Transmission #17 from Tycho (Impacts)

On impacts
"the most fundamental process on the terrestial planet" - Eugene and Carolyn Shoemaker

Phase of the Moon Today: 7:00pm Hip hip hooray, it is a beautiful night and I see the moon perfectly outside my balcony looks like a Waxing Crescent.

The more I learn and read about the Moon the more I appreciate it. I researched crater formation today and looked at why this process is important. Impact craters allow us to investigate the history of the planetary surface. It can be used as a clock for estimating ages of the surface, ie the more impacts the older the surface. It can provide information on the physical properties of near-surface rocks without having to retrieve samples. They can also be used as marker fossils as evidence/clues to other previous geological processes such as erosion, sedimentation or lava flooding.

There are two main types of crater formed on the lunar surface: Simple craters and Complex craters. The simple craters are characterised by a bowl-shaped depression on the planetary surface and is caused by a smaller projectile. As the projectile hits the surface geologic material is ejected into the air as the compression wave moves through the mantle. The ejecta is essentially excavated from the surface and falls back to the ground blanketing the surface in debris. The impact causes the bedrock to become fractured and the layer above to either melt or form breccia leaving behind a crater.

The complex crater results from greatrer impact energy due to a larger projectile. The rock debris crushed in the compression stage beneath a crater moves like a viscous fluid. This occurs due to the strong impact pressure wave passing through it. This 'fluidized' region allows the walls to fow or collapse inward toward the center of the cavity. The moving material converges in the midle and pushes the rocks up forming the central peak.

Pretty interesting stuff...

kb