What to do if a giant meteor is coming at you

[Spyman]

What if the asteroid is a rubble pile? Aren't many asteroids now thought to be rubble piles instead of large solid bodies?

A large rubber pile would be much harder to deflect and to do so safely. But I don't think we can say for certain what amounts and kinds of different boulders there are out there.

 

Deep Impact is a NASA space probe launched on January 12, 2005. It was designed to study the composition of the comet interior of 9P/Tempel, by releasing an impactor into the comet.

(...)

Initial results were surprising as the material excavated by the impact contained more dust and less ice than had been expected. The only models of cometary structure astronomers could positively rule out were the very porous models which had comets as loose aggregates of material. In addition, the material was finer than expected; scientists compared it to talcum powder rather than sand.

http://en.wikipedia.org/wiki/Deep_Impact_(spacecraft)

 

 

Yes, a murder of crows visits the field next to my house every morning....

Even if several kinds of mammals like rats survives and then evolves they would still not be humans.

 

Numerous groups of organisms went extinct during the K-T event, most notably the non-avian dinosaurs. Non-avian dinosaur fossils are found only below the K–T boundary, indicating that they became extinct during the boundary event. A very small number of dinosaur fossils have been found above the K–T boundary, but they have been explained as reworked fossils, that is, fossils that have been eroded from their original locations then preserved in later sedimentary layers. Mosasaurs, plesiosaurs, pterosaurs and many species of plants and invertebrates also became extinct. Mammalian clades passed through the boundary with few extinctions, evolving and thriving well past the event. Rates of extinction and radiation varied across different clades of organisms.

http://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event

Edited April 1, 2012 by Spyman

[Moontanman]

I agree with you, i was just being a smart ass but a KT level event is survivable by humans, mostly because we have technology and can prepare but very few humans would survive and the world we would be in would be very difficult to live in but not impossible. With out technology humans would be very unlikely to survive.

 

There is some contention on the dinosaur fossils above the KT event, some still argue a small population of ceratopsin type dinosaurs survived a few hundred to a thousand years but it is splitting hairs, all the non avian dinosaurs are gone...

[questionposter]

You are wrong.

Dude, you don't even have any proof I'm wrong. What do you think happens with sunlight? Sure, 1 second may not be as much as a meteor, but over even a day its a ton of energy, but its distributed in such away that it doesn't destroy everything, If we can do that with a 10km meteor, things will end up being mostly alright. Probably a more hostile environment, but at least many things wouldn't be completely destroyed.

 

 

Obviously we are talking about something able to cause a mass extincion in this context and not something actually able to destroy the planet.

Well in that case it's probably around 10km, in which case try to reduce it's speed, then fragment it into not too big or too small of pieces. If we reduce its speed that will reduce the amount of force it has anyway.

 

 

 

In other words you still believe that fragmenting the rock will help. You are of course free to keep your belief and put faith in your speculations.

 

However facts and experts does not agree with you and since your evidence is lacking, I strongly suggest others to not trust you on this.

 

 

Your not learning anything, your stuck in this mindset of everything you previously thought has to be the absolute truth. However, I learned different methods just by exploring this topic that only fragmenting a giant meteor into only very small pieces that would completely vaporize in the atmosphere like I had previously believed won't necessarily work. Instead, what would logically work which you have nothing to disprove with is that the pieces have to be the right size as to almost evenly distribute their energy through both friction and Newtons so that no particular part, whether its the atmosphere, ocean or land, get's completely destroyed.

Dalton's theory of an atom wasn't completely wrong, and you don't just throw it in the trash, you build off of it.

 

 

Siddhartha's opinion doesn't have any weight here...

If you think there's an "in-between" option, then the philosophy does.

 

 

 

So have you seen any dinosaurs lately?

Have you seen any birds lately? Ostriches are pretty large...Man, 18 foot alligator in Australia? That's pretty big. Many things still survived. Not ideally, but enough to get to where we are now.

 

Experts seems to agree with me that large asteroids are a seriously threat.

I never would have guessed...

 

Earth has collided with several asteroids in recent geological history. The Cretaceous-Tertiary asteroid, for example, is theorized to have caused the extinction of the dinosaurs 65 million years ago. If such an object struck Earth it could have a serious impact on civilization. It is even possible that humanity would be completely destroyed; for this to occur the asteroid would need to be at least 1 km (0.62 mi) in diameter, but probably between 3 and 10 km (2–6 miles).

http://en.wikipedia....eteorite_impact

That implies that the meteor has to be more or less completely intact or in one piece in order to do that. And as history has shown, even a fully intact asteroid doesn't destroy every species. The best thing probably would be to go underground like how many mammals did, and use geothermal energy, whether the meteor is fragmented or not. I think that's what the book "The City of Ember" was based on.

 

Just to make sure, are you imagining that if its fragmented, it all hits the Earth at once and in one spot? Because that wouldn't happen, the fragments would spread out over some considerable distance and if you look at meteor showers, the fragments would rain down over the period of probably between an hour and a day.

Edited April 1, 2012 by questionposter

[Spyman]

I agree with you, i was just being a smart ass but a KT level event is survivable by humans, mostly because we have technology and can prepare but very few humans would survive and the world we would be in would be very difficult to live in but not impossible. With out technology humans would be very unlikely to survive.

 

There is some contention on the dinosaur fossils above the KT event, some still argue a small population of ceratopsin type dinosaurs survived a few hundred to a thousand years but it is splitting hairs, all the non avian dinosaurs are gone...

It would truly be the end of civilization as we know it, but large military facilities with supplies and equipment like the Cheyenne Mountain Directorate or something like the private Ark Two Shelter could protect small groups of humans that possibly could restart our civilization.

 

However studies have showed that most people on the planet would have starved to death within the following year after the impact blast since it would be to cold for any outdoor food production and the Nuclear Winter could very well last for more than a decade.

 

With reasonable pre warning we could build a lot of shelters and outfit them with food, tools to build large greenhouses and the needed seeds. But protecting these buildings would also be a real problem since large crowds of wandering marauders would tear them apart in their battle for survival.

 

I think most people are likely more eager to pay for the threat to be deflected than for a few *others* to survive in a *luxuary* shelter. But for optimal protection of our existence we should both develop collision avoidance strategies and build several large shelters.

Edited April 2, 2012 by Spyman

[questionposter]

It would truly be the end of civilization as we know it, but large military facilities with supplies and equipment like the Cheyenne Mountain Directorate or something like the private Ark Two Shelter could protect small groups of humans that possibly could restart our civilization.

 

However studies have showed that most people on the planet would have starved to death within the following year after the impact blast since it would be to cold for any outdoor food production and the Nuclear Winter could very well last for more than a decade.

 

With reasonable pre warning we could build a lot of shelters and outfit them with food, tools to build large greenhouses and the needed seeds. But protecting these buildings would also be a real problem since large crowds of wandering marauders would tear them apart in their battle for survival.

 

I think most people are likely more eager to pay for the threat to be deflected than for a few *others* to survive in a *luxuary* shelter. But for optimal protection of our existence we should both develop collision avoidance strategies and build several large shelters.

 

I repeated at least a couple times that the environment would become more harsh, however, an equal deflection for energy of both the atmosphere and land in the form of both kelvins and newtons of a 10km might split the difference enough for many parts of the world to not be completely destroyed.

If it did somehow have enough kelvin to heat up the Earth and cause it to go into a cool even though that's also based off the location of the continents, much of the tropical region could easily still be very habitable.

However, if there's warming, there's large floods due to the rise in the ocean level from the melting ice, in which case civilizations aren't destroyed, just pushed together more.

I'm not saying its easy or that there won't be consequences, which is somehow what you got from me repeatedly stating how various things would have various negative consequences. I even mentioned that the Earth could cool to a great extend specifically. It won't be as if nothing happened, the environment would just be more hostile in some way, if the meteor is properly fragmented and deflecting it didn't work.

A 10km meteor with our current technology to not only reduce its speed, but to break it up into pieces of a relative size might be the answer for a 10km meteor. For something much bigger, anyone can say is if it's intact, it will shatter the crust, and if not, it will heat up the atmosphere too much, perhaps even past the dinosaur era, but for something that large, it would be much more detectable, and thus we would have more room to use every nuke on it.

In fact, even in a dinosaur era where the average temperature was 68 degrees Fahrenheit and the tropical regions were on average 120 degrees Fahrenheit, life was thriving. Not that global warming isn't bad for some species, but it actually does take a lot to wipe out a technologically advanced civilization of over 7 billion people.

For something larger than 10km, then what your saying with the bunkers would probably be more helpful, and staying underground for a large amount of time would probably be a good option, although those shelteres were meant for nuclear wars in the event that most of the Earth was engulfed in hydrogen bombs with nuclear fallout occupying much of the atmosphere.

Anything up to 10km I would say we can deal with in such away that modern civilization would not be mostly destroyed. Past that, probably more around the 16+ km, we would have to definitely start over if we survived. Anything past probably 30km with our currently technology that did hit Earth, assuming we didn't use any nukes or bombs on it, would just wipe everything out, and the entire cycle of life in general may have to start over with bacterium.

The asteroid at the KT even was very likely a fully intact meteor which concentrated all its force in one spot to not only severely damage local crust, but throw debris in the air to block out the sun and kill many plants.

 

I have another question for you: If I shoot a wooden board with a bullet, and throw 10000 pebbles at another board, which board do you think is more or less fully intact? If the energy was equivalent in both situations, only one board would be fully intact.

Heat is only a problem if there's too much of it, and Newtons are only a problem if they are concentrated, thus we reduce heat by having more energy transferred in the form of Newtons, and from there we have the Newtons simply not be concentrated in the one spot as to not be as much of a problem.

 

A gradual spread of Newtons of the force contained in a large meteor using vector space would simply change Earth's orbit a little bit, or sort of knock it backwards. Although I suppose if the meteor hits us in the opposite direction we are going, that reduces our speed, which means it easier to get closer to the sun or would at least lower our potential energy relative to the sun which would translate to being closer, but hopefully, the Earth carries a lot more force than a meteor as to not make that the case.

 

Also, I've been thinking more about it, and the impact would be different if the meteor hit land rather than the ocean. If the meteor hit in the middle of a large Ocean like the pacific, it would cause a massive tidal wave that would probably just sink the coastlines, but at least that energy would be transferred that way rather than a majority too Earth's crust or atmosphere. So there actually could be a greater benefit to having it land intact, depending on where it would land.

 

I at least hope by this point you don't think that I think there would be no consequences for a 10km asteroid.

Edited April 3, 2012 by questionposter

[Spyman]

Dude, you don't even have any proof I'm wrong.

It doesn't work that way, you started this thread and you are the one making the claims in the OP. If you want us to belive in your claims then it is up to you to provide the necessary evidence to convince us that you are correct.

 

It is even stated in the Speculations Forum Rules that: "Speculations must be backed up by evidence or some sort of proof."

 

You need to provide a rigorous mathematical analysis, showing exactly how all the energy gets dispersed and prove with a very high degree of margin for error that this energy will be of a substantial too low level to cause any significant harm to the biological system.

 

And since your claim seems to go against the general regarded deadliness of fragmented asteroids, you also need to supply links and quotes of statements and studies by professional experts that agree with and supports your claim.

[questionposter]

It doesn't work that way, you started this thread and you are the one making the claims in the OP. If you want us to belive in your claims then it is up to you to provide the necessary evidence to convince us that you are correct.

 

It is even stated in the Speculations Forum Rules that: "Speculations must be backed up by evidence or some sort of proof."

 

You need to provide a rigorous mathematical analysis, showing exactly how all the energy gets dispersed and prove with a very high degree of margin for error that this energy will be of a substantial too low level to cause any significant harm to the biological system.

 

And since your claim seems to go against the general regarded deadliness of fragmented asteroids, you also need to supply links and quotes of statements and studies by professional experts that agree with and supports your claim.

 

The evidence is that this happens on a smaller scale. I don't think anyone wants to test this with Earth. Did you even read the wood analogy?

 

http://science.howst...question486.htm

 

Unless you want me to prove its possible for an asteroid to transfer both Newtons and thermal energy?

Also, I'm not doing rigorous mathematics for some forum, I'll try and look up some basic things, but if it works on a smaller scale, based on our currently knowledge, a larger meteor should have the same principal, and there's no reason for it to not. There's also the evidence in history.

Also again, the wood analogy? Do you honestly think its possible for 10000 pebbles 4-5 at a time tossed by someone will destroy a large wooden board?

Also, semantics are important in this.

 

You keep saying fragments like they are all one thing, but not only are they separate objects, but they obviously come in different sizes. What if the fragments are 20000km large? Don't you think that's a pretty big difference than 1 foot? And don't you think 1 foot is a big difference between 1cm?

 

Let's use gaspara as a reference

 

http://en.wikipedia....wiki/951_Gaspra

 

mass: 2.5*10^16kg

 

velocity of gaspara:

http://www.brighthub...cles/64710.aspx

951 Gaspra: With an average orbital velocity of 19.88 kilometers per second, Gaspra orbits in the main asteroid belt. It was the first asteroid to have been closely approached by the Galileo spacecraft on October 29 1991.

 

If we say the speed stays constant, the acceleration won't change, but since it had to have gained energy to go at that speed, I guess we can say it starts at 0/km/s then goes to 19km/s, but, no idea how long it would have taken for that to happen. When the solar system was forming? No, it would have gained speed in a faster amount of time, it's probably been traveling around that speed since,

The orbital velocities of jupiter and mars

http://nssdc.gsfc.na...t/marsfact.html

 

http://nssdc.gsfc.na...upiterfact.html

 

The orbital velocity of the asteroid is between those two.

 

Since the asteroid probably orbited the sun to get to its speed that it currently has now, but more likely only did a half orbit before flying off, we can use the average time it takes between both mars and jupiter to orbit the sun divided by two as a sort of auxillary reference for how much time it took the asteroid to orbit the sun and gain its acceleration. I'm done for now, I'll get back to this later.

Edited April 3, 2012 by questionposter

[Spyman]

Let's use gaspara as a reference

 

http://en.wikipedia....wiki/951_Gaspra

 

mass: 2.5*10^16kg

I accept 951 Gaspra with an estimated mass of 2.5e16 kg and a rocky density of 2.7 g/cm³ as an valid example.

Edited April 3, 2012 by Spyman

[questionposter]

I accept 951 Gaspra with an estimated mass of 2.5e16 kg and a rocky density of 2.7 g/cm³ as an valid example.

 

Wait what? It doesn't matter if you accept it, it is what it is, and there's proof of its existence...

Edited April 4, 2012 by questionposter

[Spyman]

Wait what? It doesn't matter if you accept it, it is what it is, and there's proof of its existence...

It does matter because I mentioned another example to which you claimed would not wipe out the human species if it was fragmented and if you change the goalpost then we could end up talking about something completely different. I don't know why you want to change it but it is ok, carry on.

[questionposter]

Mean orbital velocity of Jupiter+ mean orbital velocity of Mars

Er actually before I had meant to say that because the orbital speed of the asteroid is in between those two and thus I could extrapolate the average amount of time it would take for it to orbit the sun, but apparently it just says

1199.647 days,

and to find how many seconds that is, we do

1199.647*24 because 24 hours, then times 60 because 60 minutes in an hour, then times another 60 because 60 seconds in a minute, and we get about 1.03*10^8 seconds.

Now lets try and find the average velocity to calculate the force.

For acceleration, (v2-v1)/(t2-t1)

(19.88km/s-0km/s)/(1.03*10^8s-0s)= approximately 1.93^-7km/s/s

Then we multiply that by the mass to see how much force it carries if left fully intact

2.5*10^16kg * 0000000193*10^-7km/s/s = approximately 4.82*10^9N of force.

Look ok so far?

Now all we need to do is divide that number in half to see what happens in the situations that the energy is split evenly as well as a way to convert Newtons to units of heat and then we need to find out how much heat is taken to raise the temperature of the atmosphere of the Earth exactly 1 degree C or F to see how much half the asteroid's energy would raise the atmosphere, and then for the fragments we'd need to pick some kind of number that they are fragmented in to carry half the remaining force. If we divide the force by two, I would say we divide the mass by two, so after the first half of the asteroid is gone, we have 9km of asteroid divided into x pieces. I suppose we can also look and see what happens if all the energy is converted into units of hear and see how much it raises the atmosphere's temperature.

For conversion of energy, I know that the force through friction converts some kinetic energy into thermal energy, but all I can remember is that kelvin is equal to some degrees newton, and all that really means to me at this point is that the symbol for Celsius or Fahrenheit is the Coefficient of Newtons in degrees Newtons.

Perhaps there might be another way though, like perhaps we can use momentum to calculate how much thermal energy have of it's energy would release.

The number of meteoroids in a meteor shower various greatly, but seem to often fall in the realm of 15-50 pieces per hour, although most of the things in a meteor shower are pieces of dust.

http://meteorshowers...or_showers.html

I didn't notice if it said on that website, but in all the meteor showers I've heard of, I've heard them lasting at least a day. For some reason I can't find any credible links saying how long meteor showers last, just wiki and yahoo answers.

Edited April 4, 2012 by questionposter

[Spyman]

1199.647 days,

and to find how many seconds that is, we do

1199.647*24 because 24 hours, then times 60 because 60 minutes in an hour, then times another 60 because 60 seconds in a minute, and we get about 1.03*10^8 seconds.

Now lets try and find the average velocity to calculate the force.

For acceleration, (v2-v1)/(t2-t1)

(19.88km/s-0km/s)/(1.03*10^8s-0s)= approximately 1.93^-7km/s/s

Then we multiply that by the mass to see how much force it carries if left fully intact

2.5*10^16kg * 0000000193*10^-7km/s/s = approximately 4.82*10^9N of force.

Look ok so far?

That depends on what you are trying to do, it looks like you have miscalculated the needed force to make it stop in 1200 days by 1000 times...

[Joatmon]

Just thinking about the possibility of a collision and the possible size of the asteroid reminded me of the giant impact hypothesis that may have created the moon from debris smashed from the earth. http://en.wikipedia.org/wiki/Giant_impact_hypothesis

[questionposter]

That depends on what you are trying to do, it looks like you have miscalculated the needed force to make it stop in 1200 days by 1000 times...

 

How do you know that? I just ran it through my calculator again, same answer.

I'm trying to calculate the force an intact asteroid would carry in Newtons and then trying to use that combined with the specific heat of the atmosphere to see how much half of that energy would raise the Earth's temperature.

I might have better luck with momentum though, it would make energy conversion easier.

 

Er wait, I just tried dividing the time the asteroid goes around the sun by two for the half orbit, but I still got about 9.6*10^9, same exponent, I don't know why you'd expect it to be *10^13

 

Just thinking about the possibility of a collision and the possible size of the asteroid reminded me of the giant impact hypothesis that may have created the moon from debris smashed from the earth. http://en.wikipedia....pact_hypothesis

 

Well hopefully a moon doesn't crash into us then.

Edited April 4, 2012 by questionposter

[Spyman]

How do you know that? I just ran it through my calculator again, same answer.

I'm trying to calculate the force an intact asteroid would carry in Newtons and then trying to use that combined with the specific heat of the atmosphere to see how much half of that energy would raise the Earth's temperature.

I might have better luck with momentum though, it would make energy conversion easier.

 

Er wait, I just tried dividing the time the asteroid goes around the sun by two for the half orbit, but I still got about 9.6*10^9, same exponent, I don't know why you'd expect it to be *10^13

The correct formula for calculating the kinetic energy an asteroid hits Earth with is:

 

[math]E_K=\frac{1}{2}mv^2[/math]

 

Where m is the mass of the asteroid and v is the impact speed relative Earth.

 

Regarding your miscalculation Newton is in kg*m/s^2 and you have used acceleration in km/s^2 so the kilo is unaccounted for in your answer.

Edited April 6, 2012 by Spyman

[questionposter]

The correct formula for calculating the kinetic energy an asteroid hits Earth with is:

 

[math]E_K=\frac{1}{2}mv^2[/math]

 

Where m is the mass of the asteroid and v is the impact speed relative Earth.

 

Regarding your miscalculation Newton is in kg*m/s^2 and you have used acceleration in km/s^2 so the kilo is unaccounted for in your answer.

 

Sorry that took so long, kinda forgot about this site. It's still possible I got this wrong like I did with the Newtons, but here it goes

 

 

951 Gaspara

 

Discovery

Discovered by G. N. Neujmin

Discovery date July 30, 1916

Designations

Named after Gaspra

Alternate name(s) SIGMA 45; A913 YA;

1955 MG1

Minor planet

category Main belt (Flora family)

Orbital characteristics

Epoch 6 March 2006 (JD 2453800.5)

Aphelion 2.594 AU (388.102 Gm)

Perihelion 1.825 AU (272.985 Gm)

Semi-major axis 2.210 AU (330.544 Gm)

Eccentricity 0.174

Orbital period 3.28 a (1199.647 d)

Average orbital speed 19.88 km/s

Mean anomaly 53.057°

Inclination 4.102°

Longitude of ascending node 253.2lllll18°

Argument of perihelion 129.532°

Proper orbital elements

Physical characteristics

Dimensions 18.2×10.5×8.9 km [1]

Mean radius 6.1 km[2]

Mass 2–3×1016 kg (estimate)

Mean density ~2.7 g/cm³ (estimate) [3]

Equatorial surface gravity ~0.002 m/s² (estimate)

Escape velocity ~0.006 km/s (estimate)

Rotation period 0.293 d (7.042 h) [4]

Albedo 0.22 [5]

Temperature ~181 K

max: 281 K (+8°C)

Spectral type S

Absolute magnitude (H) 11.46

 

Mean orbital velocity of Jupiter + mean orbital velocity of Mars

/2 = Average orbital velocity

 

Orbital period of Gaspara 951: 1199.647 days

 

and to find how many seconds that is:

1199.647*24 because 24 hours, then times 60 because 60 minutes in an hour,

then times another 60 because 60 seconds in a minute, and we get about

1.03*10^8 seconds.

 

average velocity to calculate the force

For acceleration, (v2-v1)/(t2-t1)

(19.88km/s-0km/s)/(1.03*10^8s-0s)= approximately 1.93^-7km/s/s

 

Then we multiply that by the mass to see how much force it carries if

left fully intact

 

2.5*10^16kg * 1.93*10^-7km/s/s = approximately 4.82*10^9N of force.

 

The number of meteoroids in a meteor shower various greatly, but seem to

often fall in the realm of 15-50 pieces per hour, although most of the

things in a meteor shower are pieces of dust.

http://meteorshowers...or_showers.html

 

Using Newtons does not make for a good conversion with dimensional analysis, so I will calculate it's

approximate kinetic energy instead.

 

E(sub k) = 1/2mv^2

 

Kinetic energy = (1/2)(2.5*10^16kg)(19.88m/s)^2=4.94*10^18J

 

1 joule of kinetic energy approximately equals 1 joule of thermal energy.

If all asteroid's energy was converted to thermal energy, it would release

approximately 4.94*10^18 joules of thermal energy.

 

2.5*10^16kg

 

Using the Specific heat of Earth's atmosphere to calculate the temperature change

 

q=McT

 

T = Temperature Change = ???

q = energy in joules = 4.94*10^18J = 4.94*10^15kJ

M= mass = 5.3×10^18

http://hypertextbook...LouiseLiu.shtml

http://en.wikipedia....osphere_of_Eart

c = specific heat = 1.01(kJ/kg K) = (specific heat capacity of "Air")

http://www.engineeri...ases-d_159.html

 

Proof:

 

 

(4.94*10^(15)kJ)=(5.3×10^(18)kg)(1.01(kJ/kg)k)(T)

 

Then I divide the left side by everything on the right side except by T, and dividing is the same as multiplying by 1 over that number

 

(4.94*10^15kJ/1)(1/5.3*10^(18)kg)(1kgK/1.01kJ) = the units cancel out and I am left with a temperature change of .0009228 Kelvin

 

And in case I forgot to multiply something by 1000 like I did with newtons, I will multiply the amount of joules the asteroid has by 1000 to play it safe

 

 

(4.94*10^18kJ/1)(1/5.3*10^(18)kg)(1kgK/1.01kJ) = the units cancel out and I am left with a temperature change of .9228... Kelvin

 

If my original theory and it's proof is correct, if the asteroid 951 Gaspara which is 6.1km large was heading for Earth and we fragmented it into pieces so small that all of it's kinetic energy would be converted to thermal energy via friction causing the heating and then vaporization of the fragments before they reached the ground, Earth would be saved and there would be a temperature change less than 1 Kelvin.

 

Based on this I think that it is safe to assume an asteroid 10km large would raise Earth's temperature a little over 1 K or a little over 1 hundredth of a K,

and an asteroid 20km large would definitely raise Earth's atmosphere's temperature by a little over 2 K or .002 K.

 

I looked about the conversion for Kelvin to Celsius and it appears 1K approximately = -272.15 degrees Celsius.

Edited April 13, 2012 by questionposter

[questionposter]

Yeah, http://en.wikipedia.org/wiki/Cordelia_(moon)

 

Cordelia is a moon that is 20km large and it only has a mass of 4.4*10^16. It's still to the same exponent so the numbers should still all be relatively close.

[Spyman]

Sorry that took so long, kinda forgot about this site.

Forgot??? How could you forget such a great place like this? But don't worry, we don't have time restrictions on replies here.

 

 

It's still possible I got this wrong like I did with the Newtons, but here it goes

Umm, if you realize you got that wrong then why repeat the exact same mistake again? Didn't you read and understand my last post?

 

 

951 Gaspara

 

Discovery

Discovered by G. N. Neujmin

Discovery date July 30, 1916

Designations

Named after Gaspra

Alternate name(s) SIGMA 45; A913 YA;

1955 MG1

Minor planet

category Main belt (Flora family)

Orbital characteristics

Epoch 6 March 2006 (JD 2453800.5)

Aphelion 2.594 AU (388.102 Gm)

Perihelion 1.825 AU (272.985 Gm)

Semi-major axis 2.210 AU (330.544 Gm)

Eccentricity 0.174

Orbital period 3.28 a (1199.647 d)

Average orbital speed 19.88 km/s

Mean anomaly 53.057°

Inclination 4.102°

Longitude of ascending node 253.2lllll18°

Argument of perihelion 129.532°

Proper orbital elements

Physical characteristics

Dimensions 18.2×10.5×8.9 km [1]

Mean radius 6.1 km[2]

Mass 2–3×1016 kg (estimate)

Mean density ~2.7 g/cm³ (estimate) [3]

Equatorial surface gravity ~0.002 m/s² (estimate)

Escape velocity ~0.006 km/s (estimate)

Rotation period 0.293 d (7.042 h) [4]

Albedo 0.22 [5]

Temperature ~181 K

max: 281 K (+8°C)

Spectral type S

Absolute magnitude (H) 11.46

If you think that posting this long list of unnecessarily data makes your post look more legitimate, you are wrong.

 

Furthermore it is against the Rules to duplicate others work without clearly quoting and linking to the source.

 

 

Mean orbital velocity of Jupiter + mean orbital velocity of Mars

/2 = Average orbital velocity

 

Orbital period of Gaspara 951: 1199.647 days

 

and to find how many seconds that is:

1199.647*24 because 24 hours, then times 60 because 60 minutes in an hour,

then times another 60 because 60 seconds in a minute, and we get about

1.03*10^8 seconds.

 

average velocity to calculate the force

For acceleration, (v2-v1)/(t2-t1)

(19.88km/s-0km/s)/(1.03*10^8s-0s)= approximately 1.93^-7km/s/s

 

Then we multiply that by the mass to see how much force it carries if

left fully intact

 

2.5*10^16kg * 1.93*10^-7km/s/s = approximately 4.82*10^9N of force.

Yeah, here we have the same bad nonsense calculation again, exactly as it was posted before, it even contains the same math error.

 

It's the wrong way to do it and since it's not even done correctly it contains a false result too.

 

 

The number of meteoroids in a meteor shower various greatly, but seem to

often fall in the realm of 15-50 pieces per hour, although most of the

things in a meteor shower are pieces of dust.

http://meteorshowers...or_showers.html

But we are not talking about a meteor shower here, we are discussing the fragmentation of one asteroid where all pieces will hit Earth in one swarm.

 

From the asteroid's point of view the Earth is a circular target with a diameter of about 12 742 km and a moving speed of around 29.78 km/s, that means that for all the pieces to hit Earth they must all fall within 12742/29.78=428 seconds or about 7 minutes, otherwise some parts will miss Earth.

 

BTW: your link is not working.

 

 

Using Newtons does not make for a good conversion with dimensional analysis, so I will calculate it's

approximate kinetic energy instead.

 

E(sub k) = 1/2mv^2

 

Kinetic energy = (1/2)(2.5*10^16kg)(19.88m/s)^2=4.94*10^18J

It is good to see that you finally are applying the correct formula for kinetic energy that I provided to you.

 

But we argued about an impact speed similar to that of Comet Shoemaker-Levy 9 that hit Jupiter with a collision speed of approximately 60 km/s.

 

I am a reasonable man so if you can provide a valid motivation to change the impact speed to another sensible value I can accept that.

 

However until then, I will consider the rest of your post as an lousy attempt to change the goalpost and fudge the numbers in your favor.

[questionposter]

Forgot??? How could you forget such a great place like this? But don't worry, we don't have time restrictions on replies here.

 

 

 

Umm, if you realize you got that wrong then why repeat the exact same mistake again? Didn't you read and understand my last post?

 

 

 

If you think that posting this long list of unnecessarily data makes your post look more legitimate, you are wrong.

 

Furthermore it is against the Rules to duplicate others work without clearly quoting and linking to the source.

 

 

 

Yeah, here we have the same bad nonsense calculation again, exactly as it was posted before, it even contains the same math error.

 

It's the wrong way to do it and since it's not even done correctly it contains a false result too.

 

 

 

But we are not talking about a meteor shower here, we are discussing the fragmentation of one asteroid where all pieces will hit Earth in one swarm.

 

From the asteroid's point of view the Earth is a circular target with a diameter of about 12 742 km and a moving speed of around 29.78 km/s, that means that for all the pieces to hit Earth they must all fall within 12742/29.78=428 seconds or about 7 minutes, otherwise some parts will miss Earth.

 

BTW: your link is not working.

 

 

 

It is good to see that you finally are applying the correct formula for kinetic energy that I provided to you.

 

But we argued about an impact speed similar to that of Comet Shoemaker-Levy 9 that hit Jupiter with a collision speed of approximately 60 km/s.

 

I am a reasonable man so if you can provide a valid motivation to change the impact speed to another sensible value I can accept that.

 

However until then, I will consider the rest of your post as an lousy attempt to change the goalpost and fudge the numbers in your favor.

 

Dude, I proved my theory right which doesn't even normally happen on these forums, your just arguing semantics and details because you don't want to admit you were wrong to automatically say humanity would be destroyed with my theory in place or there's some very very large potions of my posts your not understanding.

http://en.wikipedia....wiki/951_Gaspra

 

It says right there on the side the average orbital speed is about 20km/s which is most likely the speed it would hit Earth at.

and it has all the other stuff like about the mass, I got my info from wikipedia, I mostly just copied and pasted an extended link which is why there's useless data in there.

Maybe the Earth could be moving towards or away the asteroid, but it could also easily be an impact into the side of Earth and thus it wouldn't really matter. If all of 951 Gaspara's kinetic energy was converted to thermal energy in it's current state, it definitely wouldn't raise Earth's atmosphere's temperature by more than 2 Kelvin. I even multiplied Gaspara's energy by 1000 unnecessarily just incase I did make the same mistake like you said I had and it's still less than 1 Kelvin.

Actually, the word "impact" is a sever over-exaggeration because I'm talking about millions of small fragments, the asteroid wouldn't hit Earth at all, the pieces would burn up in the atmosphere practically harmlessly.

 

 

Also, I copied the Newtons thing to show where I had left off from, and I clearly stated I was going to use kinetic energy instead of Newtons for my calculations from that point on.

Some asteroids are faster, some are slower, but the temperature change will be around .0001-3 Kelvin with many of those relatively similar sized asteroids in our solar system since there are varying speeds.

 

What specifically do you even think needs to be multiplied by 1000 in my new calculations? Because I don't see a reason to in addition to the calculations I already did. Just because a unit is squared doesn't mean the coefficient is.

 

 

If I say 1X * 5X, I don't say (1 * 5)^2 * X^2, I say 5X^2.

(1*5)^2 would equal 25, and 1x times 5x does not equal 25x^2, it equals 5x^2.

 

 

and the only other reason I could think of for you thinking I need to multiply something by 1000 is conversion from a unit to kilo-units.

1 joule does not = 1000 kilo joules, because there are 1000 joules in one kilo-joule. 1 joule is 1 1/1000 if a kilo-joule, thus I divide joules by 1000, NOT multiply by 1000, to convert that number to kilo-joules, and it also needs to work that way so the units cancel out at all (see dimensional analysis).

 

The comet that hit Jupiter was very large and more rare anyway, it left a scars the size of Earth itself.

 

Not only that but the system of Earth would want to return to an equilibrium anyway as Earth loses much heat energy to space, and thus Earth would try to cool off even if I had to multiply Gaspara's energy by 10000 which would make the temperature change about 9 Kelvin.

 

Also, if some parts miss Earth, isn't that a good thing anyway?

Edited April 17, 2012 by questionposter

[Spyman]

Dude, I proved my theory right which doesn't even normally happen on these forums, your just arguing semantics and details because you don't want to admit you were wrong to automatically say humanity would be destroyed with my theory in place or there's some very very large potions of my posts your not understanding.

While it's generally considered good to have self esteem, one should take great care to not be too confident and overestimate one's capabilities.

(Especially when you are continuously repeating the same mistake that has been pointed out to you several times already.)

 

 

It says right there on the side the average orbital speed is about 20km/s which is most likely the speed it would hit Earth at.

and it has all the other stuff like about the mass, I got my info from wikipedia, I mostly just copied and pasted an extended link which is why there's useless data in there.

Maybe the Earth could be moving towards or away the asteroid, but it could also easily be an impact into the side of Earth and thus it wouldn't really matter. If all of 951 Gaspara's kinetic energy was converted to thermal energy in it's current state, it definitely wouldn't raise Earth's atmosphere's temperature by more than 2 Kelvin. I even multiplied Gaspara's energy by 1000 unnecessarily just incase I did make the same mistake like you said I had and it's still less than 1 Kelvin.

Actually, the word "impact" is a sever over-exaggeration because I'm talking about millions of small fragments, the asteroid wouldn't hit Earth at all, the pieces would burn up in the atmosphere practically harmlessly.

First I must say that I find it rather petty and unsportsmanlike for you to quibble on the impact speed which is only a factor of 3 times when you claim to be willing to multiply with an factor of 1000 times "just in case". 60 km/s was the speed I mentioned already back in post #10 and what you have been arguing against since then, you did not mention any speed limits in your claim in the OP or before this post.

 

Secondly, Gaspra's orbital speed is certainly not the most likely speed it will hit Earth with, it is the speed it moves around the Sun with and not a speed relative Earth in Earth's orbit. In Gaspra's current orbit it will never hit Earth or cross paths with Earth's orbit. For it to move closer to Earth inwards in the solar system its orbit will have to change and then it will certainly speed up when accelerated towards the Sun. But IF we make a hypothetical example and assume that it or a similar asteroid will hit Earth then we are free to assume any reasonable speed we want.

 

Third, the link you provided as evidence in your post #32 says:

 

"Meteoroids enter the atmosphere at extremely high speeds -- 7 to 45 miles per second (11 to 72 kilometers per second)."

http://science.howstuffworks.com/question486.htm

 

Even while changing the speed seem unfair to me, I will still let you have your speed of 20 km/s, because it's inside a reasonable speed range.

 

 

What specifically do you even think needs to be multiplied by 1000 in my new calculations? Because I don't see a reason to in addition to the calculations I already did. Just because a unit is squared doesn't mean the coefficient is.

The speed of 20 km/s equals 20e3 m/s or 20×10^3 m/s or 20 000 m/s so this speed squared equals 400 000 000 (m/s)^2 and not 400 (m/s)^2.

 

 

Now, let's scrutinize your evidence while using your speed correctly in the energy formula:

 

The total kinetic energy delivered by impact into the atmosphere is:

 

[math]E_K = \frac{1}{2}mv^2 = \frac{1}{2}*2.5\times10^{16}*(20\times10^{3})^2 = 5\times10^{24} Joules = 5\times10^{21} kiloJoules[/math]

 

I don't think applying the Heat equation like this is correct, but all I have to do is show that your current estimate is wrong so:

 

[math]Q = mc \Delta T \Rightarrow \Delta T = \frac{Q}{mc} = \frac{5\times10^{21}}{5.3\times10^{18}*1.01} = 934^o Kelvin[/math]

 

Since Kelvin and Celsius have equal scale and the average air temperature at Earth's surface is around 15°C it would rise to almost 950 °Celsius.

 

Unless you don't consider breathing air hot enough to melt aluminium to be a problem, I think your evidence just went up in smoke.

 

 

Also, if some parts miss Earth, isn't that a good thing anyway?

That would be a good thing but not what we are arguing about, I am the one proposing deflection and you are proposing destruction, remember?

 

If some parts of the asteroid miss Earth then it's not the fragmentation itself that saves Earth but the deflection of those parts.

Edited April 17, 2012 by Spyman

[questionposter]

While it's generally considered good to have self esteem, one should take great care to not be too confident and overestimate one's capabilities.

(Especially when you are continuously repeating the same mistake that has been pointed out to you several times already.)

 

 

 

First I must say that I find it rather petty and unsportsmanlike for you to quibble on the impact speed which is only a factor of 3 times when you claim to be willing to multiply with an factor of 1000 times "just in case". 60 km/s was the speed I mentioned already back in post #10 and what you have been arguing against since then, you did not mention any speed limits in your claim in the OP or before this post.

 

Secondly, Gaspra's orbital speed is certainly not the most likely speed it will hit Earth with, it is the speed it moves around the Sun with and not a speed relative Earth in Earth's orbit. In Gaspra's current orbit it will never hit Earth or cross paths with Earth's orbit. For it to move closer to Earth inwards in the solar system its orbit will have to change and then it will certainly speed up when accelerated towards the Sun. But IF we make a hypothetical example and assume that it or a similar asteroid will hit Earth then we are free to assume any reasonable speed we want.

 

Third, the link you provided as evidence in your post #32 says:

 

"Meteoroids enter the atmosphere at extremely high speeds -- 7 to 45 miles per second (11 to 72 kilometers per second)."

http://science.howst...question486.htm

 

Even while changing the speed seem unfair to me, I will still let you have your speed of 20 km/s, because it's inside a reasonable speed range.

 

 

 

The speed of 20 km/s equals 20e3 m/s or 20×10^3 m/s or 20 000 m/s so this speed squared equals 400 000 000 (m/s)^2 and not 400 (m/s)^2.

 

 

Now, let's scrutinize your evidence while using your speed correctly in the energy formula:

 

The total kinetic energy delivered by impact into the atmosphere is:

 

[math]E_K = \frac{1}{2}mv^2 = \frac{1}{2}*2.5\times10^{16}*(20\times10^{3})^2 = 5\times10^{24} Joules = 5\times10^{21} kiloJoules[/math]

 

I don't think applying the Heat equation like this is correct, but all I have to do is show that your current estimate is wrong so:

 

[math]Q = mc \Delta T \Rightarrow \Delta T = \frac{Q}{mc} = \frac{5\times10^{21}}{5.3\times10^{18}*1.01} = 934^o Kelvin[/math]

 

Since Kelvin and Celsius have equal scale and the average air temperature at Earth's surface is around 15°C it would rise to almost 950 °Celsius.

 

Unless you don't consider breathing air hot enough to melt aluminium to be a problem, I think your evidence just went up in smoke.

 

 

 

That would be a good thing but not what we are arguing about, I am the one proposing deflection and you are proposing destruction, remember?

 

If some parts of the asteroid miss Earth then it's not the fragmentation itself that saves Earth but the deflection of those parts.

 

Alright, I redid the math from scratch and it seems to match yours, so I'll agree with you for now and retract the statement and that converting all of an asteroid's kinetic energy to thermal energy via friction with Earth's atmosphere isn't the best option. I'm still going to get it looked over by an actual physicist though just to make sure.

 

That said, half and half probably wouldn't be much better either, which leaves us with 3 other options:

Blow it up completely

Deflect it,

Break it into pieces not small enough to transfer that much thermal energy but not large enough to actually cause damage, for which the only result would really be a vector map, the energy is still conserved, but all it would do in that form is simply push Earth or change its orbit a little bit or something and probably destroy some homes and knock down some trees. I suppose I could calculate the average volume and mass of each piece and see how much energy they carry depending on how many pieces its broken into, but then I'd also have ton consider the critical size for when it gets too small so that all of its energy would be converted to thermal energy, leading us back to the first problem.

I looked into canceling out its energy, the highest energy nuclear device ever detonated, castle/bravo, only released 63,000 TJ, it it took something like over 700000 of them to equal the kinetic energy of the of meteor assuming the meteor calculations are correct.

 

Maybe you can help with the "deflecting" thing since that's your theory. Maybe if it's speed is super fast, but it would have to be way way faster than the meteor to deliver enough energy to move 2.5*10^16kg of matter out of the way and there would need to be some way to push it at the right angle.

 

If anyone else has any theories free to jump in too, this is just a speculation topic.

Edited April 17, 2012 by questionposter

[Spyman]

That said, half and half probably wouldn't be much better either, which leaves us with 3 other options:

Blow it up completely

Deflect it,

Break it into pieces not small enough to transfer that much thermal energy but not large enough to actually cause damage, for which the only result would really be a vector map, the energy is still conserved, but all it would do in that form is simply push Earth or change its orbit a little bit or something and probably destroy some homes and knock down some trees. I suppose I could calculate the average volume and mass of each piece and see how much energy they carry depending on how many pieces its broken into, but then I'd also have ton consider the critical size for when it gets too small so that all of its energy would be converted to thermal energy, leading us back to the first problem.

If we "Break it into pieces" and none of them bounces off Earth then we have a perfectly inelastic collision where conservation of momentum applies.

 

[math]m_1*u_1+m_2*u_2=(m_1+m_2)*v[/math]

 

m is mass of body

u is initial velocity

v is final velocity

 

However a very large portion of the kinetic energy will still get turned into thermal energy when the bodies gets deformed in the collisions.

 

 

Maybe you can help with the "deflecting" thing since that's your theory. Maybe if it's speed is super fast, but it would have to be way way faster than the meteor to deliver enough energy to move 2.5*10^16kg of matter out of the way and there would need to be some way to push it at the right angle.

I don't have a "deflecting" theory, but IF we manage to deflect it, then it obviously won't hit Earth and we are saved.

 

There are several ideas proposed in the link I posted in post #4 and the main aspect is that an early change doesn't have to be so large.

[questionposter]

However a very large portion of the kinetic energy will still get turned into thermal energy when the bodies gets deformed in the collisions.

I know, but theoretically there should be a size of the meteor where they to release thermal energy, but they are not small enough to release too much thermal energy but not large enough to cause major damage to the ground.

 

 

 

I don't have a "deflecting" theory, but IF we manage to deflect it, then it obviously won't hit Earth and we are saved.

Right, but, how realistic is it to throw a 2 ton piece of metal and deflect 2.5*10^16 kilograms of matter?

 

Ion beams? Mass drivers? I guess, seems kind of complex, though it does say in that very link that there is a potential to let pieces burn up in the atmosphere, even if there potentially exists the same problem. Thought I suppose, Earth won't stay at 920 Kelvin, and it wouldn't happen all at once. Maybe if it could be spread out enough for Earth to return to equilibrium before the next swarm, but doing that might be too complex.

Actually, the calculations on this thread might even be the citation needed for that paragraph.

 

The only one where there doesn't seem to be any direct setbacks is I guess trying to blow it up completely, based on that link, but perhaps studies should be done on the far side of the moon where nuclear devices are detonated and there are orbiting satellites to scan how the radiation spreads out.

Edited April 19, 2012 by questionposter

[Spyman]

I know, but theoretically there should be a size of the meteor where they to release thermal energy, but they are not small enough to release too much thermal energy but not large enough to cause major damage to the ground.

No, if the kinetic energy is not released by heating the atmosphere, then it will be released violently at impact with the ground.

 

Barringer Crater in Arizona

Aerial view of Arizona Meteor Crater, September 2010

 

It is about 1,200 m (4,000 ft) in diameter, some 170 m deep (570 ft), and is surrounded by a rim that rises 45 m (150 ft) above the surrounding plains.

 

(...)

 

The object that excavated the crater was a nickel-iron meteorite about 50 meters (54 yards) across, which struck the plain at a speed of several kilometers per second. Impact energy has been estimated at about 10 megatons. The speed of the impact has been a subject of some debate. Modeling initially suggested that the meteorite struck at a speed of up to 20 kilometers per second (45,000 mph), but more recent research suggests the impact was substantially slower, at 12.8 kilometers per second (28,600 mph). It is believed that about half of the impactor's bulk was vaporized during its descent, before it hit the ground.

 

The meteorite itself was mostly vaporized upon impact. Very little of it remained within the pit that it had excavated.

http://en.wikipedia.org/wiki/Meteor_Crater

[questionposter]

No, if the kinetic energy is not released by heating the atmosphere, then it will be released violently at impact with the ground.

 

Barringer Crater in Arizona

Aerial view of Arizona Meteor Crater, September 2010

 

It is about 1,200 m (4,000 ft) in diameter, some 170 m deep (570 ft), and is surrounded by a rim that rises 45 m (150 ft) above the surrounding plains.

 

(...)

 

The object that excavated the crater was a nickel-iron meteorite about 50 meters (54 yards) across, which struck the plain at a speed of several kilometers per second. Impact energy has been estimated at about 10 megatons. The speed of the impact has been a subject of some debate. Modeling initially suggested that the meteorite struck at a speed of up to 20 kilometers per second (45,000 mph), but more recent research suggests the impact was substantially slower, at 12.8 kilometers per second (28,600 mph). It is believed that about half of the impactor's bulk was vaporized during its descent, before it hit the ground.

 

The meteorite itself was mostly vaporized upon impact. Very little of it remained within the pit that it had excavated.

http://en.wikipedia....i/Meteor_Crater

 

That's 50 meters across though which is pretty big, I as thinking more like 1 meter across at most. Most of the meteors that burn up into the atmosphere are around the size of dust particles, maybe a few cubic centimeters sometimes too. If maybe there was some approximate number for the rate that a meteor converts kinetic energy to thermal energy via friction with the atmosphere, I could use it.

Edited April 19, 2012 by questionposter