Morphological and Spectrophotometric exploitation of JANUS LEGA Dataset: Langrenus impact crater characterization and evolution of the highland "isthmus" between Mare Fecunditatis and Mare Tranquillitatis

Lucchetti, Alice; Massironi, Matteo; Gwinner, Klaus; Kenkmann, Thomas; Penasa, Luca; Baby, Namitha R.; Rotzoll, Laura; Karagoz, Oguzcan; Rizos, Juan L.; Pajola, Maurizio; Tosi, Federico; Fornasier, Sonia; Tusberti, Filippo; Stephan, Katrin; Pozzobon, Riccardo; Suarez-Valencia, Javier E.; Cagnin, Davide; Zambon, Francesca; Chiarolanza, Gianluca; Coustenis, Athena; Giacomini, Lorenza; Hauber, Ernst; Marchi, Simone; Matteoni, Pietro; Mitri, Giuseppe; Rossi, Costanza; Hueso, Ricardo; Aboudan, Alessio; Agostini, Livio; Kersten, Elke; Matz, Klaus D.; Politi, Romolo; Trauthan, Frank; Tubiana, Cecilia; Aye, Michael; Zinzi, Angelo; Evill, Ry; Belgacem, Ines; Castro-Marin, Jose M.; Della Corte, Vincenzo; Hviid, Stubbe; Roatsch, Thomas; Schmitz, Nicole; Lara, Luisa M.; Patel, Manish R.; Portyankina, Ganna; Palumbo, Pasquale; the JANUS team,

doi:10.5194/egusphere-2026-1901

Alice Lucchetti, Matteo Massironi, Klaus Gwinner, Thomas Kenkmann, Luca Penasa, Namitha R. Baby, Laura Rotzoll, Oguzcan Karagoz, Juan L. Rizos, Maurizio Pajola, Federico Tosi, Sonia Fornasier, Filippo Tusberti, Katrin Stephan, Riccardo Pozzobon, Javier E. Suarez-Valencia, Davide Cagnin, Francesca Zambon, Gianluca Chiarolanza, Athena Coustenis, Lorenza Giacomini, Ernst Hauber, Simone Marchi, Pietro Matteoni, Giuseppe Mitri, Costanza Rossi, Ricardo Hueso, Alessio Aboudan, Livio Agostini, Elke Kersten, Klaus D. Matz, Romolo Politi, Frank Trauthan, Cecilia Tubiana, Michael Aye, Angelo Zinzi, Ry Evill, Ines Belgacem, Jose M. Castro-Marin, Vincenzo Della Corte, Stubbe Hviid, Thomas Roatsch, Nicole Schmitz, Luisa M. Lara, Manish R. Patel, Ganna Portyankina, Pasquale Palumbo, and the JANUS team

Abstract. The European Space Agency’s (ESA) JUpiter ICy moons Explorer (JUICE) mission, launched in April 2023, performed the Lunar-Earth Gravity Assist (LEGA) maneuver in August 2024 as an instrument validation opportunity and science investigation. During this flyby, the Jovis, Amorum ac Natorum Undique Scrutator (JANUS) camera acquired a continuous multispectral imaging strip across the lunar surface, achieving spatial resolutions down to approximately 20 m/pixel. This paper presents a detailed morphological and spectrophotometric characterization of two regions of interest: Langrenus impact crater and the highland “isthmus” between Mare Fecunditatis and Mare Tranquillitatis.

Analysis of Langrenus reveals a structurally complex impact site located at the transition between mare and highland terrains. Spectral unmixing indicates that the crater interior is dominated by mafic components, with minor but spatially coherent olivine-compatible signatures identified within the northern hummocky floor terrain and portions of the crater rim. Although the limited spectral sampling prevents definitive mineralogical discrimination, these mafic signatures may reflect excavation of heterogeneous target materials during impact or redistribution of mare-derived components through post-impact mass wasting and regolith mixing processes. Furthermore, investigations of the highland “isthmus” bring evidence for distinct generations of volcanic activity. Spectral analysis demonstrates a long-lived, structurally modulated, low-Titanium volcanic system, distinct from large-scale mare volcanism, characterized by small-volume magmatic emplacements that exploited impact-generated fractures for ascent.

These results not only provide new insights into lunar geological processes but also serve as a successful end-to-end validation of the JANUS camera’s performance in an operational environment, confirming its readiness for the high-resolution characterization of the Galilean moons.

How to cite. Lucchetti, A., Massironi, M., Gwinner, K., Kenkmann, T., Penasa, L., Baby, N. R., Rotzoll, L., Karagoz, O., Rizos, J. L., Pajola, M., Tosi, F., Fornasier, S., Tusberti, F., Stephan, K., Pozzobon, R., Suarez-Valencia, J. E., Cagnin, D., Zambon, F., Chiarolanza, G., Coustenis, A., Giacomini, L., Hauber, E., Marchi, S., Matteoni, P., Mitri, G., Rossi, C., Hueso, R., Aboudan, A., Agostini, L., Kersten, E., Matz, K. D., Politi, R., Trauthan, F., Tubiana, C., Aye, M., Zinzi, A., Evill, R., Belgacem, I., Castro-Marin, J. M., Della Corte, V., Hviid, S., Roatsch, T., Schmitz, N., Lara, L. M., Patel, M. R., Portyankina, G., Palumbo, P., and the JANUS team: Morphological and Spectrophotometric exploitation of JANUS LEGA Dataset: Langrenus impact crater characterization and evolution of the highland "isthmus" between Mare Fecunditatis and Mare Tranquillitatis, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2026-1901, 2026.

Received: 02 Apr 2026 – Discussion started: 17 Apr 2026

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