Slow Impacts on Strong Targets Bring on the Heat. Issue 6 (30th March 2018)

• Record Type: Journal Article
• Authors: Melosh, H. J.; Ivanov, B. A.
• Is Part Of: Geophysical research letters. Volume 45:Issue 6(2018)
• Page Start: 2597
• Page End: 2599
• Publication Date: 2018-03-30
• Subjects: Impact heating -- Hydrocode simulation; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2018GL077726
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: An important new paper by Kurosawa and Genda (2017, https://doi.org/10.1002/2017GL076285 ) reports a previously overlooked source of heating in low velocity meteorite impacts. Plastic deformation of the pressure‐strengthened rocks behind the shock front dissipates energy, which appears as heat in addition to that generated across the shock wave itself. This heat source has surprisingly escaped explicit attention for decades: First, because it is minimized in the geometry typically chosen for laboratory experiments; and second because it is most important in rocks, and less so for the metals usually used in experiments. Nevertheless, modern numerical computer codes that include strength do compute this heating correctly. This raises the philosophical question of whether we can claim to understand some process just because our computer codes compute the results correctly. Plain Language Summary: A new theoretical analysis of how low‐velocity impacts heat the rock in their targets has revealed a previously overlooked source of heat that can substantially increase the temperature expected from models that do not incorporate rock strength. This heat source seldom contributes to laboratory measurements because of the simplified geometry commonly used in experiments. Although many modern hydrocodes actually do incorporate this mode of heating, impact researchers have not intellectually appreciated its role. Key Points: A previously unrecognized source of heat in low velocity impacts has been identified Although correctly computed in many computer codes, this heat source was not recognized before Just because we can compute some process correctly does not mean that we understand it