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Old 02-03-2007, 13:55   #1
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The end of sattellites

The shooting down of a sattellite by the chinesee has clearly demonstrated how vulnerable the GPS ' phone and weather sattelites are. It took such a demonstration of what the consequences of militarising spce would eventually be for mariners. The debris from even a minor skirmish in space would render most sattellites extinct as the debris fields would quickly eliminate many of them. It took such a demonstration to penetrate the skulls of planners as to the real consquences of militarising space. .
gt out your sextants and barometers.
Brent .
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Old 02-03-2007, 14:09   #2
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Old 02-03-2007, 14:23   #3
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even if they aren't shot down, there's an asteroid that is supposed to pass so close to the earth in 2029 that it will actually pass below the orbits of the geosynchronous sattelites

odds are it won't hit anything, but who knows, it just shows that missiles aren't the only things to worry about
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Old 02-03-2007, 14:28   #4
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I'm not convinced that loosing GPS would be all bad. Yes it's easy and convenient, but that has lead to an explosion in the number of cruising boats, which has led to a huge increase in the costs involved in cruising and a huge increase in government interference in cruisers lives. I say shoot those things down and I'll polish up my sextant.
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Old 02-03-2007, 14:36   #5
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I was sitting at my the window of my home office about 3 one morning and a huge blue streak crossed the sky southwest of Houston. Later that day I contacted a sailing buddy who is also a flight director with NASA. It turns out that it was an old Russian booster. There is an astounding amount of junk in space today and a number of groups, like birdwatchers, waiting for that junk to come down or bump into something else.

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The Chinese 'proof of concept' just put them into the group of countries that can already do this sort of thing.
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Old 02-03-2007, 19:11   #6
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gt out your sextants and barometers.
To prepare for all the disruption that would occur in a war between the US and China, you're going to make sure you have a sextant and barometer?

You are in North America, right? What are you going to do about radioactive fallout? What are you going to do for FOOD?

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Old 02-03-2007, 22:55   #7
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2029 that it will actually pass below the orbits of the geosynchronous sattelites
Where on earth did you read that pile of Crap Sluissa? Trust me, if an Asteriod was predicted to pass between us and the Moon, you would have so many Scientists runing around like chickens with their heads cut off shouting run for your lives, it would be unbelievable. An Asteroid passing at one Lunar unit is considered a near miss in Astronomical terms and even trying to predict a pass with that sort of accuracy is near impossible. To have one travel as close to us as our Satillite orbits would be truely worrying and I doubt very much if it would ven escape our Gravity at that close. It would most probably be a certain impact.
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Old 03-03-2007, 02:34   #8
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Old 03-03-2007, 04:31   #9
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It is inconceivable that nations could be in military conflict with each other, and observe a protocol that allowed them to kill each other's soldiers, and perhaps each other's civilians as collateral damage, but not touch each other's satellites.

Space has been increasingly perceived as a strategic asset, and progressively more “militarised” since the launch of the first satellites* in the late 1950's.
Space achievements by one country are often viewed as threatening by another.

* History of U.S. Military Satellite Communication Systems

Satellites, are typically sophisticated and expensive. Threats to satellites can be crude and inexpensive. A bag of marbles, that costs two dollars, properly inserted into space, can wreck a satellite that costs hundreds of millions of dollars or more.

Satellite Vulnerability: a post-Cold War issue? ~ by Allen Thomson
(Space Policy, February, 1995)

”The widely discussed use of US reconnaissance satellites during the Gulf War will strongly motivate future regional adversaries to seek ways of countering US space-based assets. The presumption that reconnaissance satellites can operate covertly is obsolete. Tracking US reconnaissance satellites can provide valuable support to a hostile country's concealment and deception programs. Iraq's ability to conceal both major weapons programs and many SCUD launchers is a warning of the serious consequences such programs can have. Space surveillance systems of the type likely to be acquired by Third World countries are inconspicuous and may well go undetected, while direct ascent ASAT rockets are within the reach of many countries. This article argues that fundamental reexamination of the functions and architecture of US overhead reconnaissance is needed, and should be done outside the traditional Cold War bureaucratic structures...”

An excellent treatise - Goto:
Satellite Vulnerability: a post-Cold War issue?

See also:
U.S. tries to develop anti-satellite weapon - Americas - International Herald Tribune
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Old 03-03-2007, 04:55   #10
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Originally Posted by coot
To prepare for all the disruption that would occur in a war between the US and China, you're going to make sure you have a sextant and barometer?

You are in North America, right? What are you going to do about radioactive fallout? What are you going to do for FOOD?


LOL True, true.

I would rate the chances of GPS failing because the US DOD hasn't paid it's electricity bill as being far higher than that of the Chinese shooting down all the satellites.
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Old 03-03-2007, 05:49   #11
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Where on earth did you read that pile of Crap
It's not like it's a secret. It's been in the news for some time.

Space.com

Universe Today

Wikipedia

Short News

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Old 03-03-2007, 06:31   #12
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Interesting stuff. Looks like you're right. 22,600 mile closest approach. Recent refinements seem to have been aimed at calculating the next close approach which has become less likely as they pinpointed the orbit with greater accuracy. What I couldn't find is what the lat/long of the closest approach would be. For this to have any chance of impacting a geo satelite, the points where the asteroid orbit intersects the geosynchronous altitude would have to be at the equator. The probability of impact must be quite small.

To put this another way, here's a bit of math.

Earth's radius is 3,963 mile (Earth radius) - Wikipedia, the free encyclopedia.
Geo orbit is 22,240 miles above that (Geostationary orbit - Wikipedia, the free encyclopedia)
That means the radius of the geo orbit is 26,203 miles.
The asteroid is going to cross this radius twice at two separate points over the Earth.
The surface area of a sphere of radius 26,203 miles is over 8.6 billion square miles. Imagine this laid out on the ground with several dozen satellites sitting on it. Whats the probablity of a hit if you drop an asteroid that is 250m across twice onto this area? Well - the probability of one pass hitting one object is less than 1 in 350 billion. No concerns from me.
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Old 03-03-2007, 07:34   #13
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The GPS constellation uses satellites at 12 hour orbit altitudes of about 11,000 nautical miles above the Earth (a little less than half the height of the 24 hour orbits of a geostationary satellite).
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Old 03-03-2007, 07:55   #14
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Duh, I guess we will have to go back to the way we was doing it 30 years ago.
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Old 03-03-2007, 09:13   #15
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Gord and ess105,

I doubt very much that I’ll still be able enough do a whole lot of sailing come 2029 so this may be a moot question, but...

No doubt that the chance of a direct hit on any satellite would be slim indeed, either the 12 hour or 24 hour orbits, but don’t asteroids tend to slough off an incredible amount of debris as it traverses through the atmosphere? Thus wouldn’t the “bag of marbles” thing be of concern to all, or at least quite a few of the satellites?
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