@article{LaeuterKramerRubinetal.2018, author = {L{\"a}uter, Matthias and Kramer, Tobias and Rubin, Martin and Altwegg, Kathrin}, title = {Surface localization of gas sources on comet 67P/Churyumov-Gerasimenko based on DFMS/COPS data}, series = {Monthly Notices of the Royal Astronomical Society}, volume = {483}, journal = {Monthly Notices of the Royal Astronomical Society}, publisher = {Monthly Notices of the Royal Astronomical Society}, doi = {10.1093/mnras/sty3103}, pages = {852 -- 861}, year = {2018}, abstract = {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.}, language = {en} } @inproceedings{KramerLaeuter, author = {Kramer, Tobias and L{\"a}uter, Matthias}, title = {Matching the activity of comet 67P/Churyumov-Gerasimenko with long-term ground-based astrometry}, series = {Europlanet Science Congress}, volume = {15}, booktitle = {Europlanet Science Congress}, publisher = {Europlanet Science Congress}, doi = {10.5194/epsc2021-337}, pages = {EPSC2021-337}, abstract = {50 years of astrometric data for comet 67P/C-G (orbital period about 6.45 years) provides a unique opportunity to benchmark non-gravitational acceleration models to the in situ measurements of the volatile release performed from the Rosetta rendezvous mission (2014-2016). Taken together, the Earth-bound and in-situ data yields lower fit errors and serves as a test-case for our ability to deduce thermophysical quantities of cometary nuclei from the Earth-bound observations.}, language = {en} } @inproceedings{LaeuterKramerRubinetal., author = {L{\"a}uter, Matthias and Kramer, Tobias and Rubin, Martin and Altwegg, Kathrin}, title = {Gas production of comet 67P/Churyumov-Gerasimenko reconstructed from DFMS/COPS data}, series = {Europlanet Science Congress}, volume = {12}, booktitle = {Europlanet Science Congress}, publisher = {Europlanet Science Congress}, pages = {EPSC2018-515-1}, abstract = {We reconstruct the temporal evolution of surface emissions for the four major gas species H2O, CO2, CO, and O2 emitted during the 2015 apparition of comet 67P/Churyumov-Gerasimenko (67P/C-G). Measurements from the Double Focusing Mass Spectrometer (DFMS) of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) and the COmet Pressure Sensor (COPS) are used to determine the gas sources on the surface with an inverse gas model for the entire coma. For all species, peak production rates and integrated production rates per orbit are evaluated separately for the northern and the southern hemisphere. Complemented with the total mass production, this allows us to estimate the dust-to-gas ratio of the emitted material.}, language = {en} } @inproceedings{KramerLaeuter, author = {Kramer, Tobias and L{\"a}uter, Matthias}, title = {Modelling the inner coma of comet 67P/Churyumov-Gerasimenko}, series = {Europlanet Science Congress}, volume = {12}, booktitle = {Europlanet Science Congress}, publisher = {Europlanet Science Congress}, pages = {EPSC2018-115-1}, abstract = {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.}, language = {en} } @inproceedings{LaeuterKramerRubinetal., author = {L{\"a}uter, Matthias and Kramer, Tobias and Rubin, Martin and Altwegg, Kathrin}, title = {Determination of the ice composition near the surface of comet 67P/Churyumov-Gerasimenko}, series = {Europlanet Science Congress}, booktitle = {Europlanet Science Congress}, doi = {10.5194/epsc2022-826}, pages = {EPSC2022-826}, abstract = {During the apparition of comet 67P/Churyumov-Gerasimenko (67P/C-G) solar irradiation causes varying rates for sublimation of volatile species from the cometary nucleus. Because sublimation processes take place close to the cometary surface, the relative abundance of volatiles in the coma and the ice composition are related to each other. To quantify this relation we assume a model for the expansion of a collisionless gas from the surface into the surrounding space. We use an inverse model approach to relate the in situ measurements of gas densities from the two Rosetta instruments COPS (COmet Pressure Sensor) and DFMS (Double Focusing Mass Spectrometer) at the positions of the spacecraft to the locations of surface gas emissions during the Rosetta mission 2014-2016. We assume the temporally integrated gas emissions to be representative for the ice composition close to the surface. Our analysis shows characteristic differences in the ice compositions between both hemispheres of 67P/C-G. In particular CO2 ice has a reduced abundance on the northern hemisphere. In contrast to the hemispherical differences, the two lobes do not show significant differences in terms of their ice composition.}, language = {en} } @inproceedings{BuergerGundlachBlumetal., author = {B{\"u}rger, Johanna and Gundlach, Bastian and Blum, J{\"u}rgen and Hayne, Paul and L{\"a}uter, Matthias and Kramer, Tobias}, title = {Lunar regolith properties derived from LRO/Diviner data and thermophysical modelling}, series = {Europlanet Science Congress}, booktitle = {Europlanet Science Congress}, doi = {10.5194/epsc2022-92}, pages = {EPSC2022-92}, abstract = {The Moon as our nearest celestial object is one of the most important bodies for space resource exploration and planetary science. However, knowledge of the physical properties of the lunar regolith is required for the exploitation of lunar resources and for understanding the Moon's geologic history. This knowledge comes mainly from Apollo in-situ experiments and returned samples, but the global distribution of these properties is still poorly understood. Remote sensing measurements offer the opportunity to derive properties of unsampled areas with the help of models. In our study, a microphysical thermal model for the lunar regolith was developed and the simulated surface temperatures were compared with thermal emission measurements from the Diviner radiometer on board the Lunar Reconnaissance Orbiter (LRO) to derive regolith properties. This work expands upon previous investigations of lunar regolith properties using Diviner data, by more directly simulating physical properties such as particle size and porosity.}, language = {en} } @inproceedings{KramerLaeuter, author = {Kramer, Tobias and L{\"a}uter, Matthias}, title = {The near nucleus gas and dust environment around comet 67P/Churyumov-Gerasimenko}, series = {Europlanet Science Congress}, booktitle = {Europlanet Science Congress}, doi = {10.5194/epsc2022-281}, pages = {EPSC2022-281}, abstract = {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.}, language = {en} } @inproceedings{BrookFullerSwinburneetal., author = {Brook, Glenn and Fuller, Douglas and Swinburne, John and Christgau, Steffen and L{\"a}uter, Matthias and Rodrigues Pel{\´a}, Ronaldo and Lewin, Stein and Christian, Tuma and Steinke, Thomas}, title = {An Early Scalability Study of Omni-Path Express}, address = {Hamburg}, organization = {ISC 2022 IXPUG}, doi = {10.13140/RG.2.2.21353.57442}, pages = {8}, abstract = {This work provides a brief description of Omni-Path Express and the current status of its development, stability, and performance. Basic benchmarks that highlight the gains of OPX over PSM2 are provided, and the results of an initial performance and scalability study of several applications are presented.}, language = {en} } @article{LaeuterKramerRubinetal., author = {L{\"a}uter, Matthias and Kramer, Tobias and Rubin, Martin and Altwegg, Kathrin}, title = {The ice composition close to the surface of comet 67P/Churyumov-Gerasimenko}, series = {ACS Earth and Space Chemistry}, volume = {6}, journal = {ACS Earth and Space Chemistry}, number = {5}, doi = {10.1021/acsearthspacechem.1c00378}, pages = {1189 -- 1203}, abstract = {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.}, language = {en} } @article{BuergerHayneGundlachetal., author = {B{\"u}rger, Johanna and Hayne, Paul and Gundlach, Bastian and L{\"a}uter, Matthias and Kramer, Tobias and Blum, J{\"u}rgen}, title = {A Microphysical Thermal Model for the Lunar Regolith: Investigating the Latitudinal Dependence of Regolith Properties}, series = {Journal of Geophysical Research: Planets}, volume = {129}, journal = {Journal of Geophysical Research: Planets}, number = {3}, doi = {10.1029/2023JE008152}, abstract = {The microphysical structure of the lunar regolith provides information on the geologic history of the Moon. We used remote sensing measurements of thermal emission and a thermophysical model to determine the microphysical properties of the lunar regolith. We expand upon previous investigations by developing a microphysical thermal model, which more directly simulates regolith properties, such as grain size and volume filling factor. The modeled temperatures are matched with surface temperatures measured by the Diviner Lunar Radiometer Experiment on board the Lunar Reconnaissance Orbiter. The maria and highlands are investigated separately and characterized in the model by a difference in albedo and grain density. We find similar regolith temperatures for both terrains, which can be well described by similar volume filling factor profiles and mean grain sizes obtained from returned Apollo samples. We also investigate a significantly lower thermal conductivity for highlands, which formally also gives a very good solution, but in a parameter range that is well outside the Apollo data. We then study the latitudinal dependence of regolith properties up to ±80° latitude. When assuming constant regolith properties, we find that a variation of the solar incidence-dependent albedo can reduce the initially observed latitudinal gradient between model and Diviner measurements significantly. A better match between measurements and model can be achieved by a variation in intrinsic regolith properties with a decrease in bulk density with increasing latitude. We find that a variation in grain size alone cannot explain the Diviner measurements at higher latitudes.}, language = {en} }