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Changes of the Physical Properties of Cometary surfacesIntroduction:This is a detailed and comprehensive photometric study on how the physical properties of surface dust cover change at different morphological location on comet 67P/ Churyumov-Gerasimenko and what mechanisms drive these changes. We examined different regolith alteration and dust transportation scenarios in different geomorphological locations and measured the properties with highest resolution sterophotoclinometry (SPC) methods possible.Method:Our technical approach would be to define different geomorphologic units in surface areas with different change level and perform mapping of wavelength-dependent photometric parameters of all units using the OSIRIS-NAC multiband imaging data as archived at PDS/SBN. We followed the procedure as in the previous similar work for 67P 1 and for other asteroids 2, 3 using other missions imaging and spectral data to perform photometric modeling and mapping. Once the spectrophotometric parameters and the maps are derived, we compared the differences and similarities between regions and interpret the results in the context of cometary geologic activity history. In this work, we applied a SPC method for generating global and local high-resolution shape models for describing both large scale and small-scale surface changes for multiple locations on 67P. We select our region-of-interests (ROIs) based on the surface change analysis results for further spectrophotometric studies. Then we performed a detailed modeling and mapping of the ROIs, including dramatic change like landslides, and different type of small changes. The error analysis of the modeling results follows the procedure outlined in 2, 4. Our data products, including geometric backplanes and maps will all be archived to PDS/SBN.Surface Changes:We will report the results and analysis of the surface changes from our methods. And we will also discuss the photometry findings about the changes of the surface physical properties.Acknowledgments:This research is supported by NASA Grant #80NSSC20K1152. All data used in this study are directly downloaded from the PDS small body node.Reference:1 Zou, X.D., et al., 2021, December. Detailed Geometry Data Study and Photometric Analysis with Rosetta/OSIRIS Images of Comet 67P/Churyumov-Gerasimenko. In AGU Fall Meeting 2021. AGU.2 Li, J.-Y., et al., 2019. Spectrophotometric modeling and mapping of Ceres. Icarus 322, 144-167.3 Zou, X.-D., et al., 2021. Photometry of asteroid (101955) Bennu with OVIRS on OSIRIS-REx. Icarus 358, 114183.4 Li, J.-Y., et al., 2013. Global photometric properties of Asteroid (4) Vesta observed with Dawn Framing Camera. Icarus 226, 1252-1274.
Zou et al. (Wed,) studied this question.