Paul's Here

Apophis May Destroy West Coast

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I think they exaggerate the frequency and severity of the impacts.

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Numbers like that can't possibly be right--if asteroids collisions are supposed to be this extremely catastrophic and frequent, how are we sitting here now talking about it now?

Homo Sapiens and their ancestors have only been around for 30,000 years.

Also, I was under the impression that the theory was no longer held that a giant asteroid is what killed the dinosaurs. If the dinosaurs were all killed out suddenly, how could they have had time to evolve into birds?

Some of the smaller ones survived.

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Also, I was under the impression that the theory was no longer held that a giant asteroid is what killed the dinosaurs. If the dinosaurs were all killed out suddenly, how could they have had time to evolve into birds?

Actually that's news to me--I need to look into that.

The first birds (Archaeopteryx, e.g., 150-155 million years ago) actually appeared on the scene long before the dinosaurs went extinct (65Mya).

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Homo Sapiens and their ancestors have only been around for 30,000 years.

Some of the smaller ones survived.

That doesn't really matter though, because it could have wiped out our ancestors 200,000 years ago and we would have been just as dead now.

And I don't mean just homo sapiens gone. If their numbers are accurate, then 10,000 "wipe out a continent" asteroids have hit Earth in the last 3 billion years.

If the Earth is 25% land, that means that 2,500 of these hit land, and assuming 7 continents of equal size, each continent has been hit 357 times by an asteroid that is supposed to "wipe out a continent" in the past 3 billion years. That would mean that every 8 million years, wherever you live, life as you know it is destroyed.

Their numbers and estimates must be massively exaggerated.

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A two-part summary of last week's Planetary Defense Conference is here and here.

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A two-part summary of last week's Planetary Defense Conference is here and here.

Interesting that deflection technology was so prominent in the write-up. It looks like the gravity approach won the consensus for < 200m NEAs. I take it it was your friend who discussed kinetic impactors; though little feedback was mentioned beyond the difficulty of hitting the target, I would imagine that the need for "several decades of warning" is itself a problem to overcome.

Your talks with your friend should be interesting, when he returns.

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This question is not relevant to Apophis in particular. Could one drastically decrease an asteroid's velocity by somehow generating and maintaining stratified waves of a particular composition in the local area of an asteroid? Would internal gravity waves between different layers be sufficient if the asteroid dimensions are comparable to the dimensions of the uppermost propagative layer such that the kinetic energy is subsumed to interfacial gravity wave generation?

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This question is not relevant to Apophis in particular. Could one drastically decrease an asteroid's velocity by somehow generating and maintaining stratified waves of a particular composition in the local area of an asteroid? Would internal gravity waves between different layers be sufficient if the asteroid dimensions are comparable to the dimensions of the uppermost propagative layer such that the kinetic energy is subsumed to interfacial gravity wave generation?

I don't think anyone here is qualified to even discuss such a thing, much less answer it.

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Some students from my faculty actually had their final project about this Asteroid: Link

Nine students from the Technion-Israel Institute of Technology have developed a model spacecraft for deflecting objects falling from space.

The model has been created in response to the asteroid Apophis, which could in theory collide with Earth in 2036, and was presented at a competition organised by NASA and the American Institute of Aeronautics and Astronautics.

The initial plan would put the $353m craft into space in 2020 where it will approach the asteroid and launch two penetrating devices onto it. These will deliver equipment including a specially adapted camera, transmitter and antenna. Air bags will be used to safely deliver the equipment. Solar panels attached to the air bags will deliver power to the equipment.

The equipment will collect data on the location and composition of the asteroid and relay it back to Earth. It is considered very unlikely that Apophis will collide with Earth. However, if required, the craft will be sent to it again in 2025 and, using its gravity, will begin to divert the asteroid from its path. Due to the difference in mass between the asteroid and the spacecraft, it will not be able to divert the asteroid with enough force and will need the assistance of the Earth’s mass. Since in 2029, the asteroid is supposed to pass near the Earth, the spacecraft will use the Earth’s mass in order to divert it.

According to Dr Alexander Kogan, who guided the students, the craft will use its ion thrusters to hover 200-300m from the asteroid for four months. Using the mass of the spacecraft, combined with the effect of Earths’ gravity, the craft will pull the asteroid out of its previous path.

‘The spacecraft is what will make the difference,’ said student Lior Avital. ‘It will divert the asteroid one kilometre and with the help of the Earth, in seven years - 7,000km.’

Alternatives such as blasting the asteroid with a nuclear bomb were also considered, but the group believed the danger posed by two large asteroids or many small ones would be much greater. Diverting the asteroid by connecting powerful motors to it was also ruled out as the solution was deemed too expensive and complicated.

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Some students from my faculty actually had their final project about this Asteroid: Link

I can't login to search academic journal databases right now, so I'd appreciate a direct link to any paper or research or contact information for one Lior Avital named in the article. Not knowing whether these solar panels are currently designed better than the gallium arsenide-on-silicon ones will cause me to stamp my foot.

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This question is not relevant to Apophis in particular. Could one drastically decrease an asteroid's velocity by somehow generating and maintaining stratified waves of a particular composition in the local area of an asteroid? Would internal gravity waves between different layers be sufficient if the asteroid dimensions are comparable to the dimensions of the uppermost propagative layer such that the kinetic energy is subsumed to interfacial gravity wave generation?

Reading this again I find myself confused: are you referring to gravitational waves/radiation, or only to gravity waves, as in the mechanical wave that can form on a surface?

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Some students from my faculty actually had their final project about this Asteroid: Link

I can't login to search academic journal databases right now, so I'd appreciate a direct link to any paper or research or contact information for one Lior Avital named in the article. Not knowing whether these solar panels are currently designed better than the gallium arsenide-on-silicon ones will cause me to stamp my foot.

I'll look it up for you.

However, if you wish to contact someone by Email, the project supervisor was Dr. Alexander Kogan . His Email is at the center of the page of the Technion space research institute . .

P.S - Lior Avital was one of the students working on the project, but I can look him up if you want.

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Numbers like that can't possibly be right--if asteroids collisions are supposed to be this extremely catastrophic and frequent, how are we sitting here now talking about it now?

Also, I was under the impression that the theory was no longer held that a giant asteroid is what killed the dinosaurs. If the dinosaurs were all killed out suddenly, how could they have had time to evolve into birds?

The KT iridium layer is strong evidence for the Big One that hit the earth 65 million years ago. And there were many species of dinosaur some of which were evolving into flying reptiles long long before the meteor/asteroid/comet struck.

The size of the crater, which is just off the coast of what is not Yucatan indicates that the impact could have had all the nasty effects attributed to it.

The frequency of impacts would have been much greater during the early history of the planet, closer to 4 billion years ago, when there were more loose rocks orbiting the sun than there are now. Most of the rocks that are in an orbit between Mars and Jupiter (the asteroid belt). The ones in eccentric orbits may have been sucked in by Jupiter ( recall the recent Shoemaker-Levy comet). So it would be erroneous to think that these bodies show up in regular intervals.

These bangers do not have to occur frequently. They just have to be deadly.

In addition to the bangers there are super volcanic eruptions. The eruptions that produced the Siberian Traps some 250 million years before present wiped out 95 percent of all the life on the planet.

Here is something to worry about. The La Palma volcano in the Canary Islanda is more likely to let go well before we get hit by another comet. When (not if, but when) it happens it is good bye to the East Coast of Canada, the United States and Mexico. The Tsunami generated by collapse of La Palma volcano will inundate and wreck every city on the coast. The Tsunami will move westward at over 500 mph and when it hits the shelf waves over 200 feet high will be generated. It will make the recent tsunami of 2004 look like a minor glitch.

Just because we have been lucky enough to live during a relatively quiet period on this planet during a warming period following a previous ice age (some 25,000 years before present) should not lead us to believe that over very long geological scale periods that the earth is a safe place. For example the Toba supervolcano in the Pacific only a mere 75,000 years before present nearly wiped out our species (homo sapien sapien).

This planet is not entirely safe for our kind.

ruveyn

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Does anyone know if the collision events with celestial bodies are Poisson distributed?

ruveyn

It depends on the time interval one is considering and the extent of reliability of geological findings. Some think not.

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Reading this again I find myself confused: are you referring to gravitational waves/radiation, or only to gravity waves, as in the mechanical wave that can form on a surface?

The asteroid would radiate gravitational waves, but I'm referring to the generation of the latter.

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Reading this again I find myself confused: are you referring to gravitational waves/radiation, or only to gravity waves, as in the mechanical wave that can form on a surface?

The asteroid would radiate gravitational waves, but I'm referring to the generation of the latter.

There are many labs studying weightless fluids (oil in porous rock, pulmonary edemas, etc.) that could be used to model the dynamics between different particle interactions, because one can vary the gravity rather than a zero-gravity environment only. It would be interesting to see the instabilities that could occur when some types of waves are placed on top of "lighter" waves with a suspended, non-symmetrical solid, starting with an experiment that stabilizes a top-heavy configuration by magnetically levitating a magnetic, heavier fluid, and measuring exactly what happens to the suspended solid and the two fluids when the magnetic field is turned off.

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The asteroids come from the asteroid belt between Mars and Jupiter. They are pretty close.

Most come from the asteroid belt. Some from the Kyper belt. The comets originate from the Oort Belt and the Kyper Belt. Comets can do damage. The Tunguska disaster is thought (by some) to have resulted from a comet colliding with earth. The solar system is surrounded by lots of rocks and hard pieces of ice.

ruveyn

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Homo Sapiens and their ancestors have only been around for 30,000 years.

That is too recent. Anatomically modern humans were nearly wiped out by the explosion of the Toba super volcano about 75,000 years ago.

Going by the bones, hominids originated in Africa over two million years ago. Some think that homo sapien goes back between 250,000 years and 500,000 years.

ruveyn

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This rock is supposed to be moving at "15 mph", pass under some communication satelites, and keep going? It's been many years since I studied related physics but this just doesn't pencil out. Makes for a good story, though. I think I'd prefer for it to hit downtown LA, by the way. :)

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