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Träfflista för sökning "WFRF:(Horanyi M.) "

Sökning: WFRF:(Horanyi M.)

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1.
  • Grun, E., et al. (författare)
  • The 2016 Feb 19 outburst of comet 67P/CG : an ESA Rosetta multi-instrument study
  • 2016
  • Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 462, s. S220-S234
  • Tidskriftsartikel (refereegranskat)abstract
    • On 2016 Feb 19, nine Rosetta instruments serendipitously observed an outburst of gas and dust from the nucleus of comet 67P/Churyumov-Gerasimenko. Among these instruments were cameras and spectrometers ranging from UV over visible to microwave wavelengths, in situ gas, dust and plasma instruments, and one dust collector. At 09: 40 a dust cloud developed at the edge of an image in the shadowed region of the nucleus. Over the next two hours the instruments recorded a signature of the outburst that significantly exceeded the background. The enhancement ranged from 50 per cent of the neutral gas density at Rosetta to factors > 100 of the brightness of the coma near the nucleus. Dust related phenomena (dust counts or brightness due to illuminated dust) showed the strongest enhancements (factors > 10). However, even the electron density at Rosetta increased by a factor 3 and consequently the spacecraft potential changed from similar to-16 V to -20 V during the outburst. A clear sequence of events was observed at the distance of Rosetta ( 34 km from the nucleus): within 15 min the Star Tracker camera detected fast particles (similar to 25 m s(-1)) while 100 mu m radius particles were detected by the GIADA dust instrument similar to 1 h later at a speed of 6 m s(-1). The slowest were individual mm to cm sized grains observed by the OSIRIS cameras. Although the outburst originated just outside the FOV of the instruments, the source region and the magnitude of the outburst could be determined.
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2.
  • Gruen, E., et al. (författare)
  • Ulysses Dust Detection System V3.1
  • 2010
  • Ingår i: NASA Planetary Data System. ; 140
  • Tidskriftsartikel (refereegranskat)abstract
    • This data set contains the data from the Ulysses dust detector system (UDDS) from start of mission through the end of mission, 1990-2007. (As the dust detector was turned off after Nov. 30, 2007, this is the last date for which UDDS data is recorded.) Included are the dust impact data, noise data, laboratory calibration data, and location and orientation of the spacecraft and instrument.
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3.
  • Krüger, H., et al. (författare)
  • Three years of Ulysses dust data: 1993-1995
  • 1999
  • Ingår i: Planetary and Space Science. - 1873-5088. ; 47:3-4, s. 363-383
  • Tidskriftsartikel (refereegranskat)abstract
    • The Ulysses spacecraft is orbiting the Sun on a highly inclined ellipse (i = 79°). After its Jupiter flyby in 1992 at a heliocentric distance of 5.4 AU, the spacecraftreapproached the inner solar system, flew over the Suns south polar region in September 1994,crossed the ecliptic plane at a distance of 1.3 AU in March 1995, and flew over the Suns northpolar region in July 1995. We report on dust impact data obtained with the dust detector onboardUlysses between January 1993 and December 1995. We publish and analyse the complete dataset of 509 recorded impacts of dust particles with masses between 10-16 g-10-7 g. Together with 968 dust impacts from launch until the end of 1992 published earlier ([Gruuml;n et al., 1995c]), information about 1477 particles detected with theUlysses sensor between October 1990 and December 1995 is now available. The impact ratemeasured between 1993 and 1995 stayed relatively constant at about 0.4 impacts per day andvaried by less than a factor of ten. Most of the impacts recorded outside about 3.5 AU arecompatible with particles of interstellar origin. Two populations of interplanetary particles havebeen recognized: big micrometer-sized particles close to the ecliptic plane and smallsub-micrometer-sized particles at high ecliptic latitudes. The observed impact rate is comparedwith a model for the flux of interstellar dust particles which gives relatively good agreement withthe observed impact rate. No change in the instruments noise characteristics or degradation of thechanneltron could be revealed during the three-year period.
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4.
  • Robertson, S., et al. (författare)
  • Mass analysis of charged aerosol particles in NLC and PMSE during the ECOMA/MASS campaign
  • 2009
  • Ingår i: Annales Geophysicae. - 0992-7689 .- 1432-0576. ; :27, s. 1213-1232
  • Tidskriftsartikel (refereegranskat)abstract
    • MASS (Mesospheric Aerosol Sampling Spectrometer) is a multichannel mass spectrometer for charged aerosol particles, which was flown from the Andøya Rocket Range, Norway, through NLC and PMSE on 3 August 2007 and through PMSE on 6 August 2007. The eight-channel analyzers provided for the first time simultaneous measurements of the charge density residing on aerosol particles in four mass ranges, corresponding to ice particles with radii <0.5 nm (including ions), 0.5–1 nm, 1–2 nm, and >3 nm (approximately). Positive and negative particles were recorded on separate channels. Faraday rotation measurements provided electron density and a means of checking charge density measurements made by the spectrometer. Additional complementary measurements were made by rocket-borne dust impact detectors, electric field booms, a photometer and ground-based radar and lidar. The MASS data from the first flight showed negative charge number densities of 1500–3000 cm−3 for particles with radii >3 nm from 83–88 km approximately coincident with PMSE observed by the ALWIN radar and NLC observed by the ALOMAR lidar. For particles in the 1–2 nm range, number densities of positive and negative charge were similar in magnitude (~2000 cm−3) and for smaller particles, 0.5–1 nm in radius, positive charge was dominant. The occurrence of positive charge on the aerosol particles of the smallest size and predominately negative charge on the particles of largest size suggests that nucleation occurs on positive condensation nuclei and is followed by collection of negative charge during subsequent growth to larger size. Faraday rotation measurements show a bite-out in electron density that increases the time for positive aerosol particles to be neutralized and charged negatively. The larger particles (>3 nm) are observed throughout the NLC region, 83–88 km, and the smaller particles are observed primarily at the high end of the range, 86–88 km. The second flight into PMSE alone at 84–88 km, found only small number densities (~500 cm−3) of particles >3 nm in a narrow altitude range, 86.5–87.5 km. Both positive (~2000 cm−3) and negative (~4500 cm−3) particles with radii 1–2 nm were detected from 85–87.5 km.
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5.
  • Andersson, L., et al. (författare)
  • Dust observations at orbital altitudes surrounding Mars
  • 2015
  • Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 350:6261
  • Tidskriftsartikel (refereegranskat)abstract
    • Dust is common close to the martian surface, but no known process can lift appreciable concentrations of particles to altitudes above similar to 150 kilometers. We present observations of dust at altitudes ranging from 150 to above 1000 kilometers by the Langmuir Probe and Wave instrument on the Mars Atmosphere and Volatile Evolution spacecraft. Based on its distribution, we interpret this dust to be interplanetary in origin. A comparison with laboratory measurements indicates that the dust grain size ranges from 1 to 12 micrometers, assuming a typical grain velocity of similar to 18 kilometers per second. These direct observations of dust entering the martian atmosphere improve our understanding of the sources, sinks, and transport of interplanetary dust throughout the inner solar system and the associated impacts on Mars's atmosphere.
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6.
  • Grun, E., et al. (författare)
  • South-North and Radial Traverses through the Interplanetary Dust Cloud
  • 1997
  • Ingår i: Icarus. - : Elsevier BV. - 0019-1035. ; 129:2, s. 270-288
  • Tidskriftsartikel (refereegranskat)abstract
    • Identical in situ dust detectors are flown on board the Galileo and Ulysses spacecraft. They record impacts of micrometeoroids in the ecliptic plane at heliocentric distances from 0.7 to 5.4 AU and in a plane almost perpendicular to the ecliptic from -79 deg to +79 deg ecliptic latitude. The combination of both Ulysses and Galileo measurements yields information about the radial and latitudinal distributions of micron- and sub-micron-sized dust in the Solar System. Two types of dust particles were found to dominate the dust flux in interplanetary space. Interplanetary micrometeoroids covering a wide mass range from 10^-16 to 10^-6 g are recorded mostly inside 3 AU and at latitudes below 30 deg. Interstellar grains with masses between 10^-14 and 10^-12 g have been positively identified outside 3 AU near the ecliptic plane and outside 1.8 AU at high ecliptic latitudes (>50 deg). Interstellar grains move on hyperbolic trajectories through the planetary system and constitute the dominant dust flux (1.5 x 10^-4 m^-2 sec^-1) in the outer Solar System and at high ecliptic latitudes. To compare and analyze the Galileo and Ulysses data sets, a new model is developed based on J. Geophys. Res. 98, 17029-17048, Divine's (1993, ``five populations of interplanetary meteoroids'' model. Both models describe the interplanetary meteoroid environment in terms of dust populations on distinct orbits. Taking into account the measured velocities and the effect of radiation pressure on small particles (described by the ratio of radiation pressure force to gravity, beta), we define four populations of meteoroids on elliptical orbits and one population on hyperbolic orbit that can fit the micrometeoroid flux observed by Galileo and Ulysses. Micrometeoroids with masses greater than 10^-10 g and negligible radiation pressure (beta = 0) orbit the Sun on low to moderately eccentric orbits and with low inclinations (<=30 deg). Populations of smaller particles with mean masses of 10^-11 g (beta = 0.3), 10^-13 g (beta = 0.8), and 5 x 10^-15 g (beta = 0.3), respectively, have components with high eccentricities and have increasingly wider inclination distributions with decreasing mass. Similarities among the orbit distributions of the small particle populations on bound orbits suggest that all are genetically related and are part of an overall micrometeoroid complex that prevails in the inner Solar System. The high-eccentricity component of the small particle populations may actually be beta-meteoroids which are not well characterized by our measurements. Our modeling suggests further that the interstellar dust flux is not reduced at Ulysses' perihelion distance (1.3 AU) and that it contributes about 30% of the total dust flux observed there.
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7.
  • Krueger, H., et al. (författare)
  • Five years of Ulysses dust data: 2000-2004
  • 2006
  • Ingår i: Planetary and Space Science. - : Elsevier BV. - 1873-5088 .- 0032-0633. ; 54:9-10, s. 932-956
  • Tidskriftsartikel (refereegranskat)abstract
    • The Ulysses spacecraft has been orbiting the Sun on a highly inclined ellipse (i = 79 degrees, perihelion distance 1.3 AU, aphelion distance 5.4 AU) since it encountered Jupiter in 1992. Between January 2000 and December 2004, the spacecraft completed almost an entire revolution about the Sun, passing through perihelion in May 2001 and aphelion in July 2004. In this five-year period the dust detector on board recorded 4415 dust impacts. We publish and analyse the complete data set of both raw and reduced data for particles with masses 10(-16) g <= M <= 10(-7) g. Together with. 1695 dust impacts recorded between launch of Ulysses and the end of 1999 published earlier (Grain, E., Baguhl, M., Divine, N., Fechtig, H., Hamilton, D.P, Harmer, M.S., Kissel, J., Lindblad, B.A., Linkert, D., Linkert, G., Mann, L, McDonnell, J.A.M., Morfill, G.E., Polanskey, C., Riemann, R., Schwehm, G.H., Siddique, N., Staubach, P., Zook, H.A., 1995a. Two years of Ulysses dust data. Planetary Space Sci. 43, 971-999, Paper III; Kruger, H., Grun, E., Landgraf, M., Baguhl, M., Dermott, S.F., Fechtig, H., Gustafson, B.A., Hamilton, D.P., Harmer, M.S., Horanyi, M., Kissel, J., Lindblad, B., Linkert, D., Linkert, G., Mann, L, McDonnell, J.A.M., Morfill, G.E., Polanskey, C., Schwehm, G.H., Srama, R., Zook, H.A., 1995. Three years of Ulysses dust data: 1993 to 1995. Planetary and Space Sci. 47, 363-383, Paper V; Kruger, H., Grun, E., Landgraf, M., Dermott, S.F., Fechtig, H., Gustafson, B.A., Hamilton, D.P., Harmer, M.S., Horanyi, M., Kissel, J., Lindblad, B., Linkert, D., Linkert, G., Mann, I., McDonnell, J.A.M., Morfill, G.E., Polanskey, C., Schwehm, G.H., Srama, R., Zook, H.A., 2001b. Four years of Ulysses dust data: 1996 to 1999. Planetary Space Sci. 49, 1303-1324, Paper VII), a data set of 6110 dust impacts detected with the Ulysses sensor between October 1990 and December 2004 is now available. The impact rate measured between 2000 and 2002 was relatively constant with about 0.3 impacts per day showing a maximum at 1.5 per day around ecliptic plane crossing in early-2001. The impact direction of the majority of impacts between 2000 and 2002 is compatible with particles of interstellar origin, the rest are most likely interplanetary particles. In 2003 and 2004 dust stream particles originating from the jovian system dominated the overall impact rate. Twenty-two individual dust streams were measured between November 2002 and December 2004. The observed impact rates are compared with models for interplanetary and interstellar dust. The dust measurements from the entire mission since Ulysses launch give good agreement with the interplanetary flux model of Staubach, P., Grun, E., Jehn, R., 1997. The meteoroid environment near Earth, Adv. Space Res. 19, 301-308. (c) 2006 Elsevier Ltd. All rights reserved.
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8.
  • Krueger, H., et al. (författare)
  • Galileo Dust Detection System V4.1
  • 2010
  • Ingår i: NASA Planetary Data System. ; 139
  • Tidskriftsartikel (refereegranskat)abstract
    • This data set contains the data from the Galileo dust detector system (GDDS) from start of mission through the end of mission. Included are the dust impact data, noise data, laboratory calibration data, and location and orientation of the spacecraft and instrument.
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9.
  • Krüger, H., et al. (författare)
  • Four years of Ulysses dust data: 1996-1999
  • 2001
  • Ingår i: Planetary and Space Science. - 1873-5088. ; 49:13, s. 1303-1324
  • Tidskriftsartikel (refereegranskat)abstract
    • The Ulysses spacecraft is orbiting the Sun on a highly inclined ellipse(/i=79°, perihelion distance 1.3 AU, aphelion distance 5.4 AU).Between January /1996 and December /1999 the spacecraft was beyond 3 AUfrom the Sun and crossed the ecliptic plane at aphelion in May /1998. Inthis 4-yr period 218 dust impacts were recorded with the dust detectoron board. We publish and analyse the complete data set of both raw andreduced data for particles with masses10-16-10-8g. Together with 1477 dust impactsrecorded between launch of Ulysses and the end of /1995 publishedearlier (Grün et al., Planet. Space Sci. 43 (/1995a) 971;Krüger et al., Planet. Space Sci. 47 (/1999b) 363), a data set of1695 dust impacts detected with the Ulysses sensor between October /1990and December /1999 is now available. The impact rate measured between1996 and 1999 was relatively constant with about 0.2 impacts per day.The impact direction of the majority of the impacts is compatible withparticles of interstellar origin, the rest are most likelyinterplanetary particles. The observed impact rate is compared with amodel for the flux of interstellar dust particles. The flux of particlesseveral micrometres in size is compared with the measurements of thedust instruments on board Pioneer 10 and Pioneer 11 beyond 3 AU (Humes,J. Geophys. Res. 85 /(1980) 5841). Between 3 and 5 AU, Pioneer resultspredict that Ulysses should have seen 5 times more (~10mum sized)particles than actually detected.
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10.
  • Krüger, H., et al. (författare)
  • Three years of Galileo dust data. II. 1993-1995
  • 1999
  • Ingår i: Planetary and Space Science. - 1873-5088. ; 47:1-2, s. 85-106
  • Tidskriftsartikel (refereegranskat)abstract
    • Between January 1993 - December 1995, the Galileo spacecraft traversed the interplanetary space between Earth and Jupiter and arrived at Jupiter on 7 December 1995. The dust instrument onboard the spacecraft was operating during most of the time and data from the instrument were obtained via memory readouts which occurred at rates between twice per day and once per week. All events were classified by an onboard program into 24 categories. Noise events were usually restricted to the lowest categories (class 0). During Galileo's passage through Jupiter's radiation belts on 7 December 1995, several of the higher categories (classes 1 and 2) also show evidence for contamination by noise. The highest categories (class 3) were noise-free all the time. A relatively constant impact rate of interplanetary and interstellar (big) particles of 0.4 impacts per day was detected over the whole three-year time span. In the outer solar system (outside about 2.6 AU) they are mostly of interstellar origin, whereas in the inner solar system they are mostly interplanetary particles. Within about 1.7 AU from Jupiter intense streams of small dust particles were detected with impact rates of up to 20,000 per day whose impact directions are compatible with a Jovian origin. Two different populations of dust particles were detected in the Jovian magnetosphere: small stream particles during Galileo's approach to the planet and big particles concentrated closer to Jupiter between the Galilean satellites. Information about 2883 particles detected by the dust instrument during Galileo's six-year journey to Jupiter is now available.
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