Re: Comet impact in the Eastern United States - Feasibility of Evacuation

On Mar 16, 10:52 pm, "Joel Olson" <joel_ol...@xxxxxxxxxxxxx> wrote:
"Brion K. Lienhart" <bri...@xxxxxxxxxxxxx> wrote in messagenews:87idnVhTbtmU_kDanZ2dnUVZ_tninZ2d@xxxxxxxxxxxxxx





I disagree. Given a reasonable time interval, the trajectory and mass
can be observed to almost total accuracy. Slowing/deflection as it
enters
the atmosphere would also be quickly simulated, a little less
accurately.
The result will be a calculated impact zone that will most likely be a
long
elipse, smaller if the angle of descent is steep. The approach
trajectory
may make a difference.

Six months sounds like a reasonable lead time for evacuation.

That's my kind of thinking as well. Telescopes are able to look at
galaxies from the dawn of time. There are plans to take photigraphs of
terrestrial exoplanets using interferometric nulling. And then mankind
fails at building the machinery to improve accuracy of NEO
trajectories? Doesn't make sense to me. Why pour money into NEO
observation in the first place? To boost sales of tabloids with
headlines like "THE END IS COMING! Impact in 365 days!" ? If nukes
won't work why not be more creative about evacuation scenarios?

The main problem with predicting *comet* orbits is that they aren't
totally ballistic. They have random bursts of outgassing that change their
trajectory, pretty much constantly.

The outgassing is due to solar heating? So it makes a big difference
if the comet has done a couple loops around the sun before heading
our way as opposed to its colliding on first entering from farther out.
Even with a simple slingshot around the sun, the solar heating will
be decreasing as it heads out toward our orbit.

By the time it comes, perhaps we'll have discovered how outgassing
behaves - a distribution of strengths and directions, given the comet's
size and other parameters.

And then there's the question of how much its trajectory is out of the
Earth's rotational plane. Coming in normal to that plane makes the
uncertainty very large; parallel to it defines an interval of latitudes.

I'm not saying that the answer will always be satisfactory, only that
there will be some cases where the uncertainty is small enough to
take reasonable actions.

Are you saying it's basically a chaotic (hypersensitive) system? Like
there's no forecast for the weather in two weeks?

--
Matt Browne
My webpage is at http://www.meet-matt-browne.com
"As a race, we survive on planet Earth purely by geological consent."
Bill McGuire
.

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