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  • 301.
    Stiller, G.P.
    et al.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Clarmann, T. von
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Höpfner, M.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Glatthor, N.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Grabowski, U.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Kellmann, S.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Kleinert, A.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Linden, A.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Milz, Mathias
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Reddmann, T.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Steck, T.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Fischer, H.
    Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung Karlsruhe.
    Funke, B.
    Instituto de Astrofísica de Andalucía CSIC, Granada.
    López-Puertas, M.
    Instituto de Astrofísica de Andalucía CSIC, Granada.
    Engel, A.
    Institut für Atmosphäre und Umwelt, J. W. Goethe Universität Frankfurt am Main, Frankfurt.
    Global distribution of mean age of stratospheric air from MIPAS SF6 measurements2008Ingår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 8, nr 3, 677-695 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 302.
    Takagi, M.
    et al.
    University of Tokyo, Deptartment of Earth & Planetary Science.
    Suzuki, K.
    Tokyo Gakugei University, Department of Astronomy & Earth Science.
    Sagawa, H.
    Max-Planck-Institut für Solar System Research.
    Baron, P.
    National Institute for Information & Communication Technology, Applied Electromagnet Research.
    Mendrok, Jana
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Kasai, Y.
    National Institute for Information & Communication Technology, Applied Electromagnet Research.
    Matsuda, Y.
    Tokyo Gakugei University, Department of Astronomy & Earth Science.
    Influence of CO2 line profiles on radiative and radiative-convective equilibrium states of the Venus lower atmosphere2010Ingår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 115, nr E06Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Influence of CO2 line profiles on vertical temperature distributions in the radiative and radiative-convective equilibria is examined in the Venus atmosphere. The CO2 opacity obtained by the Voigt (Lorentz) profile without the line cutoff is shown to be excessive since this opacity gives surface temperatures of about 860-1020 K in the radiative-convective equilibrium. On the other hand, the opacity obtained by the extremely sub-Lorentzian profiles of Pollack et al. (1993) and Tonkov et al. (1996) are underestimated; the surface temperature obtained with this opacity remains 600 K even in the radiative equilibrium. In this case, convection does not take place below the cloud layer because of the cloud opacity. It is also shown that Fukabori et al.' s (1986) and Meadows and Crisp's (1996) profiles, both of which have intermediate absorption coefficients, give temperature distributions close to the observed one in the radiative-convective equilibrium. In these cases, the convection layer extends from the surface to 30-50 km altitudes. Then, the temperature distribution below the cloud layer is determined by a dry adiabatic lapse rate and the temperature near the cloud bottom. The surface temperature in the radiative-convective equilibrium is strongly affected by the temperature near the cloud bottom in this situation. The detailed structure of the H2SO4 cloud must be taken into account to construct a realistic radiative transfer model.

  • 303.
    Tariq, Usama
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Robotic Grasping of Large Objects for Collaborative Manipulation2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In near future, robots are envisioned to work alongside humans in professional anddomestic environments without significant restructuring of workspace. Roboticsystems in such setups must be adept at observation, analysis and rational de-cision making. To coexist in an environment, humans and robots will need tointeract and cooperate for multiple tasks. A fundamental such task is the manip-ulation of large objects in work environments which requires cooperation betweenmultiple manipulating agents for load sharing. Collaborative manipulation hasbeen studied in the literature with the focus on multi-agent planning and controlstrategies. However, for a collaborative manipulation task, grasp planning alsoplays a pivotal role in cooperation and task completion.In this work, a novel approach is proposed for collaborative grasping and manipu-lation of large unknown objects. The manipulation task was defined as a sequenceof poses and expected external wrench acting on the target object. In a two-agentmanipulation task, the proposed approach selects a grasp for the second agentafter observing the grasp location of the first agent. The solution is computed ina way that it minimizes the grasp wrenches by load sharing between both agents.To verify the proposed methodology, an online system for human-robot manipu-lation of unknown objects was developed. The system utilized depth informationfrom a fixed Kinect sensor for perception and decision making for a human-robotcollaborative lift-up. Experiments with multiple objects substantiated that theproposed method results in an optimal load sharing despite limited informationand partial observability.

  • 304.
    Tate, C.G.
    et al.
    Department of Physics & Astronomy, University of Tennessee, Knoxville.
    Moersch, J.
    Department of Physics & Astronomy, University of Tennessee, Knoxville, Department of Earth & Planetary Sciences, University of Tennessee, Knoxville.
    Jun, L.
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Hardgrove, C.
    Department of Earth & Planetary Sciences, University of Tennessee, Knoxville.
    Mischna, M.
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Litvak, M.
    Space Research Institute, RAS, Moscow.
    Varenikov, A.
    Space Research Institute, RAS, Moscow.
    Mitrofanov, I.
    Space Research Institute, RAS, Moscow.
    Boynton, W.V.
    University of Arizona.
    Deflores, L.
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Drake, D.
    TechSource, Inc, Los Alamos.
    Fedosov, F.
    Space Research Institute, RAS, Moscow.
    Golovin, D.
    Space Research Institute, RAS, Moscow.
    Harschman, K.
    University of Arizona.
    Kozyrev, A.
    Space Research Institute, RAS, Moscow.
    Lisov, D.
    Space Research Institute, RAS, Moscow.
    Malakhov, A.
    Space Research Institute, RAS, Moscow.
    Milliken, R.E.
    Brown university.
    Mokrousov, M.
    Space Research Institute, RAS, Moscow.
    Nikiforov, S.
    Space Research Institute, RAS, Moscow.
    Sanin, A.B.
    Space Research Institute, RAS, Moscow.
    Starr, R.
    NASA Goddard Space Flight Center.
    Vostrukhin, A.
    Space Research Institute, RAS, Moscow.
    Martin-Torres, Javier
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik. Instituto Andaluz de Cienccias de la Tierra (CSIC-UGR), Grenada.
    Zorzano, María-Paz
    Centro de Astrobiologia, INTA-CSIC, Madrid.
    Thermal conductivity of the near-surface Martian regolith derived from variations in MSL passive neutron counts and ground temperature measurements2015Konferensbidrag (Refereegranskat)
  • 305.
    Thapliyal, Pradeep K.
    et al.
    Atmospheric and Oceanic Sciences Group, Space Applications Centre, Indian Space Research Organisation, Ahmedabad.
    Shukla, Munn V.
    Atmospheric and Oceanic Sciences Group, Space Applications Centre, Indian Space Research Organisation, Ahmedabad.
    Shah, Shivani
    Atmospheric and Oceanic Sciences Group, Space Applications Centre, Indian Space Research Organisation, Ahmedabad.
    Joshi, P.C.
    Atmospheric and Oceanic Sciences Group, Space Applications Centre, Indian Space Research Organisation, Ahmedabad.
    Pal, P.K.
    Atmospheric and Oceanic Sciences Group, Space Applications Centre, Indian Space Research Organisation, Ahmedabad.
    Kottayil, Ajil
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    An algorithm for the estimation of upper tropospheric humidity from Kalpana observations: Methodology and validation2011Ingår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 116, nr 1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study presents a methodology for estimating the upper tropospheric humidity (UTH) for a layer between 500 and 200 hPa from observations in the water vapor channel (5.6–7.2 μm) of the Indian geostationary satellite, Kalpana. Radiative transfer simulations for different UTH conditions have been used to develop the relationship between water vapor channel radiances and UTH. A new technique has been described to include the normalized reference pressure in the algorithm, to account for latitudinal variation of temperature that is derived from a diverse radiosonde profiles data set and is a polynomial function of the latitude for different months. This has an advantage that the forecast or analysis profiles from the operational numerical weather prediction model are not required to compute the normalized reference pressure. The operationally retrieved UTH products have been extensively compared and validated for the period of 1 March to 1 May 2009, using Meteosat-7 UTH products over the Indian Ocean and the UTH computed from the radiosonde profiles. The results suggest that UTH estimates from Kalpana match very well with the Meteosat-7 UTH products having RMS difference of ∼6%. Validation with the UTH computed from the radiosonde observed relative humidity shows that the RMS error of Kalpana UTH is 9.6% and the mean bias is −3.0%. Similar validation of Meteosat-7 UTH with the same set of radiosonde derived UTH shows an RMS error of 13.3% and the bias of −6.5%, which is higher in comparison to the Kalpana UTH.

  • 306.
    Tiainen, Arttu
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Inter-Satellite Link Antennas: Review and The Near Future2017Självständigt arbete på avancerad nivå (masterexamen), 80 poäng / 120 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The emerging trend in distributed spacecraft systems of using multiple spacecraft which share functions as opposed to independent spacecraft has given opportunities for missions previously infeasible. Inter-satellite link (ISL) communications provide a direct link within the space segment without need of an intermediate ground segment to relay the data. As the distributed spacecraft systems (DSS) have become less exotic and more complex, the need and demand for inter-satellite antenna systems has increased and the requirements for the antenna systems more diverse and become more demanding. This document is a research of the antennas currently used for ISL, already flown or will be launched in the near future. While the emphasis is strongly in the antennas, the other parts of the ISL communications sub-systems are observed. To limit the scope of the work, optical cross links are not observed in this document. ISL used only for very close proximity, such as several kilometres, are given only limited scope as the main challenges on those do not involve antennas. Furthermore, the major emphasis is given to systems which can be seen as commercially important. This document is divided in five main sections and the conclusions. In the first section the features and the challenges of ISLs are described. In the second section a parametrisation system for antennas is defined and this system is used in following sections to describe the ISL sub-systems and antenna used in them. The third part is a survey of recently flown space missions with ISLs. The fourth section is a survey on the missions which are scheduled to fly in near future and a brief survey of the solutions offered by satellite service providers and manufacturers. Due to the limited technical data available, the fourth section contains far more reverse engineering and assumptions than the survey on legacy missions. The fifth section describes the several families of ISL suitable antennas under development and discusses about several topics which relate to the ISL antenna development. In this part also are defined several example antenna specifications and the applications of those. The study concludes that antennas suitable for inter-satellite links are not inherently different from ground segment communication antennas of the S/C. The major difference is the need for greater coverage, which can be attained by multiple antenna elements, beam steering or antenna pointing. Specific considerations are needed to be taken into account and often the use of ISLs will increase the technical challenges, but it can provide solutions for problems which cannot be solved otherwise.

  • 307.
    Tinetti, Giovanna
    et al.
    Department of Physics & Astronomy, University College London.
    Drossart, Pierre
    Observatoire de Paris.
    Eccleston, Paul
    STFC Rutherford Appleton Laboratory.
    Hartogh, Paul
    Max-Planck-Institut für Sonnensystemforschung.
    Isaak, Kate
    European Space Agency-ESTEC.
    Linder, Martin
    European Space Agency-ESTEC.
    Lovis, Christophe
    Geneva Observatory.
    Micela, Giusi
    INAF: Osservatorio Astronomico di Palermo G.S. Vaiana.
    Ollivier, Marc
    Observatoire de Paris, Institut d’Astrophysique Spatiale.
    Puig, Ludovic
    European Space Agency-ESTEC.
    Ribas, Ignasi
    Institut d’Estudis Espacials de Catalunya (ICE-CSIC).
    Snellen, Ignas
    Leiden University.
    Swinyard, Bruce
    Department of Physics & Astronomy, University College London, STFC Rutherford Appleton Laboratory.
    Allard, France
    Ecole Normale Superieure de Lyon.
    Barstow, Joanna
    Oxford University.
    Cho, James
    Queen Mary University of London.
    Coustenis, Athena
    Observatoire de Paris.
    Cockell, Charles
    Royal Observatory.
    Correia, Alexandre
    Aveiro University.
    Decin, Leen
    University of Leuven.
    Kok, Remco de
    SRON Netherlands Institute for Space Research.
    Deroo, Pieter
    California Institute of Technology, Jet Propulsion Laboratory.
    Encrenaz, Therese
    Observatoire de Paris.
    Forget, Francois
    Campus Jussieu.
    Glasse, Alistair
    Martin-Torres, Javier
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Yurchenko, S. N.
    Department of Physics & Astronomy, University College London.
    The EChO science case2015Ingår i: Experimental astronomy (Print), ISSN 0922-6435, E-ISSN 1572-9508, Vol. 40, nr 2-3, 329-391 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The discovery of almost two thousand exoplanets has revealed an unexpectedly diverse planet population. We see gas giants in few-day orbits, whole multi-planet systems within the orbit of Mercury, and new populations of planets with masses between that of the Earth and Neptune—all unknown in the Solar System. Observations to date have shown that our Solar System is certainly not representative of the general population of planets in our Milky Way. The key science questions that urgently need addressing are therefore: What are exoplanets made of? Why are planets as they are? How do planetary systems work and what causes the exceptional diversity observed as compared to the Solar System? The EChO (Exoplanet Characterisation Observatory) space mission was conceived to take up the challenge to explain this diversity in terms of formation, evolution, internal structure and planet and atmospheric composition. This requires in-depth spectroscopic knowledge of the atmospheres of a large and well-defined planet sample for which precise physical, chemical and dynamical information can be obtained. In order to fulfil this ambitious scientific program, EChO was designed as a dedicated survey mission for transit and eclipse spectroscopy capable of observing a large, diverse and well-defined planet sample within its 4-year mission lifetime. The transit and eclipse spectroscopy method, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allows us to measure atmospheric signals from the planet at levels of at least 10−4 relative to the star. This can only be achieved in conjunction with a carefully designed stable payload and satellite platform. It is also necessary to provide broad instantaneous wavelength coverage to detect as many molecular species as possible, to probe the thermal structure of the planetary atmospheres and to correct for the contaminating effects of the stellar photosphere. This requires wavelength coverage of at least 0.55 to 11 μm with a goal of covering from 0.4 to 16 μm. Only modest spectral resolving power is needed, with R ~ 300 for wavelengths less than 5 μm and R ~ 30 for wavelengths greater than this. The transit spectroscopy technique means that no spatial resolution is required. A telescope collecting area of about 1 m2 is sufficiently large to achieve the necessary spectro-photometric precision: for the Phase A study a 1.13 m2 telescope, diffraction limited at 3 μm has been adopted. Placing the satellite at L2 provides a cold and stable thermal environment as well as a large field of regard to allow efficient time-critical observation of targets randomly distributed over the sky. EChO has been conceived to achieve a single goal: exoplanet spectroscopy. The spectral coverage and signal-to-noise to be achieved by EChO, thanks to its high stability and dedicated design, would be a game changer by allowing atmospheric composition to be measured with unparalleled exactness: at least a factor 10 more precise and a factor 10 to 1000 more accurate than current observations. This would enable the detection of molecular abundances three orders of magnitude lower than currently possible and a fourfold increase from the handful of molecules detected to date. Combining these data with estimates of planetary bulk compositions from accurate measurements of their radii and masses would allow degeneracies associated with planetary interior modelling to be broken, giving unique insight into the interior structure and elemental abundances of these alien worlds. EChO would allow scientists to study exoplanets both as a population and as individuals. The mission can target super-Earths, Neptune-like, and Jupiter-like planets, in the very hot to temperate zones (planet temperatures of 300–3000 K) of F to M-type host stars. The EChO core science would be delivered by a three-tier survey. The EChO Chemical Census: This is a broad survey of a few-hundred exoplanets, which allows us to explore the spectroscopic and chemical diversity of the exoplanet population as a whole. The EChO Origin: This is a deep survey of a subsample of tens of exoplanets for which significantly higher signal to noise and spectral resolution spectra can be obtained to explain the origin of the exoplanet diversity (such as formation mechanisms, chemical processes, atmospheric escape). The EChO Rosetta Stones: This is an ultra-high accuracy survey targeting a subsample of select exoplanets. These will be the bright “benchmark” cases for which a large number of measurements would be taken to explore temporal variations, and to obtain two and three dimensional spatial information on the atmospheric conditions through eclipse-mapping techniques. If EChO were launched today, the exoplanets currently observed are sufficient to provide a large and diverse sample. The Chemical Census survey would consist of > 160 exoplanets with a range of planetary sizes, temperatures, orbital parameters and stellar host properties. Additionally, over the next 10 years, several new ground- and space-based transit photometric surveys and missions will come on-line (e.g. NGTS, CHEOPS, TESS, PLATO), which will specifically focus on finding bright, nearby systems. The current rapid rate of discovery would allow the target list to be further optimised in the years prior to EChO’s launch and enable the atmospheric characterisation of hundreds of planets.

  • 308.
    Ullán, Aurora
    et al.
    Departamento de Teoría de la Señal y Comunicaciones, Escuela Politécnica Superior , Universidad de Alcalá, Madrid.
    Zorzano Mier, Maria-Paz
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Martin-Torres, Javier
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Valentin-Serrano, Patricia
    nstituto Andaluz de Ciencias de la Tierra (CSIC - UGR), Granada.
    Kahanpää, Henrik
    Finnish Meteorological Institute, Helsinki.
    Harri, Ari-Matti
    Finnish Meteorological Institute, Helsinki.
    Gómez-Elvira, Javier
    Centro de Astrobiologí a (CSIC-INTA), Torrejón de Ardoz, Madrid.
    Navarro, Sara
    Centro de Astrobiología (CSIC - INTA), Torrejón de Ardoz, Madrid.
    Analysis of wind-induced dynamic pressure fluctuations during one and a half Martian years at Gale Crater2017Ingår i: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 288, 78-87 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Rover Environmental Monitoring Station (REMS) instrument on-board the Mars Science Laboratory (MSL) has acquired unprecedented measurements of key environmental variables at the base of Gale Crater. The pressure measured by REMS shows modulations with a very structured pattern of short-time scale (of the order of seconds to several minutes) mild fluctuations (typically up to 0.2 Pa at daytime and 1 Pa at night-time). These dynamic pressure oscillations are consistent with wind, air and ground temperature modulations measured simultaneously by REMS. We detect the signals of a repetitive pattern of upslope/downslope winds, with maximal speeds of about 21 m/s, associated with thermal changes in the air and surface temperatures, that are initiated after sunset and finish with sunrise proving that Gale, a 4.5 km deep impact crater, is an active Aeolian environment. At nighttime topographic slope winds are intense with maximal activity from 17:00 through 23:00 Local Mean Solar Time, and simultaneous changes of surface temperature are detected. During the day, the wind modulations are related to convection of the planetary boundary layer, winds are softer with maximum wind speed of about 14 m/s. The ground temperature is modulated by the forced convection of winds, with amplitudes between 0.2 K and 0.5 K, and the air temperatures fluctuate with amplitudes of about 2 K. The analysis of more than one and a half Martian years indicates the year-to-year repeatability of these environmental phenomena. The wind pattern minimizes at the beginning of the south hemisphere winter (Ls 90) season and maximizes during late spring and early summer (Ls 270). The procedure that we present here is a useful tool to investigate in a semi-quantitative way the winds by: i) filling both seasonal and diurnal gaps where wind measurements do not exist, ii) providing an alternative way for comparisons through different measuring principia and, iii) filling the gap of observation of short time-wind variability, where the REMS wind-sensor is blind

  • 309.
    Vakkada Ramachandran, Abhilash
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Design and Testing of Thermal Chambers for Space Qualification and Planetary Protection2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 310.
    Villlalba Corbacho, Víctor Manuel
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik. Cranfield University.
    Vibro-acoustic monitoring for in-flight spacecraft2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The concept of using the vibration transmitted through the structure of space systems whilst they are in flight for monitoring purposes is proposed and analysed.The performed patent review seems to indicate that this technique is not currently used despite being, in principle, a good way to obtain valuable knowledge about the spacecraft’s condition. Potential sources of vibration were listed and some of them were down-selected via a trade-off analysis for implementation in a numerical model of a CubeSat structure. Models were proposed for the sources chosen and implemented in the Ansys Workbench software, along with a simplified structure designed to be representative of a generic picosatellite mission.The results confirmed very different amplitude and frequency ranges for the sources of interest, which would make it difficult to monitor them with one type of sensor.Basic system requirements for accelerometer operating under space conditions were derived and commercial sources were identified as already having the technologies needed.The conclusion was a positive evaluation of the overall concept, although revising negatively the initial expectations for its performance due to the diversity encountered in the sources.

  • 311.
    Walden, Aleksi
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    SMOS satellite hardware anomaly prediction methods based on Earth radiation environment data sets2016Självständigt arbete på avancerad nivå (masterexamen), 80 poäng / 120 hpStudentuppsats (Examensarbete)
    Abstract [en]

    SMOS (Soil Moisture and Ocean Salinity) is ESA's Earth Explorer series satellite carrying the novel MIRAS (Microwave Imaging Radiometer with Aperture Synthesis) interferometric synthetic aperture radar. Its objective is monitoring and studying the planet's water cycle by following the changes in soil moisture levels and ocean surface salt concentrations on a global scale. The success of the mission calls for nearly uninterrupted operation of the science payload. However, the instrument experiences sporadically problems with its hardware, which cause losses of scientific data and may require intervention from ground to resolve. The geographical areas in which most of these anomalies occur, polar regions and the South-Atlantic anomaly, give cause to assume these problems are caused by charged particles in the planet's ionosphere. In this thesis, methods of predicting occurrence of hardware anomalies from indicators of Earth radiation environment are investigated.

  • 312.
    Webster, Christopher R.
    et al.
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Mahaffy, Paul R.
    NASA Goddard Space Flight Center.
    Atreya, Sushil K.
    University of Michigan, Ann Arbor.
    Flesch, Gregory J.
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Mischna, Michael A.
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Meslin, Pierre-Yves
    Institut de Recherche en Astrophysique et Planetologie, Toulouse.
    Farley, Kenneth A.
    California Institute of Technology, Pasadena.
    Conrad, Pamela G.
    NASA Goddard Space Flight Center.
    Christensen, Lance E.
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Pavlov, Alexander A.
    NASA Goddard Space Flight Center.
    Martin-Torres, Javier
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Zorzano, María-Paz
    Centro de Astrobiologia, INTA-CSIC, Madrid.
    McConnochie, Timothy H.
    Department of Astronomy, University of Maryland, College Park.
    Owen, Tobias
    University of Hawaii, Honolulu.
    Eigenbrode, Jennifer L.
    NASA Goddard Space Flight Center.
    Glavin, Daniel P.
    NASA Goddard Space Flight Center.
    Steele, Andrew
    Carnegie Institution of Washington, Washington, DC..
    Malespin, Charles A.
    NASA Goddard Space Flight Center.
    Jr., P. Douglas Archer
    Jacobs Technology, NASA Johnson Space Center.
    Sutter, Brad
    Jacobs Technology, NASA Johnson Space Center.
    Coll, Patrice
    Laboratoire Inter-Universitaires des Systèmes Atmosphériques, Paris.
    Freissinet, Caroline
    NASA Goddard Space Flight Center.
    McKay, Christopher P.
    NASA Ames Research Center, Division of Space Sciences and Astrobiology, Mail Stop 245-3, Moffett Field, CA , NASA Ames Research Center.
    Moores, John E.
    York University, Toronto.
    Schwenzer, Susanne P.
    Open University, Milton Keynes.
    Lemmon, Mark T.
    Texas A&M University, College Station.
    Mars methane detection and variability at Gale crater2015Ingår i: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 347, nr 6220, 415-417 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Reports of plumes or patches of methane in the Martian atmosphere that vary over monthly timescales have defied explanation to date. From in situ measurements made over a 20-month period by the Tunable Laser Spectrometer (TLS) of the Sample Analysis at Mars (SAM) instrument suite on Curiosity at Gale Crater, we report detection of background levels of atmospheric methane of mean value 0.69 ± 0.25 ppbv at the 95% confidence interval (CI). This abundance is lower than model estimates of ultraviolet (UV) degradation of accreted interplanetary dust particles (IDP’s) or carbonaceous chondrite material. Additionally, in four sequential measurements spanning a 60-sol period, we observed elevated levels of methane of 7.2 ± 2.1 (95% CI) ppbv implying that Mars is episodically producing methane from an additional unknown source.

  • 313.
    Wedlund, Cyril Simon
    et al.
    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.
    Alho, Markku
    Aalto University, School of Electrical Engineering, Department of Radio Science and Engineering.
    Nilsson, Hans
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Wieser, Gabriella Stenberg
    Swedish Institute of Space Physics.
    Gunell, Herbert
    Swedish Institute of Space Physics / Institutet för rymdfysik , Belgian Institute for Space Aeronomy, Brussels.
    Behar, Etienne
    Luleå tekniska universitet, Institutionen för system- och rymdteknik.
    Pusa, J.
    Aalto University, School of Electrical Engineering, Department of Radio Science and Engineering.
    Gronoff, Guillaume
    Science Directorate, Chemistry and Dynamics Branch, NASA Langley Research Center, Hampton, Virginia.
    The atmosphere of comet 67P/Churyumov-Gerasimenko diagnosed by charge-exchanged solar wind alpha particles2016Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 587, A154Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Context. The ESA/Rosetta mission has been orbiting comet 67P/Churyumov-Gerasimenko since August 2014, measuring its dayside plasma environment. The ion spectrometer onboard Rosetta has detected two ion populations, one energetic with a solar wind origin (H+, He2+, He+), the other at lower energies with a cometary origin (water group ions such as H2O+). He+ ions arise mainly from charge-exchange between solar wind alpha particles and cometary neutrals such as H2O. Aims. The He+ and He2+ ion fluxes measured by the Rosetta Plasma Consortium Ion Composition Analyser (RPC-ICA) give insight into the composition of the dayside neutral coma, into the importance of charge-exchange processes between the solar wind and cometary neutrals, and into the way these evolve when the comet draws closer to the Sun. Methods. We combine observations by the ion spectrometer RPC-ICA onboard Rosetta with calculations from an analytical model based on a collisionless neutral Haser atmosphere and nearly undisturbed solar wind conditions. Results. Equivalent neutral outgassing rates Q can be derived using the observed RPC-ICA He+/He2+ particle flux ratios as input into the analytical model in inverse mode. A revised dependence of Q on heliocentric distance Rh in AU is found to be Rh -7.06Rh-7.06 between 1.8 and 3.3 AU, suggesting that the activity in 2015 differed from that of the 2008 perihelion passage. Conversely, using an outgassing rate determined from optical remote sensing measurements from Earth, the forward analytical model results are in relatively good agreement with the measured RPC-ICA flux ratios. Modelled ratios in a 2D spherically-symmetric plane are also presented, showing that charge exchange is most efficient with solar wind protons. Detailed cometocentric profiles of these ratios are also presented. Conclusions. In conclusion, we show that, with the help of a simple analytical model of charge-exchange processes, a mass-capable ion spectrometer such as RPC-ICA can be used as a "remote-sensing" instrument for the neutral cometary atmosphere.

  • 314.
    Weighton, David
    et al.
    Luleå tekniska universitet.
    Pellinen-Wannberg, Asta
    Umeå universitet.
    Barabash, Victoria
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Molin, Sven
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    The development of masters programs in space science and technology in northern Scandinavia2008Ingår i: Proceedings of the 59th International Astronautical Congress: Glascow, Scotland, 29 Sept - 3 Oct 2008, 2008Konferensbidrag (Övrigt vetenskapligt)
  • 315.
    Wetzel, G.
    et al.
    Karlsruhe Institute of Technology.
    Oelhaf, H.
    Karlsruhe Institute of Technology.
    Berthet, G.
    CNRS.
    Bracher, A.
    Universität Bremen.
    Cornacchia, C.
    CNR, IMAA.
    Feist, D.G.
    Max-Planck-Institut.
    Fischer, H.
    Karlsruhe Institute of Technology.
    Fix, A.
    Iarlori, M.
    Università Degli Studi dell'Aquila.
    Kleinert, A.
    Karlsruhe Institute of Technology.
    Lengel, A.
    Karlsruhe Institute of Technology.
    Milz, Mathias
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Mona, L.
    CNR, IMAA.
    Muller, S.C.
    University of Bern.
    Ovarlez, J.
    CNRS.
    Pappalardo, G.
    CNR, IMAA.
    Piccolo, C.
    CNR.
    Paspollini, P.
    CNR.
    Renard, J-P
    CNRS.
    Rizi, V.
    Università Degli Studi dell'Aquila.
    Rohs, S.
    Schiller, C.
    Stiller, G.
    Karlsruhe Institute of Technology.
    Weber, M.
    Universität Bremen.
    Zhang, G.
    Karlsruhe Institute of Technology.
    Validation of MIPAS-ENVISAT H2O operational data collected between July 2002 and March 20042013Ingår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 13, nr 11, 5791-5811 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Water vapour (H2O) is one of the operationally retrieved key species of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument aboard the Environmental Satellite (ENVISAT) which was launched into its sun-synchronous orbit on 1 March 2002 and operated until April 2012. Within the MIPAS validation activities, independent observations from balloons, aircraft, satellites, and ground-based stations have been compared to European Space Agency (ESA) version 4.61 operational H2O data comprising the time period from July 2002 until March 2004 where MIPAS measured with full spectral resolution. No significant bias in the MIPAS H2O data is seen in the lower stratosphere (above the hygropause) between about 15 and 30 km. Differences of H2O quantities observed by MIPAS and the validation instruments are mostly well within the combined total errors in this altitude region. In the upper stratosphere (above about 30 km), a tendency towards a small positive bias (up to about 10 %) is present in the MIPAS data when compared to its balloon-borne counterpart MIPAS-B, to the satellite instruments HALOE (Halogen Occultation Experiment) and ACE-FTS (Atmospheric Chemistry Experiment, Fourier Transform Spectrometer), and to the millimeter-wave airborne sensor AMSOS (Airborne Microwave Stratospheric Observing System). In the mesosphere the situation is unclear due to the occurrence of different biases when comparing HALOE and ACE-FTS data. Pronounced deviations between MIPAS and the correlative instruments occur in the lowermost stratosphere and upper troposphere, a region where retrievals of H2O are most challenging. Altogether it can be concluded that MIPAS H2O profiles yield valuable information on the vertical distribution of H2O in the stratosphere with an overall accuracy of about 10 to 30% and a precision of typically 5 to 15% - well within the predicted error budget, showing that these global and continuous data are very valuable for scientific studies. However, in the region around the tropopause retrieved MIPAS H2O profiles are less reliable, suffering from a number of obstacles such as retrieval boundary and cloud effects, sharp vertical discontinuities, and frequent horizontal gradients in both temperature and H2O volume mixing ratio (VMR). Some profiles are characterized by retrieval instabilities.

  • 316.
    Wickramanayake, Anura
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Ekman, Jonas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Buehler, Stefan
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Hobbs, Stephen
    School of Engineering, Cranfield University, Cranfield, Bedford.
    Mine induced deformation measurements using SAR interferometry at high latitudes2012Konferensbidrag (Refereegranskat)
  • 317.
    Wickramanayake, Anura
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Hanshel, Michael
    MDA.
    Hobbs, Stephen
    Cranfield University.
    Buehler, Stefan
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Ekman, Jonas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Lehrbass, Brad
    MDA Geospatial Services.
    Seasonal Variation of Coherence in SAR Interferograms in Kiruna, Northern Sweden2016Ingår i: International Journal of Remote Sensing, ISSN 0143-1161, E-ISSN 1366-5901, Vol. 37, nr 2, 370-387 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article presents the results of a study conducted to quantify the seasonal variation of coherence in synthetic aperture radar (SAR) interferograms in Kiruna, Northern Sweden. In SAR interferometry (InSAR), coherence is an important concept that provides a good indication of the phase stability of the scatterers. Therefore, in this study, the degree of coherence is used as a parameter to identify the seasonal variation interferograms. For this study, 34 Radarsat-2 ultra-fine beam mode (U6D) images of the Kiruna area (67°51ʹN, 20°14ʹE) and the improved digital elevation model (DEM) created by merging the Radarsat-2 DEM and ASTER DEM were used to produce 561 differential interferograms. The interferograms were arranged in three different ways for the analysis, with the first including common master interferograms (with the summer master image), the second including the sequential interferograms that have the shortest temporal baseline, and the third accounting for all possible combinations of the interferograms (full network of interferograms). Following this step, the variation of coherence for forest areas, urban areas, and flat waste rock areas was studied. This study shows that interferograms generated for the Kiruna region exhibit seasonal variations in coherence due to the ground snow layer in winter. Furthermore, when there is water on the ground due to the melting of the snow layer (in the spring) or due to rains in autumn, the coherence is reduced considerably. Another significant feature is that there is a significant change in summer-to-summer coherence for some regions even over the course of a few years. Based on this study, it is clear that the winter Radarsat-2 U6D beam mode images are not suitable for differential interferometric SAR (DInSAR) deformation measurements in flat waste rock regions in Kiruna. It is expected that even with winter images, PSInSAR or CTM techniques will be able to provide better deformation measurements, but, in this study, those techniques were not assessed. The next step will be to study the seasonal variations in coherence in natural or man-made targets/persistent scatterers using persistent scatter InSAR (PSInSAR) or coherence target monitoring (CTM) techniques

  • 318.
    Wiens, R.C.
    et al.
    Los Alamos National Laboratory, Space Remote Sensing, Los Alamos National Laboratory, Los Alamos, International Space and Response Division, Los Alamos National Laboratory.
    Maurice, Sylvestre
    Institut de Recherche en Astrophysique et Planetologie, Toulouse.
    Martin-Torres, Javier
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    ChemCam: Chemostratigraphy by the First Mars Microprobe2015Ingår i: Elements, ISSN 1811-5209, E-ISSN 1811-5217, Vol. 11, nr 1, 33-38 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The ChemCam laser-induced breakdown spectrometer on the rover Curiosity has provided more than 200,000 spectra from over 5000 different locations on Mars. This instrument is the first chemical microprobe on Mars and has an analytical footprint 0.3–0.6 mm in diameter. ChemCam has observed a measure of hydration in all the sedimentary materials encountered along the rover traverse in Gale Crater, indicating the ubiquity of phyllosilicates as a constituent of the analyzed sandstones, mudstones, and conglomerates. Diagenetic features, including calcium sulfate veins, millimeter-thick magnesium-rich diagenetic ridges, and manganese-rich rock surfaces, provide clues to water–rock interactions. Float clasts of coarse-grained igneous rocks are rich in alkali feldspars and some are enriched in fluorine, indicating greater magmatic evolution than expected on Mars. The identification of individual soil components has contributed to our understanding of the evolution of Martian soil. These observations have broadened our understanding of Mars as an active and once habitable planet.

  • 319.
    Xavier, Prince K.
    et al.
    Met Office Hadley Centre, Exeter.
    John, Viju O.
    Met Office Hadley Centre, Exeter.
    Buehler, Stefan
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Ajayamohan, R.S.
    Canadian Centre for Climate Modelling and Analysis, University of Victoria.
    Sijikumar, S.
    Space Physics Laboratory, Trivandrum.
    Variability of Indian summer monsoon in a new upper tropospheric humidity data set2010Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 37, nr 5, L05705- s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Using a new data set we demonstrate the variability of upper troposphere humidity (UTH) associated with the Indian Summer Monsoon (ISM). The main advantage of the new data set is its all-sky representation which is essential to capture the full variability of humidity even in cloudy areas. We show that UTH undergoes significant variations during the active/break phases of the monsoon and discuss the mechanisms. The interannual variations of monsoon are also well reflected in the UTH. A preliminary investigation into the cause of the 2009 monsoon failure reveals anomalous subsidence and suppressed convection over the monsoon region due to anomalous warm conditions in the equatorial Pacific throughout the summer. The large scale drying of the upper troposphere may also have contributed to a negative feedback in suppressing convection. Citation: Xavier, P. K., V. O. John, S. A. Buehler, R. S. Ajayamohan, and S. Sijikumar (2010), Variability of Indian summer monsoon in a new upper tropospheric humidity data set

  • 320.
    Zamouril, Jakub
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Flight Software Development for Demise Observation Capsule2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This work describes the process of the design of a flight software for a space-qualified device, outlines the development and testing of the SW, and provides a description of the final product. The flight software described in this work has been developed for the project Demise Observation Capsule (DOC). DOC is a device planned to be attached to an upper stage of a launch vehicle and observe its demise during atmospheric re-entry at the end of its mission. Due to constraint on communication time during the mission and the need to maximize the amount of transferred data, a custom communication protocol has been developed.

  • 321.
    Zhou, X-Z
    et al.
    Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles.
    Angelopoulos, V.
    Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles.
    Poppe, A.R.
    Space Science Laboratory, University of California, Berkeley.
    Halekas, J.S.
    Space Science Laboratory, University of California, Berkeley.
    Khurana, K.K.
    Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles.
    Kivelson, M.G.
    Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles.
    Fatemi, Shahab
    Luleå tekniska universitet, Institutionen för system- och rymdteknik.
    Holmström, Mats
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Lunar dayside current in the terrestrial lobe: ARTEMIS observations2014Ingår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 119, nr 5, 3381-3391 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report Acceleration, Reconnection, Turbulence and Electrodynamics of Moon's Interaction with the Sun (ARTEMIS) dual-probe observations of two events in the terrestrial magnetotail lobe, both characterized by upward moving heavy ions of lunar origin at one of the probes that is magnetically connected with the dayside lunar surface. By treating magnetic measurements at the other probe as the unperturbed lobe fields, we obtain background-subtracted magnetic perturbations (most significantly in Bz) when the first probe moved in the dawn-dusk direction across flux tubes magnetically connected to the Moon. These magnetic perturbations indicate the presence of field-aligned current above the lunar surface. By examining possible carriers of field-aligned current, we find that lunar heavy ions and accompanying electrons both contribute considerably to the current. Observations of the field-aligned current also suggest that the charging process at the dayside lunar surface and the associated lobe plasma environment, which have traditionally been viewed as a one-dimensional current balance problem, are actually more complicated. These observations give the first insights into how heavy ions affect the lunar dayside environment in terms of multispecies plasma dynamics.

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