FUNDAMENTAL COMPONENTS OF ANY
IMPACT CRATER COMPUTER MODEL
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LAW OF MECHANICS |
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Definition: Force = Mass x Acceleration |
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Implementation: EASY |
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The physics of the process are established and well-known. |
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MATERIAL PROPERTIES |
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Definition: A material's reaction to strong compression and high temperature pulses (i.e., shocks), and reaction to damage and motion (stress, strain). |
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Implementation: DIFFICULT |
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Material properties are well defined under normal conditions, but in an impact event the conditions are beyond normal, and require difficult experimental setups. These properties are necessary for building theoretical models of the material that can work under a wide range of conditions. |
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SCALE AND RESOLUTION |
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Definition: The problem under investigation defines the spatial region that must be modeled and how accurately it should be represented. This is important because the spatial region (scale) must be discretized into smaller elements (cells), which defines the resolution of the problem. |
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Implementation: Theoretically EASY, realistically DIFFICULT |
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The discretization process can be done as long as there is enough computer power and storage. The problem is that to realistically model an impact cratering event, it is necessary to use three-dimensional simulations, which require incredible amounts of computer power and storage. |
INTRODUCTION TO IMPACT SIMULATIONS: NUMERICAL MODELING
Impact craters form when huge asteroids or comets, sometimes kilometers in size, hit the surface
of a
planetary body. Images of various planets and moons in the solar system show thousands
and thousands of impact craters on their surfaces.
Impact craters can also be reproduced on a smaller scale. Laboratory experiments can create
craters that are centimeters to meters in size, by launching small projectiles against solid targets
at high speeds, just like firing a bullet into a board. Unfortuntately, laboratory experiments
are limited by the size and speed of the projectile. While images of planetary surfaces do
show the result of impacts, they do not provide us with information on the impactor and
the
impact event itself.
Computer models have played a very important role in understanding the process of impact
cratering, providing a connection from laboratory scale impacts (i.e., craters centimeters to
meters in size) to the large planetary scale events (kilometers to hundreds of kilometers in size),
which allows scientists to verify their understanding of the process, the physical laws that govern
it, and the characteristics that influence the final outcome of the impact event.
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MOVIE |
IMPACTOR |
SIZE |
SPEED |
ANGLE |
SURFACE |
CRATER SIZE |
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Asteroid |
12 km |
20 km/s |
45° |
Land |
120-140 km |
|
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Asteroid |
12 km |
20 km/s |
45° |
Ocean |
130-150 km |
|
|
Asteroid |
12 km |
15 km/s |
45° |
Ocean |
115-140 km |
|
|
Asteroid |
10 km |
20 km/s |
45° |
Shallow Sea |
Chicxulub |
|
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Asteroid |
1.5 km |
20 km/s |
30° |
Land |
Ries |
|
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Comet |
13 km |
25 km/s |
45° |
Ocean |
115-140 km |
|
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Comet |
8 km |
60 km/s |
45° |
Ocean |
110-140 km |
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