Asteroid 99942 Apophis impacting the Earth in 2029

In summary, some people feel that a nuclear detonation is the only way to divert an asteroid, while others are doubtful that it would be effective.
  • #1
at94official
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19
Good Day everyone! :wink:
I don't know if this thread is repeated already. Because I can't find one.
I just want to ask you guys what are your insights for the asteroid apophis' possible impact to Earth by 2029? Upon its discovery in 2004, Apophis was briefly estimated to have a 2.7% chance of impacting the Earth in 2029. :nb) :nb) Don't you think we have enough technology to avoid this impact? :wideeyed: :wideeyed:
 
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  • #2
The possibility of apophis impacting Earth in 2029 [or 2036] has been virtually eliminated bases on improved data accumulated in 2012 - 2013 - re: http://neo.jpl.nasa.gov/apophis/
 
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  • #4
Joseph Austin said:
Good Day everyone! :wink:
I don't know if this thread is repeated already. Because I can't find one.
Use the search tool. There have been a number of threads on Apophis.

I just want to ask you guys what are your insights for the asteroid apophis' possible impact to Earth by 2029? Upon its discovery in 2004, Apophis was briefly estimated to have a 2.7% chance of impacting the Earth in 2029. :nb) :nb) Don't you think we have enough technology to avoid this impact? :wideeyed: :wideeyed:
There's no impact to avoid. Apophis is now deemed a non-threat, both in 2029 and in 2036.

What about other asteroids? The best defense is time, lots and lots of time. Suppose a 1 km diameter asteroid is on a collision course with the Earth, and we first see it two weeks prior to impact. We're dead. There's nothing we can do. We need time, many years of advance warning. Even then, diverting a 1 km diameter asteroid is a daunting problem. Many are of the opinion that the best option is hitting it with nukes to slightly change the asteroid's orbit. A long period comet is much worse. Now nukes aren't just the best option, they're the only option.
 
  • #5
D H said:
Use the search tool. There have been a number of threads on Apophis.There's no impact to avoid. Apophis is now deemed a non-threat, both in 2029 and in 2036.

What about other asteroids? The best defense is time, lots and lots of time. Suppose a 1 km diameter asteroid is on a collision course with the Earth, and we first see it two weeks prior to impact. We're dead. There's nothing we can do. We need time, many years of advance warning. Even then, diverting a 1 km diameter asteroid is a daunting problem. Many are of the opinion that the best option is hitting it with nukes to slightly change the asteroid's orbit. A long period comet is much worse. Now nukes aren't just the best option, they're the only option.

Not an expert, but I tend to agree with this. A nuke would be unlikely to split a dino-killer, but even if it did, and only a part of it struck the planet, that would be worth it.

Actually though, if we DID get sufficient warning (probably more than the necessary notice for bombing the body) to land a nuke-powered machine on the missile, or perhaps match orbits, I bet we could do better than exploding anything, nuke or not.
 
  • #6
Project Orion will be able to alter the orbit. George Dyson discusses this here.
 
  • #7
Hey John, THANKS! It wasn't the idea that *I* had, but I loved it all the same, and Dyson's presentation was really entertaining.

Much appreciated,
Jon
 
  • #8
Apophis, even if missing us, could be very good for raising funds for Space Security programs, currently under-funded all over the world although very important for future safety of the Planet.
It could also boost asteroid-mining programs, also important for future space missions.

People wouldn't like to see its money "wasted" to explore/deviate/destroy astreroids millions of kilometers away, in asteroid belt. But I guess people would appreciate using its money to monitor and study Apophis.

I really hope somebody will successfully land a camera on it before 2029! :-) It would be a big engineering/science achievement. I won't be surprised when a project will appear on Kickstarter for a private mission on Apophis.
 
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  • #9
If we were serious about diverting an asteroid with a nuclear detonation, which is the only realistic short notice option in the foreseeable future, a test would be the natural first step. Unfortunately, politics is a constraint. Whoever launched such a 'test' would face severe criticism, even to the point of attempting to induce impact on an unfriendly state. The effects of a nuclear blast in the vacuum of space are largely unknown, but, certainly much differently than one in Earth's atmosphere. The blast wave would be essentially non existent, so it would necessitate detonation very near or at the surface of the target. Material ablated from the target body would serve to provide the blast energy necessary to nudge its trajectory. Unfortunately, detonation at such proximity would likely fragment the target, and not appreciably alter its trajectory, resulting in a 'buckshot' impact. It appears 'testing' will only occur in the face of imminent disaster. I anticipate it will be a very big 'test', should the occasion arise. Existing nuclear weapons are only designed to achieve low orbit trajectories, so some unknown number of extra terrestrial capable rockets probably [hopefully?] already exist for such an exigency.
 
  • #10
A nuke is totally useless in diverting an asteroid: it has the needed energy, but it acts in all directions. We'd need a "collimated nuclear blast"... which unfortunately has not yet been invented! But we could use nuclear power to power a huge ion engine.
 
  • #11
Joseph Austin said:
Good Day everyone! :wink:
I don't know if this thread is repeated already. Because I can't find one.
I just want to ask you guys what are your insights for the asteroid apophis' possible impact to Earth by 2029? Upon its discovery in 2004, Apophis was briefly estimated to have a 2.7% chance of impacting the Earth in 2029. :nb) :nb) Don't you think we have enough technology to avoid this impact? :wideeyed: :wideeyed:
There is a new website I found that seems to still be in the works, but there is some good information on the site. http://www.apophisasteroid.org/ Check it out. From what I read on this website, the Sun could cause out-gassing, causing the asteroid to tumble through space. Nothing is 100% guaranteed, the chance of the asteroid hitting the Earth in 2029 is very small, but the chance of the asteroid hitting Earth in 2036 is much larger.
 
  • #13
Greg Bernhardt said:
Link is broken
Hmmmm, It works for me. I tried the link in google and explorer and both worked. Try this www.apophisasteroid.org
 
  • #14
Inphinity said:
Hmmmm, It works for me. I tried the link in google and explorer and both worked. Try this www.apophisasteroid.org

naaa that doesn't work either
 
  • #15
davenn said:
naaa that doesn't work either
I'm in South Africa and I simply clicked on the link in Inphinity's posting and it worked immediately. You must have something funny about your service provider or your LAN's regulations or firewalls or the like. Check with your admins.
 
  • #16
I think we agree that placing a nuke on an asteroid and fracturing it is not a good idea for a variety of reasons. But that leaves open the possibility that we could explode the weapon some distance, to be determined, from the asteroid. The idea is that this would either slow it or speed it up if exploded in front or behind it. Or exploded it at some angle away from the asteroid's path, directly pushing it out of orbit. But that raised other questions, at least to me. By what mechanism would a nuclear explosion in a vacuum exert force at a distance?
Shock waves, as usually understood, wouldn't exist in a vacuum, or would they? A fireball of outrushing matter would exert frictional forces on an object in its way. But how much matter is released by nuclear explosion? The rest mass of a thermonuclear warhead is not that great, really. So I wouldn't expect one to generate much force, relative to an asteroid's inertia. Radiation in the form of infrared, visible light and gamma rays would exert force as well; perhaps radiation pressure would generate a greater force than a rapidly expanding plasma or a shock wave. Of course, energy and mass not radiated within the solid angle subtended by the asteroid would be wasted. That consideration seems to me to be the most damnable objection to the bomb idea - the extremely small yield of energy from the explosion.
The only other measure I can think of is placing a rocket of some sort on the asteroid. That way the force exerted on the body would be directed. Knowledge of the asteroid's mass and the force integrated over the lifetime of the rocket's combustion would enable one to calculate both the changes in the asteroid's velocity and its direction over time. When we place satellites in orbit or send vehicles to other planets, these factors must be known to high precision. The success of these missions gives me confidence that the rocket method could succeed. Someone mentioned the Project Orion concept. But isn't the nuclear weapon-powered rocket just a variant of exploding a warhead at some distance from the object? We would still be wasting most of the energy through radiation into empty space. Given the present state of art, how precisely could the force of these mini-explosions be calculated? Haven't we already designed rockets based on electromagnetic propulsion and propulsion provided by the flow of cooling gasses or liquid metals through a fission reactor? Those latter approaches sound the most plausible to me. What do other folks think?
 
  • #17
Jon Richfield said:
I'm in South Africa and I simply clicked on the link in Inphinity's posting and it worked immediately. You must have something funny about your service provider or your LAN's regulations or firewalls or the like. Check with your admins.

I don't need to check with any admins ... I'm not the only one it doesn't work for !
 
  • #18
jumpjack said:
A nuke is totally useless in diverting an asteroid: it has the needed energy, but it acts in all directions. We'd need a "collimated nuclear blast"... which unfortunately has not yet been invented! But we could use nuclear power to power a huge ion engine.
Not correct, even allowing for hyperbole in "totally useless".
1: Even if the uncollimated blast is only 10% effective, if the nuke is ten times the notionally necessary size, that would suffice to justify the venture -- far from useless.
2: Suppose the nuke were triggered a millisecond before impact at high relative velocity, so that what hits the surface is a small, penetrating, but rapidly expanding fireball. The effect would amount to quite a highly collimated propulsion, with most of the reaction mass supplied by the target's own surface and shallow material. Even if the target fragmented (by no means certain for a largish object), most of its mass would be be accelerated in the desired general direction, though not all equally well or precisely.
3: Even if the fragmentation amounted to converting a "rubble-pile" object into a shotgun blast, not only would that blast be collimated in a favourable direction, but fine fragmentation would produce essentially a (probably harmless) meteor shower of particles. The effect would be drastically less disastrous than the rubble striking as a pile in a single spot at a single moment, rather than a shower over a few million square km over perhaps a period of some minutes.
4: Even if the blast neatly split a physically strong and dense missile into just a few large fragments, each too large to be acceptable "incoming", each being far from harmless on striking Earth, then if in fact in fact not all were effectively deflected, the chances are that not all would hit the planet, so the effect certainly would be mitigated by that at least. And even if every last fragment hit Earth with unaltered energy, divided impacts would be less catastrophic than a single large one. To achieve such a lesser disaster would be no means a "totally useless" investment, but a highly profitable or at least provident one.
5: Even if the cleanly split body left a few large missiles still on target, then if a flotilla of small nukes followed the large nuke by a few days, then in the interval before the trailing flotilla arrived, the trajectories of the major lumps could be measured and calculated with great precision. Surgically smaller nukes could nudge remaining really dangerous rocks the extra mile. Space billiards. No problemo!
Example: suppose something like our "rubber-duck" Comet 67P/C-G broke its neck when the nuke hit it, it is quite likely that the spinning halves would follow different courses, both missing Earth. But even if one did not miss Earth, the smaller impact would be a worthwhile mitigation. And a flotilla nuke now could tackle the dangerous remnant more surgically. And if there were no significant fragmentation, the smaller nukes could tackle the main body again for further longer-term improvements in prospects.
6: Gentler nudges could be negotiated in various ways. A series of blasts from space could vapourise part of the missile's surface each in turn till the reaction produced sufficient deflection.
7: Or the nuke could carry packing in the right orientation for the packing mass (wadding if you like) to be accelerated for impact, but not vapourised by the blast. That wadding then could hit the target at enormous velocity without vapourisation. Such a soggy solid wadding striking the target would amount to a high degree of collimation of blast. The mass of the carrier craft could act as a tamper from behind, or might act as the missile itself. The most probably efficient approach should be left to some intelligent engineer (if the project could afford one; if not, they could always get a lawyer or politician or priest instead... Details, details...)
8: I bet that a very high degree of collimation could be achieved, though expensively, by including an asymmetrical hollow shell around the nuke, so designed that it vapourises progressively from the far end, driving the target end with great acceleration. Whether this would be worth the extra mass required to deliver to the ignition site, is a different question. Whether such a mass as a missile would be more useful as a reflector or tamper, is also something to be calculated rather than argued.

It is dangerous to dismiss as absolutely useless any technology that offers wide ranges of modes of possible application. Someone might have worked out more ways of applying it than were at first obvious.
 
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  • #19
I think you got the gist of it Mark, a nuke would be ineffective without mass to propagate a shock wave. That mass would have to come from the target, and probably splinter it. My guess is you would need a timed chain of detonations to be effective. But, none of this has ever been attempted, so any such 'solution' is suspect. If, however, you only have a matter of weeks to act, is there any other realistic option? I lean towards the idea of a fleet of space capable missiles lurking in secret silos - assuming we have sufficient foresight, and will, to mount anything resembling a defensive strategy.
 
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  • #20
Chronos said:
...The blast wave would be essentially non existent, so it would necessitate detonation very near or at the surface of the target. Material ablated from the target body would serve to provide the blast energy necessary to nudge its trajectory. Unfortunately, detonation at such proximity would likely fragment the target, and not appreciably alter its trajectory, resulting in a 'buckshot' impact. ...

Generally reasonable, but we are being peppered by what seem to be very varied masses. They vary in size from a few tens of metres diameter to a few tens of km. Yes, I know there are smaller ones, all the way down to dust, and that the smaller,the very much more frequent, but the impact of anything just tens of metres across would be a local, not a global, emergency unless it were shown to be aiming for Washington DC, Moscow, Beijing, Pyongyang, Tehran, Naypyidaw or the like; some place that no one could tolerate the destruction of and that couldn't be evacuated. Then again, I am sure that solid bodies on the multi-km scale will not be split by a typical nuke, and I am not sure that any but a marginal example could be sufficiently deflected by any nuke less than tens of years in advance.

Where a nuke would be possible, converting a 10-30 m rock to buckshot would amount to solving the problem, and diverting it shouldn't be a very big deal, so we might nuke it in a hurry if a major city were at definite risk, but for large projectiles say 100m +, we could consider three classes:
1: Ni-Fe pretty solid mass. Forget it. It won't shatter worth a dam, but might well divert neatly. Anyway, it could be valuable if it landed in the right spot! :)
2: Pretty solid rock (basalt?) I doubt it would shatter badly, and it might deflect nicely. It would be worth a try for anything too big for us to deflect by other means.
3: Rubble pile/snowball etc These could present problems. For one thing it would be difficult to determine their actual nature well enough to predict their behaviour. They might deform instead of diverting. However, again, if a pile were shown to be heading unacceptably, we might have to nuke it in the hope that it does largely spall into relatively harmless scattered buckshot instead of striking in a concentrated mass that would for practical purposes amount to a solid projectile.
 
  • #21
A bunch of unknowns - all of which matter, to be sure!. I believe the nuclear option is the only defense we can realistically offer in the foreseeable future, and it's far from perfect. I seriously doubt we can currently and confidently identify any potential threat years in advance. Apophis is merely an example of our ineptitude.
 
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  • #22
jumpjack said:
A nuke is totally useless in diverting an asteroid: it has the needed energy, but it acts in all directions. We'd need a "collimated nuclear blast"... which unfortunately has not yet been invented! But we could use nuclear power to power a huge ion engine.

Mark Harder said:
I think we agree that placing a nuke on an asteroid and fracturing it is not a good idea for a variety of reasons. But that leaves open the possibility that we could explode the weapon some distance, to be determined, from the asteroid. The idea is that this would either slow it or speed it up if exploded in front or behind it. Or exploded it at some angle away from the asteroid's path, directly pushing it out of orbit. But that raised other questions, at least to me. By what mechanism would a nuclear explosion in a vacuum exert force at a distance?
Chronos said:
I think you got the gist of it Mark, a nuke would be ineffective without mass to propagate a shock wave.

The Department of Defense, NASA, the National Academy of Sciences disagree with you. Nukes are the only effective way to deal with large (1 km diameter or more) objects, and also with smaller objects that are detected with only a short lead time.

With more lead time, kinetic impactors might provide an alternative to nukes. With even more lead time (many decades to centuries), gravity tractors might provide an alternative to kinetic impactors. With even more lead time, there are a lot of hairbrained schemes that might work. Then again, they might not.

Aside: With a minimal lead time, the only options are to evacuate the peoples in the subject area or to tell them to get far away from windows (almost all of the casualties from the Chelyabinsk event were from broken glass).

The way nukes work to divert an impact by an asteroid or comet is simple. Nuclear explosions generate a lot of high frequency radiation (X-rays and gamma rays) and neutrons, preferably a lot of neutrons. A thin layer of the asteroid/comet absorbs this bath of incoming neutrons and high frequency EM radiation. The radiated material then evaporates, making for the equivalent of a rocket. Neutrons are best because they penetrate deeper than does the high frequency EM radiation. Ideally, a nuclear explosion will result in a few percent of the material of the asteroids/comets material vaporizing.
 
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  • #24
I wonder if a huge "solar sail" linked to the asteroid could capture "nuclear wind" (high speed particles
Jon Richfield said:
Not correct, even allowing for hyperbole in "totally useless".
1:
2:
3:
Wen thinking of asteroids diverting we think to nuclear bombs just because it's the only method we know to handle the amount of energy required for the task, but a bomb is not the solution; the solution is "huge energy amount management technology", yet to be developed.
Interesting thing is that once we'll develop such a technology, it will also be useful for great space exploration mission, besides asteroids divertion!:-)

In lack of such an energy management technology, current feasible option is gravitational tractor and huge amount of time: put a small spacecraft close to the asteroid when still millions kilometers apart, push the spacecraft away gently, and it will gently pull the asteroid with it. Newton will do the remaining job.
 
  • #25
Greg Bernhardt said:
Link is broken
Link doesn't work for me either. I am able to ping the site but no pages get returned. The best that I could do is get Google's cached version from two days ago:
http://webcache.googleusercontent.com/search?q=cache:gA792R4ePrMJ:www.apophisasteroid.org/home.html+&cd=2&hl=en&ct=clnk&gl=us [Broken]
 
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  • #26
jumpjack said:
I wonder if a huge "solar sail" linked to the asteroid could capture "nuclear wind" (high speed particles

Wen thinking of asteroids diverting we think to nuclear bombs just because it's the only method we know to handle the amount of energy required for the task, but a bomb is not the solution; the solution is "huge energy amount management technology", yet to be developed.
Interesting thing is that once we'll develop such a technology, it will also be useful for great space exploration mission, besides asteroids divertion!:-)

In lack of such an energy management technology, current feasible option is gravitational tractor and huge amount of time: put a small spacecraft close to the asteroid when still millions kilometers apart, push the spacecraft away gently, and it will gently pull the asteroid with it. Newton will do the remaining job.
Do note that the list of options I jotted were put down at typing speed, starting cold and I am neither an engineer or physicist. If you ask the pros round here I bet they could come up with a lot more ways of using bombs (read "civil engineering explosives"). But I listed those purely to illustrate how bombs could be feasible options under many circumstances, and the only viable known option if we are in a hurry (as Chronos remarked).
When we are in a bit less of a hurry I reckon that nukes of various flavours still are the most promising option, but that they should be applied in a different way. Maybe by electret acceleration, say. But that is still speculative, and you know what happens to speculation round here... ;)
 
  • #27
Chronos said:
A bunch of unknowns - all of which matter, to be sure!. I believe the nuclear option is the only defense we can realistically offer in the foreseeable future, and it's far from perfect. I seriously doubt we can currently and confidently identify any potential threat years in advance. Apophis is merely an example of our ineptitude.
Well I think the best way to avoid the impact (Let's just say there will be a collision by 2029) is by towing the Asteroid itself. By using the Gravitational force of the Apophis and A rocket that will divert it's trajectory, As what Neil Degrasse Tyson says on a Open Forum about Aphophis.
 
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  • #28
Joseph Austin said:
Well I think the best way to avoid the impact (Let's just say there will be a collision by 2029) is by towing the Asteroid itself. By using the Gravitational force of the Apophis and A rocket that will divert it's trajectory, As what Neil Degrasse Tyson says on a Open Forum about Aphophis.

Gravitational steering is neat in that it requires no contact, but that is about all I can think of in its favour. For the gravitational tractor we need gravitation, which means getting a large mass up there. Not cheap, not easy, not even flexible on any reasonable timescale. Personally the only version of that idea that I come close to liking is not to lug an inert mass up there, but the equivalent mass of extra fuel. Certainly that mass will reduce progressively, but it will keep on working after the inert mass carrier runs out of juice.But that is not all. If you need more traction in a hurry, your mass tractor is not the way to go. I reckon that this is one of the cases where one can appeal to the principle of the superior merits of brute force and ignorance: "If it still don't work, get a bigger 'ammer".** One such approach would be to lug a rope up there. Well, that is of course really, seriously brain-dead, isn't it? I mean, what kind of idiot would want to attach a rope to a tumbling mass of millions of tonnes of rock?

Hmmm… good question.

Let's try: "the kind of idiot who reckons that:

* a rock tumbling about an axis once in 30 hours could easily be towed by a harpoon explosively inserted near either of its poles, and that

* at least one pole would be in a favourable position to pull it in a desirable direction."

Consider a stiff rope (perhaps more of a plastic rod) perhaps with a swivel attachment. A few tens of metres plus suitable tackle shouldn't mass more than a few kg and would not need to be rated at a continuous working stress of even a tonne (about 10000N); 1000N should be plenty. The technology would not be challenging and the fuel could be applied very efficiently and precisely.

Rope hauling is a technology with its origin lost in prehistory, but you know, compared to gravitation, it has its points…** Another approach of even greater venerability and yet even greater flexibility, is pushing, and yet I think it shows even more promise because it requires no special attachment: pushing. In fact, both approaches could be combined in the same craft in case one of the options proves disappointing. At the nose end of the craft attach a light, rigid rod, possibly hollow, of suitable specifications, perhaps a metre or two in length. Any of several types of tip would do, though recent experience suggests that it would be nice if it didn't bounce badly on impact. The rod need not be strong (1000N continuous working stress, remember?) but it could be braced against any of a number of spots on the surface of the body and apply thrust. Because it would have no tackle to speak of, many such craft could work at once, not necessarily in unison as long as they used feedback control. They wouldn't even need to concentrate around the poles of rotation.** A less sophisticated approach would have statically parked nuclear powered ion thrusters (or better yet, electret thrusters) on the same principle. My main objection would be that it might take longer to deploy them. Then again, with long-term power like that, they could power research and responder services for many decades. We are hopelessly under-equipped with space survey facilities, and the cost of such an item as a stand-alone project would be prohibitive, but piggy-backing on such a literally vitally important mission it would cost peanuts and be justifiable purely on the basis of what it could teach us about the trajectory of such rocks in various of the most important regions of the solar system.
 
  • #29
jumpjack said:
I wonder if a huge "solar sail" linked to the asteroid could capture "nuclear wind" (high speed particles...

Oh yes, sorry I forgot that one. The huge solar sails would almost certainly be hopelessly cumbersome and costly if they worked at all, but I did figure a scheme some years ago for removing largeish potential orbital garbage from round Earth. Not feasible for small fragments already in orbit, sorry. But at a very small cost in payload it might work very well for dealing with threatening large items for which we have sufficient warning.

The first requirement will be to plant on any such target a number of hmmm... "antennae"? designed to convert the momentum of charged particles of solar wind (mainly protons and electrons, but all moving charges will be grist for the mill) into acceleration. Photons of suitable frequencies might contribute thrust as well, but I suspect their contribution would be negligible. A sizable number of comparatively small, simple craft land on the target in various spots more or less evenly over the surface, the more the merrier. Each would contain a sprung conductive coil that gets deployed on landing, and is designed to generate thrust (or drag if you prefer) mainly by induction and electrostatically, irrespective of the angle of incidence of the passing charges and magnetic fields.

It would be possible to design such coils to deploy and retract according to the prevailing space weather and the attitude and trajectory of the target, but I am doubtful whether that would generally be worth consideration. On approaching the sun the antennae would have a braking effect, and in retreat they would accelerate the target. Suitably deployed, that effect should suffice, though their effect would have to be monitored. As they would consume practically no power (rather generate it in fact) they could be left in place indefinitely.

Oh, and I forgot, their general effect would be to damp rotation and nutation, which should have a beneficial effect on cooperative efforts by other technologies.
 
  • #30
Chronos said:
I seriously doubt we can currently and confidently identify any potential threat years in advance. Apophis is merely an example of our ineptitude.
I am not clear in what way the work on Apophis' orbital characteristics is an example of our ineptitude. Would you elaborate?
 
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  • #31
no the asteroid will not collapse on Earth but sure it will pass through Earth's closest atmosphere and will go
 
  • #32
Mohit 1o2 said:
no the asteroid will not collapse on Earth but sure it will pass through Earth's closest atmosphere and will go

and what do you base that on ?
 
  • #33
Ophiolite said:
I am not clear in what way the work on Apophis' orbital characteristics is an example of our ineptitude. Would you elaborate?
For discussion of the uncertainties in predicting asteroid trajectories, see http://neo.jpl.nasa.gov/1950da/. Most diversion strategies have lead times of years or even decades. Such plans are only useful in cases of asteroids already known. In the case of previously undetected bodies, or one unexpectedly diverted, we can expect a very much smaller window of opportunity. The Chelyabinsk meteor illustrated our vulnerability to space debris - re:http://phys.org/news/2013-11-results-russian-chelyabinsk-meteor-published.html
 
  • #34
D H said:
Use the search tool. There have been a number of threads on Apophis.There's no impact to avoid. Apophis is now deemed a non-threat, both in 2029 and in 2036.

What about other asteroids? The best defense is time, lots and lots of time. Suppose a 1 km diameter asteroid is on a collision course with the Earth, and we first see it two weeks prior to impact. We're dead. There's nothing we can do. We need time, many years of advance warning. Even then, diverting a 1 km diameter asteroid is a daunting problem. Many are of the opinion that the best option is hitting it with nukes to slightly change the asteroid's orbit. A long period comet is much worse. Now nukes aren't just the best option, they're the only option.
It really is not the 1 km diameter or larger asteroids that concern me. We know where 99% of them are, and none are likely to hit within the next ~400 years. It is the much smaller (50 m to 100 m) asteroids that concern me the most. They are large enough to impact the surface of the planet and could easily wipe out a large city, yet so small they are extremely difficult to detect. We know where fewer than 1% of those size asteroids are located. Often we do not discover them until they are just weeks or days away, if we see them at all.

If we ever do detect an asteroid under 100 m in diameter about to impact Earth, the only option would be to use nuclear weapons. As long as the pieces of the asteroid are smaller than ~40 m in diameter (and not made of iron), the pieces should burn up in the atmosphere without ever reaching the ground. If we cannot guarantee that all the pieces of the asteroid after the nuclear explosion will be smaller than ~40 m in diameter, then we should not be trying to destroy it with a nuke. Perhaps a deflection with a nuclear explosion, so that the asteroid is still in one piece but hits a different location on the planet, would be a better approach.
 
  • #35
Chronos said:
For discussion of the uncertainties in predicting asteroid trajectories, see http://neo.jpl.nasa.gov/1950da/. Most diversion strategies have lead times of years or even decades. Such plans are only useful in cases of asteroids already known. In the case of previously undetected bodies, or one unexpectedly diverted, we can expect a very much smaller window of opportunity. The Chelyabinsk meteor illustrated our vulnerability to space debris - re:http://phys.org/news/2013-11-results-russian-chelyabinsk-meteor-published.html
Perhaps I have misunderstood you. I see ineptitude and incompetence as being very close in their meaning. If I understand your clarification, you were noting the great difficulty and current limitations in determining orbits for NEOs. If that is the case, from my perspective, the extent to which we can presently determine these orbits is an example of considerable competence and ingenuity, not ineptitude. Clearly much more needs to be done in the three spheres of identifying objects, determining their orbits with great accuracy and developing strategies for any that would constitute a real threat, but I cannot find the excellent work done to date to be inept.
 
<h2>1. What is Asteroid 99942 Apophis?</h2><p>Asteroid 99942 Apophis is a near-Earth asteroid that was first discovered in 2004. It is approximately 370 meters in diameter and is classified as a potentially hazardous asteroid due to its close proximity to Earth.</p><h2>2. Is Asteroid 99942 Apophis going to impact the Earth in 2029?</h2><p>No, current predictions show that Asteroid 99942 Apophis will not impact the Earth in 2029. However, it will come very close to Earth, passing within 31,000 kilometers, which is closer than some satellites in orbit.</p><h2>3. How close will Asteroid 99942 Apophis come to Earth in 2029?</h2><p>Asteroid 99942 Apophis will pass within 31,000 kilometers of Earth in 2029. This is a very close distance, but it is not close enough to cause any impact or damage to Earth.</p><h2>4. What would happen if Asteroid 99942 Apophis did impact the Earth in 2029?</h2><p>If Asteroid 99942 Apophis were to impact the Earth in 2029, it would cause significant damage and destruction. However, the chances of this happening are very low, and scientists are constantly monitoring the asteroid's trajectory to ensure it does not pose a threat to Earth.</p><h2>5. What is being done to prevent an impact from Asteroid 99942 Apophis in the future?</h2><p>NASA and other space agencies are constantly monitoring the trajectory of Asteroid 99942 Apophis and other potentially hazardous asteroids. If any potential threat is identified, plans can be put in place to deflect the asteroid's path and prevent an impact on Earth.</p>

1. What is Asteroid 99942 Apophis?

Asteroid 99942 Apophis is a near-Earth asteroid that was first discovered in 2004. It is approximately 370 meters in diameter and is classified as a potentially hazardous asteroid due to its close proximity to Earth.

2. Is Asteroid 99942 Apophis going to impact the Earth in 2029?

No, current predictions show that Asteroid 99942 Apophis will not impact the Earth in 2029. However, it will come very close to Earth, passing within 31,000 kilometers, which is closer than some satellites in orbit.

3. How close will Asteroid 99942 Apophis come to Earth in 2029?

Asteroid 99942 Apophis will pass within 31,000 kilometers of Earth in 2029. This is a very close distance, but it is not close enough to cause any impact or damage to Earth.

4. What would happen if Asteroid 99942 Apophis did impact the Earth in 2029?

If Asteroid 99942 Apophis were to impact the Earth in 2029, it would cause significant damage and destruction. However, the chances of this happening are very low, and scientists are constantly monitoring the asteroid's trajectory to ensure it does not pose a threat to Earth.

5. What is being done to prevent an impact from Asteroid 99942 Apophis in the future?

NASA and other space agencies are constantly monitoring the trajectory of Asteroid 99942 Apophis and other potentially hazardous asteroids. If any potential threat is identified, plans can be put in place to deflect the asteroid's path and prevent an impact on Earth.

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