit transfer capabilities of the concurrent controller, a smooth elliptical orbit transfer trajectory for co-planar circular orbits is designed. The velocity change and energy consumption of the designed orbit transfer trajectory is observed to be equivalent to that of Hohmann transfer.

  • 274.
    Navas-Guzmán, Francisco
    et al.
    Institute of Applied Physics, University of Bern.
    Kämpfer, Nklaus
    Institute of Applied Physics, University of Bern.
    Murk, Axel
    Institute of Applied Physics, University of Bern.
    Larsson, Richard
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Buehler, Stefan
    Meteorological Institute, Center for Earth System Research and Sustainability, University of Hamburg.
    Eriksson, Patrik
    Chalmers University of Technology, Chalmers University of Technology, Department of Earth and Space Sciences.
    Zeeman effect in atmospheric O2 measured by ground-based microwave radiometry2015In: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, Vol. 8, no 4, p. 1863-1874Article in journal (Refereed)
    Abstract [en]

    In this work we study the Zeeman effect on stratospheric O2 using ground-based microwave radiometer measurements. The interaction of the Earth magnetic field with the oxygen dipole leads to a splitting of O2 energy states, which polarizes the emission spectra. A special campaign was carried out in order to measure this effect in the oxygen emission line centered at 53.07 GHz. Both a fixed and a rotating mirror were incorporated into the TEMPERA (TEMPERature RAdiometer) in order to be able to measure under different observational angles. This new configuration allowed us to change the angle between the observational path and the Earth magnetic field direction. Moreover, a high-resolution spectrometer (1 kHz) was used in order to measure for the first time the polarization state of the radiation due to the Zeeman effect in the main isotopologue of oxygen from ground-based microwave measurements. The measured spectra showed a clear polarized signature when the observational angles were changed, evidencing the Zeeman effect in the oxygen molecule. In addition, simulations carried out with the Atmospheric Radiative Transfer Simulator (ARTS) allowed us to verify the microwave measurements showing a very good agreement between model and measurements. The results suggest some interesting new aspects for research of the upper atmosphere

  • 275.
    Nazarious, Miracle Israel
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Design, Development and Characterization of a Digital Sun Sensor prototype for Nano Satellite Applications2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sun sensors serve as eyes of satellites. It is one of the basic components in satellites used for the purpose of determining the position of the sun in order to properly orient the solar arrays. The technological challenge involved in such sensors is to find the right balance between the field-of-view and the accuracy characteristics. For every sun sensor, there is a trade-off between these two performance parameters which has to be optimized for the expected performance requirements. Developing a low-weight, low-power sun sensorfor nano-satellite applications managing better performance in terms of field-of-view and accuracy is the challenge, this project has accepted to address.

    The true motivation behind this project was to develop an advanced solar-powered, bluetooth enabled digital sun sensor entitled as Multihead Autonomous Wireless Digital Sun Sensor (MAWDSS). To reach this ambitious goal, the footpath to be followed includes developing a prototype of a digital sun sensor and an autonomous wireless digitalsun sensor leading to the final product.

    This thesis work lays the first step and proposes a design of a digital sun sensor using low-cost commercial-off-the-shelf (COTS) components, develop a prototype and conduct performance characterization to compare with a commercial benchmarking sun sensor.The desired performance requirements were predefined prior to describing the detailed design aspects of the sun sensor. The problems encountered during experimental testing and the recommended suggestions to overcome them are presented.

    This thesis defines a complete product development life cycle involving skills from all three aspects of engineering: mechanical, electrical and programming. Each individual regime of the project are properly addressed with relevant figures and plots in separate chapters for the ease of following the report.

  • 276.
    Newsom, Horton E.
    et al.
    Institute of Meteoritics, Department of Earth and Planetary Sciences, Albuquerque, New Mexico.
    Mangold, Nicolas
    LPGN, CNRS, UMR 6112, Université Nantes.
    Kah, Linda C.
    Department of Earth and Planetary Sciences, University of Tennessee, Knoxville.
    Williams, Joshua M.
    Institute of Meteoritics, Department of Earth and Planetary Sciences, Albuquerque, New Mexico.
    Arvidson, Ray E.
    Washington University, St. Louis.
    Stein, Nathan
    Washington University, St. Louis.
    Ollila, Ann M.
    Institute of Meteoritics, Department of Earth and Planetary Sciences, Albuquerque, New Mexico.
    Bridges, John C.
    Space Research Centre, Department of Physics and Astronomy, University of Leicester.
    Schwenzer, Susanne P.
    Department of Physical Science, The Open University, Walton Hall, Milton Keynes.
    King, Penelope L.
    Research School of Earth Sciences, Australian National University, Canberra.
    Grant, John A.
    Center for Earth and Planetary Studies, National Air and Space Museum, Smithsonian Institution, Washington.
    Pinet, Patrick
    Université Paul Sabatier, Institut de Recherche en Astrophysique et Planétologie (IRAP), Toulouse.
    Bridges, Nathan T.
    Applied Physics Laboratory, Laurel, Maryland.
    III, Fred Calef
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Wiens, Roger C.
    Los Alamos National Laboratory.
    Spray, John G.
    Planetary and Space Science Centre, University of New Brunswick, Fredericton.
    Vaniman, David T.
    Planetary Science Institute, Tucson.
    Elston, Wolf E.
    Institute of Meteoritics, Department of Earth and Planetary Sciences, Albuquerque, New Mexico.
    Berger, Jeff A.
    University of Western Ontario, London.
    Garvin, James B.
    NASA Goddard Space Flight Center, Greenbelt, Maryland.
    Palucis, Marisa C.
    Department of Earth and Planetary Science, University of California, Berkeley.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Gale crater and impact processes: Curiosity's first 364 Sols on Mars2015In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 249, p. 108-128Article in journal (Refereed)
    Abstract [en]

    Impact processes at all scales have been involved in the formation and subsequent evolution of Gale crater. Small impact craters in the vicinity of the Curiosity MSL landing site and rover traverse during the 364 Sols after landing have been studied both from orbit and the surface. Evidence for the effect of impacts on basement outcrops may include loose blocks of sandstone and conglomerate, and disrupted (fractured) sedimentary layers, which are not obviously displaced by erosion. Impact ejecta blankets are likely to be present, but in the absence of distinct glass or impact melt phases are difficult to distinguish from sedimentary/volcaniclastic breccia and conglomerate deposits. The occurrence of individual blocks with diverse petrological characteristics, including igneous textures, have been identified across the surface of Bradbury Rise, and some of these blocks may represent distal ejecta from larger craters in the vicinity of Gale. Distal ejecta may also occur in the form of impact spherules identified in the sediments and drift material. Possible examples of impactites in the form of shatter cones, shocked rocks, and ropy textured fragments of materials that may have been molten have been observed, but cannot be uniquely confirmed. Modification by aeolian processes of craters smaller than 40 m in diameter observed in this study, are indicated by erosion of crater rims, and infill of craters with aeolian and airfall dust deposits. Estimates for resurfacing suggest that craters less than 15 m in diameter may represent steady state between production and destruction. The smallest candidate impact crater observed is ∼0.6 m in diameter. The observed crater record and other data are consistent with a resurfacing rate of the order of 10 mm/Myr; considerably greater than the rate from impact cratering alone, but remarkably lower than terrestrial erosion rates.

  • 277.
    Niles, P.B.
    et al.
    Astromaterials Research and Exploration Science, NASA Johnson Space Center, Houston.
    Archer, P.D.
    Jacobs Technology, NASA Johnson Space Center.
    Heil, E.
    HX5-Jacobs JETS Contract, NASA Johnson Space Center, Houston.
    Eigenbrode, J.
    NASA Goddard Space Flight Center.
    McAdam, A.
    NASA Goddard Space Flight Center.
    Sutter, B.
    Jacobs Technology, NASA Johnson Space Center.
    Franz, H.
    NASA Goddard Space Flight Center.
    Navarro-Gonzalez, R.
    Instituto Andaluz de Cienccias de la Tierra (CSIC-UGR), Grenada.
    Ming, D.
    Astromaterials Research and Exploration Science, NASA Johnson Space Center, Houston.
    Mahaffy, P.
    NASA Goddard Space Flight Center.
    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.
    Centro de Astrobiologia, INTA-CSIC, Madrid.
    Investigating CO2 reservoirs at Gale Crater and evidence for a dense early atmosphere2015Conference paper (Refereed)
  • 278.
    Nilsson, H.
    et al.
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Carlsson, Ella
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Gunell, H.
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Futaana, Y.
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Barabash, Stas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Lundin, R.
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Fedorov, A.
    Centre d’Etude Spatiale des Rayonnements, Toulouse.
    Soobiah, Y.
    Mullard Space Science Laboratory, Imperial College.
    Coates, A.
    Mullard Space Science Laboratory, Imperial College.
    Fränz, M.
    MPI für Sonnensystemforschung, Katlenberg-Lindau.
    Roussos, E.
    MPI für Sonnensystemforschung, Katlenberg-Lindau.
    Investigation of the influence of magnetic anomalies on ion distributions at Mars2006In: Space Science Reviews, ISSN 0038-6308, E-ISSN 1572-9672, Vol. 126, no 1-4, p. 355-372Article in journal (Refereed)
    Abstract [en]

    Using data from the Mars Express Ion Mass Analyzer (IMA) we investigate the distribution of ion beams of planetary origin and search for an influence from Mars crustal magnetic anomalies. We have concentrated on ion beams observed inside the induced magnetosphere boundary (magnetic pile-up boundary). Some north-south asymmetry is seen in the data, but no longitudinal structure resembling that of the crustal anomalies. Comparing the occurrence rate of ion beams with magnetic field strength at 400 km altitude below the spacecraft (using statistical Mars Global Surveyor results) shows a decrease of the occurrence rate for modest (< 40 nT) magnetic fields. Higher magnetic field regions (above 40 nT at 400 km) are sampled so seldom that the statistics are poor but the data is consistent with some ion outflow events being closely associated with the stronger anomalies. This ion flow does not significantly affect the overall distribution of ion beams around Mars.

  • 279.
    Nilsson, H.
    et al.
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Fedorov, A.
    CESR, Toulouse.
    Lundin, R.
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Carlsson, Ella
    Gunell, H.
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Barabash, Stas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Coates, A.
    MSSL, London.
    Fränz, M.
    MPI, Katlenburg-Lindau.
    A survey of heavy ion beam events observed by Mars Express and the possible influence of magnetic anomalies2006Conference paper (Other academic)
    Abstract [en]

    We extend previous studies of heavy ion beams observed in the vicinity of Mars by the Mars Express ASPERA-3 ion mass analyzer. The spatial properties, i.e. location and direction of flow are investigated. It is discussed whether any of the spatial characteristics indicate an influence of magnetic anomalies. The ion events concern heated/accelerated ions with energies above 300 eV so the gyro radii of the ions are mostly large compared to the size of magnetic anomalies. Therefore phenomena such as bending of the ion path or heating up to some threshold energy after which the ions are lost from the anomaly due to gyro radii effects are the kind of effects we are looking for.

  • 280.
    Nilsson, Hans
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Barghouthi, Imad A.
    Department of Physics, Al-Quds University, Jerusalem.
    Slapak, Rikard
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Eriksson, A.I
    Swedish Institute of Space Physics, Uppsala.
    André, M.
    Swedish Institute of Space Physics, Uppsala.
    Hot and cold ion outflow: Observations and implications for numerical models2013In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 118, no 1, p. 105-117Article in journal (Refereed)
    Abstract [en]

    Cluster observations of oxygen ion outflow and low-frequency waves at high altitude above the polar cap and cold ion outflow in the lobes are used to determine ion heating rates and low-altitude boundary conditions suitable for use in numerical models of ion outflow. Using our results, it is possible to simultaneously reproduce observations of high-energy O+ ions in the high-altitude cusp and mantle and cold H+ ions in the magnetotail lobes. To put the Cluster data in a broader context, we first compare the average observed oxygen temperatures and parallel velocities in the high-altitude polar cap with the idealized cases of auroral (cusp) and polar wind (polar cap) ion outflow obtained from a model based on other data sets. A cyclotron resonance model using average observed electric field spectral densities as input fairly well reproduces the observed velocities and perpendicular temperatures of both hot O+ and cold H+, if we allow the fraction of the observed waves, which is efficient in heating the ions to increase with altitude and decrease toward the nightside. Suitable values for this fraction are discussed based on the results of the cyclotron resonance model. Low-altitude boundary conditions, ion heating rates, and centrifugal acceleration are presented in a format suitable as input for models aiming to reproduce the observations

  • 281.
    Nilsson, Hans
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Hamrin, Maria
    Department of Physics, Umeå University.
    Pitkänen, Timo
    Department of Physics, Umeå University.
    Karlsson, Tomas
    Space and Plasma Physics, School of Electrical Engineering Royal Institute of Technology Stockholm.
    Slapak, Rikard
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Andersson, Laila O.
    Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado.
    Gunell, Herbert
    Swedish Institute of Space Physics / Institutet för rymdfysik , Belgian Institute for Space Aeronomy, Brussels.
    Schillings, Audrey
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Vaivads, Andris
    Swedish Institute of Space Physics, Uppsala.
    Oxygen ion response to proton bursty bulk flows2016In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 121, no 8, p. 7535-7546Article in journal (Refereed)
    Abstract [en]

    We have used Cluster spacecraft data from the years 2001 to 2005 to study how oxygen ions respond to bursty bulk flows (BBFs) as identified from proton data. We here define bursty bulk flows as periods of proton perpendicular velocities more than 100 km/s and a peak perpendicular velocity in the structure of more than 200 km/s, observed in a region with plasma beta above 1 in the near-Earth central tail region. We find that during proton BBFs only a minor increase in the O+ velocity is seen. The different behavior of the two ion species is further shown by statistics of H+ and O+ flow also outside BBFs: For perpendicular earthward velocities of H+ above about 100 km/s, the O+ perpendicular velocity is consistently lower, most commonly being a few tens of kilometers per second earthward. In summary, O+ ions in the plasma sheet experience less acceleration than H+ ions and are not fully frozen in to the magnetic field. Therefore, H+ and O+ motion is decoupled, and O+ ions have a slower earthward motion. This is particularly clear during BBFs. This may add further to the increased relative abundance of O+ ions in the plasma sheet during magnetic storms. The data indicate that O+ is typically less accelerated in association with plasma sheet X lines as compared to H+.

  • 282.
    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.

  • 283.
    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, article id 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 (

  • 284.
    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, article id 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.

  • 285. Noelle, A
    et al.
    Hartmann, G.K
    Fahr, A
    Larry, D
    Lee, Y.P
    Locht, R
    Limao-Vieira, P
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Orlando, J.J
    Salama, F
    Vandaele, A.C
    Wayne, R.P
    Wu, C.Y.R
    UV/Vis+ Spectra Data base2015Data set (Refereed)
  • 286. 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)
  • 287.
    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, p. 3592-3601Article 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.

  • 288.
    Nyström, Max
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    GNSS Interference Localization Through PDOA-Methods2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As GPS signals are of low power, the receiving end is always highly susceptible to interference, both unintentional and deliberate. As such there is a need to develop practical ways of detecting and localizing interference sources. This paper evaluates different methods of localization, and also demonstrates a novel method of both practical and cheap localization.

  • 289.
    Pellinen-Wannberg, Asta
    et al.
    Umeå universitet, Swedish Institute of Space Physics.
    Murad, Edmond
    AFRL.
    Broasch, Noah
    The Wise Observatory and Tel Aviv University.
    Häggström, Ingemar
    EISCAT Scientific Association, Kiruna.
    Khayrov, Timur
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Julius Maximilians Universität Würzburg.
    The solar cycle effect on the atmosphere as a scintillator for meteor observations2009Conference paper (Refereed)
    Abstract [en]

    We discuss using high solar cycle atmospheric conditions as sensors for observing meteors and their properties. High altitude meteor trails (HAMTs) have sometimes been observed with HPLA (High Power Large Aperture) radars. At other times they are not seen. In the absence of systematic studies on this topic, we surmise that the reason might be differing atmospheric conditions during the observations. At EISCAT HAMTs were observed in 1990 and 1991. Very high meteor trails were observed with Israeli L-band radars in 1998, 1999 and 2001.Through the Leonid activity, around the latest perihelion passage of comet Tempel-Tuttle, optical meteors as high as 200 km were reported. This was partly due to new and better observing methods. However, all the reported periods of high altitude meteors seem to correlate with solar cycle maximum. The enhanced atmospheric and ionospheric densities extend the meteoroid interaction range with the atmosphere along its path, offering a better possibility to distinguish differential ablation of the various meteoric constituents. This should be studied during the next solar maximum, due within a few years.

  • 290.
    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, p. 346-351, article id 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.

  • 291.
    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, p. 645-650Article 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 ...

  • 292.
    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 Maneuvers2018In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 61, no 3, p. 862-878Article 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.

  • 293.
    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.

  • 294.
    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, p. 3766-3773Article 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.

  • 295.
    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. 

  • 296.
    Rapp, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Julius-Maximilians University of Würzburg, Department of Mathematics and Computer Science, Chair of Aerospace Information Technology, Professorship of Space Technology.
    Development and Implementation of a Mission Planning Tool for SONATE2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the scope of the master's project which is documented with the present thesis a mission planning tool (MPT) for SONATE was developed and implemented. After a thorough research on the current state of the art of MPTs and taking especially the early stage of the SONATE mission into account, it was decided to develop a generic timeline-based MPT. In contrast to existing MPTs a system is envisioned which is both powerful, regarding advanced features like resource control, and applicable for small satellite missions regarding the overall complexity and the associated configuration and training effort. Although it was obvious from an early stage that this vision cannot be reached in the scope of this project, it was kept during the project definition, object oriented analysis and early design stages in order to allow future extensions. Also the decision to develop the MPT on top of the Eclipse Rich Client Platform is mainly due to the argument of future extensibility.

    The MPT, which is released with this thesis, hence is a very basic generic timeline-based MPT omitting all possible advanced features like resource control or procedure validation, but featuring all essential parts of a MPT, i.e. modelling of procedures, scheduling of activities, and the generation of telecommand sequences. Furthermore, the user is supported by an intuitive graphical user interface. The thesis documents the development process, thus giving a broad understanding of the design and the implementation. For specific details of the implementation one may also refer to the separate technical documentation, while a user handbook included as appendix.

    The characteristics of the SONATE mission as a technology demonstrator for highly autonomous systems raise several important questions regarding the overall mission planning process. Therefore, besides the actual development of the MPT, those questions are discussed in a theoretical manner in the scope of this thesis, taking also account of the general emergence of highly autonomous satellites systems.Three concepts, Safe Planning, Sigma Resource Propagation, and Direct Telemetry Feedback, are proposed to face the challenges rising from the foreseen alternation of phases of classical mission operations and phases of autonomous operations of the satellite.

    Concluding the thesis, the final software product's features and capabilities are verified against the previously defined requirements and thus the overall success of the project is determined to be a 100% success fulfilling all primary project objectives. Finally, several fields for further research on the topic in general and work on the MPT itself are identified and outlined to pave the way for follow-up projects.

  • 297.
    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.

  • 298.
    Romero, Faviola
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    In-orbit performance analysis of the image sensors from Pleiades mission2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The image sensors embedded in the instruments on board of different satellites are a key aspect in the success of a mission of any type such as Earth observation, astronomy or planetary and universe exploration. The quality of the sensor itself as well as the electronics embedded in the instrument suffer from aging, not only due to the usage, but also due to the space environment factors. The outer space harsh environment is composed of charged particles with an incredibly high energy that can get through the shielding of the spacecraft thus causing damage to the sensors, or any part of the spacecraft. After a satellite is placed in orbit, there is no other way to check on its condition than to analyse the data transmitted to the ground stations.

     

    It is well known that we can measure the evolution of the instrument’s detection unit by measuring the variation of the quality of the images taken in orbit. As it has been done in past work, the atypical behaviour can be detected at a pixel level by analysing the images taken in orbit, preferably in complete darkness to discard any parasitic light. Past analysis of the dark images from the sensors on board the Picard, SPOT4 and Sentinel2A mission, proposed a classification of the different atypical behaviour that a pixel can show, such as hot, transitory-hot or RTS. By the end of the mission this defects may even be present in several pixels.

     

    The purpose of this work is to process the dark images obtained on orbit, at the end of the mission PLEIADES, to better understand the behaviour both Panchromatic and Multispectral CCD sensors and the differences in performance with respect to the tests made previously on ground. For this, a description of the framework of the PLEIADES mission and the technical design aspects of the CCD sensors on board are presented. Subsequently, the different image processing techniques used and developed are described, along with the tests made to get to the positive conclusion of no major anomalies detected in the PLEIADES images sensors. The analysis is done by means of new set of functions adjusted to the structure of the data, as well as the same detection software used in the previous analysis. Finally, a discussion is presented along with a further perspective for the analysis of future sets of data. 

  • 299.
    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, p. 151-162Article 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.

  • 300.
    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, p. 621-637Article 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.

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