Geomorphologic mapping of the lunar crater Tycho and its impact melt deposits

• Published in: Icarus (New York, N.Y. 1962) N.Y. 1962), 2016-07, Vol.273, p.164-181
• Main Authors: Krüger, T., van der Bogert, C.H., Hiesinger, H.
• Format: Article
• Language: English
• Subjects: Cameras; Cratering; Craters; Ejecta; Geomorphology; Impact melts; Impact processes; Lunar craters; Moon; Pixels; Selene (Japanese spacecraft); Surface
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2016.02.018

•We present a new high-resolution geomorphological and impact melt map of Tycho.•The distribution of melt ponds and ejecta are characteristic for an oblique impact.•Topographic observations also support an oblique impact from the W–SW.•Melt occurrence decreases with increasing distance from the crater rim.•Melt pools and the crater floor show younger apparent ages than the ejecta blanket. Using SELENE/Kaguya Terrain Camera and Lunar Reconnaissance Orbiter Camera (LROC) data, we produced a new, high-resolution (10m/pixel), geomorphological and impact melt distribution map for the lunar crater Tycho. The distal ejecta blanket and crater rays were investigated using LROC wide-angle camera (WAC) data (100m/pixel), while the fine-scale morphologies of individual units were documented using high resolution (∼0.5m/pixel) LROC narrow-angle camera (NAC) frames. In particular, Tycho shows a large coherent melt sheet on the crater floor, melt pools and flows along the terraced walls, and melt pools on the continuous ejecta blanket. The crater floor of Tycho exhibits three distinct units, distinguishable by their elevation and hummocky surface morphology. The distribution of impact melt pools and ejecta, as well as topographic asymmetries, support the formation of Tycho as an oblique impact from the W-SW. The asymmetric ejecta blanket, significantly reduced melt emplacement uprange, and the depressed uprange crater rim at Tycho suggest an impact angle of ∼25–45°.