[ExI] Asteroid on track for possible Mars hit

[Amara Graps]

>  From: extropy-chat-bounces at lists.extropy.org [mailto:extropy-chat-
>  bounces at lists.extropy.org] On Behalf Of Samantha Atkins
...
>  >
>  > Ja, but it isn't clear to me what would cause the thing to
>  > fragment.  The
>  > surface heats up and boils away violently.  I suppose individual
>  > fragments
>  > could come flying off, but I don't see that as a major problem.
>
>  Doesn't it depend quite a lot on the composition of the mass?...

Spike I didn't read all of the threads (I'm with my family at this
moment on Maui), so I don't know the details of the physical process
proposed.  Samantha's comment about composition has either relevance
to the material's optical properties (for radiation pressure force)
or for fragmentation (tensile strength). Comets are usually (not
always) less dense than asteroids, though but many of these results
could apply, in the right conditions.

If you think about what caused comet P/Holmes to flare in brightness
four hundred thousand times,

http://dorigo.wordpress.com/2007/11/08/17pholmes-continues-the-show/

then that tells you something about the conditions that cause a release
of large quantities of dust. See also the pdf link to Peter Jenniskens'
article: "Meteor Showers from Broken Comets" here:
http://www.mpi-hd.mpg.de/dustgroup/~graps/dips2005/dipschapters.html

There are many examples of small particles fragmenting from larger
bodies, and then because of their smaller size and optical properties,
they move on different orbits (for example beta meteoroids).

And if you think about what caused comet P/Holmes to lose its tail:

http://dorigo.wordpress.com/2007/11/11/comet-holmes-loses-its-tail/

then that tells you something about the plasma and magnetic field
conditions (here we are looking at the ion tail) for weird plasma
comet events.

but then.. the Universe is simply Turtles (*), all of the way down.

Ciao,
Amara


(*) On my first, and only so far, snorkeling, I accompanied a sea turtle.
It appeared out of nowhere, so I followed it, and it didn't seem to mind me
swimming alongside (maybe about 6 feet away). But when I stopped to
clear my mask, and then returned to follow it, it disappeared. The previous
time I went snorkeling (2005  in Molokai), I accompanied a sea turtle
too.

-- 

Amara Graps, PhD      www.amara.com
Research Scientist, Southwest Research Institute (SwRI), Boulder, Colorado