[meteorite-list] Planet V (for Five)

[David Weir]

Sterling K. Webb wrote:

>    Maybe it hit Planet V-for-Five. Maybe it WAS
> Planet V-for-Five or a good chunk of it. Or a satellite of Planet 
> V-for-Five dragged along for the ride when its
> orbit became unstable. Or...  I look at my little chunks of mesosiderite 
> with new respect. I sidle up to them at the bar and buy them a drink in 
> the hope that they will tell me their life story...

Sterling,

It may be just another one of those O-isotope coincidences, like the 
fact that E chondrites have O-isotopic values that are indistinguishable 
from those of the Earth, or that brachinites have values that are 
identical to the HEDs, but a new O-isotope study by Greenwood et al. 
(http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1768.pdf) of numerous 
mesosiderites demonstrates that their oxygen isotopic values are almost 
identical to those of the HED clan, which suggests that there may be a 
genetic link between them. The results suggest that both HEDs and 
mesosiderites may be derived from Vesta; or, if you want to speculate 
like me - I think the arrival of Dawn (in Sept. 2011) will reveal that 
HED and MES meteorites were derived from a separate, significantly 
disrupted, Vesta-like PB. This latter possibility may leave the door 
open for a possible Planet V origin for these two groups.

David