Preprints
https://doi.org/10.5194/egusphere-2026-1901
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/egusphere-2026-1901
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
17 Apr 2026
| 17 Apr 2026
Status: this preprint is open for discussion and under review for Annales Geophysicae (ANGEO).
Morphological and Spectrophotometric exploitation of JANUS LEGA Dataset: Langrenus impact crater characterization and evolution of the highland "isthmus" between Mare Fecunditatis and Mare Tranquillitatis
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.
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INAF-OAPD Astronomical Observatory of Padova, Padova, Italy
Matteo Massironi
Dipartimento di Geoscienze, Università di Padova, Padova, Italy
Klaus Gwinner
German Aerospace Center (DLR), Berlin, Germany
Thomas Kenkmann
University of Freie, Germany
Luca Penasa
INAF-OAPD Astronomical Observatory of Padova, Padova, Italy
Namitha R. Baby
University of Freie, Germany
Laura Rotzoll
University of Freie, Germany
Oguzcan Karagoz
University of Freie, Germany
Juan L. Rizos
Institute of Astrophysics of Andalusia - IAA-CSIC, Granada, Spain
Maurizio Pajola
INAF-OAPD Astronomical Observatory of Padova, Padova, Italy
Federico Tosi
INAF-IAPS, Rome, Italy
Sonia Fornasier
LIRA, Université Paris Cité, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, CY Cergy Paris Université, F-92190 MEUDON, France
Filippo Tusberti
INAF-OAPD Astronomical Observatory of Padova, Padova, Italy
Katrin Stephan
German Aerospace Center (DLR), Berlin, Germany
Riccardo Pozzobon
deceased
Javier E. Suarez-Valencia
Dipartimento di Geoscienze, Università di Padova, Padova, Italy
Davide Cagnin
Dipartimento di Geoscienze, Università di Padova, Padova, Italy
Francesca Zambon
INAF-IAPS, Rome, Italy
Gianluca Chiarolanza
University G. d’Annunzio Chieti - Pescara, Italy
Athena Coustenis
LIRA, Université Paris Cité, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, CY Cergy Paris Université, F-92190 MEUDON, France
Lorenza Giacomini
INAF-IAPS, Rome, Italy
Ernst Hauber
German Aerospace Center (DLR), Berlin, Germany
Simone Marchi
Southwest Research Institute, Boulder, CO, USA
Pietro Matteoni
University of Freie, Germany
Giuseppe Mitri
University G. d’Annunzio Chieti - Pescara, Italy
Costanza Rossi
INAF-OAPD Astronomical Observatory of Padova, Padova, Italy
Ricardo Hueso
UPV/EHU, Bilbao, Spain
Alessio Aboudan
CISAS G. Colombo, Padova University, Italy
Livio Agostini
Institute of Astrophysics of Andalusia - IAA-CSIC, Granada, Spain
Elke Kersten
German Aerospace Center (DLR), Berlin, Germany
Klaus D. Matz
German Aerospace Center (DLR), Berlin, Germany
Romolo Politi
INAF-IAPS, Rome, Italy
Frank Trauthan
German Aerospace Center (DLR), Berlin, Germany
Cecilia Tubiana
INAF-IAPS, Rome, Italy
Michael Aye
University of Freie, Germany
Angelo Zinzi
Italian Space Agency (ASI), Rome, Italy
Ry Evill
ESOC, Germany
Ines Belgacem
ESTEC, The Netherlands
Jose M. Castro-Marin
Institute of Astrophysics of Andalusia - IAA-CSIC, Granada, Spain
Vincenzo Della Corte
INAF-OAC, Napoli, Italy
Stubbe Hviid
German Aerospace Center (DLR), Berlin, Germany
Thomas Roatsch
German Aerospace Center (DLR), Berlin, Germany
Nicole Schmitz
German Aerospace Center (DLR), Berlin, Germany
Luisa M. Lara
Institute of Astrophysics of Andalusia - IAA-CSIC, Granada, Spain
Manish R. Patel
School of Physical Sciences, Open University, Milton Keynes, UK
Ganna Portyankina
German Aerospace Center (DLR), Berlin, Germany
Pasquale Palumbo
INAF-IAPS, Rome, Italy
A full list of authors appears at the end of the paper.
Short summary
During a lunar flyby, the JANUS camera on board the Jupiter Icy Moons Explorer mission captured detailed images of the Moon’s surface. We studied a large impact crater and a nearby highland region, finding evidence of complex surface changes over time and signs of unusual volcanic activity. These results improve our understanding of how the Moon evolved and confirm that the JANUS camera is ready for future exploration of Jupiter’s moons.
During a lunar flyby, the JANUS camera on board the Jupiter Icy Moons Explorer mission captured...
General aspects
The work is about the results of the JANUS camera based spectral observations of a selected Lunar area. The work is interesting partly as the calibration / validation of JANUS does matter and will influence many works in the future in the Jovian system, and the work also provides some new scientific results. The structure of the work is good, the language is perfect. The methods are described however few improvements would be useful. Minor revise is suggested. Please also mention how much was topographic dataset used during the photometric correction? Please also discuss any „correlation” between the possibility of spectral identification and optical maturity. This aspect as well as the domes also should receive more specific emphasis in the abstract also.
Specific aspects
Abstract
„Spectral unmixing indicates that the crater interior is dominated by mafic components,”
It is good and useful of course, but would make more sense if some comparative aspects have been mentioned on the crater’s interior properties compared to the surrounding terrain.
around line 65
some info on the spectral coverage would be needed here
91
„Lunar_LRO_LROC-WAC_Mosaic_global_100m_June2013”
consider moving it to the references
111
„declination”
not clear what is it here, relative to „something”?
130
„highland “isthmus” region”
would be good to have an overview with marked the mentioned sites / features, maybe on FIg.3 some texts for site identification could help
179
„distinctive herringbone pattern”
might be not clear for all readers, would help to cite the Springer based encyclopaedia of planetary landforms
around 210
Could have been melt ponds identified /separated in the spectral datasets?
229
„vertical throws”
many readers might not be familiar with this term
247
„The data suggest that crater modification is influenced by somewhat weaker mare lithologies in the western and stronger highland lithologies in the eastern terrace zone”
this might fit better with some explanation to the reasons to the Discussion section – this is a figure caption only
Fig 9
the colour based identification of measured locations is not easy, might be accompanied with small numbers in the panels – but I let this to be decided by the authors
364-366
important, might mention later in the summary also
Fig 10
scalebars are needed on the left image stripes
405-407
„However, given the limited number of spectral bands and expected degeneracies between mafic endmembers, these results should be interpreted as indicative of dominant spectral trends rather than precise modal mineralogy.”
yes and the multicolour based spectral resolution aslo matters
427
„to bridge regional and local scales and provide reliable data for geomorphological and crater-counting analyses”
the numerical size of this spatial scale might be also mentioned
430
„such as the extensive terrace zone in the western crater sector, indicate that the Langrenus impact event occurred into a heterogeneous target, where the western target portion already bears characteristics of the mare basin”
this might or need not be. Terraced wall might (and usually) form by large scale mass wasting during the collapse of transient crater regardless the subsurface structure
440-450
did you consider dating of ejecta also or only the inner crater units?
475-476
does this mean the mare/highland boundary was not well located previously?
around 500 and elsewhere
domes are mentioned but specifically not discussed enough, please include in the abstract also
538
„The D2 and D3 domes are spatially associated with pre-existing impact craters (OC) suggesting magma rising induced by impact fracturing”
not clear enough why such connection is expected
536
„The maria smooth plains locally infill the relatively recent craters (RRC).”
not clear, basaltic emplacement happened long time ago, would it be younger than recent craters?
Fig 13.
„the highland “isthmus”
could be indicated as text in the image – or does it cover large part of the image?
579
„Blue Channel”
please unify the writing mode of channels, capitalize all or do not capitalize any
679
„structurally modulated volcanic regime”
does it mean differentiated or evolved magma appearance as time passed by?