10 results on '"Rynö, J."'
Search Results
2. Radar—CubeSat transionospheric HF propagation observations:Suomi 100 satellite and EISCAT HF facility
- Author
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Kallio, E. (Esa), Kero, A. (Antti), Harri, A.-M. (Ari-Matti), Kestilä, A. (Antti), Aikio, A. (Anita), Fontell, M. (Mathias), Jarvinen, R. (Riku), Kauristie, K. (Kirsti), Knuuttila, O. (Olli), Koskimaa, P. (Petri), Loyala, J. (Jauaries), Lukkari, J.-M. (Juha-Matti), Modabberian, A. (Amin), Niittyniemi, J. (Joonas), Rynö, J. (Jouni), Vanhamäki, H. (Heikki), and Varberg, E. (Erik)
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transionospheric measurements ,CubeSat ,nanosatellite ,ionosphere ,radio instrument ,EISCAT HF facility - Abstract
Radio waves provide a useful diagnostic tool to investigate the properties of the ionosphere because the ionosphere affects the transmission and properties of high frequency (HF) electromagnetic waves. We have conducted a transionospheric HF-propagation research campaign with a nanosatellite on a low-Earth polar orbit and the EISCAT HF transmitter facility in Tromsø, Norway, in December 2020. In the active measurement, the EISCAT HF facility transmitted sinusoidal 7.953 MHz signal which was received with the High frEquency rAdio spectRomEteR (HEARER) onboard 1 Unit (size: 10 × 10 × 10 cm) Suomi 100 space weather nanosatellite. Data analysis showed that the EISCAT HF signal was detected with the satellite’s radio spectrometer when the satellite was the closest to the heater along its orbit. Part of the observed variations seen in the signal was identified to be related to the heater’s antenna pattern and to the transmitted pulse shapes. Other observed variations can be related to the spatial and temporal variations of the ionosphere and its different responses to the used transmission frequencies and to the transmitted O- and X-wave modes. Some trends in the observed signal may also be associated to changes in the properties of ionospheric plasma resulting from the heater’s electromagnetic wave energy. This paper is, to authors’ best knowledge, the first observation of this kind of “self-absorption” measured from the transionospheric signal path from a powerful radio source on the ground to the satellite-borne receiver.
- Published
- 2022
3. Cosima – High Resolution Time-of-Flight Secondary Ion Mass Spectrometer for the Analysis of Cometary Dust Particles onboard Rosetta
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Kissel, J., Altwegg, K., Clark, B. C., Colangeli, L., Cottin, H., Czempiel, S., Eibl, J., Engrand, C., Fehringer, H. M., Feuerbacher, B., Fomenkova, M., Glasmachers, A., Greenberg, J. M., Grün, E., Haerendel, G., Henkel, H., Hilchenbach, M., von Hoerner, H., Höfner, H., Hornung, K., Jessberger, E. K., Koch, A., Krüger, H., Langevin, Y., Parigger, P., Raulin, F., Rüdenauer, F., Rynö, J., Schmid, E. R., Schulz, R., Silén, J., Steiger, W., Stephan, T., Thirkell, L., Thomas, R., Torkar, K., Utterback, N. G., Varmuza, K., Wanczek, K. P., Werther, W., and Zscheeg, H.
- Published
- 2007
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4. D/H in the refractory organics of comet 67P/Churyumov-Gerasimenko measured by Rosetta/COSIMA.
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Paquette, J A, Fray, N, Bardyn, A, Engrand, C, Alexander, C M O'D, Siljeström, S, Cottin, H, Merouane, S, Isnard, R, Stenzel, O J, Fischer, H, Rynö, J, Kissel, J, and Hilchenbach, M
- Subjects
CHURYUMOV-Gerasimenko comet ,SOLAR system ,DUST ,SPACE sciences ,SEAWATER ,CHEMICAL species - Abstract
The D/H ratio is a clue to the origin and evolution of hydrogen-bearing chemical species in Solar system materials. D/H has been observed in the coma of many comets, but most such measurements have been for gaseous water. We present the first in situ measurements of the D/H ratios in the organic refractory component of cometary dust particles collected at very low impact speeds in the coma of comet 67P/Churyumov-Gerasimenko (hereafter 67P) by the COSIMA instrument onboard Rosetta. The values measured by COSIMA are spatial averages over an approximately 35 × 50 µm
2 area. The average D/H ratio for the 25 measured particles is (1.57 ± 0.54) × 10−3 , about an order of magnitude higher than the Vienna Standard Mean Ocean Water (VSMOW), but more than an order of magnitude lower than the values measured in gas-phase organics in solar-like protostellar regions and hot cores. This relatively high averaged value suggests that refractory carbonaceous matter in comet 67P is less processed than the most primitive insoluble organic matter (IOM) in meteorites, which has a D/H ratio in the range of about 1 to 7 × 10−4 . The cometary particles measured in situ also have a higher H/C ratio than the IOM. We deduce that the measured D/H in cometary refractory organics is an inheritance from the presolar molecular cloud from which the Solar system formed. The high D/H ratios observed in the cometary particles challenges models in which high D/H ratios result solely from processes that operated in the protosolar disc. [ABSTRACT FROM AUTHOR]- Published
- 2021
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5. The oxygen isotopic composition (18O/16O) in the dust of comet 67P/Churyumov-Gerasimenko measured by COSIMA on-board Rosetta.
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Paquette, J A, Engrand, C, Hilchenbach, M, Fray, N, Stenzel, O J, Silen, J, Rynö, J, Kissel, J, and The Cosima Team
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OXYGEN isotopes ,COSMIC dust ,PLANETARY systems ,ASTRONOMICAL observations ,CHURYUMOV-Gerasimenko comet - Abstract
The oxygen isotopic ratio
18 O/16 O has been measured in cometary gas for a wide variety of comets, but the only measurements in cometary dust were performed by the Stardust cometary sample return mission. Most such measurements find a value of the ratio that is consistent with Vienna Standard Mean Ocean Water (VSMOW) within errors. In this work we present the result of a measurement, using the COSIMA (the COmetary Secondary Ion Mass Analyser) instrument on the Rosetta orbiter, of the oxygen isotopic ratio in dust from Comet 67P/Churyumov-Gerasimenko. Measuring the18 O/16 O ratio with COSIMA is challenging for a number of reasons, but it is possible with a reasonable degree of precision. We find a result of 2.00 × 10−3 ± 1.2 × 10−4 , which is consistent within errors with VSMOW. [ABSTRACT FROM AUTHOR]- Published
- 2018
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6. Analysis of COSIMA spectra: Bayesian approach.
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Lehto, H. J., Zaprudin, B., Lehto, K. M., Lönnberg, T., Silén, J., Rynö, J., Krüger, H., Hilchenbach, M., and Kissel, J.
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MASS spectrometers ,SPECTRUM analysis ,MASS spectrometry ,PROBABILITY density function ,PROBLEM solving ,BAYESIAN analysis - Abstract
We describe the use of Bayesian analysis methods applied to time-of-flight secondary ion mass spectrometer (TOF-SIMS) spectra. The method is applied to the COmetary Secondary Ion Mass Analyzer (COSIMA) TOF-SIMS mass spectra where the analysis can be broken into subgroups of lines close to integer mass values. The effects of the instrumental dead time are discussed in a new way. The method finds the joint probability density functions of measured line parameters (number of lines, and their widths, peak amplitudes, integrated amplitudes and positions). In the case of two or more lines, these distributions can take complex forms. The derived line parameters can be used to further calibrate the mass scaling of TOF-SIMS and to feed the results into other analysis methods such as multivariate analyses of spectra. We intend to use the method, first as a comprehensive tool to perform quantitative analysis of spectra, and second as a fast tool for studying interesting targets for obtaining additional TOF-SIMS measurements of the sample, a property unique to COSIMA. Finally, we point out that the Bayesian method can be thought of as a means to solve inverse problems but with forward calculations, only with no iterative corrections or other manipulation of the observed data. [ABSTRACT FROM AUTHOR]
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- 2014
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7. Evidence of sub-surface energy storage in comet 67P from the outburst of 2016 July 03
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Agarwal, J., Della Corte, V., Feldman, P. D., Geiger, B., Merouane, S., Bertini, I., Bodewits, D., Fornasier, S., Grün, E., Hasselmann, P., Hilchenbach, M., Höfner, S., Ivanovski, S., Kolokolova, L., Pajola, M., Rotundi, A., Sierks, H., Steffl, A. J., Thomas, Nicolas, A'Hearn, M. F., Barbieri, C., Barucci, M. A., Bertaux, J.-L., Boudreault, S., Cremonese, G., Da Deppo, V., Davidsson, B., Debei, S., De Cecco, M., Deller, J. F., Feaga, L. M., Fischer, H., Fulle, M., Gicquel, A., Groussin, O., Güttler, C., Gutiérrez, P. J., Hofmann, M., Hornung, K., Hviid, S. F., Ip, W.-H., Jorda, L., Keller, H. U., Kissel, J., Knollenberg, J., Koch, A., Koschny, D., Kramm, J.-R., Kührt, E., Küppers, M., Lamy, P. L., Langevin, Y., Lara, L. M., Lazzarin, M., Lin, Z.-Y., Lopez Moreno, J. J., Lowry, S. C., Marzari, F., Mottola, S., Naletto, G., Oklay, N., Parker, J. Wm., Rodrigo, R., Rynö, J., Shi, X., Stenzel, O., Tubiana, C., Vincent, J.-B., Weaver, H. A., and Zaprudin, B.
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13. Climate action ,520 Astronomy ,Physics::Space Physics ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,620 Engineering - Abstract
On 2016 July 03, several instruments onboard ESA’s Rosetta spacecraft detected signs of an outburst event on comet 67P, at a heliocentric distance of 3.32 au from the Sun, outbound from perihelion. We here report on the inferred properties of the ejected dust and the surface change at the site of the outburst. The activity coincided with the local sunrise and continued over a time interval of 14–68 min. It left a 10-m-sized icy patch on the surface. The ejected material comprised refractory grains of several hundred microns in size, and sub-micron-sized water ice grains. The high dust mass production rate is incompatible with the free sublimation of crystalline water ice under solar illumination as the only acceleration process. Additional energy stored near the surface must have increased the gas density. We suggest a pressurized sub-surface gas reservoir, or the crystallization of amorphous water ice as possible causes.
8. Mechanical and electrostatic experiments with dust particles collected in the inner coma of comet 67P by COSIMA onboard Rosetta.
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Hilchenbach M, Fischer H, Langevin Y, Merouane S, Paquette J, Rynö J, Stenzel O, Briois C, Kissel J, Koch A, Schulz R, Silen J, Altobelli N, Baklouti D, Bardyn A, Cottin H, Engrand C, Fray N, Haerendel G, Henkel H, Höfner H, Hornung K, Lehto H, Mellado EM, Modica P, Le Roy L, Siljeström S, Steiger W, Thirkell L, Thomas R, Torkar K, Varmuza K, and Zaprudin B
- Abstract
The in situ cometary dust particle instrument COSIMA (COmetary Secondary Ion Mass Analyser) onboard ESA's Rosetta mission has collected about 31 000 dust particles in the inner coma of comet 67P/Churyumov-Gerasimenko since August 2014. The particles are identified by optical microscope imaging and analysed by time-of-flight secondary ion mass spectrometry. After dust particle collection by low speed impact on metal targets, the collected particle morphology points towards four families of cometary dust particles. COSIMA is an in situ laboratory that operates remotely controlled next to the comet nucleus. The particles can be further manipulated within the instrument by mechanical and electrostatic means after their collection by impact. The particles are stored above 0°C in the instrument and the experiments are carried out on the refractory, ice-free matter of the captured cometary dust particles. An interesting particle morphology class, the compact particles, is not fragmented on impact. One of these particles was mechanically pressed and thereby crushed into large fragments. The particles are good electrical insulators and transform into rubble pile agglomerates by the application of an energetic indium ion beam during the secondary ion mass spectrometry analysis.This article is part of the themed issue 'Cometary science after Rosetta'., (© 2017 The Author(s).)
- Published
- 2017
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9. High-molecular-weight organic matter in the particles of comet 67P/Churyumov-Gerasimenko.
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Fray N, Bardyn A, Cottin H, Altwegg K, Baklouti D, Briois C, Colangeli L, Engrand C, Fischer H, Glasmachers A, Grün E, Haerendel G, Henkel H, Höfner H, Hornung K, Jessberger EK, Koch A, Krüger H, Langevin Y, Lehto H, Lehto K, Le Roy L, Merouane S, Modica P, Orthous-Daunay FR, Paquette J, Raulin F, Rynö J, Schulz R, Silén J, Siljeström S, Steiger W, Stenzel O, Stephan T, Thirkell L, Thomas R, Torkar K, Varmuza K, Wanczek KP, Zaprudin B, Kissel J, and Hilchenbach M
- Abstract
The presence of solid carbonaceous matter in cometary dust was established by the detection of elements such as carbon, hydrogen, oxygen and nitrogen in particles from comet 1P/Halley. Such matter is generally thought to have originated in the interstellar medium, but it might have formed in the solar nebula-the cloud of gas and dust that was left over after the Sun formed. This solid carbonaceous material cannot be observed from Earth, so it has eluded unambiguous characterization. Many gaseous organic molecules, however, have been observed; they come mostly from the sublimation of ices at the surface or in the subsurface of cometary nuclei. These ices could have been formed from material inherited from the interstellar medium that suffered little processing in the solar nebula. Here we report the in situ detection of solid organic matter in the dust particles emitted by comet 67P/Churyumov-Gerasimenko; the carbon in this organic material is bound in very large macromolecular compounds, analogous to the insoluble organic matter found in the carbonaceous chondrite meteorites. The organic matter in meteorites might have formed in the interstellar medium and/or the solar nebula, but was almost certainly modified in the meteorites' parent bodies. We conclude that the observed cometary carbonaceous solid matter could have the same origin as the meteoritic insoluble organic matter, but suffered less modification before and/or after being incorporated into the comet.
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- 2016
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10. Comet 67P/Churyumov-Gerasimenko sheds dust coat accumulated over the past four years.
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Schulz R, Hilchenbach M, Langevin Y, Kissel J, Silen J, Briois C, Engrand C, Hornung K, Baklouti D, Bardyn A, Cottin H, Fischer H, Fray N, Godard M, Lehto H, Le Roy L, Merouane S, Orthous-Daunay FR, Paquette J, Rynö J, Siljeström S, Stenzel O, Thirkell L, Varmuza K, and Zaprudin B
- Abstract
Comets are composed of dust and frozen gases. The ices are mixed with the refractory material either as an icy conglomerate, or as an aggregate of pre-solar grains (grains that existed prior to the formation of the Solar System), mantled by an ice layer. The presence of water-ice grains in periodic comets is now well established. Modelling of infrared spectra obtained about ten kilometres from the nucleus of comet Hartley 2 suggests that larger dust particles are being physically decoupled from fine-grained water-ice particles that may be aggregates, which supports the icy-conglomerate model. It is known that comets build up crusts of dust that are subsequently shed as they approach perihelion. Micrometre-sized interplanetary dust particles collected in the Earth's stratosphere and certain micrometeorites are assumed to be of cometary origin. Here we report that grains collected from the Jupiter-family comet 67P/Churyumov-Gerasimenko come from a dusty crust that quenches the material outflow activity at the comet surface. The larger grains (exceeding 50 micrometres across) are fluffy (with porosity over 50 per cent), and many shattered when collected on the target plate, suggesting that they are agglomerates of entities in the size range of interplanetary dust particles. Their surfaces are generally rich in sodium, which explains the high sodium abundance in cometary meteoroids. The particles collected to date therefore probably represent parent material of interplanetary dust particles. This argues against comet dust being composed of a silicate core mantled by organic refractory material and then by a mixture of water-dominated ices. At its previous recurrence (orbital period 6.5 years), the comet's dust production doubled when it was between 2.7 and 2.5 astronomical units from the Sun, indicating that this was when the nucleus shed its mantle. Once the mantle is shed, unprocessed material starts to supply the developing coma, radically changing its dust component, which then also contains icy grains, as detected during encounters with other comets closer to the Sun.
- Published
- 2015
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