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Simulations

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.


MOVIE

IMPACTOR

SIZE

SPEED

ANGLE

SURFACE

CRATER SIZE

  A1

Asteroid

12 km

20 km/s

45°

Land

120-140 km

  A2

Asteroid

12 km

20 km/s

45°

Ocean

130-150 km

  A3

Asteroid

12 km

15 km/s

45°

Ocean

115-140 km

  A4

Asteroid

10 km

20 km/s

45°

Shallow Sea

Chicxulub

Tektites

Asteroid

1.5 km

20 km/s

30°

Land

Ries

  C1

Comet

13 km

25 km/s

45°

Ocean

115-140 km

  C2

Comet

8 km

60 km/s

45°

Ocean

110-140 km

FUNDAMENTAL COMPONENTS OF ANY IMPACT CRATER COMPUTER MODEL

LAW OF MECHANICS

Definition: Force = Mass x Acceleration

Implementation: EASY

The physics of the process are established and well-known.

MATERIAL PROPERTIES

Definition: A material's reaction to strong compression and high temperature pulses (i.e., shocks), and reaction to damage and motion (stress , strain).

Implementation: DIFFICULT

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.

SCALE AND RESOLUTION

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.

Implementation: Theoretically EASY, realistically DIFFICULT

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.

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