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lunar-impact

FROM:   “SCIENCE” magazine, 28 Oct 2016, Reports, pages 441 – 444

IMPACT CRATERS

Formation of the ‘Orientale’ Lunar Multi-ring Basin

This research report in “SCIENCE” discusses large lunar impact craters characterized by multiple concentric topographic rings; Multi-ring Basins.

These basins dominate the Moon. The researchers used iSALE open source modeling code, a well-established, world-class tool for studying impacts. The research simulated the formation of the ‘Orientale’ multi-ring basin consistent with high-resolution gravity data from the Gravity Recovery and Interior Laboratory (GRAIL) spacecraft.

The simulated impact produced a large transient crater approximately 390 kilometers in diameter. The crater was not maintained due to subsequent gravitational collapse. These simulations indicated that a deep warm weak material was crucial to the formation of the outer rings.

The rings formed at different times during the gravitational collapse. Ring location and spacing are controlled by the diameter of the impact medium and lunar thermal gradients.

The researchers used graphs to depict the results of several model modifications to iSale (iSale open code is modifiable using Apache Subversion; SVN). The modified model utilized an impact speed of 15 kilometers per second, an impact medium diameter of 64 kilometers, a crustal thickness of 52 kilometers, a linear temperature gradient of 14 Kelvin per meter from a surface temperature of 300 Kelvin ( ~ 27 °C)

 

This method/data could be used to extrapolate crustal depths of planets and their lunar surfaces from observed multi-ring structures IF we knew the surface temperatures and gravitational forces of those planets.

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