title: Sesquinary catenae on the Martian satellite Phobos from reaccretion of escaping ejecta.
abstract: The Martian satellite Phobos is criss-crossed by linear grooves and crater chains whose origin is unexplained. Anomalous grooves are relatively young, and crosscut tidally predicted stress fields as Phobos spirals towards Mars. Here we report strong correspondence between these anomalous features and reaccretion patterns of sesquinary ejecta from impacts on Phobos. Escaping ejecta persistently imprint Phobos with linear, low-velocity crater chains (catenae) that match the geometry and morphology of prominent features that do not fit the tidal model. We prove that these cannot be older than Phobos' current orbit inside Mars' Roche limit. Distinctive reimpact patterns allow sesquinary craters to be traced back to their source, for the first time across any planetary body, creating a novel way to probe planetary surface characteristics. For example, we show that catena-producing craters likely formed in the gravity regime, providing constraints on the ejecta velocity field and knowledge of source crater material properties.
authors: Red Sky Research, LLC, 67 Northland Meadows Drive, Edgewood, New Mexico 87015, USA.|Department of Earth &Planetary Sciences, University of California at Santa Cruz, 1156 High Street, Santa Cruz, California 95064, USA.
authors: M
authors: M
authors: Nayak
authors: Department of Earth &Planetary Sciences, University of California at Santa Cruz, 1156 High Street, Santa Cruz, California 95064, USA.|School of Earth &Space Exploration, Arizona State University, 781 S Terrace Road, Tempe, Arizona 85281, USA.
authors: E
authors: E
authors: Asphaug