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138 results on '"Hviid, S.F."'

1. Regional unit definition for the nucleus of comet 67P/Churyumov-Gerasimenko on the SHAP7 model

Author

Thomas, N., El Maarry, M.R., Theologou, P., Preusker, F., Scholten, F., Jorda, L., Hviid, S.F., Marschall, R., Kührt, E., Naletto, G., Sierks, H., Lamy, P.L., Rodrigo, R., Koschny, D., Davidsson, B., Barucci, M.A., Bertaux, J.L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, V., Debei, S., De Cecco, M., Fornasier, S., Fulle, M., Groussin, O., Gutièrrez, P.J., Güttler, C., Ip, W.H., Keller, H.U., Knollenberg, J., Lara, L.M., Lazzarin, M., Lòpez-Moreno, J.J., Marzari, F., Tubiana, C., and Vincent, J.B.

Published
2018
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2. On deviations from free-radial outflow in the inner coma of comet 67P/Churyumov–Gerasimenko

Author

Gerig, S.-B., Marschall, R., Thomas, N., Bertini, I., Bodewits, D., Davidsson, B., Fulle, M., Ip, W.-H., Keller, H.U., Küppers, M., Preusker, F., Scholten, F., Su, C.C., Toth, I., Tubiana, C., Wu, J.-S., Sierks, H., Barbieri, C., Lamy, P.L., Rodrigo, R., Koschny, D., Rickman, H., Agarwal, J., Barucci, M.A., Bertaux, J.-L., Cremonese, G., Da Deppo, V., Debei, S., De Cecco, M., Deller, J., Fornasier, S., Groussin, O., Gutierrez, P.J., Güttler, C., Hviid, S.F., Jorda, L., Knollenberg, J., Kramm, J.-R., Kührt, E., Lara, L.M., Lazzarin, M., Lopez Moreno, J.J., Marzari, F., Mottola, S., Naletto, G., Oklay, N., and Vincent, J.-B.

Published
2018
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3. Distance determination method of dust particles using Rosetta OSIRIS NAC and WAC data

Author

Drolshagen, E., Ott, T., Koschny, D., Güttler, C., Tubiana, C., Agarwal, J., Sierks, H., Barbieri, C., Lamy, P.I., Rodrigo, R., Rickman, H., A'Hearn, M.F., Barucci, M.A., Bertaux, J.-L., Bertini, I., Cremonese, G., Deppo, V. Da, Davidsson, B., Debei, S., Cecco, M. De, Deller, J., Feller, C., Fornasier, S., Fulle, M., Gicquel, A., Groussin, O., Gutiérrez, P.J., Hofmann, M., Hviid, S.F., Ip, W.-H., Jorda, L., Keller, H.U., Knollenberg, J., Kramm, J.R., Kührt, E., Küppers, M., Lara, L.M., Lazzarin, M., Moreno, J.J. Lopez, Marzari, F., Naletto, G., Oklay, N., Shi, X., Thomas, N., and Poppe, B.

Published
2017
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6. The geomorphology of (21) Lutetia: Results from the OSIRIS imaging system onboard ESA's Rosetta spacecraft

Author

Thomas, N., Barbieri, C., Keller, H.U., Lamy, P., Rickman, H., Rodrigo, R., Sierks, H., Wenzel, K.P., Cremonese, G., Jorda, L., Küppers, M., Marchi, S., Marzari, F., Massironi, M., Preusker, F., Scholten, F., Stephan, K., Barucci, M.A., Besse, S., El-Maarry, M.R., Fornasier, S., Groussin, O., Hviid, S.F., Koschny, D., Kührt, E., Martellato, E., Moissl, R., Snodgrass, C., Tubiana, C., and Vincent, J.-B.

Published
2012
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9. Venus Monitoring Camera for Venus Express

Author

Markiewicz, W.J., Titov, D.V., Ignatiev, N., Keller, H.U., Crisp, D., Limaye, S.S., Jaumann, R., Moissl, R., Thomas, N., Esposito, L., Watanabe, S., Fiethe, B., Behnke, T., Szemerey, I., Michalik, H., Perplies, H., Wedemeier, M., Sebastian, I., Boogaerts, W., Hviid, S.F., Dierker, C., Osterloh, B., Böker, W., Koch, M., Michaelis, H., Belyaev, D., Dannenberg, A., Tschimmel, M., Russo, P., Roatsch, T., and Matz, K.D.

Published
2007
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10. Evidence from Opportunity's Microscopic Imager for water on Meridiani Planum

Author

Herkenhoff, K.E., Squyres, S.W., Arvidson, R., Bass, D.S., Bell, III, J.F., Bertelsen, P., Ehlmann, B.L., Farrand, W., Gaddis, L., Greeley, R., Grotzinger, J., Hayes, A.G., Hviid, S.F., Johnson, J.R., Jolliff, B., Kinch, K.M., Knoll, A.H., Madsen, M.B., Maki, J.N., McLennan, S.M., McSween, H.Y., Ming, D.W., Rice, Jr., J.W., Richter, L., Sims, M., Smith, P.H., Soderblom, L.A., Spanovich, N., Sullivan, R., Thompson, S., Wdowiak, T., Weitz, C., and Whelley, P.

Subjects
Opportunity (Space probe) -- Research, Discovery and exploration, Research, Environmental aspects, Water -- Discovery and exploration -- Research -- Environmental aspects, Surface (Geology) -- Discovery and exploration -- Research -- Environmental aspects, Mars (Planet) -- Discovery and exploration -- Environmental aspects -- Research
Abstract

The Athena science payload on the Mars Exploration Rover (MER) mission includes the Microscopic Imager (MI), a camera designed to provide views that are similar to that seen through a [...], The Microscopic Imager on the Opportunity rover analyzed textures of sois and rocks at Meridiani Planum at a scale of 31 micrometers per pixel. The uppermost millimeter of some soils is weakly cemented, whereas other soils show little evidence of cohesion. Rock outcrops are laminated on a millimeter scale; image mosaics of cross-stratification suggest that some sediments were deposited by flowing water. Vugs in some outcrop faces are probably molds formed by dissolution of relatively soluble minerals during diagenesis. Microscopic images support the hypothesis that hematite-rich spherules observed in outcrops and soils also formed diagenetically as concretions.

Published
2004

11. The microscope for Beagle 2

Author

Thomas, N., Lüthi, B.S., Hviid, S.F., Keller, H.U., Markiewicz, W.J., Blümchen, T., Basilevsky, A.T., Smith, P.H., Tanner, R., Oquest, C., Reynolds, R., Josset, J.-L., Beauvivre, S., Hofmann, B., Rüffer, P., and Pillinger, C.T.

Published
2004
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12. Textures of the soils and rocks at Gusev crater from Spirit's microscopic imager

Author

Herkenhoff, K.E., Squyres, S.W., Arvidson, R., Bass, D.S., Bell, III, J.F., Bertelsen, P., Cabrol, N.A., Gaddis, L., Hayes, A.G., Hviid, S.F., Johnson, J.R., Kinch, K.M., Madsen, M.B., Maki, J.N., McLennan, S.M., McSween, H.Y., Rice, Jr., J.W., Sims, M., Smith, P.H., Soderblom, L.A., Spanovich, N., Sullivan, R., and Wang, A.

Subjects
Spirit (Space probe) -- Observations, Observations, Research, Properties, Geology -- Research -- Observations, Mars (Planet) -- Properties -- Research
Abstract

The Microscopic Imager (MI) is a fixed-focus camera mounted on a robotic arm (1, 2). The MI was designed to function like a geologist's hand lens, acquiring images at aspatial [...], The Microscopic Imager on the Spirit rover analyzed the textures of the soil and rocks at Gusev crater on Mars at a resolution of 100 micrometers. Weakly bound agglomerates of dust are present in the soil near the Columbia Memorial Station. Some of the brushed or abraded rock surfaces show igneous textures and evidence for alteration rinds, coatings, and veins consistent with secondary mineralization. The rock textures are consistent with a volcanic origin and subsequent alteration and/or weathering by impact events, wind, and possibly water.

Published
2004

13. Magnetic properties experiments on the Mars exploration Rover Spirit at Gusev crater

Author

Bertelsen, P., Goetz, W., Madsen, M.B., Kinch, K.M., Hviid, S.F., Knudsen, J.M., Gunnlaugsson, H.P., Merrison, J., Nornberg, P., Squyres, S.W., Bell, III, J.F., Herkenhoff, K.E., Gorevan, S., Yen, A.S., Myrick, T., Klingelhofer, G., Rieder, R., and Gellert, R.

Subjects
Spirit (Space probe) -- Observations, Observations, Research, Properties, Geology -- Properties -- Research, Mars (Planet) -- Research -- Properties
Abstract

The history of liquid water on Mars may be reflected in the magnetic minerals present in the surface materials on Mars today: If liquid water is present in an oxidizing [...], The magnetic properties experiments are designed to help identify the magnetic minerals in the dust and rocks on Mars--and to determine whether liquid water was involved in the formation and alteration of these magnetic minerals. Almost all of the dust particles suspended in the martian atmosphere must contain ferrimagnetic minerals (such as maghemite or magnetite) in an amount of ~2% by weight, The most magnetic fraction of the dust appears darker than the average dust. Magnetite was detected in the first two rocks ground by Spirit.

Published
2004

15. Seasonal variations in source regions of the dust jets on comet 67P/Churyumov-Gerasimenko

Author

German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, Ministry of Science and Technology (Taiwan), Science and Technology Development Fund (Macau), Lai, IL, Ip, W. H., Lee, J.C., Lin, Zhong-Yi, Vincent, J.B., Oklay, N., Sierks, H., Barbieri, C, Lamy, P., Rodrigo Montero, Rafael, Koschny, D., Rickman, H., Keller, H.U., Agarwal, J., Barucci, M.A., Bertaux, J.L., Bertini, I., Bodewits, D., Boudreault, S., Cremonese, G., Da Deppo, Vania, Davidsson, B., Debei, S., De Cecco, M., Deller, J., Fornasier, S., Fulle, M., Groussin, O., Gutiérrez, Pedro J., Güttler, C., Hofmann, M., Hviid, S.F., Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J.R., Kührt, E., Küppers, M., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Marzari, F., Naletto, G., Shi, X., Tubiana, C., Thomas, N, German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, Ministry of Science and Technology (Taiwan), Science and Technology Development Fund (Macau), Lai, IL, Ip, W. H., Lee, J.C., Lin, Zhong-Yi, Vincent, J.B., Oklay, N., Sierks, H., Barbieri, C, Lamy, P., Rodrigo Montero, Rafael, Koschny, D., Rickman, H., Keller, H.U., Agarwal, J., Barucci, M.A., Bertaux, J.L., Bertini, I., Bodewits, D., Boudreault, S., Cremonese, G., Da Deppo, Vania, Davidsson, B., Debei, S., De Cecco, M., Deller, J., Fornasier, S., Fulle, M., Groussin, O., Gutiérrez, Pedro J., Güttler, C., Hofmann, M., Hviid, S.F., Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J.R., Kührt, E., Küppers, M., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Marzari, F., Naletto, G., Shi, X., Tubiana, C., and Thomas, N

Abstract

We investigate the surface distribution of the source regions of dust jets on comet 67P/Churyumov-Gerasimenko as a function of time. Methods. The dust jet source regions were traced by the comprehensive imaging data set provided by the OSIRIS scientific camera. Results. We show in detail how the projected footpoints of the dust jets and hence the outgassing zone would move in consonance with the sunlit belt. Furthermore, a number of source regions characterized by repeated jet activity might be the result of local topographical variations or compositional heterogeneities. Conclusions. The spatial and temporal variations in source regions of the dust jets are influenced significantly by the seasonal effect. The strong dependence on the solar zenith angle and local time could be related to the gas sublimation process driven by solar insolation on a surface layer of low thermal inertia.© ESO 2019

Published
2019

16. Bilobate comet morphology and internal structure controlled by shear deformation

Author

Matonti, C., Attree, N., Groussin, O., Jorda, L., Viseur, S., Hviid, S.F., Bouley, S., Nébouy, D., Auger, A.T., Lamy, P.L., Sierks, H., Naletto, G., Rodrigo Montero, Rafael, Koschny, D., Davidsson, B., Barucci, M.A., Bertaux, J.L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., Fornasier, S., Fulle, M., Gutiérrez, Pedro J., Güttler, C., Ip, W. H., Keller, H.U., Lara, Luisa María, La Forgia, F., Lazzarin, M., Lucchetti, A., López-Moreno, José Juan, Marzari, F., Massironi, M., Mottola, S., Oklay, N., Pajola, M., Penasa, L., Preusker, F., Rickman, H., Scholten, F., Shi, X., Toth, I., Tubiana, C., Vincent, J.B., Matonti, C., Attree, N., Groussin, O., Jorda, L., Viseur, S., Hviid, S.F., Bouley, S., Nébouy, D., Auger, A.T., Lamy, P.L., Sierks, H., Naletto, G., Rodrigo Montero, Rafael, Koschny, D., Davidsson, B., Barucci, M.A., Bertaux, J.L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., Fornasier, S., Fulle, M., Gutiérrez, Pedro J., Güttler, C., Ip, W. H., Keller, H.U., Lara, Luisa María, La Forgia, F., Lazzarin, M., Lucchetti, A., López-Moreno, José Juan, Marzari, F., Massironi, M., Mottola, S., Oklay, N., Pajola, M., Penasa, L., Preusker, F., Rickman, H., Scholten, F., Shi, X., Toth, I., Tubiana, C., and Vincent, J.B.

Abstract

Bilobate comets—small icy bodies with two distinct lobes—are a common configuration among comets, but the factors shaping these bodies are largely unknown. Cometary nuclei, the solid centres of comets, erode by ice sublimation when they are sufficiently close to the Sun, but the importance of a comet’s internal structure on its erosion is unclear. Here we present three-dimensional analyses of images from the Rosetta mission to illuminate the process that shaped the Jupiter-family bilobate comet 67P/Churyumov–Gerasimenko over billions of years. We show that the comet’s surface and interior exhibit shear-fracture and fault networks, on spatial scales of tens to hundreds of metres. Fractures propagate up to 500 m below the surface through a mechanically homogeneous material. Through fracture network analysis and stress modelling, we show that shear deformation generates fracture networks that control mechanical surface erosion, particularly in the strongly marked neck trough of 67P/Churyumov–Gerasimenko, exposing its interior. We conclude that shear deformation shapes and structures the surface and interior of bilobate comets, particularly in the outer Solar System where water ice sublimation is negligible.© 2019, The Author(s), under exclusive licence to Springer Nature Limited.

Published
2019

17. Multidisciplinary analysis of the Hapi region located on Comet 67P/Churyumov-Gerasimenko

Author

European Space Agency, Swedish National Space Board, Ministerio de Educación y Ciencia (España), Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, German Centre for Air and Space Travel, Pajola, M., Lee, J.C., Oklay, N., Hviid, S.F., Penasa, L., Mottola, S., Shi, X., Fornasier, S., Davidsson, B., Giacomini, L., Lucchetti, A., Massironi, M., Vincent, J.B., Bertini, I., Naletto, G., Ip, W. H., Sierks, H., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Keller, H.U., Agarwal, J., Barucci, M.A., Bertaux, J.L., Bodewits, D., Cambianica, P., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., El Maarry, M. R., Feller, C., Ferrari, S., Fulle, M., Gutiérrez, Pedro J., Güttler, C., Lara, Luisa María, La Forgia, F., Lazzarin, M., Lin, Zhong-Yi, López-Moreno, José Juan, Marzari, F., Preusker, F., Scholten, F., Toth, I., Tubiana, C., European Space Agency, Swedish National Space Board, Ministerio de Educación y Ciencia (España), Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, German Centre for Air and Space Travel, Pajola, M., Lee, J.C., Oklay, N., Hviid, S.F., Penasa, L., Mottola, S., Shi, X., Fornasier, S., Davidsson, B., Giacomini, L., Lucchetti, A., Massironi, M., Vincent, J.B., Bertini, I., Naletto, G., Ip, W. H., Sierks, H., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Keller, H.U., Agarwal, J., Barucci, M.A., Bertaux, J.L., Bodewits, D., Cambianica, P., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., El Maarry, M. R., Feller, C., Ferrari, S., Fulle, M., Gutiérrez, Pedro J., Güttler, C., Lara, Luisa María, La Forgia, F., Lazzarin, M., Lin, Zhong-Yi, López-Moreno, José Juan, Marzari, F., Preusker, F., Scholten, F., Toth, I., and Tubiana, C.

Abstract

By using the Rosetta/OSIRIS-NAC data set taken in 2014 August, we focus on the neck region, called Hapi, located on 67P Churyumov-Gerasimenko's Northern hemisphere. The gravitational potential and slopes of Hapi, coupled with the geological unit identification and the boulder size-frequency distributions, support the interpretation that both taluses and gravitational accumulation deposits observable on Hapi are the result of multiple cliff collapses that occurred at different times. By contrast, the fine-particle deposits observable in the central part of the study area are made of aggregates coming from the Southern hemisphere and deposited during each perihelion passage. Both the consolidated terrains on the western part of Hapi, as well as the centrally aligned ridge made of boulder-like features, suggest that Hapi is in structural continuity with the onion-like structure of the main lobe of 67P. Despite the dusty blanket observable on Hapi, its terrains are characterized by water-ice-rich components that, once repeatedly and rapidly illuminated, sublimate, hence resulting in the strong jet activity observed in 2014 August.© 2019 The Author(s).

Published
2019

18. Magnetic properties experiments on the Mars Pathfinder lander: preliminary results

Author

Hviid, S.F., Madsen, M.B., Gunnlaugsson, H.P., Goetz, W., Knudsen, J.M., Hargraves, R.B., Smith, P., Britt, D., Dinesen, A.R., Mogensen, C.T., Olsen, M., Pedersen, C.T., and Vistisen, L.

Subjects
Mars Pathfinder (Space probe) -- Research, Research, Natural history, Mars (Planet) -- Natural history -- Research, Planets -- Natural history -- Research
Abstract

Many of the particles currently suspended in the martian atmosphere are magnetic, with an average saturation magnetization of about 4 A [multiplied by] [m.sup.2]/kg (amperes times square meters per kilogram). [...]

Published
1997

19. On deviations from free-radial outflow in the inner coma of comet 67P/Churyumov–Gerasimenko

Author

Swiss National Science Foundation, European Commission, Gerig, S. -B., Marschall, R., Thomas, N., Bertini, I., Bodewits, D., Davidsson, B., Fulle, M., Ip, W. H., Keller, H.U., Küppers, M., Preusker, F., Scholten, F., Su, C. C., Toth, I., Tubiana, C., Wu, J. -S., Sierks, H., Barbieri, C., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Rickman, H., Agarwal, J., Barucci, M.A., Bertaux, J.L., Cremonese, G., Da Deppo, V., Debei, S., De Cecco, M., Deller, J., Fornasier, S., Groussin, O., Gutiérrez, Pedro J., Güttler, C., Hviid, S.F., Jorda, L., Knollenberg, J., Kramm, J.R., Kührt, E., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Marzari, F., Mottola, S., Naletto, G., Oklay, N., Vincent, J.B., Swiss National Science Foundation, European Commission, Gerig, S. -B., Marschall, R., Thomas, N., Bertini, I., Bodewits, D., Davidsson, B., Fulle, M., Ip, W. H., Keller, H.U., Küppers, M., Preusker, F., Scholten, F., Su, C. C., Toth, I., Tubiana, C., Wu, J. -S., Sierks, H., Barbieri, C., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Rickman, H., Agarwal, J., Barucci, M.A., Bertaux, J.L., Cremonese, G., Da Deppo, V., Debei, S., De Cecco, M., Deller, J., Fornasier, S., Groussin, O., Gutiérrez, Pedro J., Güttler, C., Hviid, S.F., Jorda, L., Knollenberg, J., Kramm, J.R., Kührt, E., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Marzari, F., Mottola, S., Naletto, G., Oklay, N., and Vincent, J.B.

Abstract

The Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) onboard the European Space Agency's Rosetta spacecraft acquired images of comet 67P/Churyumov–Gerasimenko (67P) and its surrounding dust coma starting from May 2014 until September 2016. In this paper we present methods and results from analysis of OSIRIS images regarding the dust outflow in the innermost coma of 67P. The aim is to determine the global dust outflow behaviour and place constraints on physical processes affecting particles in the inner coma. We study the coma region right above the nucleus surface, spanning from the nucleus centre out to a distance of about 50 km comet centric distance (approximately 25 average comet radii). We primarily adopt an approach used by Thomas and Keller (1990) to study the dust outflow. We present the effects on azimuthally-averaged values of the dust reflectance of non-radial flow and non-point-source geometry, acceleration of dust particles, sublimation of icy dust particles after ejection from the surface, dust particle fragmentation, optical depth effects and the influence of gravitationally bound particles. All of these physical processes could modify the observed distribution of light scattered by the dust coma. In the image analysis, profiles of azimuthally averaged dust brightness as a function of impact parameter b (azimuthal average, “Ā-curve”) were fitted with a simple function that best fits the shape of our profile curves (f(b;u,v,w,z)=u/b+wb+z). The analytical fit parameters (u, v, w, z), which hold the key information about the dust outflow behaviour, were saved in a comprehensive database. Through statistical analysis of these information, we show that the spatial distribution of dust follows free-radial outflow behaviour (i.e. force-free radial outflow with constant velocity) beyond distances larger than ∼11.9 km from the comet centre, which corresponds to a relative distance of about 6 average comet radii from the comet centre. Hence

Published
2018

20. Regional unit definition for the nucleus of comet 67P/Churyumov-Gerasimenko on the SHAP7 model

Author

Swiss National Science Foundation, European Commission, State Secretariat for Education, Research and Innovation (Switzerland), Thomas, N., El Maarry, M. R., Theologou, P., Preusker, F., Scholten, F., Jorda, L., Hviid, S.F., Marschall, R., Kührt, E., Naletto, G., Sierks, H., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Davidsson, B., Barucci, M.A., Bertaux, J.L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Fornasier, S., Fulle, M., Groussin, O., Gutiérrez, Pedro J., Güttler, C., Ip, W. H., Keller, H.U., Knollenberg, J., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Marzari, F., Tubiana, C., Vincent, J.B., Swiss National Science Foundation, European Commission, State Secretariat for Education, Research and Innovation (Switzerland), Thomas, N., El Maarry, M. R., Theologou, P., Preusker, F., Scholten, F., Jorda, L., Hviid, S.F., Marschall, R., Kührt, E., Naletto, G., Sierks, H., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Davidsson, B., Barucci, M.A., Bertaux, J.L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Fornasier, S., Fulle, M., Groussin, O., Gutiérrez, Pedro J., Güttler, C., Ip, W. H., Keller, H.U., Knollenberg, J., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Marzari, F., Tubiana, C., and Vincent, J.B.

Abstract

The previously defined regions on the nucleus of comet 67P/Churyumov-Gerasimenko have been mapped back onto the 3D SHAP7 model of the nucleus (Preusker et al., 2017). The resulting regional definition is therefore self-consistent with boundaries that are well defined in 3 dimensions. The facets belonging to each region are provided as supplementary material. The shape model has then been used to assess inhomogeneity of nucleus surface morphology within individual regions. Several regions show diverse morphology. We propose sub-division of these regions into clearly identifiable units (sub-regions) and a comprehensive table is provided. The surface areas of each sub-region have been computed and statistics based on grouping of unit types are provided. The roughness of each region is also provided in a quantitative manner using a technique derived from computer graphics applications. The quantitative method supports the sub-region definition by showing that differences between sub-regions can be numerically justified.© 2018 The Authors

Published
2018

21. Coma morphology of comet 67P controlled by insolation over irregular nucleus

Author

German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, Shi, X., Hu, X., Mottola, S., Sierks, H., Keller, H.U., Rose, M., Güttler, C., Fulle, M., Fornasier, S., Agarwal, J., Pajola, M., Tubiana, C., Bodewits, D., Barbieri, C., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Barucci, M.A., Bertaux, J.L., Bertini, I., Boudreault, S., Cremonese, G., Da Deppo, Vania, Davidsson, B., Debei, S., De Cecco, M., Deller, J., Groussin, O., Gutiérrez, Pedro J., Hviid, S.F., Ip, W. H., Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J.R., Kührt, E., Küppers, M., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Marzari, F., Naletto, G., Oklay, N., Toth, I., Vincent, J.B., German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, Shi, X., Hu, X., Mottola, S., Sierks, H., Keller, H.U., Rose, M., Güttler, C., Fulle, M., Fornasier, S., Agarwal, J., Pajola, M., Tubiana, C., Bodewits, D., Barbieri, C., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Barucci, M.A., Bertaux, J.L., Bertini, I., Boudreault, S., Cremonese, G., Da Deppo, Vania, Davidsson, B., Debei, S., De Cecco, M., Deller, J., Groussin, O., Gutiérrez, Pedro J., Hviid, S.F., Ip, W. H., Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J.R., Kührt, E., Küppers, M., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Marzari, F., Naletto, G., Oklay, N., Toth, I., and Vincent, J.B.

Abstract

While the structural complexity of cometary comae is already recognizable from telescopic observations, the innermost region, within a few radii of the nucleus, was not resolved until spacecraft exploration became a reality. The dust coma displays jet-like features of enhanced brightness superposed on a diffuse background . Some features can be traced to specific areas on the nucleus, and result conceivably from locally enhanced outgassing and/or dust emission. However, diffuse or even uniform activity over topographic concavity can converge to produce jet-like features. Therefore, linking observed coma morphology to the distribution of activity on the nucleus is difficult. Here, we study the emergence of dust activity at sunrise on comet 67P/Churyumov-Gerasimenko using high-resolution, stereo images from the OSIRIS camera onboard the Rosetta spacecraft, where the sources and formation of the jet-like features are resolved. We perform numerical simulations to show that the ambient dust coma is driven by pervasive but non-uniform water outgassing from the homogeneous surface layer. Physical collimations of gas and dust flows occur at local maxima of insolation and also via topographic focusing. Coma structures are projected to exhibit jet-like features that vary with the perspective of the observer. For an irregular comet such as 67P/Churyumov-Gerasimenko, near-nucleus coma structures can be concealed in the shadow of the nucleus, which further complicates the picture.© 2018 The Author(s).

Published
2018

22. The big lobe of 67P/Churyumov-Gerasimenko comet: Morphological and spectrophotometric evidences of layering as from OSIRIS data

Author

German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, Ferrari, S., Penasa, L., La Forgia, F., Massironi, M., Naletto, G., Lazzarin, M., Fornasier, S., Hasselmann, P.H., Lucchetti, A., Pajola, M., Ferri, F., Cambianica, P., Oklay, N., Tubiana, C., Sierks, H., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Davidsson, B., Barucci, M.A., Bertaux, J.L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., Franceschi, M., Frattin, E., Fulle, M., Groussin, O., Gutiérrez, Pedro J., Güttler, C., Hviid, S.F., Ip, W. H., Jorda, L., Keller, H.U., Knollenberg, J., Kührt, E., Küppers, M., Lara, Luisa María, López-Moreno, José Juan, Marzari, F., Shi, X., Simioni, E., Thomas, N., Vincent, J.B., German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, Ferrari, S., Penasa, L., La Forgia, F., Massironi, M., Naletto, G., Lazzarin, M., Fornasier, S., Hasselmann, P.H., Lucchetti, A., Pajola, M., Ferri, F., Cambianica, P., Oklay, N., Tubiana, C., Sierks, H., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Davidsson, B., Barucci, M.A., Bertaux, J.L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., Franceschi, M., Frattin, E., Fulle, M., Groussin, O., Gutiérrez, Pedro J., Güttler, C., Hviid, S.F., Ip, W. H., Jorda, L., Keller, H.U., Knollenberg, J., Kührt, E., Küppers, M., Lara, Luisa María, López-Moreno, José Juan, Marzari, F., Shi, X., Simioni, E., Thomas, N., and Vincent, J.B.

Abstract

Between 2014 and 2016, ESA's Rosetta OSIRIS cameras acquired multiple-filters images of the layered nucleus of comet 67P/Churyumov-Gerasimenko, ranging from ultraviolet to near-infrared wavelengths. No correlation between layers disposition and surface spectral variegation has been observed so far. This paper investigates possible spectral differences among decametre-thickness outcropping layers of the biggest lobe of the comet by means of OSIRIS image dataset. A two-classes maximum likelihood classification was applied on consolidated outcrops and relative deposits identified on post-perihelion multispectral images of the big lobe. We distinguished multispectral data on the basis of the structural elevation of the onion-shell Ellipsoidal Model of 67P. The spatial distribution of the two classes displays a clear dependence on the structural elevation, with the innermost class resulting over 50 per cent brighter than the outermost one. Consolidated cometarymaterials located at different structural levels are characterized by different brightness and revealed due to the selective removal of large volumes. This variegation can be attributed to a different texture of the outcrop surface and/or to a different content of refractory materials.© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.

Published
2018

23. Exposed bright features on the comet 67P/Churyumov-Gerasimenko: Distribution and evolution

Author

German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Ministerio de Educación y Ciencia (España), European Space Agency, Swedish National Space Board, Deshapriya, J.D.P., Barucci, M.A., Fornasier, S., Hasselmann, P.H., Feller, C., Sierks, H., Lucchetti, A., Pajola, M., Oklay, N., Mottola, S., Masoumzadeh, N., Tubiana, C., Güttler, C., Barbieri, C., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Rickman, H., Bertaux, J.L., Bertini, I., Bodewits, D., Boudreault, S., Cremonese, G., Da Deppo, Vania, Davidsson, Björn J. R., Debei, S., Cecco, M.D., Deller, J., Fulle, M., Groussin, O., Gutiérrez, Pedro J., Hoang, H. V., Hviid, S.F., Ip, W. H., Jorda, L., Keller, H.U., Knollenberg, J., Kramm, R., Kührt, E., Küppers, M., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Marzari, F., Naletto, G., Preusker, F., Shi, X., Thomas, N., Vincent, J.B., German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Ministerio de Educación y Ciencia (España), European Space Agency, Swedish National Space Board, Deshapriya, J.D.P., Barucci, M.A., Fornasier, S., Hasselmann, P.H., Feller, C., Sierks, H., Lucchetti, A., Pajola, M., Oklay, N., Mottola, S., Masoumzadeh, N., Tubiana, C., Güttler, C., Barbieri, C., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Rickman, H., Bertaux, J.L., Bertini, I., Bodewits, D., Boudreault, S., Cremonese, G., Da Deppo, Vania, Davidsson, Björn J. R., Debei, S., Cecco, M.D., Deller, J., Fulle, M., Groussin, O., Gutiérrez, Pedro J., Hoang, H. V., Hviid, S.F., Ip, W. H., Jorda, L., Keller, H.U., Knollenberg, J., Kramm, R., Kührt, E., Küppers, M., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Marzari, F., Naletto, G., Preusker, F., Shi, X., Thomas, N., and Vincent, J.B.

Abstract

Context. Since its arrival at the comet 67P/Churyumov-Gerasimenko in August 2014, the Rosetta spacecraft followed the comet as it went past the perihelion and beyond until September 2016. During this time there were many scientific instruments operating on board Rosetta to study the comet and its evolution in unprecedented detail. In this context, our study focusses on the distribution and evolution of exposed bright features that have been observed by OSIRIS, which is the scientific imaging instrument aboard Rosetta. Aims. We envisage investigating various morphologies of exposed bright features and the mechanisms that triggered their appearance. Methods. We co-registered multi-filter observations of OSIRIS images that are available in reflectance. The Lommel-Seeliger disk function was used to correct for the illumination conditions and the resulting colour cubes were used to perform spectrophotometric analyses on regions of interest. Results. We present a catalogue of 57 exposed bright features observed on the nucleus of the comet, all of which are attributed to the presence of HO ice on the comet. Furthermore, we categorise these patches under four different morphologies and present geometric albedos for each category. Conclusions. Although the nucleus of 67P/Churyumov-Gerasimenko appears to be dark in general, there are localised HO ice sources on the comet. Cometary activity escalates towards the perihelion passage and reveals such volatile ices. We propose that isolated HO ice patches found in smooth terrains in regions, such as Imhotep, Bes, and Hapi, result from frost as an aftermath of the cessation of the diurnal water cycle on the comet as it recedes from perihelion. Upon the comet's return to perihelion, such patches are revealed when sublimation-driven erosion removes the thin dust layers that got deposited earlier. More powerful activity sources such as cometary outbursts are capable of revealing much fresher, less contaminated HO ice that is preserved

Published
2018

25. Opposition effect on comet 67P/Churyumov-Gerasimenko using Rosetta-OSIRIS images

Author

Swedish National Space Board, Ministerio de Economía y Competitividad (España), Agenzia Spaziale Italiana, Centre National de la Recherche Scientifique (France), German Centre for Air and Space Travel, European Space Agency, Masoumzadeh, N., Oklay, N., Kolokolova, L., Sierks, H., Fornasier, S., Barucci, M.A., Vincent, J.B., Tubiana, C., Güttler, C., Preusker, F., Scholten, F., Mottola, S., Hasselmann, P.H., Feller, C., Barbieri, C., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Rickman, H., A'Hearn, M. F., Bertaux, J.L., Bertini, I., Cremonese, G., Da Deppo, Vania, Davidsson, Björn J. R., Debei, S., De Cecco, M., Fulle, M., Gicquel, A., Groussin, O., Gutiérrez, Pedro J., Hall, I., Hofmann, M., Hviid, S.F., Ip, W. H., Jorda, L., Keller, H.U., Knollenberg, J., Kovacs, G., Kramm, J.R., Kührt, E., Küppers, M., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Marzari, F., Naletto, G., Shi, X., Thomas, N., Swedish National Space Board, Ministerio de Economía y Competitividad (España), Agenzia Spaziale Italiana, Centre National de la Recherche Scientifique (France), German Centre for Air and Space Travel, European Space Agency, Masoumzadeh, N., Oklay, N., Kolokolova, L., Sierks, H., Fornasier, S., Barucci, M.A., Vincent, J.B., Tubiana, C., Güttler, C., Preusker, F., Scholten, F., Mottola, S., Hasselmann, P.H., Feller, C., Barbieri, C., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Rickman, H., A'Hearn, M. F., Bertaux, J.L., Bertini, I., Cremonese, G., Da Deppo, Vania, Davidsson, Björn J. R., Debei, S., De Cecco, M., Fulle, M., Gicquel, A., Groussin, O., Gutiérrez, Pedro J., Hall, I., Hofmann, M., Hviid, S.F., Ip, W. H., Jorda, L., Keller, H.U., Knollenberg, J., Kovacs, G., Kramm, J.R., Kührt, E., Küppers, M., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Marzari, F., Naletto, G., Shi, X., and Thomas, N.

Abstract

Aims. We aim to explore the behavior of the opposition effect as an important tool in optical remote sensing on the nucleus of comet 67P/Churyumov-Gerasimenko (67P), using Rosetta-OSIRIS images acquired in different filters during the approach phase, July-August 2014 and the close flyby images on 14 of February 2015, which contain the spacecraft shadow. Methods. We based our investigation on the global and local brightness from the surface of 67P with respect to the phase angle, also known as phase curve. The local phase curve corresponds to a region that is located at the Imhotep-Ash boundary of 67P. Assuming that the region at the Imhotep-Ash boundary and the entire nucleus have similar albedo, we combined the global and local phase curves to study the opposition-surge morphology and constrain the structure and properties of 67P. The model parameters were furthermore compared with other bodies in the solar system and existing laboratory study. Results. We found that the morphological parameters of the opposition surge decrease monotonically with wavelength, whereas in the case of coherent backscattering this behavior should be the reverse. The results from comparative analysis place 67P in the same category as the two Mars satellites, Phobos and Deimos, which are notably different from all airless bodies in the solar system. The similarity between the surface phase function of 67P and a carbon soot sample at extremely small angles is identified, introducing regolith at the boundary of the Imhotep-Ash region of 67P as a very dark and fluffy layer.© ESO, 2017.

Published
2017

26. Seasonal erosion and restoration of the dust cover on comet 67P/Churyumov-Gerasimenko as observed by OSIRIS onboard Rosetta

Author

European Space Agency, Centre National de la Recherche Scientifique (France), Agenzia Spaziale Italiana, Swedish National Space Board, Ministerio de Economía y Competitividad (España), International Max Planck Research Schools, German Centre for Air and Space Travel, Hu, X., Shi, X., Sierks, H., Fulle, M., Blum, J., Keller, H.U., Kührt, E., Davidsson, B., Güttler, C., Gundlach, B., Pajola, M., Bodewits, D., Vincent, J.B., Oklay, N., Massironi, M., Fornasier, S., Tubiana, C., Groussin, O., Boudreault, S., Höfner, S., Mottola, S., Barbieri, C., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Rickman, H., A'Hearn, M. F., Agarwal, J., Barucci, M.A., Bertaux, J.L., Bertini, I., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., El-Maarry, M. R., Gicquel, A., Gutierrez-Marques, P., Gutiérrez, Pedro J., Hofmann, M., Hviid, S.F., Ip, W. H., Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J.R., Küppers, M., Lara, Luisa María, López-Moreno, José Juan, European Space Agency, Centre National de la Recherche Scientifique (France), Agenzia Spaziale Italiana, Swedish National Space Board, Ministerio de Economía y Competitividad (España), International Max Planck Research Schools, German Centre for Air and Space Travel, Hu, X., Shi, X., Sierks, H., Fulle, M., Blum, J., Keller, H.U., Kührt, E., Davidsson, B., Güttler, C., Gundlach, B., Pajola, M., Bodewits, D., Vincent, J.B., Oklay, N., Massironi, M., Fornasier, S., Tubiana, C., Groussin, O., Boudreault, S., Höfner, S., Mottola, S., Barbieri, C., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Rickman, H., A'Hearn, M. F., Agarwal, J., Barucci, M.A., Bertaux, J.L., Bertini, I., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., El-Maarry, M. R., Gicquel, A., Gutierrez-Marques, P., Gutiérrez, Pedro J., Hofmann, M., Hviid, S.F., Ip, W. H., Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J.R., Küppers, M., Lara, Luisa María, and López-Moreno, José Juan

Abstract

Context. Dust deposits or dust cover are a prevalent morphology in the northern hemi-nucleus of comet 67P/Churyumov-Gerasimenko (67P). The evolution of the dust deposits was captured by the OSIRIS camera system onboard the Rosetta spacecraft having escorted the comet for over two years. The observations shed light on the fundamental role of cometary activity in shaping and transforming the surface morphology. Aims. We aim to present OSIRIS observations of surface changes over the dust deposits before and after perihelion. The distribution of changes and a timeline of their occurrence are provided. We perform a data analysis to quantify the surface changes and investigate their correlation to water activity from the dust deposits. We further discuss how the results of our investigation are related to other findings from the Rosetta mission. Methods. Surface changes were detected via systematic comparison of images, and quantified using shape-from-shading technique. Thermal models were applied to estimate the erosion of water ice in response to the increasing insolation over the areas where surface changes occurred. Modeling results were used for the interpretation of the observed surface changes. Results. Surface changes discussed here were concentrated at mid-latitudes, between about 20â-N and 40â-N, marking a global transition from the dust-covered to rugged terrains. The changes were distributed in open areas exposed to ample solar illumination and likely subject to enhanced surface erosion before perihelion. The occurrence of changes followed the southward migration of the sub-solar point across the latitudes of their distribution. The erosion at locations of most changes was at least about 0.5 m, but most likely did not exceed several meters. The erosive features before perihelion had given way to a fresh, smooth cover of dust deposits after perihelion, suggesting that the dust deposits had been globally restored by at least about 1 m with ejecta from the intens

Published
2017

27. Evidence of sub-surface energy storage in comet 67P from the outburst of 2016 July 03

Author

Centre National de la Recherche Scientifique (France), German Centre for Air and Space Travel, Agenzia Spaziale Italiana, Swedish National Space Board, Ministerio de Economía y Competitividad (España), European Space Agency, Agarwal, J., Della Corte, V., Feldman, P. D., Geiger, B., Merouane, S., Bertini, I., Bodewits, D., Fornasier, S., Grün, E., Hasselmann, P.H., Hilchenbach, M., Höfner, S., Ivanovski, S., Kolokolova, L., Pajola, M., Rotundi, A., Sierks, H., Steffl, A. J., Thomas, N., A'Hearn, M. F., Barbieri, C., Barucci, M.A., Bertaux, J.L., Boudreault, S., Cremonese, G., Da Deppo, Vania, Davidsson, B., Debei, S., De Cecco, M., Deller, J. F., Feaga, L. M., Fischer, H., Fulle, M., Gicquel, A., Groussin, O., Güttler, C., Gutiérrez, Pedro 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., Langevin, Y., Lara, Luisa María, López-Moreno, José Juan, Rodrigo Montero, Rafael, Centre National de la Recherche Scientifique (France), German Centre for Air and Space Travel, Agenzia Spaziale Italiana, Swedish National Space Board, Ministerio de Economía y Competitividad (España), European Space Agency, Agarwal, J., Della Corte, V., Feldman, P. D., Geiger, B., Merouane, S., Bertini, I., Bodewits, D., Fornasier, S., Grün, E., Hasselmann, P.H., Hilchenbach, M., Höfner, S., Ivanovski, S., Kolokolova, L., Pajola, M., Rotundi, A., Sierks, H., Steffl, A. J., Thomas, N., A'Hearn, M. F., Barbieri, C., Barucci, M.A., Bertaux, J.L., Boudreault, S., Cremonese, G., Da Deppo, Vania, Davidsson, B., Debei, S., De Cecco, M., Deller, J. F., Feaga, L. M., Fischer, H., Fulle, M., Gicquel, A., Groussin, O., Güttler, C., Gutiérrez, Pedro 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., Langevin, Y., Lara, Luisa María, López-Moreno, José Juan, and Rodrigo Montero, Rafael

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.© 2015 The Authors.

Published
2017

28. Characterization of dust aggregates in the vicinity of the Rosetta spacecraft

Author

Swedish National Space Board, Ministerio de Economía y Competitividad (España), German Centre for Air and Space Travel, Agenzia Spaziale Italiana, Centre National de la Recherche Scientifique (France), European Space Agency, Güttler, C., Hasselmann, P.H., Li, Y., Fulle, M., Tubiana, C., Kovacs, G., Agarwal, J., Sierks, H., Fornasier, S., Hofmann, M., Gutiérrez Marqués, P., Ott, T., Drolshagen, E., Bertini, I., Barbieri, C., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Rickman, H., A'Hearn, M. F., Barucci, M.A., Bodewits, D., Bertaux, J.L., Boudreault, S., Cremonese, G., Da Deppo, Vania, Davidsson, B., Debei, S., De Cecco, M., Deller, J., Geiger, B., Groussin, O., Gutiérrez, Pedro J., Hviid, S.F., Ip, W. H., Jorda, L., Keller, H.U., Knollenberg, J., Kramm, J.R., Kührt, E., Küppers, M., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Marzari, F., Mottola, S., Naletto, G., Oklay, N., Pajola, M., Swedish National Space Board, Ministerio de Economía y Competitividad (España), German Centre for Air and Space Travel, Agenzia Spaziale Italiana, Centre National de la Recherche Scientifique (France), European Space Agency, Güttler, C., Hasselmann, P.H., Li, Y., Fulle, M., Tubiana, C., Kovacs, G., Agarwal, J., Sierks, H., Fornasier, S., Hofmann, M., Gutiérrez Marqués, P., Ott, T., Drolshagen, E., Bertini, I., Barbieri, C., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Rickman, H., A'Hearn, M. F., Barucci, M.A., Bodewits, D., Bertaux, J.L., Boudreault, S., Cremonese, G., Da Deppo, Vania, Davidsson, B., Debei, S., De Cecco, M., Deller, J., Geiger, B., Groussin, O., Gutiérrez, Pedro J., Hviid, S.F., Ip, W. H., Jorda, L., Keller, H.U., Knollenberg, J., Kramm, J.R., Kührt, E., Küppers, M., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Marzari, F., Mottola, S., Naletto, G., Oklay, N., and Pajola, M.

Abstract

In a Rosetta/OSIRIS imaging activity in 2015 June, we have observed the dynamic motion of particles close to the spacecraft. Due to the focal setting of the OSIRIS wide angle camera, these particles were blurred, which can be used to measure their distances to the spacecraft. We detected 109 dust aggregates over a 130 min long sequence, and find that their sizes are around a millimetre and their distances cluster between 2 and 40 m from the spacecraft. Their number densities are about a factor 10 higher than expected for the overall coma and highly fluctuating. Their velocities are small compared to the spacecraft orbital motion and directed away from the spacecraft, towards the comet. From this we conclude that they have interacted with the spacecraft and assess three possible scenarios. In the likeliest of the three scenarios, centimetre-sized aggregates collide with the spacecraft and we would observe the fragments. Ablation of a dust layer on the spacecraft's z panel (remote instrument viewing direction) when rotated towards the Sun is a reasonable alternative. We could also measure an acceleration for a subset of 18 aggregates, which is directed away from the Sun and can be explain by a rocket effect, which requires a minimum ice fraction of the order of 0.1 per cent.© 2017 The Authors.

Published
2017

30. 67P/Churyumov-Gerasimenko: Activity between March and June 2014 as observed from Rosetta/OSIRIS

Author

Tubiana, C., Snodgrass, C., Bertini, I., Mottola, S., Vincent, J.-B., Lara, L., Fornasier, S., Knollenberg, J., Thomas, N., Fulle, M., Agarwal, J., Bodewits, D., Ferri, F., Güttler, C., Gutiérrez, P.J., La Forgia, F., Lowry, S., Magrin, S., Oklay, N., Pajola, M., Rodrigo, R., Sierks, H., A'hearn, M.F., Angrilli, F., Barbieri, C., Barucci, M.A., Bertaux, J.-L., Cremonese, G., Da Deppo, V., Davidsson, B., De Cecco, M., Debei, S., Groussin, O., Hviid, S.F., Ip, W., Jorda, L., Keller, H.U., Koschny, D., Kramm, R., Kührt, E., Küppers, M., Lazzarin, M., Lamy, P.L., Lopez Moreno, J.J., Marzari, F., Michalik, H., Naletto, G., Rickman, H., Sabau, L., Wenzel, K.-P., Tubiana, C., Snodgrass, C., Bertini, I., Mottola, S., Vincent, J.-B., Lara, L., Fornasier, S., Knollenberg, J., Thomas, N., Fulle, M., Agarwal, J., Bodewits, D., Ferri, F., Güttler, C., Gutiérrez, P.J., La Forgia, F., Lowry, S., Magrin, S., Oklay, N., Pajola, M., Rodrigo, R., Sierks, H., A'hearn, M.F., Angrilli, F., Barbieri, C., Barucci, M.A., Bertaux, J.-L., Cremonese, G., Da Deppo, V., Davidsson, B., De Cecco, M., Debei, S., Groussin, O., Hviid, S.F., Ip, W., Jorda, L., Keller, H.U., Koschny, D., Kramm, R., Kührt, E., Küppers, M., Lazzarin, M., Lamy, P.L., Lopez Moreno, J.J., Marzari, F., Michalik, H., Naletto, G., Rickman, H., Sabau, L., and Wenzel, K.-P.

Abstract

Aims. 67P/Churyumov-Gerasimenko is the target comet of the ESA's Rosetta mission. After commissioning at the end of March 2014, the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) onboard Rosetta, started imaging the comet and its dust environment to investigate how they change and evolve while approaching the Sun.

Published
2015

31. Large-scale dust jets in the coma of 67P/Churyumov-Gerasimenko as seen by the OSIRIS instrument onboard Rosetta

Author

Lara, L.M., Lowry, S., Vincent, J.-B., Gutierrez, P.J., Rożek, A., La Forgia, F., Oklay, N., Sierks, H., Barbieri, C., Lamy, P.L., Rodrigo, R., Koschny, D., Rickman, H., Keller, H.U., Agarwal, J., Auger, A.-T., A'Hearn, M.F., Barucci, M.A., Bertaux, J.-L., Bertini, I., Besse, S., Bodewits, D., Cremonese, G., Davidsson, B., Da Deppo, V., Debei, S., De Cecco, M., El-Maarry, M.R., Ferri, F., Fornasier, S., Fulle, M., Groussin, O., Gutiérrez-Marques, P., Güttler, C., Hviid, S.F., Ip, W.-H., Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J.-R., Kührt, E., Küppers, M., Lazzarin, M., Lin, Z.-Y., López-Moreno, J.J., Magrin, S., Marzari, F., Michalik, H., Moissl-Fraund, R., Moreno, F., Mottola, S., Naletto, G., Pajola, M., Pommerol, A., Thomas, N., Sabau, M.D., Tubiana, C., Lara, L.M., Lowry, S., Vincent, J.-B., Gutierrez, P.J., Rożek, A., La Forgia, F., Oklay, N., Sierks, H., Barbieri, C., Lamy, P.L., Rodrigo, R., Koschny, D., Rickman, H., Keller, H.U., Agarwal, J., Auger, A.-T., A'Hearn, M.F., Barucci, M.A., Bertaux, J.-L., Bertini, I., Besse, S., Bodewits, D., Cremonese, G., Davidsson, B., Da Deppo, V., Debei, S., De Cecco, M., El-Maarry, M.R., Ferri, F., Fornasier, S., Fulle, M., Groussin, O., Gutiérrez-Marques, P., Güttler, C., Hviid, S.F., Ip, W.-H., Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J.-R., Kührt, E., Küppers, M., Lazzarin, M., Lin, Z.-Y., López-Moreno, J.J., Magrin, S., Marzari, F., Michalik, H., Moissl-Fraund, R., Moreno, F., Mottola, S., Naletto, G., Pajola, M., Pommerol, A., Thomas, N., Sabau, M.D., and Tubiana, C.

Abstract

During the most recent perihelion passage in 2009 of comet 67P/Churyumov-Gerasimenko (67P), ground-based observations showed an anisotropic dust coma where jet-like features were detected at ~ 1.3 AU from the Sun. The current perihelion passage is exceptional as the Rosetta spacecraft is monitoring the nucleus activity since March 2014, when a clear dust coma was already surrounding the nucleus at 4.3 AU from the Sun. Subsequently, the OSIRIS camera also witnessed an outburst in activity between April 27 and 30, and since mid-July, the dust coma at rh ~ 3.7-3.6 AU preperihelion is clearly non-isotropic, pointing to the existence of dust jet-like features. We aim to ascertain on the nucleus surface the origin of the dust jet-like features detected as early as in mid-July 2014. This will help to establish how the localized comet nucleus activity compares with that seen in previous apparitions and will also help following its evolution as the comet approaches its perihelion, at which phase most of the jets were detected from ground-based observations. Determining these areas also allows locating them in regions on the nucleus with spectroscopic or geomorphological distinct characteristics. Methods. Three series of dust images of comet 67P obtained with the Wide Angle Camera (WAC) of the OSIRIS instrument onboard the Rosetta spacecraft were processed with different enhancement techniques. This was made to clearly show the existence of jet-like features in the dust coma, whose appearance toward the observer changed as a result of the rotation of the comet nucleus and of the changing observing geometry from the spacecraft. The position angles of these features in the coma together with information on the observing geometry, nucleus shape, and rotation, allowed us to determine the most likely locations on the nucleus surface where the jets originate from. Results. Geometrical tracing of jet sources indicates that the activity of the nucleus of 67P gave rise during July and

Published
2015

32. OSIRIS observations of meter-sized exposures of H2O ice at the surface of 67P/Churyumov-Gerasimenko and interpretation using laboratory experiments

Author

Pommerol, A., Thomas, N., El-Maarry, M.R., Pajola, M., Groussin, O., Auger, A.-T., Oklay, N., Fornasier, S., Feller, C., Davidsson, B., Gracia-Berna, A., Jost, B., Marschall, R., Poch, O., Barucci, M.A., Bertaux, J.-L., La Forgia, F., Keller, H.U., Kührt, E., Lowry, S.C., Mottola, S., Naletto, G., Sierks, H., Barbieri, C., Lamy, P.L., Rodrigo, R., Koschny, D., Rickman, H., Agarwal, J., A'Hearn, M.F., Bertini, I., Boudreault, S., Cremonese, G., Da Deppo, V., De Cecco, M., Debei, S., Güttler, C., Fulle, M., Gutiérrez, P.J., Hviid, S.F., Ip, W.-H., Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J.-R., Kuppers, E., Lara, L., Lazzarin, M., Lopez Moreno, J.L., Marzari, F., Michalik, H., Preusker, F., Scholten, F., Tubiana, C., Vincent, J.-B., Pommerol, A., Thomas, N., El-Maarry, M.R., Pajola, M., Groussin, O., Auger, A.-T., Oklay, N., Fornasier, S., Feller, C., Davidsson, B., Gracia-Berna, A., Jost, B., Marschall, R., Poch, O., Barucci, M.A., Bertaux, J.-L., La Forgia, F., Keller, H.U., Kührt, E., Lowry, S.C., Mottola, S., Naletto, G., Sierks, H., Barbieri, C., Lamy, P.L., Rodrigo, R., Koschny, D., Rickman, H., Agarwal, J., A'Hearn, M.F., Bertini, I., Boudreault, S., Cremonese, G., Da Deppo, V., De Cecco, M., Debei, S., Güttler, C., Fulle, M., Gutiérrez, P.J., Hviid, S.F., Ip, W.-H., Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J.-R., Kuppers, E., Lara, L., Lazzarin, M., Lopez Moreno, J.L., Marzari, F., Michalik, H., Preusker, F., Scholten, F., Tubiana, C., and Vincent, J.-B.

Abstract

Since OSIRIS started acquiring high-resolution observations of the surface of the nucleus of comet 67P/Churyumov-Gerasimenko, over one hundred meter-sized bright spots have been identified in numerous types of geomorphologic regions, but mostly located in areas receiving low insolation. The bright spots are either clustered, in debris fields close to decameter-high cliffs, or isolated without structural relation to the surrounding terrain. They can be up to ten times brighter than the average surface of the comet at visible wavelengths and display a significantly bluer spectrum. They do not exhibit significant changes over a period of a few weeks. All these observations are consistent with exposure of water ice at the surface of boulders produced by dislocation of the weakly consolidated layers that cover large areas of the nucleus. Laboratory experiments show that under simulated comet surface conditions, analog samples acquire a vertical stratification with an uppermost porous mantle of refractory dust overlaying a layer of hard ice formed by recondensation or sintering under the insulating dust mantle. The evolution of the visible spectrophotometric properties of samples during sublimation is consistent with the contrasts of brightness and color seen at the surface of the nucleus. Clustered bright spots are formed by the collapse of overhangs that is triggered by mass wasting of deeper layers. Isolated spots might be the result of the emission of boulders at low velocity that are redepositioned in other regions. © 2015 ESO.

Published
2015

33. Orbital elements of the material surrounding comet 67P/Churyumov-Gerasimenko

Author

Davidsson, B.J.R., Gutierrez, P.J., Sierks, H., Barbieri, C., Lamy, P.L., Rodrigo, R., Koschny, D., Rickman, H., Keller, H.U., Agarwal, J., A'Hearn, M.F., Barucci, M.A., Bertaux, J.-L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, V., Debei, S., De Cecco, M., Fornasier, S., Fulle, M., Groussin, O., Guttler, C., Hviid, S.F., Ip, W.-H., Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J.-R., Kuhrt, E., Kuppers, M., La Forgia, F., Lara, L.M., Lazzarin, M., Lopez Moreno, J.J., Lowry, S., Magrin, S., Marzari, F., Michalik, H., Moissl-Fraund, R., Naletto, G., Oklay, N., Pajola, M., Snodgrass, C., Thomas, N., Tubiana, C., Vincent, J.-B., Davidsson, B.J.R., Gutierrez, P.J., Sierks, H., Barbieri, C., Lamy, P.L., Rodrigo, R., Koschny, D., Rickman, H., Keller, H.U., Agarwal, J., A'Hearn, M.F., Barucci, M.A., Bertaux, J.-L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, V., Debei, S., De Cecco, M., Fornasier, S., Fulle, M., Groussin, O., Guttler, C., Hviid, S.F., Ip, W.-H., Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J.-R., Kuhrt, E., Kuppers, M., La Forgia, F., Lara, L.M., Lazzarin, M., Lopez Moreno, J.J., Lowry, S., Magrin, S., Marzari, F., Michalik, H., Moissl-Fraund, R., Naletto, G., Oklay, N., Pajola, M., Snodgrass, C., Thomas, N., Tubiana, C., and Vincent, J.-B.

Abstract

We investigate the dust coma within the Hill sphere of comet 67P/Churyumov-Gerasimenko. We aim to determine osculating orbital elements for individual distinguishable but unresolved slow-moving grains in the vicinity of the nucleus. In addition, we perform photometry and constrain grain sizes. Methods. We performed astrometry and photometry using images acquired by the OSIRIS Wide Angle Camera on the European Space Agency spacecraft Rosetta. Based on these measurements, we employed standard orbit determination and orbit improvement techniques. Results. Orbital elements and effective diameters of four grains were constrained, but we were unable to uniquely determine them. Two of the grains have light curves that indicate grain rotation. Conclusions. The four grains have diameters nominally in the range 0.14-0.50 m. For three of the grains, we found elliptic orbits, which is consistent with a cloud of bound particles around the nucleus. However, hyperbolic escape trajectories cannot be excluded for any of the grains, and for one grain this is the only known option. One grain may have originated from the surface shortly before observation. These results have possible implications for the understanding of the dispersal of the cloud of bound debris around comet nuclei, as well as for understanding the ejection of large grains far from the Sun.

Published
2015

34. Dust measurements in the coma of comet 67P/Churyumov-Gerasimenko inbound to the sun

Author

Rotundi, A., Sierks, H., Della Corte, V., Fulle, M., Gutierrez, P.J., Lara, L., Barbieri, C., Lamy, P.L., Rodrigo, R., Koschny, D., Rickman, H., Keller, H.U., López-Moreno, J.J., Accolla, M., Agarwal, J., A'Hearn, M.F., Altobelli, N., Angrilli, F., Barucci, M.A., Bertaux, J.-L., Bertini, I., Bodewits, D., Bussoletti, E., Colangeli, L., Cosi, M., Cremonese, G., Crifo, J.-F., Da Deppo, V., Davidsson, B., Debei, S., De Cecco, M., Esposito, F., Ferrari, M., Fornasier, S., Giovane, F., Gustafson, B., Green, S.F., Groussin, O., Grün, E., Güttler, C., Herranz, M.L., Hviid, S.F., Ip, W., Ivanovski, S., Jerónimo, J.M., Jorda, L., Knollenberg, J., Kramm, R., Kührt, E., Küppers, M., Lazzarin, M., Leese, M.R., López-Jiménez, A.C., Lucarelli, F., Lowry, S.C., Marzari, F., Epifani, E.M., McDonnell, J.A.M., Mennella, V., Michalik, H., Molina, A., Morales, R., Moreno, F., Mottola, S., Naletto, G., Oklay, N., Ortiz, J.L., Palomba, E., Palumbo, P., Perrin, J.-M., Rodríguez, J., Sabau, L., Snodgrass, C., Sordini, R., Thomas, N., Tubiana, C., Vincent, J.-B., Weissman, P., Wenzel, K.-P., Zakharov, V., Zarnecki, J.C., Rotundi, A., Sierks, H., Della Corte, V., Fulle, M., Gutierrez, P.J., Lara, L., Barbieri, C., Lamy, P.L., Rodrigo, R., Koschny, D., Rickman, H., Keller, H.U., López-Moreno, J.J., Accolla, M., Agarwal, J., A'Hearn, M.F., Altobelli, N., Angrilli, F., Barucci, M.A., Bertaux, J.-L., Bertini, I., Bodewits, D., Bussoletti, E., Colangeli, L., Cosi, M., Cremonese, G., Crifo, J.-F., Da Deppo, V., Davidsson, B., Debei, S., De Cecco, M., Esposito, F., Ferrari, M., Fornasier, S., Giovane, F., Gustafson, B., Green, S.F., Groussin, O., Grün, E., Güttler, C., Herranz, M.L., Hviid, S.F., Ip, W., Ivanovski, S., Jerónimo, J.M., Jorda, L., Knollenberg, J., Kramm, R., Kührt, E., Küppers, M., Lazzarin, M., Leese, M.R., López-Jiménez, A.C., Lucarelli, F., Lowry, S.C., Marzari, F., Epifani, E.M., McDonnell, J.A.M., Mennella, V., Michalik, H., Molina, A., Morales, R., Moreno, F., Mottola, S., Naletto, G., Oklay, N., Ortiz, J.L., Palomba, E., Palumbo, P., Perrin, J.-M., Rodríguez, J., Sabau, L., Snodgrass, C., Sordini, R., Thomas, N., Tubiana, C., Vincent, J.-B., Weissman, P., Wenzel, K.-P., Zakharov, V., and Zarnecki, J.C.

Abstract

Critical measurements for understanding accretion and the dust/gas ratio in the solar nebula, where planets were forming 4.5 billion years ago, are being obtained by the GIADA (Grain Impact Analyser and Dust Accumulator) experiment on the European Space Agency's Rosetta spacecraft orbiting comet 67P/Churyumov-Gerasimenko. Between 3.6 and 3.4 astronomical units inbound, GIADA and OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) detected 35 outflowing grains of mass 10-10 to 10-7 kilograms, and 48 grains of mass 10-5 to 10-2 kilograms, respectively. Combined with gas data from the MIRO (Microwave Instrument for the Rosetta Orbiter) and ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) instruments, we find a dust/gas mass ratio of 4 ± 2 averaged over the sunlit nucleus surface. A cloud of larger grains also encircles the nucleus in bound orbits from the previous perihelion. The largest orbiting clumps are meter-sized, confirming the dust/gas ratio of 3 inferred at perihelion from models of dust comae and trails. © 2015, American Association for the Advancement of Science. All rights reserved.

Published
2015

35. Morphology and dynamics of the jets of comet 67P/Churyumov-Gerasimenko: Early-phase development

Author

Lin, Z.-Y., Ip, W.-H., Lai, I.-L., Lee, J.-C., Vincent, J.-B., Lara, L.M., Bodewits, D., Sierks, H., Barbieri, C., Lamy, P.L., Rodrigo, R., Koschny, D., Rickman, H., Keller, H.U., Agarwal, J., A'Hearn, M.F., Barucci, M.A., Bertaux, J.-L., Bertini, I., Cremonese, G., Da Deppo, V., Davidsson, B., Debei, S., De Cecco, M., Fornasier, S., Fulle, M., Groussin, O., Gutiérrez, P.J., Güttler, C., Hviid, S.F., Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J.-R., Kührt, E., Küppers, M., La Forgia, F., Lazzarin, M., López-Moreno, J.J., Lowry, S.C., Marzari, F., Michalik, H., Mottola, S., Naletto, G., Oklay, N., Pajola, M., Rożek, A., Thomas, N., Liao, Y., Tubiana, C., Lin, Z.-Y., Ip, W.-H., Lai, I.-L., Lee, J.-C., Vincent, J.-B., Lara, L.M., Bodewits, D., Sierks, H., Barbieri, C., Lamy, P.L., Rodrigo, R., Koschny, D., Rickman, H., Keller, H.U., Agarwal, J., A'Hearn, M.F., Barucci, M.A., Bertaux, J.-L., Bertini, I., Cremonese, G., Da Deppo, V., Davidsson, B., Debei, S., De Cecco, M., Fornasier, S., Fulle, M., Groussin, O., Gutiérrez, P.J., Güttler, C., Hviid, S.F., Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J.-R., Kührt, E., Küppers, M., La Forgia, F., Lazzarin, M., López-Moreno, J.J., Lowry, S.C., Marzari, F., Michalik, H., Mottola, S., Naletto, G., Oklay, N., Pajola, M., Rożek, A., Thomas, N., Liao, Y., and Tubiana, C.

Abstract

Aims. The OSIRIS camera onboard the Rosetta spacecraft obtained close-up views of the dust coma of comet 67P. The jet structures can be used to trace their source regions and to examine the possible effect of gas-surface interaction. Methods. We analyzed the wide-angle images obtained in the special dust observation sequences between August and September 2014. The jet features detected in different images were compared to study their time variability. The locations of the potential source regions of some of the jets are identified by ray tracing. We used a ring-masking technique to calculate the brightness distribution of dust jets along the projected distance. Results. The jets detected between August and September 2014 mostly originated in the Hapi region. Morphological changes appeared over a timescale of several days in September. The brightness slope of the dust jets is much steeper than the background coma. This might be related to the sublimation or fragmentation of the emitted dust grains. Interaction of the expanding gas flow with the cliff walls on both sides of Hapi could lead to erosion and material down-fall to the nucleus surface. © ESO, 2015.

Published
2015

36. Winds at the Mars Phoenix landing site

Author

Holstein-Rathlou, Christina, Gunnlaugsson, Haraldur Pall, Merrison, Jonathan P., Bean, K.M., Cantor, B.A., Davis, J.A., Davy, R., Drake, N.B., Ellehøj, Mads Dam, Walter, Goetz, Hviid, S.F., Lange, C.F., Larsen, S.E., Lemmon, M., Madsen, M.B., Malin, M., Moores, J.E., Nørnberg, Per, Smith, P., Taylor, P., and Tamppari, L.

Published
2009

37. H20 at the Phoenix Landing Site

Author

Smith, P.H., Tamppari, L.K., Arvidson, R.E., Bass, D., Blaney, D., Boynton, W.V., Carswell, A., Catling, D.C., Clark, B.C., Duck, T., DeJong, E., Fisher, D., Goetz, W., Gunnlaugsson, Haraldur Pall, Hecht, M.H., Hipkin, V., Hoffman, J., Hviid, S.F., Keller, H.U., Kounaves, S.P., Lange, C.F., Lemmon, M.T., Madsen, M.B., Markiewicz, W.J., Marshall, J., McKay, C.P., Mellon, M.T., Ming, D.W., Morris, R.W., Pike, W.T., Renno, N., Staufer, U., Stoker, C., Taylor, P., Whiteway, J.A., and Zent, A.P.

Published
2009

41. Backscattering Mössbauer spectroscopy of Martian dust

Author

Bertelsen, P., Madsen, M.B., Binau, C.S., Goetz, W., Gunnlaugsson, Haraldur Pall, Hviid, S.F., Klingelhöfer, K.M., Leer, K., Madsen, D.E., Merrison, Jonathan, Olsen, M., and Squyers, S.W.

Published
2005

43. Preliminary identification of minerals in silt- and sand-size grains on mars from phoenix om images using three-channel color photometry

Author

Velbel, M.A. (author), Goetz, W. (author), Hecht, M.H. (author), Hviid, S.F. (author), Madsen, M.B. (author), Pike, W.T. (author), Staufer, U. (author), Velbel, M.A. (author), Goetz, W. (author), Hecht, M.H. (author), Hviid, S.F. (author), Madsen, M.B. (author), Pike, W.T. (author), and Staufer, U. (author)

Abstract

Micro and Nano Engineering

Published
2014

44. The rotation state of 67P/Churyumov-Gerasimenko from approach observations with the OSIRIS cameras on Rosetta

Author

Mottola, S., Lowry, S., Snodgrass, C., Lamy, P.L., Toth, I., Rożek, A., Sierks, H., A'Hearn, M.F., Angrilli, F., Barbieri, C., Barucci, M.A., Bertaux, J.-L., Cremonese, G., Da Deppo, V., Davidsson, B., De Cecco, M., Debei, S., Fornasier, S., Fulle, M., Groussin, O., Gutiérrez, P., Hviid, S.F., Ip, W., Jorda, L., Keller, H.U., Knollenberg, J., Koschny, D., Kramm, R., Kührt, E., Küppers, M., Lara, L., Lazzarin, M., Lopez Moreno, J.J., Marzari, F., Michalik, H., Naletto, G., Rickman, H., Rodrigo, R., Sabau, L., Thomas, N., Wenzel, K.-P., Agarwal, J., Bertini, I., Ferri, F., Güttler, C., Magrin, S., Oklay, N., Tubiana, C., Vincent, J.-B., Mottola, S., Lowry, S., Snodgrass, C., Lamy, P.L., Toth, I., Rożek, A., Sierks, H., A'Hearn, M.F., Angrilli, F., Barbieri, C., Barucci, M.A., Bertaux, J.-L., Cremonese, G., Da Deppo, V., Davidsson, B., De Cecco, M., Debei, S., Fornasier, S., Fulle, M., Groussin, O., Gutiérrez, P., Hviid, S.F., Ip, W., Jorda, L., Keller, H.U., Knollenberg, J., Koschny, D., Kramm, R., Kührt, E., Küppers, M., Lara, L., Lazzarin, M., Lopez Moreno, J.J., Marzari, F., Michalik, H., Naletto, G., Rickman, H., Rodrigo, R., Sabau, L., Thomas, N., Wenzel, K.-P., Agarwal, J., Bertini, I., Ferri, F., Güttler, C., Magrin, S., Oklay, N., Tubiana, C., and Vincent, J.-B.

Abstract

Aims. Approach observations with the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) experiment onboard Rosetta are used to determine the rotation period, the direction of the spin axis, and the state of rotation of comet 67P's nucleus. Methods. Photometric time series of 67P have been acquired by OSIRIS since the post wake-up commissioning of the payload in March 2014. Fourier analysis and convex shape inversion methods have been applied to the Rosetta data as well to the available ground-based observations. Results. Evidence is found that the rotation rate of 67P has significantly changed near the time of its 2009 perihelion passage, probably due to sublimation-induced torque. We find that the sidereal rotation periods P1 = 12.76129 ± 0.00005 h and P2 = 12.4043 ± 0.0007 h for the apparitions before and after the 2009 perihelion, respectively, provide the best fit to the observations. No signs of multiple periodicity are found in the light curves down to the noise level, which implies that the comet is presently in a simple rotation state around its axis of largest moment of inertia. We derive a prograde rotation model with spin vector J2000 ecliptic coordinates ? = 65° ± 15°, ? = + 59° ± 15°, corresponding to equatorial coordinates RA = 22°, Dec = + 76°. However, we find that the mirror solution, also prograde, at ? = 275° ± 15°, ? = + 50° ± 15° (or RA = 274°, Dec = + 27°), is also possible at the same confidence level, due to the intrinsic ambiguity of the photometric problem for observations performed close to the ecliptic plane. © 2014 ESO.

Published
2014

45. Microscopy analysis of soils at the Phoenix landing site, Mars: Classification of soil particles and description of their optical and magnetic properties

Author

Goetz, W. (author), Pike, W.T. (author), Hviid, S.F. (author), Madsen, M.B. (author), Morris, R.V. (author), Hecht, M.H. (author), Staufer, U. (author), Leer, K. (author), Sykulska, H. (author), Hemmig, E. (author), Marshall, J. (author), Morookian, J.M. (author), Parrat, D. (author), Vijendran, S. (author), Bos, B.J. (author), El Maarry, M.R. (author), Keller, H.U. (author), Kramm, R. (author), Markiewicz, W.J. (author), Drube, L. (author), Blaney, D. (author), Arvidson, R.E. (author), Bell, J.F. (author), Reynolds, R. (author), Smith, P.H. (author), Woida, P. (author), Woida, R. (author), Tanner, R. (author), Goetz, W. (author), Pike, W.T. (author), Hviid, S.F. (author), Madsen, M.B. (author), Morris, R.V. (author), Hecht, M.H. (author), Staufer, U. (author), Leer, K. (author), Sykulska, H. (author), Hemmig, E. (author), Marshall, J. (author), Morookian, J.M. (author), Parrat, D. (author), Vijendran, S. (author), Bos, B.J. (author), El Maarry, M.R. (author), Keller, H.U. (author), Kramm, R. (author), Markiewicz, W.J. (author), Drube, L. (author), Blaney, D. (author), Arvidson, R.E. (author), Bell, J.F. (author), Reynolds, R. (author), Smith, P.H. (author), Woida, P. (author), Woida, R. (author), and Tanner, R. (author)

Abstract

The optical microscope onboard the Phoenix spacecraft has returned color images (4 ?m pixel?1) of soils that were delivered to and held on various substrates. A preliminary taxonomy of Phoenix soil particles, based on color, size, and shape, identifies the following particle types [generic names in brackets]: (1) reddish fines, mostly unresolved, that are spectrally similar to (though slightly darker than) global airborne dust [red fines], (2) silt? to sand?sized brownish grains [brown sand], (3) silt? to sand?sized black grains [black sand], and (4) small amounts of whitish fines, possibly salts [white fines]. Most particles have a saturation magnetization in the range 0.5?2 Am2 kg?1 as inferred from their interaction with magnetic substrates. The particle size distribution has two distinct peaks below 10 ?m (fines) and in the range 20–100 ?m (grains), respectively, and is different from that of ripple soils in Gusev crater. In particular medium to large sand grains appear to be absent in Phoenix soils. Most sand grains have subrounded shape with variable texture. A fractured grain (observed on sol 112) reveals evidence of micrometer?sized crystal facets. The brown sand category displays a large diversity in color including shiny, almost colorless particles. Potential source regions for these grains may be the Tharsis volcanoes or Heimdal crater (20 km east of the landing site). The black grains are suggested to belong to a more widespread population of particles with mafic mineralogy. The absence of black/brown composite grains is consistent with different formation pathways and source regions for each grain type., Precision and Microsystems Engineering, Mechanical, Maritime and Materials Engineering

Published
2010
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46. E-type asteroid (2867) steins as imaged by OSIRIS on board rosetta

Author

Keller, H.U., Barbieri, C., Koschny, D., Lamy, P., Rkkman, H., Rodrigo, R., Sierks, H., A'Hearn, M.F., Angrilli, F., Barucci, M.A., Bertaux, J.-L., Cremonese, G., Da Deppo, V., Davidsson, B., De Cecco, M., Debei, S., Fornasier, S., Fulle, M., Groussin, O., Gutiérrez, P.J., Hviid, S.F., Ip, W.-H., Jorda, L., Knollenberg, J., Kramm, J.R., Kührt, E., Küppers, M., Lara, L.-M., Lazzarin, M., Lopez Moreno, J., Marzari, F., Michalik, H., Naletto, G., Sabau, L., Thomas, N., Wenzel, K.-P., Bertini, I., Besse, S., Ferri, F., Kaasalainen, M., Lowry, S.C., Marchi, S., Mottola, S., Sabolo, W., Schröder, S.E., Spjuth, S., Vernazza, P., Keller, H.U., Barbieri, C., Koschny, D., Lamy, P., Rkkman, H., Rodrigo, R., Sierks, H., A'Hearn, M.F., Angrilli, F., Barucci, M.A., Bertaux, J.-L., Cremonese, G., Da Deppo, V., Davidsson, B., De Cecco, M., Debei, S., Fornasier, S., Fulle, M., Groussin, O., Gutiérrez, P.J., Hviid, S.F., Ip, W.-H., Jorda, L., Knollenberg, J., Kramm, J.R., Kührt, E., Küppers, M., Lara, L.-M., Lazzarin, M., Lopez Moreno, J., Marzari, F., Michalik, H., Naletto, G., Sabau, L., Thomas, N., Wenzel, K.-P., Bertini, I., Besse, S., Ferri, F., Kaasalainen, M., Lowry, S.C., Marchi, S., Mottola, S., Sabolo, W., Schröder, S.E., Spjuth, S., and Vernazza, P.

Abstract

The European Space Agency's Rosetta mission encountered the main-belt asteroid (2867) Steins while on its way to rendezvous with comet 67P/Churyumov-Gerasimenko. Images taken with the OSIRIS (optical, spectroscopic, and infrared remote imaging system) cameras on board Rosetta show that Steins is an oblate body with an effective spherical diameter of 5.3 kilometers. Its surface does not show color variations. The morphology of Steins is dominated by linear faults and a large 2.1-kilometer-diameter crater near its south pole. Crater counts reveal a distinct lack of small craters. Steins is not solid rock but a rubble pile and has a conical appearance that is probably the result of reshaping due to Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) spin-up. The OSIRIS images constitute direct evidence for the YORP effect on a main-belt asteroid.

Published
2010

47. Comparison of some Phoenix and gusev soil types:inferences on possible origin and global distribution, in the Woodlands, Texas

Author

Walter..[et al.], Goetz, Hviid, S.F., Madsen, Morten Bo, Leer, Kristoffer, Drube, Line, Walter..[et al.], Goetz, Hviid, S.F., Madsen, Morten Bo, Leer, Kristoffer, and Drube, Line

Abstract

The comparison of soil particles at the Phoenix landing site and in Gusev Crater provides clues on their origin and global distribution. Some unusual Phoenix particles are possibly of (more) local origin, as they appear to be absent in Gusev dunes.

Published
2010

49. Observations of comet 9P/Tempel 1 and deep impact by the OSIRIS cameras onboard Rosetta

Author

Küppers, M., Keller, H.U., Fornasier, S., Gutiérrez, P.J., Hviid, S.F., Jorda, L., Knollenberg, J., Lowry, S.C., Rengel, M., Küppers, M., Keller, H.U., Fornasier, S., Gutiérrez, P.J., Hviid, S.F., Jorda, L., Knollenberg, J., Lowry, S.C., and Rengel, M.

Abstract

The OSIRIS cameras onboard ESA's Rosetta spacecraft observed comet 9P/Tempel 1 near-continuously from 28 June until 14 July 2005. The Narrow Angle Camera (NAC) monitored the cometary dust, while the wide angle camera (WAC) observed through filters sensitive to emissions of OH, CN, OI, Na, and the associated continuum. The brightness of the dust increased by a factor of 4.5 within 30 minutes, measured in a circular aperture of 3000 km radius centered on the nucleus. The brightening is likely caused by ejection of material from the crater, decreasing optical depth of the ejecta, and the evaporation of icy grains in the ejecta cloud. The dust moved with a typical velocity of 160 ms-1, suggesting acceleration of the dust by gas in the inner cometary coma. Images of the dust cloud taken several days after the impact show the effect of solar radiation pressure. The size distribution derived from an analysis of the radiation pressure is comparable to that commonly observed in cometary comae. The increase of the intensity of the OH emission due to the impact corresponds to a water production of (1.5-3)x10(+32) molecules. The dust production depends on the uncertain amount of large dust grains ejected by the impact, but the dust/gas ratio is likely to be larger than one. © 2009 Springer-Verlag Berlin Heidelberg.

Published
2009

50. Triple F-a comet nucleus sample return mission

Author

Küppers, Michael, Keller, H.U., Kührt, E., A'Hearn, M.F., Altwegg, K., Bertrand, R., Busemann, H., Capria, M.T., Colangeli, L., Davidsson, B., Ehrenfreund, P., Knollenberg, J., Mottola, S., Rathke, A., Weiss, P., Zolensky, M., Akim, E., Basilevsky, A., Galimov, E., Gerasimov, M., Korablev, O., Lomakin, I., Marov, M., Martynov, M., Nazarov, M., Zakharov, A., Zelenyi, L., Aronica, A., Ball, A.J., Barbieri, C., Bar-Nun, A., Benkhoff, J., Biele, J., Biver, N., Blum, J., Bockelée-Morvan, D., Botta, O., Bredehöft, J., Capaccioni, F., Charnley, S., Cloutis, E., Cottin, H., Cremonese, G., Crovisier, J., Crowther, S.A., Epifani, E.M., Esposito, F., Ferrari, A.C., Ferri, F., Fulle, M., Gilmour, J., Goesmann, F., Gortsas, N., Green, S.F., Groussin, O., Grün, E., Gutiérrez, P.J., Hartogh, P., Henkel, T., Hilchenbach, M., Ho, T., Horneck, G., Hviid, S.F., Ip, W., Jäckel, A., Jessberger, E., Kallenbach, R., Kargl, G., Kömle, N.I., Korth, A., Kossacki, K., Krause, C., Krüger, H., Li, Z., Licandro, J., Lopez-Moreno, J.J., Lowry, S.C., Lyon, I., Magni, G., Mall, U., Mann, I., Markiewicz, W., Martins, Z., Maurette, M., Meierhenrich, U., Mennella, V., Ng, T.C., Nittler, L.R., Palumbo, P., Pätzold, M., Prialnik, D., Rengel, M., Rickman, H., Rodriguez, J., Roll, R., Rost, D., Rotundi, A., Sandford, S., Schönbächler, M., Sierks, H., Srama, R., Stroud, R.M., Szutowicz, S., Tornow, C., Ulamec, S., Wallis, M., Waniak, W., Weissman, P., Wieler, R., Wurz, P., Yung, K.L., Zarnecki, J.C., Küppers, Michael, Keller, H.U., Kührt, E., A'Hearn, M.F., Altwegg, K., Bertrand, R., Busemann, H., Capria, M.T., Colangeli, L., Davidsson, B., Ehrenfreund, P., Knollenberg, J., Mottola, S., Rathke, A., Weiss, P., Zolensky, M., Akim, E., Basilevsky, A., Galimov, E., Gerasimov, M., Korablev, O., Lomakin, I., Marov, M., Martynov, M., Nazarov, M., Zakharov, A., Zelenyi, L., Aronica, A., Ball, A.J., Barbieri, C., Bar-Nun, A., Benkhoff, J., Biele, J., Biver, N., Blum, J., Bockelée-Morvan, D., Botta, O., Bredehöft, J., Capaccioni, F., Charnley, S., Cloutis, E., Cottin, H., Cremonese, G., Crovisier, J., Crowther, S.A., Epifani, E.M., Esposito, F., Ferrari, A.C., Ferri, F., Fulle, M., Gilmour, J., Goesmann, F., Gortsas, N., Green, S.F., Groussin, O., Grün, E., Gutiérrez, P.J., Hartogh, P., Henkel, T., Hilchenbach, M., Ho, T., Horneck, G., Hviid, S.F., Ip, W., Jäckel, A., Jessberger, E., Kallenbach, R., Kargl, G., Kömle, N.I., Korth, A., Kossacki, K., Krause, C., Krüger, H., Li, Z., Licandro, J., Lopez-Moreno, J.J., Lowry, S.C., Lyon, I., Magni, G., Mall, U., Mann, I., Markiewicz, W., Martins, Z., Maurette, M., Meierhenrich, U., Mennella, V., Ng, T.C., Nittler, L.R., Palumbo, P., Pätzold, M., Prialnik, D., Rengel, M., Rickman, H., Rodriguez, J., Roll, R., Rost, D., Rotundi, A., Sandford, S., Schönbächler, M., Sierks, H., Srama, R., Stroud, R.M., Szutowicz, S., Tornow, C., Ulamec, S., Wallis, M., Waniak, W., Weissman, P., Wieler, R., Wurz, P., Yung, K.L., and Zarnecki, J.C.

Abstract

The Triple F (Fresh From the Fridge) mission, a Comet Nucleus Sample Return, has been proposed to ESA's Cosmic Vision program. A sample return from a comet enables us to reach the ultimate goal of cometary research. Since comets are the least processed bodies in the solar system, the proposal goes far beyond cometary science topics (like the explanation of cometary activity) and delivers invaluable information about the formation of the solar system and the interstellar molecular cloud from which it formed. The proposed mission would extract three sample cores of the upper 50cm from three locations on a cometary nucleus and return them cooled to Earth for analysis in the laboratory. The simple mission concept with a touch-and-go sampling by a single spacecraft was proposed as an M-class mission in collaboration with the Russian space agency ROSCOSMOS. © The Author(s) 2008.

Published
2009

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