Radar backscatter properties of the landing site

L. E. Bonnefoy1, R. D. Lorenz2, A. G. Hayes3, A. Lucas1, D. Lalich3, V. Poggiali3, S. Rodriguez1, A. Le Gall4

1Université de Paris, Institut de physique du globe de Paris, CNRS, Paris, France, 2Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA, 3Department of Astronomy, 4 Cornell University, Ithaca, NY, USA, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), UVSQ /CNRS/Paris VI, UMR 8190, 78280 Guyancourt, France

RESULTS DISCUSSION INTRODUCTION Resolved SAR The dunes are radar-dark, especially at high The Dragonfly mission, observations of incidence angles, similar dunes in Belet, selected as the next New Selk crater Shangri-la, and Fensal (e.g., Lucas et al., Frontiers mission by NASA, have been 2019), indicating a smooth and absorbing will send a rotorcraft to acquired surface consistent with organic, fine-grained in the mid-2030s (launching during six sand. in 2027). The chosen Cassini flybys, landing site (Lorenz et al., 2021), in the with incidence The radar-bright Selk crater rim likely Shangri-la dune field near the geologically angles that presents: young Selk crater (6.5°N, 161.5°E), has vary between • High 2.2-cm scale surface roughness been observed by several instruments 20° and 70°. • Multiple subsurface scattering on onboard the Cassini spacecraft (in orbit organized structures (cracks, layering) around Saturn from 2004 to 2017), with the • A radar-transparent material like water ice Radar in Synthetic Aperture Radar (SAR) (allowing for multiple scattering) mode providing the highest resolution data We mapped four terrain units in the immediate vicinity of Selk  The impact excavated the icy bedrock and (up to ~300 m/pixel). crater and constructed their backscatter curves, revealing created a rough, blocky, cracked surface.

variations in the composition and structure of the medium.

METHOD Measured backscattered radar signal (the PERSPECTIVES normalized radar cross-section σ0) depends on: Current and future work include: • Surface Figure from Wye (2011) • Analysis of distant radar scatterometry to complete the backscatter curve roughness • Subsurface • Analysis of radar altimetry over nearby roughness terrains and • Application of physical models to structures constrain surface properties (e.g., Lucas Candidate landing (cracks, et al., 2019) ellipse (Lorenz layers, grain et al., 2021) • Comparison with similar craters over Titan sizes) •Composition (dielectric constant, probed depths) Click on the Zoom button to REFERENCES • Surface slopes (which modify incidence [1] Lorenz, R. D. et al., Planetary Science Journal, 2021 [2] talk to me about my poster Wye, L. C., PhD thesis, 2011 [3] Lucas, A. et al., J. angles) Geophys. Res.: Planets (2019) rd Available: April 23 2:15-2:45 pm EDT