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Threat of Cometary Impacts may be Underestimated
SpaceDaily ^ | 10/27/2004

Posted on 10/27/2004 7:54:44 AM PDT by cogitator

Chance Of A Cometary Impact Re-assessed

The chances of the Earth suffering a collision with a cometary body may be higher than previously thought, according to new research by astronomers Bill Napier and Chandra Wickramasinghe.

If so, international programmes designed to detect a large class of potentially threatening objects, namely near-Earth asteroids, as well as strategies to mitigate the worst effects of collisions, may be in need of urgent review.

This is the disturbing conclusion reached by the astronomers in a paper which is to be published shortly in the Monthly Notices of the Royal Astronomical Society.

Their argument is based on the known rate at which comets enter the inner solar system from the Oort cloud, a nearly spherical swarm of some 100 billion comets that surrounds the solar system out to a distance almost halfway to the Sun's nearest neighbouring star.

With about 1 percent of incoming comets ending up on relatively short-period Earth-crossing orbits, it is expected that several thousand dormant comets could be currently posing a potential threat to our planet.

Recent surveys of the Earth's immediate vicinity should have turned up some 400 such objects, whereas only a handful have so far been found.

The researchers dismiss the current belief that all the "missing" comets have disintegrated into meteor streams. If this had happened, they argue, then we should be seeing a far greater number of meteor showers and a much brighter zodiacal cloud than is observed.

They propose instead that the majority of these comets have become exceedingly black, with such low surface reflectivities that they could not be observed against the blackness of space by optical means.

Surfaces reflecting less than 0.1 percent of the incident sunlight could be formed when a comet made up of a mixture of organic grains and ices approaches the sun and sublimates, leaving an outer layer of loosely connected organic material.


TOPICS: Culture/Society; Foreign Affairs; Front Page News; Government; Miscellaneous
KEYWORDS: catastrophe; catastrophism; comet; damage; disaster; emiliospedicato; impact; spedicato; study; tunguska
Stealth comets! Gotta put that one in my anxiety closet now.
1 posted on 10/27/2004 7:54:44 AM PDT by cogitator
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To: cogitator

Organic grains and ices? Sounds like something sold at a boardwalk food cart in California.


2 posted on 10/27/2004 7:57:09 AM PDT by SlowBoat407 ("Don't bother giving me liberty: I'll take it for myself, thanks.")
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To: cogitator

What's anybody gonna do about it? Me? I'm sleeping in.


3 posted on 10/27/2004 7:57:11 AM PDT by thegreatbeast (Quid lucrum istic mihi est?)
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To: cogitator

Calling Ted Hamner! (lead character of the Niven/Pournelle must-read "Lucifer's Hammer")


4 posted on 10/27/2004 7:58:50 AM PDT by Turk82_1 (They also serve who merely stand and wait.)
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To: thegreatbeast

That's it. Screw Scoresby, I'm drinking Johnny Walker Black Label from now on.


5 posted on 10/27/2004 7:59:20 AM PDT by AppyPappy (If You're Not A Part Of The Solution, There's Good Money To Be Made In Prolonging The Problem.)
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To: thegreatbeast
What's anybody gonna do about it?

It's analogous to fighting terrorists; first you have to determine where they are and if they pose a danger before steps can be taken to take them out.

6 posted on 10/27/2004 7:59:31 AM PDT by cogitator
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To: Turk82_1
Calling Ted Hamner!

I forgot his name but read the book. Actually, I posted awhile ago (after the Columbia disaster) that one of the best justifications for an international space effort would be "Spaceguard" as described in Arthur C. Clarke's "Rendesvous with Rama". Actually, it's nicely findable with Google, so here it is:

Now is the time for 'Spaceguard'

7 posted on 10/27/2004 8:04:34 AM PDT by cogitator
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To: cogitator

Don't Worry! Kerry Has A Plan For This!!


8 posted on 10/27/2004 8:05:23 AM PDT by SWAMPSNIPER
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To: thegreatbeast

> What's anybody gonna do about it?

Me, I'm resurecting circa 1961 USAF plans to station large Orion vehicles in high orbit. 4,000 ton space battleships armed with Thiokol "Sprint" booster motors with Casaba Howitzer nuke warheads are just the thing for dealing with threats like this.


9 posted on 10/27/2004 8:08:59 AM PDT by orionblamblam
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To: SWAMPSNIPER

It's W's fault! Tom Daschle is deeply saddened


10 posted on 10/27/2004 8:09:00 AM PDT by JackHawk
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To: SWAMPSNIPER

It's W's fault! Tom Daschle is deeply saddened!


11 posted on 10/27/2004 8:09:47 AM PDT by JackHawk
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To: thegreatbeast

I'm not worried. Bruce Willis and Ben Afflick will be there for us if this happens.


12 posted on 10/27/2004 8:11:23 AM PDT by Alas Babylon!
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To: orionblamblam

The Orion would have to be WAY high orbit, so the EMP doesn't fry all the damn satelites.

Read Niven/Pournelle's FootFall for a fascinating look at an Orion spaceship.


13 posted on 10/27/2004 8:12:22 AM PDT by Turk82_1 (They also serve who merely stand and wait.)
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To: cogitator

Actually, between LEAP, SOHO, Catalina SkySyrvey, and a variety of other systemic sky surveys, SPaceGuard is practically here.

I remember reading an article about how a NASA geek used the finder scope on a defunct satellite to conduct some cool astronomy work. What I don't understand is why we don't do something like equipping the GPS satellites with 10" scopes. They already have a very accurate atomic clock, you could probably do some "virtual lens" work with these craft to look around the sky and find these rocks.


14 posted on 10/27/2004 8:16:33 AM PDT by Turk82_1 (They also serve who merely stand and wait.)
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To: orionblamblam
NO no no no no no. NONONONONO!

We need to get together, at the last minute, a team of oil-drillers. Then, we teach them how to pilot a really stupid looking shuttle, and land on the comet in question - because that's easy. THEN, we drill like a really deep hole, and put some super mega awesome 4 gigaton nuke into the comet, and like totally blow it up n' stuff. Yeah.

In all seriousness, I'd love to see some Orions up there.

15 posted on 10/27/2004 8:16:42 AM PDT by Shryke (Rumpologist)
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To: orionblamblam
Me, I'm resurecting circa 1961 USAF plans to station large Orion vehicles in high orbit. 4,000 ton space battleships armed with Thiokol "Sprint" booster motors with Casaba Howitzer nuke warheads are just the thing for dealing with threats like this.

But at the cost that it would take NASA to do this it would be cheaper to take the hit and try to re-establish society through the evolutionary process.

16 posted on 10/27/2004 8:19:05 AM PDT by thegreatbeast (Quid lucrum istic mihi est?)
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To: cogitator

17 posted on 10/27/2004 8:19:17 AM PDT by mysterio
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To: cogitator

I'll be in the shower.


18 posted on 10/27/2004 8:28:04 AM PDT by finnman69 (cum puella incedit minore medio corpore sub quo manifestus globus, inflammare animos)
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To: cogitator

See also:

Small Comets and Our Origins
http://www.freerepublic.com/focus/f-bloggers/1250694/posts


19 posted on 10/27/2004 8:48:54 AM PDT by Boundless (Was your voter registration sabotaged by ACORN? Don't find out Nov. 2. Vote early.)
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To: Turk82_1

> The Orion would have to be WAY high orbit, so the EMP doesn't fry all the damn satelites.

You say that like it's a bad thing.

If you fry all the satellites, you have to launch all-new ones. That, coupled with the launch system market needed to launch the Orions and their support and maintenance infrastructure, will meant hat flight rate for launch systems will go through the roof, and price will plummet. This means that you will be able to launch a lot *more* satellites, as well as people, including colonists. Which means that even if the Orions fail to stop the comet, civilization will go on... just on the Moon, Mars and asteroids.


Plus... I'm unlcear that high-orbit (GEO to L4/L5) would result in meaningful EMP. EMP is a result of the Compton effect... charged particles hitting the upper ionosphere and causing a big magnetic bloom. But if the bombs are *far* away from the ionosphere, then the charged particle flux would be pretty low, and the ionosphere would not take much of a hit.

> Read Niven/Pournelle's FootFall for a fascinating look at an Orion spaceship.

Even better: Look up back issues from Volumes 1 and 2 of Aerospace Projects Review for info on the *real* Orion spacecraft designs...
http://up-ship.com/apr/apr.htm


20 posted on 10/27/2004 9:33:01 AM PDT by orionblamblam
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To: thegreatbeast

> But at the cost that it would take NASA to do this ...

Who said NASA? I want the Air Force and the US Marines running this show. Soon enough, they'll transform into Fleet and Mobile Infantry....


21 posted on 10/27/2004 9:34:41 AM PDT by orionblamblam
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To: orionblamblam

In order to really protect from EMP, I would GUESS (SWAG) that you would have to be outside the Van Allen Belt at the very least, and preferentially beyond the Earth's magnetosphere.

As for frying all the satelites, sure, I am into planned obsolecense - new satelites in the same slots now occupied by dead satelites means more capability. Only one question: How do you clean up near-Earth space? I mean, the maintenance flights to rendezvous with the hulks, attach deorbitting engines, and sling them back to Earth is huge. Assuming that the satellites are all dead, then perhaps the best thing would be to fill near Earth space with gas (boil a few comets?), which would act to deorbit the dead ones.

Orions are still the best use for obsolete nuke weapons.


22 posted on 10/27/2004 9:40:08 AM PDT by Turk82_1 (They also serve who merely stand and wait.)
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To: Turk82_1

> How do you clean up near-Earth space?

The new WPA.

> sling them back to Earth is huge

Bah. Thousands of tons of metal already on orbit would be useful things to have if you plan on having space-based industry or colonization. Don't drop 'em... use 'em.


> Orions are still the best use for obsolete nuke weapons.

Nope. Orion woudl need *all* *new* nukes. Bomb-nukes are wholly inappropriate. Until you get to Really, Really Friggen GIANT Orions, you need bombs with yields of one kiloton or less. Very low yield nukes have been built (the Davy Crockett, frex), but they are incredibly filthy and wasteful, and not that reliable. Orion will need a whoel new bomb development program to produce sub-kiloton, dirt-cheapt, preferable fission-free nukes. They would also be just the thing for *other* applications. Bad guy in a cave? Fine. BOOM.


23 posted on 10/27/2004 9:51:02 AM PDT by orionblamblam
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this topic is from 2004, thanks cogitator.

Comet Holmes is Bigger than the Sun
Universe Today | November 13th, 2007 | Fraser Cain
Posted on 11/14/2007 10:06:58 PM EST by annie laurie
http://www.freerepublic.com/focus/f-chat/1925933/posts
12 posted on 11/15/2007 1:31:47 AM EST by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1925933/posts?page=12#12

[warming] Cometary impacts and ice-ages
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Published: April 2001 (275: 367-376)
Author: Sir Fred Hoyle and Chandra Wickramasinghe
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http://www.freerepublic.com/forum/a3acfed532bff.htm

Evidence Of Tunguska-Type Impacts
Over The Pacific Basin Around The Year 1178 AD
SIS Conference | Emilio Spedicato
Posted on 01/26/2003 12:36:14 PM EST by blam
http://www.freerepublic.com/focus/news/829934/posts

Astronomers unravel a mystery of the Dark Ages
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http://www.freerepublic.com/focus/f-news/1070892/posts

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Cardiff University | 10 February 2004 | Staff
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http://www.freerepublic.com/focus/f-news/1076665/posts


24 posted on 11/17/2007 3:51:52 PM PST by SunkenCiv (Profile updated Saturday, November 17, 2007'''':''''1'''':'''https://secure.freerepublic.com/donate/)
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Catastrophism
 
· join · view topics · view or post blog · bookmark · post new topic ·
 

25 posted on 11/17/2007 3:55:36 PM PST by SunkenCiv (Profile updated Saturday, November 17, 2007'''':''''1'''':'''https://secure.freerepublic.com/donate/)
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