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Fw: RE- Much Bolide activity being reported?
Thought the List may be interested in a recent correspondence of Brian
Marsden of cfa Harvard on the subject of his concerns - PHA's (Potentially
Hazardous Asteroid).
Victor D. Noto
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Victor Noto - Kissimmee, Florida USA
vnn2@phoenixat.com
http://www.phoenixat.com/~vnn2/BIGROCK.htm
Website theme quote:
"Life really is a Rock and
the Big Rock giveth and taketh away all life!!"
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> From: brian%cfaps1.span@vms.noao.edu
> To: vnn2@phoenixat.com
> Subject: RE- Much Bolide activity being reported?
> Date: Wednesday, February 18, 1998 11:12 AM
>
> I don't go for short-term statistics. I also don't want to have to
contend
> with an impending large impact with only months (let alone weeks) notice.
> The whole point about 1997 BR and the 107 objects on the PHA list
generally
> is that we need to boost searches to the extent that it just won't happen
> that one could appear and be on a collision course without notice
amounting
> to at least decades, and preferably centuries and more. Then there
really
> would be time to "attend to the matter" in a sensibly intelligent manner,
> rather than be forced into a potential disaster, perhaps involving
nuclear
> weapons deployed with disastrous consequences unrelated to any real
asteroid
> hazard. Actually, we are fortunate that most of the potential danger, in
> both human and economic terms, is from objects in the PHA class with
short-
> period orbits. This is a tremenous advantage! Not only are these
therefore
> bright enough to be found easily when they are NOT right on top of the
earth,
> but they don't go all that far from the sun, so in principle we can
observe,
> even discover them all the way around their orbits! The astronomical
part
> of the problem can actually be essentially solved, with the appropriate
> expenditure of time and money (like 30 years at $10 million worldwide,
say).
> Yes, there are smaller objects too, and they hit more often, and they
could,
> like Tunguska in 1908, do tremendous local damage: but the financial
impact
> is a lot less, and they don't threaten the very survival of our species.
> And there are also objects in larger orbits, where we do not have the
> possibility of discovering them whole revolutions before they may hit.
> These are somewhat of a worry, and we need to be aware of that, but,
object
> for object, long-period objects are at most 2 percent the threat of
> short-period objects (and even this is probably an overestimate) over any
> given interval of time; actually, the most troublesome objects may in
fact
> be objects in orbits of intermediate period, say, a century or so, like
> comet 109P/Swift-Tuttle, where a 30-year search is not going to yield
them.
> At some level, therefore, one is going to have to continue the search
> indefinitely, even after the 30-year search has produced most of the
PHAs.
> I hope this helps put things into perspective for you.
> Brian G. Marsden