Radar Identification and Geomorphic Characterization of Distal Tycho Secondary Craters
4 affiliations
- 1Purdue University
- 2Johns Hopkins Applied Physics Laboratory
- 3CRESST-II University of Maryland
- 4Planetary Science Institute
Abstract
Tycho (43.37°S, 348.68°E) is a ∼100 Myr old lunar impact crater distinguished by an extensive ray system populated by numerous secondary craters. While proximal secondaries display elongated and asymmetric crater morphologies, distal secondaries can resemble primary craters, increasing the risk of misclassification in crater-based age determinations. Here, we use radar observations of bright, extended, asymmetric ejecta deposits that point in the downrange direction from Tycho to identify and characterize potential Tycho-related secondary craters. We identify 663 such craters along Tycho’s rays and review additional morphometric evidence of their secondary nature. Although some of these craters appear in linear chains or clustered groups, others are isolated and would otherwise be difficult to recognize as secondaries. The radar-bright asymmetric ejecta generally align with ray orientations, although ∼10% of craters show ejecta patterns likely influenced by local slopes. Radar backscatter from the ejecta is enhanced in depolarized and even-bounce scattering, indicative of rough terrains. Inspection of Narrow Angle Camera and ShadowCam images, though, indicates little to no contribution by surface meter-scale boulders. As such, these observations suggest that scattering may be dominated by subsurface structural heterogeneity or small-scale roughness below the image resolution. Similar radar-bright asymmetric ejecta are also observed around other large rayed craters, including Byrgius A (25.621°S, 62.659°E), Glushko (9.221°N, 76.389°E), and Kepler (9.724°N, 41.54°E), spanning a range of ages and suggesting long-term preservation of wavelength-scale complexity. These results demonstrate that radar observations provide a robust means of identifying distal secondary craters and characterizing ejecta emplacement processes.
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BibTeX
@article{perezcortes2026radar,
title = {{Radar Identification and Geomorphic Characterization of Distal Tycho Secondary Craters}},
author = {Santa L. Pérez-Cortés and Edgard G. Rivera-Valentín and Caitlin J. Ahrens and Ali M. Bramson and Caleb I. Fassett and Cole A. Nypaver and Gareth Morgan and G. Wesley Patterson and Tyler M. Powell},
journal = {The Planetary Science Journal},
year = {2026},
month = oct,
doi = {10.3847/psj/aea98b},
url = {https://iopscience.iop.org/article/10.3847/PSJ/aea98b},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Radar Identification and Geomorphic Characterization of Distal Tycho Secondary Craters
AU - Santa L. Pérez-Cortés
AU - Edgard G. Rivera-Valentín
AU - Caitlin J. Ahrens
AU - Ali M. Bramson
AU - Caleb I. Fassett
AU - Cole A. Nypaver
AU - Gareth Morgan
AU - G. Wesley Patterson
AU - Tyler M. Powell
PY - 2026
DA - 2026/10/09
JO - The Planetary Science Journal
DO - 10.3847/psj/aea98b
UR - https://iopscience.iop.org/article/10.3847/PSJ/aea98b
AB - Tycho (43.37°S, 348.68°E) is a ∼100 Myr old lunar impact crater distinguished by an extensive ray system populated by numerous secondary craters. While proximal secondaries display elongated and asymmetric crater morphologies, distal secondaries can resemble primary craters, increasing the risk of misclassification in crater-based age determinations. Here, we use radar observations of bright, extended, asymmetric ejecta deposits that point in the downrange direction from Tycho to identify and characterize potential Tycho-related secondary craters. We identify 663 such craters along Tycho’s rays and review additional morphometric evidence of their secondary nature. Although some of these craters appear in linear chains or clustered groups, others are isolated and would otherwise be difficult to recognize as secondaries. The radar-bright asymmetric ejecta generally align with ray orientations, although ∼10% of craters show ejecta patterns likely influenced by local slopes. Radar backscatter from the ejecta is enhanced in depolarized and even-bounce scattering, indicative of rough terrains. Inspection of Narrow Angle Camera and ShadowCam images, though, indicates little to no contribution by surface meter-scale boulders. As such, these observations suggest that scattering may be dominated by subsurface structural heterogeneity or small-scale roughness below the image resolution. Similar radar-bright asymmetric ejecta are also observed around other large rayed craters, including Byrgius A (25.621°S, 62.659°E), Glushko (9.221°N, 76.389°E), and Kepler (9.724°N, 41.54°E), spanning a range of ages and suggesting long-term preservation of wavelength-scale complexity. These results demonstrate that radar observations provide a robust means of identifying distal secondary craters and characterizing ejecta emplacement processes.
SN - 2632-3338
ER -