This is a way too simplistic view of what would happen. First, as someone else pointed out, nukes in a vacuum do not produce a blast. They just emit several metric buttloads of high energy radiation. Some of that radiation will be absorbed by the asteroid (also by any space vessels nearby) but it won’t produce a single jet in response. Not only that, but what does jet out from the asteroid will go in various directions (some opposed to each other), partly because of the spin and internal forces (also internal composition) that you dismiss so cavalierly.
BTW, is calling it an “asteroid” the correct terminology? I thought an asteroid orbits the sun, and a rock that falls from space is a meteorite.
It’s still going to be in orbit around the sun at the time we try to change its trajectory. Waiting for it to get to the edge of the atmosphere is way too late.
The sudden flash is what generates most of the impulse. I dismiss it cavalierly because I know what I’m talking about.
And a nuclear shaped charges, where fragments of the weapon are impinging on the asteroid itself, are completely unaffected by the asteroid’s spin. Note that “shaped” is a misnomer, it’s just a warhead where a big chunk of material is facing the asteroid at detonation, forming a high velocity jet that impacts and embeds itself into the asteroid.
Like the Chelyabinsk meteor did a few years ago. About 2000 injuries IIRC. I thought post-Chelyabinsk therereading of data revealed that such strikes happened multiple times a year but were often missed since theyusually occurred in the Ocean or in uninhabited areas?
Ok, won’t a large blast or at least multiple large one, especially if the warhead strikes when the object is well away from the planet, cause sufficient change in trajectory that the object will miss the Earth?
That situation is not the same as the random heterogenous material found in an asteroid. There’s going to be all kinds of irregularities in an asteroid: surfaces pointing in multitudinal directions, internal voids, variation in composition, etc. The radiation from the nuke will not just ablate away the surface, but will be absorbed at various distances within the asteroid. There may be a voids that accumulate gases generated by the radiation and it may be several minutes to hours later that it gets released. At which time, the rotation of the asteroid has changed the direction it goes.
Asteroid=big rock that orbits the sun
Meteoroid=small rock that orbits the sun. The line between asteroid and meteoroid is fuzzily defined, call it 1 meter, call it 10 meters, call it “too small to detect with a telescope.”
Meteor=the visible effect of a meteoroid moving deepish in the atmosphere
Bolide=really bright meteor
Meteorite=a fragment of a meteoroid (or asteroid) that has landed on the ground.
When a meteoroid is traveling through the atmosphere and ablating (not really “burning”) that heat has to go somewhere. If the meteor is big enough and close enough to you, the heat from it will roast you as surely as would the heat from an atmospheric nuclear explosion. A single bigger asteroid would keep most of its mass and most of its kinetic energy would go into excavating a crater. Break it into multiple chunks with multiple trajectories, and thanks to massively increased surface area the collected fragments would release far more energy into the atmosphere than the intact original.
There is only so bad you can be killed-being exposed to 5,000 degree air isn’t going to make you more dead than being exposed to 1,000 degree air. (For similar reasons if you wanted to maximize bang for the buck you’d make 50 1mt nukes instead of 1 50mt nuke.)
Cool data viz. Didn’t see the compiler/presenter, but he does have a field filter for “most valuable.”
But what we need (demand!?) is their ranking on most blowable-upable.
I have been informed that there is some drama about this statement, and specifically the interpretation that I implied here or elsewhere that momentum (impulse) is not conserved, which was not the intent. The problem with striking only a small portion of the aspect of an asteroid or comet is that it will not act as a single object but will fragment or liquify, ejecting material or disaggregating into multiple objects with potentially diverging trajectories which could still pose a significant or unintended hazard, each of which have to be tracked and redirected if they are still a potential hazard. Even if such an object does not directly strike the Earth with enough energy to pose a threat, if it is sufficiently dispersed into a wide debris field it could pose a hazard to satellites as it passes by, and particularly if it is in a periodic orbit. Striking the entire aspect of the object with an impulse of roughly equal proportion will at least impart a roughly equal velocity change, so that even if it is disaggregated it is still in a localized field for subsequent impulses.
Relying on the the heating of the surface of the object by impingment of X-rays to provide suffiicent impulse will give very poor efficiency and likely cause massive thermal stresses, hence the need to form a directional jet of some sacrificial material to uniformly push the object and mediate the impulse to minimize inelastic behavior. Even at that, the impulse is likely to fragment the object but with the expectation that the aggregate will remain on a similar trajectory. On the study I worked on some consideration was given to trying to wrap the object in some kind of a net to hold it together, but modeling found this to be unworkable and potentially even counterproductive, notwithstanding the logistics of delivering a separate spacecraft to attempt to deploy the net.
In any case, a ~10 km diameter object will have enough mass that hitting it with impulses from even very large nuclear weapons is about as effective as stopping an oncoming train by shooting at it with a pistol, and trying to push on it from some surface-mounted propulsion system is more likely crack it into pieces than redirect the entire object, and hence, would require an entirely different approach. The “gravity tug” idea that is often floated around is one of those notions that is a nice concept provided you have essentially magical propulsion technology that can maintain constant thrust for an intermittant duration, or an ability to propel other large objects to rendezvous on a swing-by pass to incrementally modify the trajectory. In reality, this is no more practical with any extant or practicable technology than invoking a Celestial Babe Ruth to knock the object out of the solar system.
Stranger
Destroying quantities of old actors seems a quirky bucket-list item. (But not necessarily a bad one, mind.)
Bump. Hammertime.
Here is the horrifically fascinating Last Day of the Dinosaurs. I start it about 11 minutes in, twenty minutes before impact.
I don’t remember when I saw it, but this article is at least a year or two old, and simply updated recently. 101955 Bennu has been known about for several years and Hypervelocity Asteroid Mitgation Mission for Emergency Response (HAMMER) has been around for a while in different guises, presented here to the NASA Small Bodies Assessment Group. Kinetic interception is well and good if you can manage it, but most asteroids larger than 50 m in largest dimension are not solid bodies but agglomerations of material that will readily fracture and disperse on impact, making multiple threats that have to be independently tracked and diverted, notwithstanding the expense of launching dozens of intercept missions to divert, hence the consideration of radiation-augmented momentum transfer or the use of a mediated nuclear pulse to apply a large impulse spread across the entire aspect to impart momentum to the entire body.
Stranger
Considering the fact that an asteroid might very well have the mass of Mount Everest, it would take a tremendous force detonating at precisely the right place to give it the “nudge” needed. Considering the fact that it might be chugging in at 150,000 MPH (give or take), that kind of precision is very difficult, especially over a large distance. If something of that mass and speed is even inside the moon’s orbit, we won’t be able to give it a big enough “nudge” to do any good.
Another fact to take into consideration is that most asteroids are spinning or, even worse, tumbling their way through space. If they are irregularly shaped, the correct spot for a detonation is going to change from second to second because it’s shape and mass relative to the detonation point will be constantly changing.
But that’s not the real issue. The real issue is if we blow one 10km hunk of rock into a bunch of smaller, 1km rocks, will they have the same effect as one big rock? That is, would a bunch of smaller impacts still churn enough stuff into the atmosphere to cause the global temperature drop that triggers mass extinction?
Or, do the smaller rocks, having lesser mass, not smash into the Earth with enough force? Sure, there’d be a lot of smaller impacts, but I can tap a piece of drywall in a bunch of different places with a 2-pound hammer and leave only dimples. If I put the same force behind a 100-pound hammer, I’ll probably break through.
Being roasted/pulped by the heat and concussion of a million airbursts will kill you just as dead as a nuclear winter. (As the strange train guy tried to get sunk in in this thread from 2010 that I found while googling for this one.)
That was a fun one.
A 10 km diameter spheroid broken into ~1 km diameter smaller spheriods would produce approximately seventy such objects plus the smaller interstitial debris, assuming it is essentially uniform in density. Impact of an object of ~1000 m in diameter, impacting the Earth at a velocity on the order of Earth orbital speed would cause global devastation. Fortunately, it is expected that there are no objects on the order of 10 km in orbital periods of less than a century that are unaccounted for, and should one appear within the plane of the ecliptic we would expect to identify it long before it approaches the Earth. (Very long period and rogue planetoids approaching from a direction oblique to the ecliptic plane are another matter, and unless they have a very high albedo we would probably not see them, but the likelihood of one intercepting the Earth’s orbit, much less actually striking the planet, are thought to be exceedingly remote.)
There is a common misconception that that just breaking up a very large hazardous celestial object into smaller components so that it “burns up in the atmosphere” will address the problem, which ignores the fact that the atmosphere is part of the Earth and is actually a very critical part of regulating the terrestrial biosphere. Breaking, say, a 1 km object into seventy-odd 100 m objects would produce a level of devastation which would not be much if at all reduced from that presented by the intact object. Although the results may differ somewhat in type, the end result would still be a massive amount of kinetic energy delivered to the atmosphere, converted to thermal and blast effects as well as ground impacts kicking fine dust and ash from firestorms into the upper atmosphere and the resulting climate impacts. It is possible that the initial disruption that breaks up the object may put the smaller objects on differing trajectories so that they do not all impact at once and could even be spread across centuries or millenia, but that may be actually worse as whatever civilization survives the initial impact will be subject to periodic disruption before being able to rebuild an industrial culture sufficient to develop the technology to protect against subsequent impacts. The Earth-intercepting debris from such an impact could also destroy satellites and produce an unintended Kessler syndrome, denying access to orbital space for some indeterminate period and potentially eliminating our ability to track further hazards.
Attempting to intercept a hazardous object within days or hours of an impact, e.g. within the orbit of the Moon, is a case of far too little and way too late. This is why there is a need for long term tracking of all potentially hazardous objects, both Near Earth Asteroids in periodic crossing orbits and longer period transNeptunian objects which could be perturbed into an Earth-orbit-crossing trajectory by some cosmic confluence of events. The interception and redirection should occur decades or centuries before the potential for impact rises to the probability > 1% at a confidence of 50% (P99/50), and preferably using some mechanism that maintains the integrity of the object while gently pushing it into an orbit which will assuredly miss the Earth and any other valuable assets.
A constellation of solar orbiting observatories and communications relay satellites between the orbit of Venus and Earth would serve well to both space hazard observation as well as provide a communications infrastructure for expansion of future space exploration of the outer planets rather than depending on the antiquidated ground-based NASA Deep Space Network, and would be a smart investment for the United States going forward, not only for our own capabilities but to lease paid access to other nations with ambitions on interplanetary exploration. Unfortunately, that is not part of any Decadal plan (was eliminated from the 2010 Decadal survey and not even included in the 2020 survey as a proposal). Except for the very occasional use of the Hubble Space Telescope to look at known objects in the solar system we don’t have any space-based capability dedicated to look for such hazards, and ground observation has some significant limitation, particularly in looking at objects inside of Earth orbit. So we’re not doing much to address the issue beyond PowerPoint presentations and flashy pop-science articles.
Stranger
I’d guess a bit more would burn up entering the atmosphere if it was a lot of pieces v. one large one. probably wouldn’t really make much difference though.
Getting back to the OP (too late), this raises a good question, the difference in time warning between naked eye (at the time) and telescopic (modern day) of impact. I imagine one big difference is at a distance it would still have a lateral movement against the background stars vs close up (naked eye distance) it would be moving pretty much head on.