[meteorite-list] Science Journal: Earth's water didn't come from comets, scientists now say

From: Chris Peterson <clp_at_meteoritecentral.com>
Date: Fri, 12 Dec 2014 16:36:57 -0700
Message-ID: <548B7C19.9030109_at_alumni.caltech.edu>

There is nothing definitive about it. The paper describes many factors
that could change the D/H ratio in different samples, and is much more
cautious in its conclusions than the typical press reports suggest:

"From the ROSINA measurements on comet 67P/Churyumov-Gerasimenko, we
conclude that the D/H values of JFCs [Jupiter family comets] may be
highly heterogeneous, possibly reflecting the diverse origins of JFCs.
If this is the case, then the new measurement supports models advocating
an asteroidal (i.e., carbonaceous chondrite-like), rather than cometary
origin for the oceans, and by extension for the terrestrial atmosphere."

Chris

*******************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

On 12/12/2014 1:50 PM, Michael Mulgrew via Meteorite-list wrote:
> I am curious how such a definitive conclusion can be reached from the
> analysis of a singular cometary body? How many comets are out there
> floating around the solar system? I guess they are assuming all
> comets have the same make-up? Seems a bit short sighted to me,
> considering, for example, how diverse asteroidal composition is.
> Imagine if we landed a probe on one asteroid, then extrapolated the
> results of that landing to apply to all asteroids, what a gross
> neglect of diversity that would be.
>
> Hopefully I'm missing something here and someone will chime in and
> explain it to me.
>
> Michael in so. Cal.
Received on Fri 12 Dec 2014 06:36:57 PM PST