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Re: Hot and cold
michel franco schrieb:
> Dear All,
>
> As the subject was about temperature of just landed meteorites, I
> was wondering about Antarctica ( and Greenland as well) and
> meteorites there. We all know that they concentrate on blue ice
> fields. The question is what happens when a meteorite lands on a
> snowy area ( usually covered with sastrugis*) Will the meteorite,
> depending its mass, dig a hole ? Melts a hole? Just lies on top
> to be gathered by a lucky traveler ?
Bonjour Michel, hello List,
*sastrugi = ridges of snow formed on a snowfield
by the action of the wind.
> Melts a hole?
No, I don't think so. In spite of all those reports like "too hot
to handle", etc., most of them will be "cold" or at most "warm
to the touch". The perception of a meteorite being "hot" is
probably a psychological phenomenon triggered by a feeling of
touching something unknown, something your experience can't
"handle" or hasn't "handled" yet. Of course, there may be
exceptions to the rule.
> Will the meteorite, depending its mass, dig a hole ?
Yes, I think so. Heavy Anarctic masses like DRPA78009 (IIB, 138 kg)
or LEW 85320 (H5, 110 kg) will probably excavate an (impact) hole on
landing IF they actually fell on ice or snow. As for LEW 85320, some
of its regmaglypts contained Antarctic soil, so it may have hit solid
ground on landing.
> Just lies on top to be gathered by a lucky traveler ?
Well, this part of the scenario is pretty well known:
1. The incoming meteorite is buried in snow.
2. The snow recrystallizes into ice.
3. The encased meteorites are carried toward the sea, but:
4. Some of them become trapped behind mountain ranges.
5. Downhill winds scour away the snow.
6. The ice pushes upward against the mountain barrier.
6. The wind cuts into the different layers of ice, and
7. Exposes the meteorites (wind erosion).
Best wishes,
Bernd
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