Re: two-page synopsis of Message Received

Rich Weyand <weyand@xxxxxxx> wrote in article <NtidnZ4NWvcognPenZ2dnUVZ_s2dnZ2d@xxxxxxxxxxxxxxxx>:
In article <1139646026.311380.264310@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>, "Bob Throllop" <bobthrollop@xxxxxxxxxx> wrote:

Mmm. The problem, detailed in the book but which is well beyond the scope of
a synopsis, is the size. The designers planned for an object three times
larger than the previous known maximum -- the six-mile diameter rock that
ended the Cambrian (and the dinosaurs). This asteroid is 10 miles in diameter
and 20 miles long -- a volume 10 times that of the K-T asteroid and three
times bigger than the design spec.

It can't deflect the whole thing. First it deflects the whole thing enough
so that it will hit the Pacific Ocean instead of N and S America. Then it
breaks it in half, deflecting them so one hits the Moon and one sails past --
barely. The fragments of the breakup are still coming, on trajectory for the
Pacific, and it nudges the biggest with the remaining energy to make sure none
of them hit within 500 miles of land.

Last weekend I was at a convention where there was a strong space
science programming track. I attended a lecture about the current
thinking about asteroids, and given current knowledge it's highly
unlikely that your asteroid is one chunk that's amenable to being
deflected in one piece. Even the large asteroids appear to be more like
gravel and sand piles held together by their own gravity. Unlike a
planet, they're generally (as far as we can tell) not one cohesive
lump. The density measurements we have show that (if memory serves)
they tend to be 20-60% matter, and the rest vacuum. (A bucket of dry
beach sand is about 50% rock, for comparison)

Even the solidish ones appear to have large fracture planes such that
they'd likely fall to pieces.

This isn't to say there aren't large solid lumps out there, but they
appear to be rare.

(All this is from sleep-deprived memory; check with an astronomer.)

--
"I disapprove of what you have to say, but I will defend to the death
your right to say it." -- Beatrice Hall

Cally Soukup soukup@xxxxxxxxx
.

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