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

[jeffrey wilson]

What exactly is a pork pie?  Hey, ive got an idea, everyone go out tonight and see if there is any increase in sporadic activity as compared to last year at this time.

Jeff.W.
--- On Sat, 3/26/11, Marco Langbroek <marco.langbroek at wanadoo.nl> wrote:

From: Marco Langbroek <marco.langbroek at wanadoo.nl>
Subject: Re: (meteorobs) Meteorites on The Ground! (Was: To Dirk)
To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
Date: Saturday, March 26, 2011, 8:26 AM

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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