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United States24761 Posts
On March 14 2013 15:34 sheaRZerg wrote:
That's Barringer crater correct? The flow of the post looks like you were saying that was the result of the Tunguska impact (which was smaller).
Also blowing it up isn't a good idea. Most of the fragments will keep their momentum and hit anyway...and we'd have less idea where they were going to land.
Other than that I agree.
Oh, I didn't mean to imply that that crater was Tunguska. Sorry about that. However, I think they were comparable in size. The Tunguska was rock though and took more damage entering the atmosphere.
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On March 14 2013 08:26 pinnacle wrote:
It's sort of stunning how the US ignores such a large threat even if its unlikely. We're so paranoid about everything else
Dont be riddiculus. It's not about protection, it's all about avoiding prohibition of space armistice. That's a great excuse to start militarisation of space, and thats what it ("asterois shield") really is (but offcourse the possitive side effect is preparation to asteroid threat)
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My country is doing nothing against this as far as i know and i think there should be an international effort to make this happen and to wich every country should make an apropiate contribution.
The change that an astroid strikes is small on a year to year basis but if we realy plan on humanity surviving for 1m+ years (and why shouldnt be) then we should face that fact that an astroid will hit sooner or later.
Astroids are the only thing that can whipe out human civilisation and even human life,at least i cant think of annything else for now.
Since the possible damage is extremely high it would be economically worth it to protect against it, even if the change of it happening is verry small. There are already manny things done, manny space agencys are looking activly for objects that might hit the earth in the future.Am not sure if it is possible to make a shield against astroids but if it is possible countrys should work together to make it happen, as long as its economically viable.
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As long as the American continues to cut grants for science. We cannot compete with the Russians on this. I say collaborate.
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On March 14 2013 13:57 HeavenS wrote:Show nested quote +On March 14 2013 10:11 furymonkey wrote:
IMO preventing asteroids from hitting is pointless if it cannot be done in a cost efficient manner, however ramping up detection make sense, if you can see it coming, you could evacuate the population from impact zone. what does cost efficient mean under these circumstances? If we discover an asteroid heading towards us that can annihilate a portion of the planet or something, and it's going to hit us in 20 years...im willing to bet that the world would fund a project to prevent it from hitting us no matter what the cost. It would be the number one priority and cost would be irrelevant.
And that is why spending on more than detection is pointless.
If anything threatening is detected it will have a budget.
Planning for what to do if something is detected is one thing.
But actually building it (with no observable threats) would be a waste.
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United States24761 Posts
On March 15 2013 00:24 gyth wrote:Show nested quote +On March 14 2013 13:57 HeavenS wrote:On March 14 2013 10:11 furymonkey wrote:
IMO preventing asteroids from hitting is pointless if it cannot be done in a cost efficient manner, however ramping up detection make sense, if you can see it coming, you could evacuate the population from impact zone. what does cost efficient mean under these circumstances? If we discover an asteroid heading towards us that can annihilate a portion of the planet or something, and it's going to hit us in 20 years...im willing to bet that the world would fund a project to prevent it from hitting us no matter what the cost. It would be the number one priority and cost would be irrelevant. And that is why spending on more than detection is pointless. If anything threatening is detected it will have a budget. Planning for what to do if something is detected is one thing. But actually building it (with no observable threats) would be a waste.
Detection is definitely a plus, but what about situations where we discover something is coming but don't have time to defend against it? Perhaps if the efforts were started sooner (even just the research stage with not physical testing), before the threat was detected, it would not be too late to prevent the damage. On the other hand, delaying that type of work just a few years while working on detection should be perfectly reasonable, given the statistics involved.
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We are nowhere near the tech required to avoid an impact.
The best we can do is invest in detection and evacuation plans, and hope it's not a 5 mile long rock
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We should totally invest in technology capable of rotating Earth, so we can use China and Russia as shields.
On a serious note, it's competely pointless at this stage of human development, this is a long term issue and we have several more pressing short term issues, like resource exhaustion. Instead of this silly shield, we should focus on energy & fuel R&D, otherwise human civilization has <100 years left, and all kind of asteroid threat against it becomes a non-issue.
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like the one in mib3? good idea
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United States24761 Posts
On March 15 2013 01:36 Frigo wrote:
Instead of this silly shield, we should focus on energy & fuel R&D, otherwise human civilization has <100 years left, and all kind of asteroid threat against it becomes a non-issue.
You know, they aren't mutually exclusive. We should certainly focus our efforts more on the more important things. What you suggested is one of the more important ones for sure, but if we just put asteroid detection into a "wait until our other major problems are solved" category we will never work on it, and we may really pay as a result. That's true for many problems.
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Problem is as a specie, we HUMAN don't trust each other. I don't see countries will willingly join together to build up something like this unless we got hit and got terrbily damaged from an asteroid/comet etc.
Why? Because developing something like this has a very thin line for some powerful weapon development. Anyway, if continue like this human will kill each other long before a body from space destroy earth assume that shits won't hit earth in the next few thousands years(very short time, like a blink of an eye in term of solar system).
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Stop pretending anyone's going to nuke the asteroid. Great job, we just blew up an asteroid, now what do we do with all the pieces of asteroid that are falling towards several locations on Earth.
Any country with nuclear weapons probably has at least a few people advising the powers that be about not nuking an asteroid.
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United States24761 Posts
On March 15 2013 04:13 [UoN]Sentinel wrote:
Stop pretending anyone's going to nuke the asteroid. Great job, we just blew up an asteroid, now what do we do with all the pieces of asteroid that are falling towards several locations on Earth.
Any country with nuclear weapons probably has at least a few people advising the powers that be about not nuking an asteroid.
I think that might depend on mass, speed trajectory, composition, and lead time. Certainly, nuking doesn't make sense for many if not most scenarios. In some cases, with very little warning, increasing the surface area of an object via a large explosion might be preferable to changing course.
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I thought the idea was to detonate a nuke near the asteroid to try to nudge it somewhat with high speed neutrons and x-ray radiation, not to actually "blow up" the thing. This too goes back to the early detection of potential impacts. If you know an asteroid will pass through a gravitational keyhole in 10 years that will cause an impact 5 years after that, then nudging it just a little is enough.
OTOH, if you have an asteroid that is heading straight towards you and will hit in 2 weeks the amount of work you need to do on it to make it miss the Earth is much, much higher.
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On March 15 2013 04:13 [UoN]Sentinel wrote:
Stop pretending anyone's going to nuke the asteroid. Great job, we just blew up an asteroid, now what do we do with all the pieces of asteroid that are falling towards several locations on Earth.
Any country with nuclear weapons probably has at least a few people advising the powers that be about not nuking an asteroid.
That's not the only reason nukes would be viable. Nukes are a relatively lightweight and off-the-shelf technology that we already have a lot of. And they happen to be great at imparting impulses to propel things, as in Project Orion.
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On March 15 2013 04:43 micronesia wrote:Show nested quote +On March 15 2013 04:13 [UoN]Sentinel wrote:
Stop pretending anyone's going to nuke the asteroid. Great job, we just blew up an asteroid, now what do we do with all the pieces of asteroid that are falling towards several locations on Earth.
Any country with nuclear weapons probably has at least a few people advising the powers that be about not nuking an asteroid. I think that might depend on mass, speed trajectory, composition, and lead time. Certainly, nuking doesn't make sense for many if not most scenarios. In some cases, with very little warning, increasing the surface area of an object via a large explosion might be preferable to changing course.
Except it's much easier to calculate an approximate trajectory for one asteroid and take appropriate action. If we can't burn it/stop it, then a hasty evacuation of the blast area or preparation for medical relief to said area can be done as soon as we find out where the asteroid will go. If we blast it, then we have to individually calculate the trajectories of all the fragments of the asteroid, so more evacuation and splitting up the medical relief.
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I don't believe it's worth the money to develop and create such shield over something that happens every century or so. Better to just improve the already established tracking system and implement an emergency response plan from it. The latter is smaller, cheaper, not politically sensitive, and feasible as you don't sound like a crackpot crying the sky is going to fall.
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On March 15 2013 04:13 [UoN]Sentinel wrote:
Stop pretending anyone's going to nuke the asteroid. Great job, we just blew up an asteroid, now what do we do with all the pieces of asteroid that are falling towards several locations on Earth.
Any country with nuclear weapons probably has at least a few people advising the powers that be about not nuking an asteroid.
Quick napkin physics brings me to conclusion smaller pieces of objects descending all at same speed than an object with its mass equal to the sum of the smaller pieces mass. This is because the kinetic energy of both are the same , but this isn't calculating the larger surface area from smaller pieces being burned up in the sky than a single object. Finally, many man made structures are more likely to deflect several pieces of small mass than a huge one
So yes, smaller pieces are better: more pieces burning up and less likely to do damage on buildings.
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United States24761 Posts
I finished reading a >10 year old book which had some interesting ideas. For example, NEO detection involves analyzing tremendous amounts of data collected in the search for new objects. This might lend itself to a similar decentralized computing system similar to SETI/Folding/etc.
I've turned my attention over to the 2007 NASA Report to Congress, which was linked to earlier in this thread. I will sum some of this up.
Congress asked NASA to submit a report on the following:
- how to carry out a survey program of near-Earth objects
- recommended procedures/budget to carry out such a program
- analysis of methods for diverting an object on a likely collision course with Earth
Specifically, Congress wanted to know how we could successfully detect, track, and characterize all NEOs greater than 140 meters in diameter to 90% completion by 2020. An NEO is any comet/asteroid that travels within 1.3 AU of the sun (Earth is at 1 AU).
NASA came to the following conclusions:
- Rather than reach Congress' stated goal of understanding the properties of 90% of all NEOs greater than 140m, we should modify it to search for 90% of all Potentially Hazardous Objects (PHOs) greater than 140m; objects that come within 0.05 AU of Earth's orbit
- The above goal is viable by 2020 with the additional construction of certain searching assets (they go into detail)
- New space-based infrared systems PLUS shared ground-based assets (bigass telescopes) would work well
- Radar based systems don't help with searching, but might with tracking
- How much information we need to measure about each NEO depends on what mitigation strategy we wish to use
Regarding #1, we should obviously focus our attention on the most dangerous rocks first. Regarding #2-3, it can be summed up as more observational equipment is needed to reach any kind of a reasonable deadline. Regarding #5, you can get away with only knowing the mass, speed, and trajectory of a PHO if the only way you intend to affect it is by smashing it with a big explosion. However, if you want to use one of many other methods of deflection, you will need to know composition, spin, and other details that are more difficult to measure. Thus, a study of how to best deflect asteroids is actually relevant to a discussion of how to best detect asteroids.
I will provide some more information in a subsequent post, such as why 140m is chosen as a cutoff, and what methods have been proposed for deflection.
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United States24761 Posts
I will summarize what NASA found regarding methods for diverting a PHO:
- Nuclear standoff explosions are 10-100 times more effective than non-nuclear alternatives
- Surface/subsurface explosions carry additional risk of fracturing the NEO. They are also more expensive/risky to implement.
- Kinetic Impactors are the closest to being available currently, and might be viable in certain circumstances
- Slow-push methods are the most expensive, are the furthest from being technologically ready, and would require a great deal of warning in order to implement.
- Roughly half of all PHOs are in orbits that we cannot reach currently with modern launch systems. Given enough time, routes using slingshots around other planets could be used, but they would require a great deal of warning as well. Alternately, on-orbit assembly of propulsion systems could be used.
Currently, NASA's Spaceguard Survey finds NEOs greater than 1000m in diameter ($4.1 million per year).
Population
- Extinction comets make up 5-15% of the NEO population.
- In 2006 NASA had identified 701 NEOs greater than 1km in size, and 3656 NEOs smaller than 1km in size
- NASA estimates 1100 NEOs greater than 1km in size, and 100,000 NEOs smaller than 1km but greater than 140m in size
- About one in five NEOs in any class/size are PHOs
An object would be able to pass through the Earth's atmosphere and do significant damage if it was about 50m or larger. Up to 140m in size, impactors would have regional effects, but not sub-global or global effects. 300m asteroids would have sub-global effects whereas 1km asteroids would have global effects. 10km+ events would result in mass extinctions. The lower limit of 140m in our NEO search is based on the idea that we should be looking for impacts that would do damage at the state/seaboard level rather than at the city level.
This is one of those threats where you can't just look at historical data to determine if action is necessary. If you wait for the first significant loss of life to say 'hm I guess impacts actually do pose a threat worth addressing' it will be too late for a potentially large number of people.
For those of you who are interested please read the actual report which goes into more detail.
http://neo.jpl.nasa.gov/neo/report2007.html
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