[meteorite-list] Hayabusa Spots Its Asteroid Target

[Sterling K. Webb]

Darren,

    Tantalum is the tenth most dense element,
with a density of 21.02 times that of water,
or three times that of iron. There are others
more dense, but they suffer from various
disadvantages: low melting point (osmium),
danger (plutonium), expense (gold).
    As you said, one of tantalum's advantages
is a clear signature to discount. It is hard
(6.5 on the mineral hardness scale). It has
a reflectivity of 0.78, and it looks a lot like
pewter.

Sterling Webb
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Darren Garrison wrote:

> On Thu, 18 Aug 2005 08:16:09 -0700 (PDT), Ron Baalke <baalke at zagami.jpl.nasa.gov> wrote:
>
> >the firing of a tantalum pellet into the asteroid at 300 metres per second.
>
> Why such an exotic material?  So that you could find and discount it's signature in the returned
> sample?