Cratering impact fragmentation

KL) Anon, "Military Explosives", TM 9-1300-214/TO 11A-1-34 (1967). Chapter 5. Properties and Tests of High Explosives Sensitivity to Frictional Impact (pp 5 1 to 5-3) Sensitivity to Friction (5 3 to 5-6) Sensitivity to Frictional Impact (5-6) Sensitivity to Heat and Spark, which includes Explosion Temperature Test (5-6 to 5-9) Sensitivity to Initiation (5-9) Stability Tests, which include 75° International Test, 100° Heat Test, Vacuum Stability Test and Potassium Iodide—Starch Test (5 9 to 5-15) Brisance Tests which include Sand Test, Plate Dent Test and Fragmentation Test (5 15 to 5-18 and Fig 5 13 on p 5-19) Initiating Value (5-18 5-20) Sympathetic Detonation (5-20 to 5-21) Power which includes Heat of Explosion Test, Ballistic Pendulum Test and Trauzl Lead Block Test (5-21. to 5-24) Blast Effect (5-24 to 5-27) Cratering Effect (5-28 5 29) and Munroe-Neumann Effect (5-29 to 5 35)... 

Some meteoroids shatter upon impact, while others remain intact. Those that break when they hit the ground may be found in fragments around the site of impact. Some of these fragments may weigh a couple of tons All of the meteorites from a single fall are given the same name. Thus, the many hundreds of meteorites that have been found at Meteor Crater in Arizona are called by the name Canyon Diablo. 

When the mass of the planetesimals exceeds 1024 kg, the escape velocity becomes larger than the random velocity. As a result, the collision velocity is a few km/s. With increasing collision velocity, cratering, vaporization, and fragmentation rather than growth of the planetesimals becomes dominant. Therefore, investigation of impact phenomena over a wide range of velocities is essential for discussion of the formation and disruption of planets. Especially, it becomes a key as to whether the velocity of impact ejecta exceeds the escape velocity of the planetesimal or protoplanet. 

The Earth and planetary system were formed 4.6 billion years ago. Certain meteorites as fragments from small planets have preserved a primitive cosmic composition and contain records of the early history of the solar system. Because of the lack of an atmosphere, the lunar surface has not been reworked and still exhibits the craters from the impact of large planetesimals which were abundant in space at the stage of planet formation. The oldest rocks on earth have an age of 3.5 to 4 billion years. 

In a related study, Basu et al. (2003) reported finding meteorite fragments and metalUc grains in rock samples from Graphite Peak. However, in the absence of an impact crater and other geomorphic evidence that is characteristic of impact events, the search for the causes of the Permo-Triassic extinction event continues. 

Appendix 18.12.3 recovered in Antarctica (Zeigler et al. 2005). Several specimens are paired because they are either fragments of a lunar rock sample that broke up during its passage through the atmosphere or because they originated from the same impact crater on the Moon (i.e., source pairing, Warren 2005). 

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