ALBERT

Description: Abstract Rosetta observations of 67P/Churyumov‐Gerasimenko (67P) reveal that most changes occur in the fallback‐generated smooth terrains, vast deposits of granular material blanketing the comet's northern hemisphere. These changes express themselves both morphologically and spectrally across the nucleus, yet we lack a model that describes their formation and evolution. Here we present a self‐consistent model that thoroughly explains the activity and mass loss from Hapi's smooth terrains. Our model predicts the removal of dust via re‐radiated solar insolation localized within depression scarps that are substantially more ice‐rich than previously expected. We couple our model with numerous Rosetta observations to thoroughly capture the seasonal erosion of Hapi's smooth terrains, where local scarp retreat gradually removes the uppermost dusty mantle. As sublimation‐regolith interactions occur on rocky planets, comets, icy moons and KBOs, our coupled model and observations provide a foundation for future understanding of the myriad of sublimation‐carved worlds.

Description: Pits have been observed on many cometary nuclei mapped by spacecraft. It has been argued that cometary pits are a signature of endogenic activity, rather than impact craters such as those on planetary and asteroid surfaces. Impact experiments and models cannot reproduce the shapes of most of the observed cometary pits, and the predicted collision rates imply that few of the pits are related to impacts. Alternative mechanisms like explosive activity have been suggested, but the driving process remains unknown. Here we report that pits on comet 67P/Churyumov-Gerasimenko are active, and probably created by a sinkhole process, possibly accompanied by outbursts. We argue that after formation, pits expand slowly in diameter, owing to sublimation-driven retreat of the walls. Therefore, pits characterize how eroded the surface is: a fresh cometary surface will have a ragged structure with many pits, while an evolved surface will look smoother. The size and spatial distribution of pits imply that large heterogeneities exist in the physical, structural or compositional properties of the first few hundred metres below the current nucleus surface.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Vincent, Jean-Baptiste -- Bodewits, Dennis -- Besse, Sebastien -- Sierks, Holger -- Barbieri, Cesare -- Lamy, Philippe -- Rodrigo, Rafael -- Koschny, Detlef -- Rickman, Hans -- Keller, Horst Uwe -- Agarwal, Jessica -- A'Hearn, Michael F -- Auger, Anne-Therese -- Barucci, M Antonella -- Bertaux, Jean-Loup -- Bertini, Ivano -- Capanna, Claire -- Cremonese, Gabriele -- Da Deppo, Vania -- Davidsson, Bjorn -- Debei, Stefano -- De Cecco, Mariolino -- El-Maarry, Mohamed Ramy -- Ferri, Francesca -- Fornasier, Sonia -- Fulle, Marco -- Gaskell, Robert -- Giacomini, Lorenza -- Groussin, Olivier -- Guilbert-Lepoutre, Aurelie -- Gutierrez-Marques, P -- Gutierrez, Pedro J -- Guttler, Carsten -- Hoekzema, Nick -- Hofner, Sebastian -- Hviid, Stubbe F -- Ip, Wing-Huen -- Jorda, Laurent -- Knollenberg, Jorg -- Kovacs, Gabor -- Kramm, Rainer -- Kuhrt, Ekkehard -- Kuppers, Michael -- La Forgia, Fiorangela -- Lara, Luisa M -- Lazzarin, Monica -- Lee, Vicky -- Leyrat, Cedric -- Lin, Zhong-Yi -- Lopez Moreno, Jose J -- Lowry, Stephen -- Magrin, Sara -- Maquet, Lucie -- Marchi, Simone -- Marzari, Francesco -- Massironi, Matteo -- Michalik, Harald -- Moissl, Richard -- Mottola, Stefano -- Naletto, Giampiero -- Oklay, Nilda -- Pajola, Maurizio -- Preusker, Frank -- Scholten, Frank -- Thomas, Nicolas -- Toth, Imre -- Tubiana, Cecilia -- England -- Nature. 2015 Jul 2;523(7558):63-6. doi: 10.1038/nature14564.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Max-Planck-Institut fur Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Gottingen, Germany. ; University of Maryland, Department of Astronomy, College Park, Maryland 20742-2421, USA. ; Scientific Support Office, European Space Research and Technology Centre/ESA, Keplerlaan 1, Postbus 299, 2201 AZ Noordwijk ZH, The Netherlands. ; University of Padova, Department of Physics and Astronomy, Vicolo dell'Osservatorio 3, 35122 Padova, Italy. ; Laboratoire d'Astrophysique de Marseille, UMR 7326, CNRS and Aix Marseille Universite, 13388 Marseille Cedex 13, France. ; 1] Centro de Astrobiologia, CSIC-INTA, 28850 Torrejon de Ardoz, Madrid, Spain [2] International Space Science Institute, Hallerstrasse 6, 3012 Bern, Switzerland. ; 1] Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden [2] PAS Space Research Center, Bartycka 18A, 00716 Warszawa, Poland. ; Institut fur Geophysik und extraterrestrische Physik (IGEP), Technische Universitat Braunschweig, Mendelssohnstrasse 3, 38106 Braunschweig, Germany. ; 1] University of Maryland, Department of Astronomy, College Park, Maryland 20742-2421, USA [2] Akademie der Wissenschaften zu Gottingen and Max-Planck-Institut fur Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Gottingen, Germany. ; LESIA-Observatoire de Paris, CNRS, Universite Pierre et Marie Curie, Universite Paris Diderot, 5 place Jules Janssen, 92195 Meudon, France. ; LATMOS, CNRS/UVSQ/IPSL, 11 boulevard d'Alembert, 78280 Guyancourt, France. ; Centro di Ateneo di Studi ed Attivita Spaziali "Giuseppe Colombo" (CISAS), University of Padova, via Venezia 15, 35131 Padova, Italy. ; INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy. ; CNR-IFN UOS Padova LUXOR, via Trasea 7, 35131 Padova, Italy. ; Centro de Astrobiologia, CSIC-INTA, 28850 Torrejon de Ardoz, Madrid, Spain. ; Department of Industrial Engineering, University of Padova, via Venezia 1, 35131 Padova, Italy. ; University of Trento, via Mesiano 77, 38100 Trento, Italy. ; Physikalisches Institut der Universitat Bern, Sidlerstrasse 5, 3012 Bern, Switzerland. ; INAF Osservatorio Astronomico, via Tiepolo 11, 34014 Trieste, Italy. ; Planetary Science Institute, Tucson, Arizona 85719, USA. ; Instituto de Astrofisica de Andalucia (CSIC), Glorieta de la Astronomia s/n, 18008 Granada, Spain. ; Deutsches Zentrum fur Luft- und Raumfahrt (DLR), Institut fur Planetenforschung, Rutherfordstrasse 2, 12489 Berlin, Germany. ; National Central University, Graduate Institute of Astronomy, 300 Chung-Da Rd, Chung-Li 32054, Taiwan. ; Operations Department, European Space Astronomy Centre/ESA, PO Box 78, 28691 Villanueva de la Canada, Madrid, Spain. ; The University of Kent, School of Physical Sciences, Canterbury, Kent CT2 7NZ, UK. ; University of Padova, Deptartment of Physics and Astronomy, via Marzolo 8, 35131 Padova, Italy. ; Solar System Exploration Research Virtual Institute, Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, Colorado 80302, USA. ; Dipartimento di Geoscienze, University of Padova, via Giovanni Gradenigo 6, 35131 Padova, Italy. ; Institut fur Datentechnik und Kommunikationsnetze der Technische Universitat Braunschweig, Hans-Sommer-Strasse 66, 38106 Braunschweig, Germany. ; 1] Centro di Ateneo di Studi ed Attivita Spaziali "Giuseppe Colombo" (CISAS), University of Padova, via Venezia 15, 35131 Padova, Italy [2] CNR-IFN UOS Padova LUXOR, via Trasea 7, 35131 Padova, Italy [3] University of Padova, Department of Information Engineering, via Gradenigo 6/B, 35131 Padova, Italy. ; Konkoly Observatory of the Hungarian Academy of Sciences, PO Box 67, 1525 Budapest, Hungary.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26135448" target="_blank"〉PubMed〈/a〉

Description: The factors shaping cometary nuclei are still largely unknown, but could be the result of concurrent effects of evolutionary and primordial processes. The peculiar bilobed shape of comet 67P/Churyumov-Gerasimenko may be the result of the fusion of two objects that were once separate or the result of a localized excavation by outgassing at the interface between the two lobes. Here we report that the comet's major lobe is enveloped by a nearly continuous set of strata, up to 650 metres thick, which are independent of an analogous stratified envelope on the minor lobe. Gravity vectors computed for the two lobes separately are closer to perpendicular to the strata than those calculated for the entire nucleus and adjacent to the neck separating the two lobes. Therefore comet 67P/Churyumov-Gerasimenko is an accreted body of two distinct objects with 'onion-like' stratification, which formed before they merged. We conclude that gentle, low-velocity collisions occurred between two fully formed kilometre-sized cometesimals in the early stages of the Solar System. The notable structural similarities between the two lobes of comet 67P/Churyumov-Gerasimenko indicate that the early-forming cometesimals experienced similar primordial stratified accretion, even though they formed independently.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Massironi, Matteo -- Simioni, Emanuele -- Marzari, Francesco -- Cremonese, Gabriele -- Giacomini, Lorenza -- Pajola, Maurizio -- Jorda, Laurent -- Naletto, Giampiero -- Lowry, Stephen -- El-Maarry, Mohamed Ramy -- Preusker, Frank -- Scholten, Frank -- Sierks, Holger -- Barbieri, Cesare -- Lamy, Philippe -- Rodrigo, Rafael -- Koschny, Detlef -- Rickman, Hans -- Keller, Horst Uwe -- A'Hearn, Michael F -- Agarwal, Jessica -- Auger, Anne-Therese -- Barucci, M Antonella -- Bertaux, Jean-Loup -- Bertini, Ivano -- Besse, Sebastien -- Bodewits, Dennis -- Capanna, Claire -- Da Deppo, Vania -- Davidsson, Bjorn -- Debei, Stefano -- De Cecco, Mariolino -- Ferri, Francesca -- Fornasier, Sonia -- Fulle, Marco -- Gaskell, Robert -- Groussin, Olivier -- Gutierrez, Pedro J -- Guttler, Carsten -- Hviid, Stubbe F -- Ip, Wing-Huen -- Knollenberg, Jorg -- Kovacs, Gabor -- Kramm, Rainer -- Kuhrt, Ekkehard -- Kuppers, Michael -- La Forgia, Fiorangela -- Lara, Luisa M -- Lazzarin, Monica -- Lin, Zhong-Yi -- Lopez Moreno, Jose J -- Magrin, Sara -- Michalik, Harald -- Mottola, Stefano -- Oklay, Nilda -- Pommerol, Antoine -- Thomas, Nicolas -- Tubiana, Cecilia -- Vincent, Jean-Baptiste -- England -- Nature. 2015 Oct 15;526(7573):402-5. doi: 10.1038/nature15511. Epub 2015 Sep 28.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Dipartimento di Geoscienze, University of Padova, via G. Gradenigo 6, 35131 Padova, Italy. ; Centro di Ateneo di Studi ed Attivita Spaziali "Giuseppe Colombo" (CISAS), University of Padova, via Venezia 15, 35131 Padova, Italy. ; CNR-IFN UOS Padova LUXOR, via Trasea 7, 35131 Padova, Italy. ; University of Padova, Department of Physics and Astronomy, Vicolo dell'Osservatorio 3, 35122 Padova, Italy. ; INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy. ; Aix Marseille Universite, CNRS, LAM (Laboratoire d'Astrophysique de Marseille), UMR 7326, 38 rue Frederic Joliot-Curie, 13388 Marseille, France. ; Department of Information Engineering, University of Padova, via Gradenigo 6/B, 35131 Padova, Italy. ; The University of Kent, School of Physical Sciences, Canterbury, Kent CT2 7NZ, UK. ; Physikalisches Institut der Universitat Bern, Sidlerstrasse 5, 3012 Bern, Switzerland. ; Deutsches Zentrum fur Luft- und Raumfahrt (DLR), Institut fur Planetenforschung, Rutherfordstrasse 2, 12489 Berlin, Germany. ; Max-Planck-Institut fur Sonnensystemforschung, Justus-von-Liebig Weg 3, 37077 Gottingen, Germany. ; Centro de Astrobiologia, CSIC-INTA, 28850 Torrejon de Ardoz, Madrid, Spain. ; International Space Science Institute, Hallerstrasse 6, 3012 Bern, Switzerland. ; Scientific Support Office, European Space Research and Technology Centre/ESA, Keplerlaan 1, Postbus 299, 2201 AZ Noordwijk ZH, The Netherlands. ; Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden. ; PAS Space Research Center, Bartycka 18A, 00716 Warszawa, Poland. ; Institut fur Geophysik und extraterrestrische Physik (IGEP), Technische Universitat Braunschweig, Mendelssohnstrasse 3, 38106 Braunschweig, Germany. ; University of Maryland, Department of Astronomy, College Park, Maryland 20742-2421, USA. ; Akademie der Wissenschaften zu Gottingen and Max-Planck-Institut fur Sonnensystemforschung, Justus-von-Liebig Weg 3, 37077 Gottingen, Germany. ; LESIA-Observatoire de Paris, CNRS, Universite Pierre et Marie Curie, Universite Paris Diderot, 5 place J. Janssen, 92195 Meudon, France. ; LATMOS, CNRS/UVSQ/IPSL, 11 boulevard d'Alembert, 78280 Guyancourt, France. ; Department of Industrial Engineering, University of Padova, via Venezia 1, 35131 Padova, Italy. ; University of Trento, Via Mesiano 77, 38100 Trento, Italy. ; INAF-Osservatorio Astronomico, Via Tiepolo 11, 34014 Trieste, Italy. ; Planetary Science Institute, Tucson, Arizona 85719, USA. ; Instituto de Astrofisica de Andalucia (CSIC), Glorieta de la Astronomia s/n, 18008 Granada, Spain. ; National Central University, Graduate Institute of Astronomy, 300 Chung-Da Road, Chung-Li 32054 Taiwan. ; Operations Department, European Space Astronomy Centre/ESA, PO Box 78, 28691 Villanueva de la Canada, Madrid, Spain. ; Institut fur Datentechnik und Kommunikationsnetze der TU Braunschweig, Hans-Sommer Strasse 66, 38106 Braunschweig, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26416730" target="_blank"〉PubMed〈/a〉

Description: Understanding how comets work--what drives their activity--is crucial to the use of comets in studying the early solar system. EPOXI (Extrasolar Planet Observation and Deep Impact Extended Investigation) flew past comet 103P/Hartley 2, one with an unusually small but very active nucleus, taking both images and spectra. Unlike large, relatively inactive nuclei, this nucleus is outgassing primarily because of CO(2), which drags chunks of ice out of the nucleus. It also shows substantial differences in the relative abundance of volatiles from various parts of the nucleus.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉A'Hearn, Michael F -- Belton, Michael J S -- Delamere, W Alan -- Feaga, Lori M -- Hampton, Donald -- Kissel, Jochen -- Klaasen, Kenneth P -- McFadden, Lucy A -- Meech, Karen J -- Melosh, H Jay -- Schultz, Peter H -- Sunshine, Jessica M -- Thomas, Peter C -- Veverka, Joseph -- Wellnitz, Dennis D -- Yeomans, Donald K -- Besse, Sebastien -- Bodewits, Dennis -- Bowling, Timothy J -- Carcich, Brian T -- Collins, Steven M -- Farnham, Tony L -- Groussin, Olivier -- Hermalyn, Brendan -- Kelley, Michael S -- Li, Jian-Yang -- Lindler, Don J -- Lisse, Carey M -- McLaughlin, Stephanie A -- Merlin, Frederic -- Protopapa, Silvia -- Richardson, James E -- Williams, Jade L -- New York, N.Y. -- Science. 2011 Jun 17;332(6036):1396-400. doi: 10.1126/science.1204054.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Astronomy, University of Maryland, College Park, MD 20742-2421 USA. ma@astro.umd.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21680835" target="_blank"〉PubMed〈/a〉

Description: Images of comet 67P/Churyumov-Gerasimenko acquired by the OSIRIS (Optical, Spectroscopic and Infrared Remote Imaging System) imaging system onboard the European Space Agency's Rosetta spacecraft at scales of better than 0.8 meter per pixel show a wide variety of different structures and textures. The data show the importance of airfall, surface dust transport, mass wasting, and insolation weathering for cometary surface evolution, and they offer some support for subsurface fluidization models and mass loss through the ejection of large chunks of material.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Thomas, Nicolas -- Sierks, Holger -- Barbieri, Cesare -- Lamy, Philippe L -- Rodrigo, Rafael -- Rickman, Hans -- Koschny, Detlef -- Keller, Horst Uwe -- Agarwal, Jessica -- A'Hearn, Michael F -- Angrilli, Francesco -- Auger, Anne-Therese -- Barucci, M Antonella -- Bertaux, Jean-Loup -- Bertini, Ivano -- Besse, Sebastien -- Bodewits, Dennis -- Cremonese, Gabriele -- Da Deppo, Vania -- Davidsson, Bjorn -- De Cecco, Mariolino -- Debei, Stefano -- El-Maarry, Mohamed Ramy -- Ferri, Francesca -- Fornasier, Sonia -- Fulle, Marco -- Giacomini, Lorenza -- Groussin, Olivier -- Gutierrez, Pedro J -- Guttler, Carsten -- Hviid, Stubbe F -- Ip, Wing-Huen -- Jorda, Laurent -- Knollenberg, Jorg -- Kramm, J-Rainer -- Kuhrt, Ekkehard -- Kuppers, Michael -- La Forgia, Fiorangela -- Lara, Luisa M -- Lazzarin, Monica -- Lopez Moreno, Jose J -- Magrin, Sara -- Marchi, Simone -- Marzari, Francesco -- Massironi, Matteo -- Michalik, Harald -- Moissl, Richard -- Mottola, Stefano -- Naletto, Giampiero -- Oklay, Nilda -- Pajola, Maurizio -- Pommerol, Antoine -- Preusker, Frank -- Sabau, Lola -- Scholten, Frank -- Snodgrass, Colin -- Tubiana, Cecilia -- Vincent, Jean-Baptiste -- Wenzel, Klaus-Peter -- New York, N.Y. -- Science. 2015 Jan 23;347(6220):aaa0440. doi: 10.1126/science.aaa0440.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Physikalisches Institut, Sidlerstrasse 5, University of Bern, 3012, Bern, Switzerland. nicolas.thomas@space.unibe.ch. ; Max-Planck-Institut fur Sonnensystemforschung, Justus-von-Liebig-Weg, 3, 37077, Gottingen, Germany. ; Department of Physics and Astronomy, University of Padova, Vicolo dell'Osservatorio 3, 35122 Padova, Italy. ; Laboratoire d'Astrophysique de Marseille, UMR 7326, CNRS, and Aix Marseille Universite, 38 Rue Frederic Joliot-Curie, 13388 Marseille Cedex 13, France. ; International Space Science Institute, Hallerstrasse 6, 3012 Bern, Switzerland, and Centro de Astrobiologia, Consejo Superior de Investigaciones Cientificas - Instituto Nacional de Tecnica Aeroespacial, 28850 Torrejon de Ardoz, Madrid, Spain. ; Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala, Sweden, and Polish Academy of Sciences Space Research Center, Bartycka 18A, PL-00716 Warszawa, Poland. ; Scientific Support Office, European Space Agency, 2201, Noordwijk, Netherlands. ; Institute for Geophysics and Extraterrestrial Physics, Technische Universitat Braunschweig, 38106, Braunschweig, Germany. Deutsches Zentrum fur Luft- und Raumfahrt (DLR), Institut fur Planetenforschung, Asteroiden und Kometen, Rutherfordstrasse 2, 12489 Berlin, Germany. ; Department of Astronomy, University of Maryland, College Park, MD 20742-2421, USA. ; Department of Industrial Engineering, University of Padova, via Venezia 1, 35131 Padova, Italy. ; Aix Marseille Universite, CNRS, Laboratoire d'Astrophysique de Marseille, UMR 7326, 38 rue Frederic Joliot-Curie, 13388 Marseille, France. ; Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique, Observatoire de Paris, CNRS, Universite Paris 06, Universite Paris-Diderot, 5 Place J. Janssen, 92195, Meudon, France. ; Laboratoire Atmospheres, Milieux, Observations Spatiales, CNRS/UVSQ/IPSL, 11 Boulevard d'Alembert, 78280, Guyancourt, France. ; Centro di Ateneo di Studi ed Attivita Spaziali, "Giuseppe Colombo" (CISAS), University of Padova, Via Venezia 15, 35131 Padova, Italy. ; Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy. ; CNR-IFN UOS Padova LUXOR, Via Trasea, 7, 35131 Padova, Italy. ; Department of Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden. ; UNITN, Universita di Trento, Via Mesiano, 77, 38100 Trento, Italy. ; Physikalisches Institut, Sidlerstrasse 5, University of Bern, 3012, Bern, Switzerland. ; INAF, Osservatorio Astronomico, Via Tiepolo 11, 34014 Trieste, Italy. ; Dipartimento di Geoscienze, University of Padova, via G. Gradenigo 6, 35131 Padova, Italy. ; Instituto de Astrofisica de Andalucia (CSIC), c/ Glorieta de la Astronomia s/n, 18008 Granada, Spain. ; Deutsches Zentrum fur Luft- und Raumfahrt (DLR), Institut fur Planetenforschung, Asteroiden und Kometen, Rutherfordstrasse 2, 12489 Berlin, Germany. Max-Planck-Institut fur Sonnensystemforschung, Justus-von-Liebig-Weg, 3, 37077, Gottingen, Germany. ; National Central University, Graduate Institute of Astronomy, 300 Chung-Da Road, Chung-Li 32054, Taiwan. ; Laboratoire d'Astrophysique de Marseille, 38 Rue de Frederic Joliot-Curie, 13388 Marseille Cedex 13, France. ; Deutsches Zentrum fur Luft- und Raumfahrt (DLR), Institut fur Planetenforschung, Asteroiden und Kometen, Rutherfordstrasse 2, 12489 Berlin, Germany. ; Science Operations Department, European Space Astronomy Centre/European Space Agency, Post Office Box 78, 28691 Villanueva de la Canada, Madrid, Spain. ; Solar System Exploration Research Virtual Institute, Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302, USA. ; Dipartimento di Geoscienze, University of Padova, via G. Gradenigo 6, 35131 Padova, Italy. Centro di Ateneo di Studi ed Attivita Spaziali, "Giuseppe Colombo" (CISAS), University of Padova, Via Venezia 15, 35131 Padova, Italy. ; Institut fur Datentechnik und Kommunikationsnetze der Technische Universitat Braunschweig, Hans-Sommer-Strasse 66, 38106 Braunschweig, Germany. ; University of Padova, Department of Information Engineering, Via Gradenigo 6/B, 35131 Padova, Italy. CNR-IFN UOS Padova LUXOR, Via Trasea, 7, 35131 Padova, Italy. Centro di Ateneo di Studi ed Attivita Spaziali, "Giuseppe Colombo" (CISAS), University of Padova, Via Venezia 15, 35131 Padova, Italy. ; Instituto Nacional de Tecnica Aeroespacial, Carretera de Ajalvir, 28850 Torrejon de Ardoz (Madrid), Spain. ; Planetary and Space Sciences, Department of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK. Max-Planck-Institut fur Sonnensystemforschung, Justus-von-Liebig-Weg, 3, 37077, Gottingen, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25613893" target="_blank"〉PubMed〈/a〉

Description: 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.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rotundi, Alessandra -- Sierks, Holger -- Della Corte, Vincenzo -- Fulle, Marco -- Gutierrez, Pedro J -- Lara, Luisa -- Barbieri, Cesare -- Lamy, Philippe L -- Rodrigo, Rafael -- Koschny, Detlef -- Rickman, Hans -- Keller, Horst Uwe -- Lopez-Moreno, Jose J -- Accolla, Mario -- Agarwal, Jessica -- A'Hearn, Michael F -- Altobelli, Nicolas -- Angrilli, Francesco -- Barucci, M Antonietta -- Bertaux, Jean-Loup -- Bertini, Ivano -- Bodewits, Dennis -- Bussoletti, Ezio -- Colangeli, Luigi -- Cosi, Massimo -- Cremonese, Gabriele -- Crifo, Jean-Francois -- Da Deppo, Vania -- Davidsson, Bjorn -- Debei, Stefano -- De Cecco, Mariolino -- Esposito, Francesca -- Ferrari, Marco -- Fornasier, Sonia -- Giovane, Frank -- Gustafson, Bo -- Green, Simon F -- Groussin, Olivier -- Grun, Eberhard -- Guttler, Carsten -- Herranz, Miguel L -- Hviid, Stubbe F -- Ip, Wing -- Ivanovski, Stavro -- Jeronimo, Jose M -- Jorda, Laurent -- Knollenberg, Joerg -- Kramm, Rainer -- Kuhrt, Ekkehard -- Kuppers, Michael -- Lazzarin, Monica -- Leese, Mark R -- Lopez-Jimenez, Antonio C -- Lucarelli, Francesca -- Lowry, Stephen C -- Marzari, Francesco -- Epifani, Elena Mazzotta -- McDonnell, J Anthony M -- Mennella, Vito -- Michalik, Harald -- Molina, Antonio -- Morales, Rafael -- Moreno, Fernando -- Mottola, Stefano -- Naletto, Giampiero -- Oklay, Nilda -- Ortiz, Jose L -- Palomba, Ernesto -- Palumbo, Pasquale -- Perrin, Jean-Marie -- Rodriguez, Julio -- Sabau, Lola -- Snodgrass, Colin -- Sordini, Roberto -- Thomas, Nicolas -- Tubiana, Cecilia -- Vincent, Jean-Baptiste -- Weissman, Paul -- Wenzel, Klaus-Peter -- Zakharov, Vladimir -- Zarnecki, John C -- New York, N.Y. -- Science. 2015 Jan 23;347(6220):aaa3905. doi: 10.1126/science.aaa3905.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Istituto di Astrofisica e Planetologia Spaziali, Istituto Nazionale di Astrofisica (INAF), Via Fosso del Cavaliere, 100, 0133 Rome, Italy. Universita degli Studi di Napoli "Parthenope," Dipartimento di Scienze e Tecnologie, CDN IC4, 80143 Naples, Italy. rotundi@uniparthenope.it. ; Max-Planck-Institut fur Sonnensystemforschung, Justus-von-Liebig-Weg, 3, 37077 Gottingen, Germany. ; Istituto di Astrofisica e Planetologia Spaziali, Istituto Nazionale di Astrofisica (INAF), Via Fosso del Cavaliere, 100, 0133 Rome, Italy. ; Osservatorio Astronomico, INAF, Via Tiepolo 11, 34143 Trieste, Italy. ; Instituto de Astrofisica de Andalucia, Consejo Superior de Investigaciones Cientificas (CSIC), P.O. Box 3008, 18080 Granada, Spain. ; Department of Physics and Astronomy, Padova University, Vicolo dell'Osservatorio 3, 35122 Padova, Italy. ; Laboratoire d'Astrophysique de Marseille, UMR 7326, CNRS and Aix-Marseille Universite, 13388 Marseille, France. ; Centro de Astrobiologia (Instituto Nacional de Tecnica Aerospacial-CSIC), 28691 Villanueva de la Canada, Madrid, Spain. International Space Science Institute, Hallerstrasse 6, CH-3012 Bern, Switzerland. ; Scientific Support Office, European Space Agency, 2201 Noordwijk, Netherlands. ; Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden. Polish Academy of Sciences Space Research Center, Bartycka 18A, PL-00716 Warszawa, Poland. ; Institute for Geophysics and Extraterrestrial Physics, Technische Universitat Braunschweig, Braunschweig 38106, Germany. ; Istituto di Astrofisica e Planetologia Spaziali, Istituto Nazionale di Astrofisica (INAF), Via Fosso del Cavaliere, 100, 0133 Rome, Italy. Universita degli Studi di Napoli "Parthenope," Dipartimento di Scienze e Tecnologie, CDN IC4, 80143 Naples, Italy. ; Department of Astronomy, University of Maryland, College Park, MD 20742-2421, USA. ; European Space Agency (ESA)-European Space Astronomy Center (ESAC), Camino Bajo del Castillo, s/n, 28692 Villanueva de la Canada, Madrid, Spagna. ; Department of Mechanical Engineering, University of Padova, via Venezia 1, 35131 Padova, Italy. ; Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique, Observatoire de Paris, CNRS, Universite Paris 06, Universite Paris-Diderot, 5 place Johannes Janssen, 92195 Meudon, France. ; Laboratoire Atmospheres, Milieux, Observations Spatiales, CNRS/Universite de Versailles Saint-Quentin-en-Yvelines/Institut Pierre-Simon Laplace, 11 boulevard d'Alembert, 78280 Guyancourt, France. ; University of Padova, Centro Interdipartimentale di Studi e Attivita Spaziali (CISAS), via Venezia 15, 35100 Padova, Italy. ; Universita degli Studi di Napoli "Parthenope," Dipartimento di Scienze e Tecnologie, CDN IC4, 80143 Naples, Italy. ; ESA, European Space Research and Technology Centre (ESTEC), Keplerlaan 1, 2201 AZ Noordwijk, Netherlands. ; Selex-ES, Via Albert Einstein, 35, 50013 Campi Bisenzio, Firenze, Italy. ; Osservatorio Astronomico di Padova, INAF, Vicolo dell'Osservatorio 5, 35122 Padova, Italy. ; Consiglio Nazionale delle Ricerche-Istituto di Fotonica e Nanotecnologie-Unita Operativa di Supporto Padova LUXOR, via Trasea 7, 35131 Padova, Italy. ; Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden. ; Universita di Trento, via Mesiano, 77, 38100 Trento, Italy. ; Osservatorio Astronomico di Capodimonte, INAF, Salita Moiariello, 16, 80133 Naples, Italy. ; Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA. ; University of Florida, Gainesville, FL 32611, USA. ; Planetary and Space Sciences, Department of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK. ; Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany. ; Institute of Planetary Research, Deutsches Zentrum fur Luft- und Raumfahrt (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany. ; Institute for Space Science, National Central University, 300 Chung Da Road, 32054 Chung-Li, Taiwan. ; The University of Kent, School of Physical Sciences, Canterbury, Kent CT2 7NZ, UK. ; Department of Physics, University of Padova, 35131 Padova, Italy. ; Planetary and Space Sciences, Department of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK. The University of Kent, School of Physical Sciences, Canterbury, Kent CT2 7NZ, UK. Unispacekent, Canterbury CT2 8EF, UK. ; Institut fur Datentechnik und Kommunikationsnetze, 38106 Braunschweig, Germany. ; Departamento de Fisica Aplicada, Universidad de Granada, Facultad de Ciencias, Avenida Severo Ochoa, s/n, 18071 Granada, Spain. ; Department of Information Engineering, Padova University, via Gradenigo 6, 35131 Padova, Italy. ; Laboratoire Atmospheres, Milieux, Observations Spatiales, CNRS/Universite de Versailles Saint-Quentin-en-Yvelines/Institut Pierre-Simon Laplace, 11 boulevard d'Alembert, 78280 Guyancourt, France. Observatoire de Haute Provence OSU Pytheas UMS 2244 CNRS-AMU, 04870 Saint Michel l'Observatoire, France. ; Instituto Nacional de Tecnica Aeroespacial, Carretera de Ajalvir, p.k. 4, 28850 Torrejon de Ardoz, Madrid, Spain. ; Max-Planck-Institut fur Sonnensystemforschung, Justus-von-Liebig-Weg, 3, 37077 Gottingen, Germany. Planetary and Space Sciences, Department of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK. ; Physikalisches Institut, Sidlerstrasse 5, University of Bern, 3012 Bern, Switzerland. ; Planetary Science Section, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, USA. ; International Space Science Institute, Hallerstrasse 6, CH-3012 Bern, Switzerland. Planetary and Space Sciences, Department of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25613898" target="_blank"〉PubMed〈/a〉

Description: Images from the OSIRIS scientific imaging system onboard Rosetta show that the nucleus of 67P/Churyumov-Gerasimenko consists of two lobes connected by a short neck. The nucleus has a bulk density less than half that of water. Activity at a distance from the Sun of 〉3 astronomical units is predominantly from the neck, where jets have been seen consistently. The nucleus rotates about the principal axis of momentum. The surface morphology suggests that the removal of larger volumes of material, possibly via explosive release of subsurface pressure or via creation of overhangs by sublimation, may be a major mass loss process. The shape raises the question of whether the two lobes represent a contact binary formed 4.5 billion years ago, or a single body where a gap has evolved via mass loss.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sierks, Holger -- Barbieri, Cesare -- Lamy, Philippe L -- Rodrigo, Rafael -- Koschny, Detlef -- Rickman, Hans -- Keller, Horst Uwe -- Agarwal, Jessica -- A'Hearn, Michael F -- Angrilli, Francesco -- Auger, Anne-Therese -- Barucci, M Antonella -- Bertaux, Jean-Loup -- Bertini, Ivano -- Besse, Sebastien -- Bodewits, Dennis -- Capanna, Claire -- Cremonese, Gabriele -- Da Deppo, Vania -- Davidsson, Bjorn -- Debei, Stefano -- De Cecco, Mariolino -- Ferri, Francesca -- Fornasier, Sonia -- Fulle, Marco -- Gaskell, Robert -- Giacomini, Lorenza -- Groussin, Olivier -- Gutierrez-Marques, Pablo -- Gutierrez, Pedro J -- Guttler, Carsten -- Hoekzema, Nick -- Hviid, Stubbe F -- Ip, Wing-Huen -- Jorda, Laurent -- Knollenberg, Jorg -- Kovacs, Gabor -- Kramm, J Rainer -- Kuhrt, Ekkehard -- Kuppers, Michael -- La Forgia, Fiorangela -- Lara, Luisa M -- Lazzarin, Monica -- Leyrat, Cedric -- Lopez Moreno, Jose J -- Magrin, Sara -- Marchi, Simone -- Marzari, Francesco -- Massironi, Matteo -- Michalik, Harald -- Moissl, Richard -- Mottola, Stefano -- Naletto, Giampiero -- Oklay, Nilda -- Pajola, Maurizio -- Pertile, Marco -- Preusker, Frank -- Sabau, Lola -- Scholten, Frank -- Snodgrass, Colin -- Thomas, Nicolas -- Tubiana, Cecilia -- Vincent, Jean-Baptiste -- Wenzel, Klaus-Peter -- Zaccariotto, Mirco -- Patzold, Martin -- New York, N.Y. -- Science. 2015 Jan 23;347(6220):aaa1044. doi: 10.1126/science.aaa1044.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Max-Planck-Institut fur Sonnensystemforschung, 37077 Gottingen, Germany. sierks@mps.mpg.de. ; Department of Physics and Astronomy, University of Padova, 35122 Padova, Italy. ; Laboratoire d'Astrophysique de Marseille, UMR 7326, CNRS & Aix Marseille Universite, 13388 Marseille Cedex 13, France. ; Centro de Astrobiologia, CSIC-INTA,28850 Madrid, Spain. International Space Science Institute, 3012 Bern, Switzerland. ; Scientific Support Office, European Space Research and Technology Centre/ESA, 2201 AZ Noordwijk ZH, Netherlands. ; Department of Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden. PAS Space Research Center, 00716 Warszawa, Poland. ; Institut fur Geophysik und extraterrestrische Physik, Technische Universitat Braunschweig, 38106 Braunschweig, Germany. Deutsches Zentrum fur Luft- und Raumfahrt, Institut fur Planetenforschung, 12489 Berlin, Germany. ; Max-Planck-Institut fur Sonnensystemforschung, 37077 Gottingen, Germany. ; Max-Planck-Institut fur Sonnensystemforschung, 37077 Gottingen, Germany. Department of Astronomy, University of Maryland, College Park, MD 20742, USA. Akademie der Wissenschaften zu Gottingen, 37077 Gottingen, Germany. ; Department of Industrial Engineering, University of Padova, 35131 Padova, Italy. ; Aix Marseille Universite, CNRS, Laboratoire d'Astrophysique de Marseille, UMR 7326, 13388 Marseille, France. ; LESIA-Observatoire de Paris, CNRS, Universite Pierre et Marie Curie, Universite Paris Diderot, 92195 Meudon, France. ; LATMOS, CNRS/UVSQ/IPSL, 78280 Guyancourt, France. ; Centro di Ateneo di Studi ed Attivita Spaziali "Giuseppe Colombo" (CISAS), University of Padova, 35131 Padova, Italy. ; Department of Astronomy, University of Maryland, College Park, MD 20742, USA. ; INAF, Osservatorio Astronomico di Padova, 35122 Padova, Italy. ; CNR-IFN UOS Padova LUXOR, 35131 Padova, Italy. ; Department of Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden. ; University of Trento, 38100 Trento, Italy. ; INAF - Osservatorio Astronomico di Trieste, 34014 Trieste, Italy. ; Planetary Science Institute, Tucson, AZ 85719, USA. ; Instituto de Astrofisica de Andalucia (CSIC), c/ Glorieta de la AstronomIa s/n, 18008 Granada, Spain. ; Max-Planck-Institut fur Sonnensystemforschung, 37077 Gottingen, Germany. Deutsches Zentrum fur Luft- und Raumfahrt, Institut fur Planetenforschung, 12489 Berlin, Germany. ; Graduate Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan. Space Science Institute, Macau University of Science and Technology, Macao, China. ; Deutsches Zentrum fur Luft- und Raumfahrt, Institut fur Planetenforschung, 12489 Berlin, Germany. ; Operations Department, European Space Astronomy Centre/ESA, 28691 Villanueva de la Canada, Madrid, Spain. ; Solar System Exploration Research, Virtual Institute, Southwest Research Institute, Boulder, CO 80302, USA. ; Centro di Ateneo di Studi ed Attivita Spaziali "Giuseppe Colombo" (CISAS), University of Padova, 35131 Padova, Italy. Dipartimento di Geoscienze, University of Padova, 35131 Padova, Italy. ; Institut fur Datentechnik und Kommunikationsnetze der TU Braunschweig, 38106 Braunschweig, Germany. ; Centro di Ateneo di Studi ed Attivita Spaziali "Giuseppe Colombo" (CISAS), University of Padova, 35131 Padova, Italy. CNR-IFN UOS Padova LUXOR, 35131 Padova, Italy. Department of Information Engineering, University of Padova, 35131 Padova, Italy. ; Department of Industrial Engineering, University of Padova, 35131 Padova, Italy. Centro di Ateneo di Studi ed Attivita Spaziali "Giuseppe Colombo" (CISAS), University of Padova, 35131 Padova, Italy. ; Instituto Nacional de Tecnica Aeroespacial, 28850 Torrejon de Ardoz, Madrid, Spain. ; Physikalisches Institut, University of Bern, 3012 Bern, Switzerland. Center for Space and Habitability, University of Bern, 3012 Bern, Switzerland. ; Rheinisches Institut fur Umweltforschung, Abteilung Planetenforschung, Universitat zu Koln, 50931 Koln, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25613897" target="_blank"〉PubMed〈/a〉

Description: Beginning in 2014 March, the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) cameras began capturing images of the nucleus and coma (gas and dust) of comet 67P/Churyumov–Gerasimenko using both the wide angle camera (WAC) and the narrow angle camera (NAC). The many observations taken since July of 2014 have been used to study the morphology, location, and temporal variation of the comet's dust jets. We analysed the dust monitoring observations shortly after the southern vernal equinox on 2015 May 30 and 31 with the WAC at the heliocentric distance R h = 1.53 AU, where it is possible to observe that the jet rotates with the nucleus. We found that the decline of brightness as a function of the distance of the jet is much steeper than the background coma, which is a first indication of sublimation. We adapted a model of sublimation of icy aggregates and studied the effect as a function of the physical properties of the aggregates (composition and size). The major finding of this paper was that through the sublimation of the aggregates of dirty grains (radius a between 5 and 50 μm) we were able to completely reproduce the radial brightness profile of a jet beyond 4 km from the nucleus. To reproduce the data, we needed to inject a number of aggregates between 8.5 x 10 13 and 8.5 x 10 10 for a = 5 and 50 μm, respectively, or an initial mass of H 2 O ice around 22 kg.