[meteorite-list] Mars Express: Phobos Flyby Images Released

From: Jerry Flaherty <grf2_at_meteoritecentral.com>
Date: Thu, 18 Mar 2010 23:05:30 -0400
Message-ID: <3D31DC7522544B3887FA4A51585676C7_at_ASUS>

Thank you Richard [et. Alan]. I'm happy to have some corroboration for my
perceptions. Rubble pile to the rescue!
Jerry

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From: "Richard Kowalski" <damoclid at yahoo.com>
Sent: Thursday, March 18, 2010 3:40 PM
To: "Meteorite Mailing List" <meteorite-list at meteoritecentral.com>; "Jerry
Flaherty" <grf2 at comcast.net>
Subject: Re: [meteorite-list] Mars Express: Phobos Flyby Images Released

> A similar question came up on MPML about the grooves on Phobos. I thought
> this answer by Alan Harris might be of interest.
>
> --
> Richard Kowalski
> Full Moon Photography
> IMCA #1081
>
>
> Alan Harris wrote:
>
> The "strings" or "grooves" have been seen since the time of the early
> Mariners and Vikings, they're just seen a little (lot) better now. They
> are not related to multiple impacts, in spite of some appearance of being
> strings of craters. They have been studied extensively over the years,
> with their nature not entirely resolved, but appear to be related in some
> way with the tidal environment of Phobos. If it were a fluid, it would
> simply come apart, since it is inside the classical Roche limit. However,
> even a "rubble pile" can persist there, held together only by the "angle
> of repose" limit of such material. When struck by an impact though, the
> vibration of the impact may allow material to "slump", just as we
> sometimes see landslides triggered by earthquakes. This kind of slumping
> may result in crack or "grooves" running across the terrain. I
> co-authored a paper in Nature many years ago putting this hypothesis
> forward (Soter, S., Harris, A. 1977, Are striations on PHOBOS evidence for
> tidal stress? Nature 268, 421). This is not the last word on the matter
> (in fact, it was sort of the
> "first word"). There are a number of more recent publications on it.
>
> Alan
>
>
>
Received on Thu 18 Mar 2010 11:05:30 PM PDT