(meteorobs) Meteorites on The Ground! (Was: To Dirk)

[Marco Langbroek]

Op 26-3-2011 21:33, Meteorites USA schreef:
> Hi Marco, List,
>
> Your point seems logical, but I have a few questions. Basically the
> ablation rates of the artificial meteorite was determined with an object
> that fell at 35% of the speed of a natural meteoroid. Slower right? So
> given that it was falling slower, and was incandescent for a longer
> period, wouldn't that mean that it would have more time to ablate?
> Perhaps a lower temperature for a longer duration, would be comparable
> to a higher temperature for a shorter duration. Would it not ablate
> comparatively to a larger faster body?
>
> Regards,
> Eric

That is a good question.

The difference in speed is probably a much larger factor than time in this case, 
as it is the speed that is the important factor in kinetic energy. You can see 
this in actual meteoroids: fast meteoroids don't make it to the ground and are 
gone in a second: slow ones that take seconds or even tens of seconds do make it 
and drop meteorites. There, time and distance travelled clearly is not the 
factor in the eventual percentage of ablation (as the slow ones taking long 
times are the ones that are less ablated in the end): speed is. The slower the 
speed, the higher the chance of survival.

With 7.5 km/s at the start, you are actually already close to the speed where 
ablation stops (it stops at approximately half that speed). So I suspect that 
ablation already isn't that effective at that speed to begin with, compared to 
meteoroid speeds.

- Marco