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

[Meteorites USA]

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




On 3/26/2011 5:26 AM, Marco Langbroek wrote:
> Op 26-3-2011 00:45, Meteorites USA schreef:
>    
>> Quote: ""Three quarters of the rock, which was about the size of a small
>> pork pie, was burnt off in the experiment."
>>
>> So only 75% of a body is ablated during atmospheric entry? This
>> disproves the 90% ablation rate hypothesis and actually proves my point.
>>      
>
> It disproves nothing. Apples and oranges.
>
> Somebody here on meteorobs already remarked this earlier: but the entry velocity
> of an earth orbiting vehicle (i.e. satellite) such as the one on which the
> samples were mounted, is clearly lower than that of meteorite dropping
> meteoroids. As a result, ablation rates will be markedly different.
>
> Re-entry from Earth orbit is with maximum speeds of 7.5 - 8 km/s. This is a mere
> 35% to at best 50% of the speed of a meteoroid (minimal 11.8 km/s, often much
> more, up to 25 km/s).
>
> In a way, this is somewhat similar to having a bicyclist at ~30 km/h run into a
> wall, and then trying to asses from that what damage will result from a car
> doing the same at 100 km/h.
>
> The two are just not comparable.
>
> - Marco
>
>
> -----
> Dr Marco (asteroid 183294) Langbroek
> Dutch Meteor Society (DMS)
>
> e-mail: dms at marcolangbroek.nl
> http://www.dmsweb.org
> http://www.marcolangbroek.nl
> -----
>
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