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Venus: Satellite orbital decay, ephemeral ring formation, and subsequent crater production
Author(s) -
Bills Bruce G.
Publication year - 1992
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/92gl01067
Subject(s) - ejecta , orbital plane , impact crater , venus , physics , geology , radius , astronomy , roche limit , debris , planet , tidal heating , saturn , orbital period , earth radius , astrobiology , magnetosphere , computer science , stars , plasma , computer security , binary star , quantum mechanics , supernova , meteorology
The remarkable state of preservation of Venus impact craters may reflect their recent origin from a circumplanetary source, rather than a recent decline in resurfacing efficiency. Many of the craters observed on Venus may have been produced by impacts of particles on tidally decaying, high inclination orbits about the planet, rather than asteroidal or cometary debris on heliocentric orbits. A single satellite with radius of 100–200 km, and initial orbital distance of 15–20 times the radius of Venus could have been the original source for all of the impacting material. Over a fairly wide range of initial conditions and tidal evolution models, the transfer of angular momentum from the satellite orbit to the planetary spin leads to a situation in which the satellite passes inside the Roche limit at high inclination to the equator of Venus. After the satellite is tidally disrupted, the fragments quickly spread out over the orbital path, and differential precession forms a partial shell of material. Subsequent collisional damping of relative inclinations collapses the particles into a flat ring, with one of three possible stable orientations; prograde equatorial, retrograde equatorial, or perpendicular to the equatorial plane. Rapid radial inflow accompanies collapse into either equatorial ring. Initial inclinations greater than 30° at the time of disruption will lead to impact onto the surface during ring formation. Fragmentation reaches a steady state when the largest remaining particles have radii of 10–20 km. Bilateral symmetry of ejecta patterns reflect grazing impacts.