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Allende & Phobos


Frank Stroik brought up the topic of the Allende meteorite connection with
Phobos and pointed out it is not very definitive.  Michael Blood replied
to this issue.  To ensure there is no misquotes, 
I've included both their statements here.  I have some
additional information on the subject which is appended below.
Also, this is not a personal attack on Michael
Blood - I'm just continuing the discussion started by Frank.

Frank Stroik writes:
>	I am troubled by what I am reading in dealer catalogs, listings, 
>and webpages. I see a lot of inaccuracies, and half truths in 
>descriptions of meteorites. This is a touchy subject, but one that needs 
>to be addressed.
>	Also The Mars moon Phobos, and Allende connection is wrong. It seems 
>that remote sensing data indicate a correlation, but nothing definative. 
>By virtue of oxygen isotopes, Allende had to form at the outer edge of 
>the asteroid belt, at the very least. The researcher needs to explain how 
>an asteroid can migrate through the belt, and stop in a parking orbit 
>around Mars. Until this acheived, it is speculation at most, and to 
>relay that to the public is not correct information.

Michael Blood replies:
>     I am probably one of the worst "offenders" to whom you referred. I
>certainly reported the Allende/Phobos connection & the recent Ibitira
>flap was in reaction to my passing on information given to me. 
>     I would like to take you up on your offer to provide info if asked:
>Specifically, (for now) the Allende/Phobos connection. This was passed
>on to me by THE most sophisticated & knowledgable collector I know. How
>was he mistaken? Is there a specific paper or article that was later
>proven to be in error? He was quite adimate no other body in the solar
>system was close to matching the "refractometer" readings of Allende &
>that Phobos was a perfect match. 

Michael,

Can you provide to me the name of this collector?  Or give him my name and phone
number?  I would very much like to talk with him.

By coincidence, Michael's latest newsletter arrived in my
mailbox this week.  After reading the paragraph from the newsletter 
on Allende/Phobos (quoted below), I could understand Frank's concern.

  "Among the other many interesting aspects of Allende, unmanned probes have
   indicated that the only formation in the solar system which has the
   same refractive qualities and weight/mass ratio as Allende is Phobos,
   one of the moons of Mars!  So, while most collectors cannot afford an
   SNC ("Mars rock") and few in the world have a piece of the earth's moon,
   you can easily afford an excellent specimen of likely Mars' lunar
   material!"

Now, it is true that spectroscopic analysis of Phobos indicates that its
composition is similar to carbonaceous chondrites.  It is also true that 
Allende is a carbonaceous chondrite.  So there is a possibility that
Phobos is the parent body of the Allende meteorite.  However, and this
is very important, the spectra matches have also been found between
carbonaceous chondrites and several other asteroids.  In other words,
Allende may have originated from an asteroid and not Phobos based on
the spectra data.  
And to make this even more interesting, Phobos is highly suspected to
be a captured asteroid in orbit around Mars.  It is highly probable that
Allende came from an asteroid, but whether this asteroid is still in the 
main asteroid belt or in orbit around Mars, no one can say for sure.  While 
it is possible Allende may have originated from Phobos, it is a rather remote 
possibility since there are several other candidate bodies, and it is
surely not definitive.

There is a 20% to 40% chance that NASA will launch a spacecraft to
collect samples from Phobos and Deimos and return them to Earth.  
In the recent round of Discovery mission proposals, the field
was narrowed down to five candidate missions.  One of the missions,
called Alladin, is the Phobos/Deimos sample return mission.  Of these
five missions, one or two of them will be selected and flown.
If the Alladin mission survives the final cut and is selected, it
would be launched to Mars, and fire projectiles (four total) into the 
moons' surface. The ejecta would be collected by the spacecraft and
the samples returned to Earth for detailed analysis.  While sample
returns from Phobos may not necessarily resolve the Allende/Phobos issue,
it will increase our understanding the composition of asteroids.

Ron Baalke