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Breaking up a rubble pile asteroid impacter
OK, so we have a pile of rubble asteroid that is gonna hit the earth.
As it approaches, the looser rubble gets removed by the atmosphere but most of the stuff stays together until impact making one big hole. So, which is worse, one big hole or several smaller ones? Clearly a 1 Km sized rock is gonna ruin everyones day but if we break it up into a bunch of 100 meter sized rocks, their surface area to volume ratio is big and so the atmosphere burns up a lot more. Even then, the sum of the damage done by the smaller craters is going to be less than the damage done by a single big rock. This is even more true considering the oceans where a big rock is going to cause major problems whereas a bunch of smaller rocks are not. So, if there's gonna be an impact, I say use nukes to break it up. |
#2
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Breaking up a rubble pile asteroid impacter
Frogwatch wrote:
OK, so we have a pile of rubble asteroid that is gonna hit the earth. As it approaches, the looser rubble gets removed by the atmosphere but most of the stuff stays together until impact making one big hole. So, which is worse, one big hole or several smaller ones? Clearly a 1 Km sized rock is gonna ruin everyones day but if we break it up into a bunch of 100 meter sized rocks, their surface area to volume ratio is big and so the atmosphere burns up a lot more. Even then, the sum of the damage done by the smaller craters is going to be less than the damage done by a single big rock. This is even more true considering the oceans where a big rock is going to cause major problems whereas a bunch of smaller rocks are not. So, if there's gonna be an impact, I say use nukes to break it up. If you break up an asteroid into smaller ones, with the smaller ones having sides 10 times smaller than the original, you get 1000 smaller asteroids. If you ever saw a 10-meter asteroid coming in, you know that you get something of comparable brightness to the sun. You are talking about having 1000 objects coming in, each of which has 1000 times the energy of that 10-meter asteroid. Imagine having 1000 suns in the sky, lots of frying will go on. Not good. Not good at all. I prefer the single km sized object. It is better to have much of the energy of the asteroid being used to melt rock than to have it ionize the atmosphere. Alain Fournier |
#3
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Breaking up a rubble pile asteroid impacter
"Frogwatch" wrote in message
... OK, so we have a pile of rubble asteroid that is gonna hit the earth. As it approaches, the looser rubble gets removed by the atmosphere but most of the stuff stays together until impact making one big hole. So, which is worse, one big hole or several smaller ones? Clearly a 1 Km sized rock is gonna ruin everyones day but if we break it up into a bunch of 100 meter sized rocks, their surface area to volume ratio is big and so the atmosphere burns up a lot more. Even then, the sum of the damage done by the smaller craters is going to be less than the damage done by a single big rock. This is even more true considering the oceans where a big rock is going to cause major problems whereas a bunch of smaller rocks are not. So, if there's gonna be an impact, I say use nukes to break it up. Keep in mind a large part of the energy of 100s of smaller objects will be dissipated in the atmosphere. That's not necessarily a net improvement. Remember it's the total energy we have to deal with, one way or the other. -- Greg Moore Ask me about lily, an RPI based CMC. |
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Breaking up a rubble pile asteroid impacter
On Dec 31 2009, 9:39*pm, "Greg D. Moore \(Strider\)"
wrote: "Frogwatch" wrote in message ... OK, so we have a pile of rubble asteroid that is gonna hit the earth. As it approaches, the looser rubble gets removed by the atmosphere but most of the stuff stays together until impact making one big hole. So, which is worse, one big hole or several smaller ones? *Clearly a 1 Km sized rock is gonna ruin everyones day but if we break it up into a bunch of 100 meter sized rocks, their surface area to volume ratio is big and so the atmosphere burns up a lot more. *Even then, the sum of the damage done by the smaller craters is going to be less than the damage done by a single big rock. This is even more true considering the oceans where a big rock is going to cause major problems whereas a bunch of smaller rocks are not. So, if there's gonna be an impact, I say use nukes to break it up. Keep in mind a large part of the energy of 100s of smaller objects will be dissipated in the atmosphere. *That's not necessarily a net improvement.. Remember it's the total energy we have to deal with, one way or the other.. -- Greg Moore Ask me about lily, an RPI based CMC. A large part of the problem is putting that much kinetic energy into a tiny spot whereas if you spread that energy over a much larger area, probably not a big problem. When a big rock hits, the bad effects are basically the result of the high power density whereas with many smaller impacts the power density is much lower. Total energy is the same but I propose to spread it over a much larger area and over a greater time interval. The time interval may be increased by only a few seconds but that is a major improvement over milliseconds. |
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Breaking up a rubble pile asteroid impacter
On Dec 31 2009, 10:47*pm, Frogwatch wrote:
On Dec 31 2009, 9:39*pm, "Greg D. Moore \(Strider\)" wrote: "Frogwatch" wrote in message ... OK, so we have a pile of rubble asteroid that is gonna hit the earth. As it approaches, the looser rubble gets removed by the atmosphere but most of the stuff stays together until impact making one big hole. So, which is worse, one big hole or several smaller ones? *Clearly a 1 Km sized rock is gonna ruin everyones day but if we break it up into a bunch of 100 meter sized rocks, their surface area to volume ratio is big and so the atmosphere burns up a lot more. *Even then, the sum of the damage done by the smaller craters is going to be less than the damage done by a single big rock. This is even more true considering the oceans where a big rock is going to cause major problems whereas a bunch of smaller rocks are not. So, if there's gonna be an impact, I say use nukes to break it up. Keep in mind a large part of the energy of 100s of smaller objects will be dissipated in the atmosphere. *That's not necessarily a net improvement. |
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Breaking up a rubble pile asteroid impacter
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#7
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Breaking up a rubble pile asteroid impacter
On Dec 31 2009, 12:14*pm, Frogwatch wrote:
OK, so we have a pile of rubble asteroid that is gonna hit the earth. As it approaches, the looser rubble gets removed by the atmosphere but most of the stuff stays together until impact making one big hole. So, which is worse, one big hole or several smaller ones? *Clearly a 1 Km sized rock is gonna ruin everyones day but if we break it up into a bunch of 100 meter sized rocks, their surface area to volume ratio is big and so the atmosphere burns up a lot more. *Even then, the sum of the damage done by the smaller craters is going to be less than the damage done by a single big rock. This is even more true considering the oceans where a big rock is going to cause major problems whereas a bunch of smaller rocks are not. So, if there's gonna be an impact, I say use nukes to break it up. Why not stuff the entire pile into the moon? ~ BG |
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Breaking up a rubble pile asteroid impacter
On Jan 1, 10:46*pm, BradGuth wrote:
On Dec 31 2009, 12:14*pm, Frogwatch wrote: OK, so we have a pile of rubble asteroid that is gonna hit the earth. As it approaches, the looser rubble gets removed by the atmosphere but most of the stuff stays together until impact making one big hole. So, which is worse, one big hole or several smaller ones? *Clearly a 1 Km sized rock is gonna ruin everyones day but if we break it up into a bunch of 100 meter sized rocks, their surface area to volume ratio is big and so the atmosphere burns up a lot more. *Even then, the sum of the damage done by the smaller craters is going to be less than the damage done by a single big rock. This is even more true considering the oceans where a big rock is going to cause major problems whereas a bunch of smaller rocks are not. So, if there's gonna be an impact, I say use nukes to break it up. Why not stuff the entire pile into the moon? *~ BG This brings up another topic that interests me: Why do we see so few impact features on the earth? The usual reason is weathering and plate tectonics but even on Venus we see them and it has extreme weathering. We see impact features on Europa with an extreme version of plate tectonics with big plates of ice moving over an ocean underneath. I think there is another reason and that reason is the moon. The moon is just large enough to move the center of mass of the earth- moon system 1000 miles away from the earths center (actually, I forget the exact number but I remember it is substantial). So, while the moon subtends a tiny solid angle in the sky, it actually has a substantial effect on the "impact paramater" of the earth reducing the effective cross section by almost half. OTOH, earth does not protect the moon but actually causes the moon to take more hits than if it was alone. The same is true of most small bodies in orbit about large bodies and the small bodies take a lot of hits. Thus, is a "Pandora" type moon likely to evolve intelligent life considering the increased probability of impacts? Is the near necessity of a moon of just the right size to protect the primary one reason why we do not detect nearby intelligent life? |
#9
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Breaking up a rubble pile asteroid impacter
On Jan 1, 8:15*pm, Frogwatch wrote:
On Jan 1, 10:46*pm, BradGuth wrote: On Dec 31 2009, 12:14*pm, Frogwatch wrote: OK, so we have a pile of rubble asteroid that is gonna hit the earth. As it approaches, the looser rubble gets removed by the atmosphere but most of the stuff stays together until impact making one big hole. So, which is worse, one big hole or several smaller ones? *Clearly a 1 Km sized rock is gonna ruin everyones day but if we break it up into a bunch of 100 meter sized rocks, their surface area to volume ratio is big and so the atmosphere burns up a lot more. *Even then, the sum of the damage done by the smaller craters is going to be less than the damage done by a single big rock. This is even more true considering the oceans where a big rock is going to cause major problems whereas a bunch of smaller rocks are not. So, if there's gonna be an impact, I say use nukes to break it up. Why not stuff the entire pile into the moon? *~ BG This brings up another topic that interests me: *Why do we see so few impact features on the earth? *The usual reason is weathering and plate tectonics but even on Venus we see them and it has extreme weathering. *We see impact features on Europa with an extreme version of plate tectonics with big plates of ice moving over an ocean underneath. *I think there is another reason and that reason is the moon. The moon is just large enough to move the center of mass of the earth- moon system 1000 miles away from the earths center (actually, I forget the exact number but I remember it is substantial). *So, while the moon subtends a tiny solid angle in the sky, it actually has a substantial effect on the "impact paramater" of the earth reducing the effective cross section by almost half. OTOH, earth does not protect the moon but actually causes the moon to take more hits than if it was alone. *The same is true of most small bodies in orbit about large bodies and the small bodies take a lot of hits. Thus, is a "Pandora" type moon likely to evolve intelligent life considering the increased probability of impacts? Is the near necessity of a moon of just the right size to protect the primary one reason why we do not detect nearby intelligent life? Having a moon is a good thing, except for the secondary global warming. We get to deal with 2e20 N/sec because of our moon(Selene). It's thought Venus once had a moon the size and similar mass of Selene. ~ BG |
#10
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Breaking up a rubble pile asteroid impacter
Frogwatch wrote:
This brings up another topic that interests me: Why do we see so few impact features on the earth? The usual reason is weathering and plate tectonics but even on Venus we see them and it has extreme weathering. We see impact features on Europa with an extreme version of plate tectonics with big plates of ice moving over an ocean underneath. Most of the objects that enter the Earth's atmosphere are fairly small in size and break up before they hit the surface due to the rapid deceleration they experience on the way down. In the case of a lot of them they are so fragile to begin with that they break up into very small pieces during entry so that almost nothing gets to the ground, like in the Tunguska blast. Since crater size is a function of both the mass of the impactor and its impact velocity, the small pieces slow down in the atmosphere enough that they just fall out of the sky at their terminal velocity, like you had tossed them out of an aircraft at high altitude, rather than keeping any of the high velocity they had as they traveled through space. Venus has such a dense atmosphere that most objects break up before impact and only the biggest chunks get through to make any crater on the surface; the smallest single-impact crater spotted on Venus was 3 km in diameter (smaller ones are sub-craters created by parts of a object that had broken up on the way down). Also, without water weathering from rain or rivers, frequent day-night temperature extremes, and high surface winds, weathering moves very slowly on Venus. Article on Venus cratering he http://www.solarviews.com/eng/vencrate.htm Pat |
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