TY - CHAP A1 - Kramer, Tobias A1 - Läuter, Matthias T1 - The near nucleus gas and dust environment around comet 67P/Churyumov-Gerasimenko T2 - Europlanet Science Congress N2 - The Rosetta mission to comet 67P/C-G provided a detailed view of the near nucleus environment of an active Jupiter family comet. The continuous monitoring of the gas pressure with the ROSINA experiment at the location of the Rosetta spacecraft in combination with the images of the dust environment acquired by the OSIRIS cameras allows one to test different hypotheses about the origin of the dust and gas emissions. In addition the orbital elements and the rotation axis and spin rate of the nucleus are affected by the gas release. Y1 - 2022 U6 - https://doi.org/10.5194/epsc2022-281 SP - EPSC2022-281 ER - TY - JOUR A1 - Läuter, Matthias A1 - Kramer, Tobias A1 - Rubin, Martin A1 - Altwegg, Kathrin T1 - The ice composition close to the surface of comet 67P/Churyumov-Gerasimenko JF - ACS Earth and Space Chemistry N2 - The relation between ice composition in the nucleus of comet 67P/Churyumov-Gerasimenko on the one hand and relative abundances of volatiles in the coma on the other hand is important for the interpretation of density measurements in the environment of the cometary nucleus. For the 2015 apparition, in situ measurements from the two ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) sensors COPS (COmet Pressure Sensor) and DFMS (Double Focusing Mass Spectrometer) determined gas densities at the spacecraft position for the 14 gas species H2O, CO2, CO, H2S, O2, C2H6, CH3OH, H2CO, CH4, NH3, HCN, C2H5OH, OCS, and CS2. We derive the spatial distribution of the gas emissions on the complex shape of the nucleus separately for 50 subintervals of the two-year mission time. The most active patches of gas emission are identified on the surface. We retrieve the relation between solar irradiation and observed emissions from these patches. The emission rates are compared to a minimal thermophysical model to infer the surface active fraction of H2O and CO2. We obtain characteristic differences in the ice composition close to the surface between the two hemispheres with a reduced abundance of CO2 ice on the northern hemisphere (locations with positive latitude). We do not see significant differences for the ice composition on the two lobes of 67P/C-G. Y1 - 2022 U6 - https://doi.org/10.1021/acsearthspacechem.1c00378 VL - 6 IS - 5 SP - 1189 EP - 1203 ER - TY - JOUR A1 - Läuter, Matthias A1 - Kramer, Tobias A1 - Rubin, Martin A1 - Altwegg, Kathrin T1 - The gas production of 14 species from comet 67P/Churyumov-Gerasimenko based on DFMS/COPS data from 2014-2016 JF - Monthly Notices of the Royal Astronomical Society N2 - The coma of comet 67P/Churyumov-Gerasimenko has been probed by the Rosetta spacecraft and shows a variety of different molecules. The ROSINA COmet Pressure Sensor and the Double Focusing Mass Spectrometer provide in-situ densities for many volatile compounds including the 14 gas species H2O, CO2, CO, H2S, O2, C2H6, CH3OH, H2CO, CH4, NH3, HCN, C2H5OH, OCS, and CS2. We fit the observed densities during the entire comet mission between August 2014 and September 2016 to an inverse coma model. We retrieve surface emissions on a cometary shape with 3996 triangular elements for 50 separated time intervals. For each gas we derive systematic error bounds and report the temporal evolution of the production, peak production, and the time-integrated total production. We discuss the production for the two lobes of the nucleus and for the northern and southern hemispheres. Moreover we provide a comparison of the gas production with the seasonal illumination. Y1 - 2020 U6 - https://doi.org/10.1093/mnras/staa2643 VL - 498 IS - 3 SP - 3995 EP - 4004 PB - Monthly Notices of the Royal Astronomical Society ER - TY - JOUR A1 - Läuter, Matthias A1 - Kramer, Tobias A1 - Rubin, Martin A1 - Altwegg, Kathrin T1 - Surface localization of gas sources on comet 67P/Churyumov-Gerasimenko based on DFMS/COPS data JF - Monthly Notices of the Royal Astronomical Society N2 - We reconstruct the temporal evolution of the source distribution for the four major gas species H2O, CO2, CO, and O2 on the surface of comet 67P/Churyumov-Gerasimenko during its 2015 apparition. The analysis applies an inverse coma model and fits to data between August 6th 2014 and September 5th 2016 measured with the Double Focusing Mass Spectrometer (DFMS) of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) and the COmet Pressure Sensor (COPS). The spatial distribution of gas sources with their temporal variation allows one to construct surface maps for gas emissions and to evaluate integrated productions rates. For all species peak production rates and integrated productions rates per orbit are evaluated separately for the northern and the southern hemisphere. The nine most active emitting areas on the comet’s surface are defined and their correlation to emissions for each of the species is discussed. Y1 - 2018 U6 - https://doi.org/10.1093/mnras/sty3103 VL - 483 SP - 852 EP - 861 PB - Monthly Notices of the Royal Astronomical Society ER - TY - JOUR A1 - Kramer, Tobias A1 - Läuter, Matthias A1 - Rubin, Martin A1 - Altwegg, Kathrin T1 - Seasonal changes of the volatile density in the coma and on the surface of comet 67P/Churyumov-Gerasimenko JF - Monthly Notices of the Royal Astronomical Society N2 - Starting from several monthly data sets of Rosetta’s COmetary Pressure Sensor we reconstruct the gas density in the coma around comet 67P/Churyumov-Gerasimenko. The underlying inverse gas model is constructed by fitting ten thousands of measurements to thousands of potential gas sources distributed across the entire nucleus surface. The ensuing self-consistent solution for the entire coma density and surface activity reproduces the temporal and spatial variations seen in the data for monthly periods with Pearson correlation coefficients of 0.93 and higher. For different seasonal illumination conditions before and after perihelion we observe a systematic shift of gas sources on the nucleus. Y1 - 2017 U6 - https://doi.org/10.1093/mnras/stx866 VL - 469 SP - S20 EP - S28 ER - TY - GEN A1 - Gutsche, Philipp A1 - Läuter, Matthias A1 - Schmidt, Frank T1 - Parameter-dependent Parallel Block Sparse Arnoldi and Döhler Algorithms on Distributed Systems N2 - We summarize the basics and first results of the analyses within our ZIB Bridge Project and give an outlook on further studies broadening the usage of hardware acceleration within the Finite Element Method (FEM) based solution of Maxwell’s equations. T3 - ZIB-Report - 16-15 KW - Generalized Eigenvalue Problem KW - Many Integrated Core Coprocessor (MIC) KW - Finite Element Method Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-58202 SN - 1438-0064 ER - TY - JOUR A1 - Kramer, Tobias A1 - Läuter, Matthias T1 - Outgassing induced acceleration of comet 67P/Churyumov-Gerasimenko JF - Astronomy & Astrophysics N2 - Cometary activity affects the orbital motion and rotation state due to sublimation induced forces. The availability of precise rotation-axis orientation and position data from the Rosetta mission allows one to accurately determine the outgassing of comet Churyumov-Gerasimenko/67P (67P). We derive the observed non-gravitational acceleration of 67P directly from the Rosetta spacecraft trajectory. From the non-gravitational acceleration we recover the diurnal outgassing variations and study a possible delay of the sublimation response with respect to the peak solar illumination. This allows us to compare the non-gravitational acceleration of 67P with expectations based on empirical models and common assumptions about the sublimation process. We use an iterative orbit refinement and Fourier decomposition of the diurnal activity to derive the outgassing induced non-gravitational acceleration. The uncertainties of the data reduction are established by a sensitivity analysis of an ensemble of best-fit orbits for comet 67P. We find that the Marsden non-gravitational acceleration parameters reproduce part of the non-gravitational acceleration but need to be augmented by an analysis of the nucleus geometry and surface illumination to draw conclusions about the sublimation process on the surface. The non-gravitational acceleration follows closely the subsolar latitude (seasonal illumination), with a small lag angle with respect to local noon around perihelion. The observed minor changes of the rotation axis do not favor forced precession models for the non-gravitational acceleration. In contrast to the sublimation induced torques, the non-gravitational acceleration does not put strong constraints on localized active areas on the nucleus. We find a close agreement of the orbit deduced non-gravitational acceleration and the water production independently derived from Rosetta in-situ measurement. Y1 - 2019 U6 - https://doi.org/10.1051/0004-6361/201935229 VL - 630 SP - A4 ER - TY - CHAP A1 - Kramer, Tobias A1 - Läuter, Matthias T1 - Non-gravitational force model vs observation: the trajectory and rotation-axis of comet 67P/Churyumov-Gerasimenko T2 - Europlanet Science Congress N2 - The determination of non-gravitational forces based on precise astrometry is one of the main tools to establish the cometary character of interstellar and solar-system objects. The Rosetta mission to comet 67P/C-G provided the unique opportunity to benchmark Earth-bound estimates of non-gravitational forces with in-situ data. We determine the accuracy of the standard Marsden and Sekanina parametrization of non-gravitational forces with respect to the observed dynamics. Additionally we analyse the rotation-axis changes (orientation and period) of 67P/C-G. This comparison provides a reference case for future cometary missions and sublimation models for non-gravitational forces. Y1 - 2020 U6 - https://doi.org/10.5194/epsc2020-403 VL - 14 SP - EPSC2020-403 PB - Europlanet Science Congress ER - TY - CHAP A1 - Läuter, Matthias A1 - Kramer, Tobias T1 - Non-gravitational acceleration and torque on comet 67P/Churyumov-Gerasimenko T2 - Bulletin of the AAS N2 - From August 2014 to September 2016, the ESA operated the Rosetta spacecraft mission alongside with comet 67P/Churyumov-Gerasimenko (67P). The mission provided valuable long-term data on the comet’s nucleus, including its volume, mass, tensor of inertia, spatial position of the orbital trajectory, and rotational state. Y1 - 2023 UR - https://baas.aas.org/pub/2023n8i218p02 VL - 55 IS - 8 ER - TY - CHAP A1 - Kramer, Tobias A1 - Läuter, Matthias T1 - Modelling the inner coma of comet 67P/Churyumov-Gerasimenko T2 - Europlanet Science Congress N2 - Based on about 1 million of pressure measurements around comet 67P/Churyumov-Gerasimenko we reconstruct the gas emission across the entire nucleus. Dust particles are seeded in the gas model and the resulting dust distribution follows a daily pattern which agrees with observations if a uniform dust release across the entire sunlit surface is assumed. Y1 - 2018 VL - 12 SP - EPSC2018-115-1 PB - Europlanet Science Congress ER -