Wednesday, March 29, 2017

This image shows the results of a lab test impact between a small sphere of aluminum travelling at approximately 6.8 km/second and a block of aluminum 18 cm thick. This test simulates what can happen when a small space debris object hits a spacecraft.

The little divot on the backside of the plate is called spalling.  Basically you have a thick plate of fairly brittle metal, and when it gets hit hard, the (compression) shockwave travels through the material without dissipating much. When it reaches the end of the plate, it can go no further and essentially 'bounces' back, turning into a pulling force, which pulls the material apart. If the impact had been a little stronger, that bottom part would have come loose entirely and could have ejected at lethal speeds.


  1. Which is why the Brits developed Chobham Armor. Layered material absorbs the shock better (Ceramic tiles layered with elastic material, encased within a metal framework and bonded to a backing plate that prevents spalling. It doesn't mean that it's full-proof but it's better than a slab of metal for the reasons that you point out above.

  2. Hi C.W.,
    "Most Cool!!!!!!"
    "Audentes, Fortuna, Ivat!!,"

    1. Fortune certainly does favor the bold. Always good to leaven the bold with a healthy dollop of prudence, though, recalling the old saw about no old, bold crop-dusters!

  3. If my arithmetic is correct that is 15,214.42 mph