Incoming!! Meteorite Crash in Russia (Wild Videos)
More pictures, videos, etc.
Meteorite crash in Russia, Russia Today
“A series of explosions in the skies of Russia’s Urals region, reportedly caused by a meteor shower, has sparked panic in three major cities. Witnesses said that houses shuddered, windows were blown out and cellphones stopped working. Atmospheric phenomena have been registered in the cities of Chelyabinsk, Yekaterinburg and Tyumen. Lifenews tabloid reported that at least one piece of the fallen object caused damage on the ground in Chelyabinsk. According to preliminary reports, it crashed into a wall near a zinc factory, disrupting the fiber-optic connections of internet providers and mobile operators. Witnesses said the explosion was so loud that it resembled an earthquake and thunder at the same time, and that there were huge trails of smoke across the sky. Others reported seeing burning objects fall to earth.”
More videos below
in Chelyabinsk. According to preliminary reports, it crashed into a
wall near a zinc factory, disrupting the fiber-optic connections of
internet providers and mobile operators.
I know it’s off topic, but how does a zinc factory in Chelyabinsk have fiber-optic and the best I can get ON A NASA FACILITY is bottom tier DSL speed?
The US is way behind in Internet speed. If you want a really fast connection go to Asia, particularly Korea. Your download is finished almost before you click the mouse.
They’re using the new Thiotimoline “look-ahead” fibre connections from Asimov Labs.
Yes. They do run hot though. They’re cooled by polywater.
Fantastic video of the meteor shower!
Wow!
“A missile salvo blew the meteorite to pieces at an altitude of 20
kilometers, local newspaper Znak reports quoting a source in the
military. Regnum news agency quoted a military source who claimed
that the vapor condensation trail of the meteorite speaks to the fact
that the meteorite was intercepted by air defenses.”
Uh…
Sure.
I can’t resist pointing out that the Earth’s atmosphere is a particularly fine “air defense” asset, protecting us from most space objects. Certainly, the atmosphere above the Urals did an admirable job today, as marked by the vapor condensation trail. Yes, this “Nitrogen Dome” is supported by Russia (in that Russia is sitting underneath it!)
Well done!
Now, I’m sort of dreading how this incident is likely to spark advocacy for human space flight. Harry Stamper, where are you when we need you?!
Helen:
‘Dreading that it will spark a call for more human spaceflight? I hope it does!
Maybe I’m playing the ‘long game’ here, but a permanent, expanding human presence in the solar system pretty much protects Earth from any folly but themselves.
Rouge asteroids? Track them, move them or use them. Earth will be safe.
Solar Flares? Give humanity a century and we’ll not only clean up the sunspots but we’ll figure out a way to put a thermostat on the sucker!
Climate Change? Geo-engineering will be easier, safer and faster than any project carried out on the planet’s surface (see previous point).
Natural Resources & Industrialization? Cleaner, safer and far more plentiful then on Earth. Materials will be cheaper to extract, time being the economic driver more than anything else. Energy is cheaper in space and ceases to be a political issue. Vacuum is a very forgiving environment for industrial processes, easily controlled.
All this and more… but we gotta get there first. The ISS isn’t even a foothold yet because they rely on Earth for everything except power. I say (to be a bit of a devil’s advocate), to hell with any science in space that doesn’t have to do with human longevity off Earth and resource utilization. Anything else is just slowing us down from reaching that foothold.
Once we do, when we do, it will be exponential growth ad infinitum. Then, we’ll have time for some ‘fundamental’ sciences.
Cheers 🙂
tinker
Nope. Think about it. We have robotic vehicles that rendezvous with, orbit, and even land on asteroids right now. Those are developed on a short time scale with a comparatively miniscule amount of money.
For the grotesquely huge cost of launching a human to an asteroid with a toolkit around his or her waist, we can send a lander to an asteroid that will self anchor, and fire a thruster to deflect it. Probably a whole bunch of them. Very little control authority is required. We’re talking deflection, not direction. In this day and age, astronauts are completely unnecessary for the job of asteroid deflection. Yes, “we” gotta get there first. Where “we” is our robotic partners that we build and control. That’s the long game that offers real value.
With regard to “to hell to any science in space that doesn’t have to do with human longevity off Earth”, I guess that’s fine for everyone who desperately wants to live off Earth. Not too many of those folks around. Can I have your car when you leave?
Expanding human presence in the solar system protects Earth? No, not at all. I think expanding human awareness of the solar system is what fundamentally protects the Earth. Because if you send stupid people out there to establish that presence (calm down, I’m not referring to you) they probably won’t have a clue about how to protect the Earth. Well, they could stand in front of an incoming asteroid, I suppose. Human awareness of the solar system doesn’t rely on human presence in the solar system.
Agreed.
Though HSF would be nice too.
Let me second that, and offer some regrets for not being more specific.
I think human space flight is marvelous. I think it’s marvelous as an adventure, marvelous as an expression of courage, and marvelous as a difficult task that exercises our technologies and organizational skills. Whether those reasons are things that offer value to the taxpayer isn’t completely obvious, though. But what demeans the case for human spaceflight most effectively is coming up with rationale for doing it that doesn’t make any sense. Effective advocacy for human spaceflight is hardly accomplished by associating it with tasks that are far better done in other ways.
Tinker,
As for “getting there”, when it comes to the HSF vs. robotic question, I am firmly committed to the “both” vote. Each needs to be used where it is the best answer (while still being practical) on a case by case basis, per mission task, not per whole mission.
The need to put people “on the scene” is a hard argument to make because we are most often talking about things that haven’t actually been done before, so we don’t know what the surprises (and short-comings) are going to be for any given mission. Like all science, you can’t know the unknowns before encountering them.
We can argue that a human might have seen or intuited something that a machine missed. But by the same token, humans are constrained to observations in the visual spectrum and to a very narrow environment. So, the argument for “both” needs to specify “or” vs. “and” as well. Any mission that employs both, together, at the same time, is logically going to provide the most and best results, but that comes, quite literally, at a price.
To manage costs better, I think we need to develop hardware that is more general purpose, and therefore usable on many and various missions. The larger and/or more sophisticated you make your robot tools, the less practical/possible this becomes. On the other hand, if your robot tools are human-operated on site, then the complexity of autonomous operation goes away, as does the need to envision every possible mission scenario at design time. If we further refine things such that multiple small tools are preferred to one large, complex tool, then we get even more capability (and lesser costs) with the ability to pull more and more future mission equipment off the shelf.
When we combine all of this with reusable spacecraft and launch systems then we’d have a much more cost -effective “space exploration system” (and a good head start on space exploitation systems).
We need to send Spock down to the surface — with his Tricorder.
All this being said, we need first transition to the point where we can do what I’ve describe above. But it looks like NASA and the other space agencies, as well as the aerospace contractors, are still heading farther in the opposite direction — they insist on making everything larger and more complex, and this, I think, is the biggest conceptual mistake being made in space systems. For passenger aircraft it make sense (mostly) to go bigger and more sophisticated. But not for space systems. If nothing else, unnecessary complexity is the enemy of reliability.
Steve
I think that saying that we should do both because we’re not sure what we’ll need is a bit simplistic. The human mission would probably cost 30-50 times more than the robotic mission, and involve some enormous risks — one of the biggest would be coordination of many separate launches. (Have you seen the conops for a human mission to an asteroid?) So the two options are hardly comparable. I mean, perhaps we should develop a 500mT-class launcher too (hey, make it a thermal nuke!), because I don’t really absolutely know what launcher I might need. So what if it’s going to cost 30-50 times that of an SLS. Better safe than sorry!
In fact, rendezvousing with, and landing on an asteroid is something that can be done largely autonomously. Igniting an upward pointing propulsion system when landed is something that we have some pretty good concepts about. Understanding the dynamics of the rotation, when there so you know when to ignite it (ideally repeatedly), is something quite feasible robotically. You’d have plenty of time to figure it out, and capably supervise your autonomous system across the inevitable time delays. One of the major uncertainties in this strategy is how to grip the asteroid when landed on it, but there are some credible approaches.
So I think the answer isn’t that for lack of any more understanding, let’s just do both, but a critical examination of whether the more economical approach can serve the need. Most workers in the space robotics community believe that the wholly robotic approach can.
Again, for half the cost of a human mission to an asteroid, you can make a stunningly capable robotic one, the likes of which we’ve never seen. You can probably make more than one. Transitioning to the point where we can do both a human mission and a robotic mission sure ain’t going to be easy.
The idea that we should be highlighting investments in concepts that are smaller and less complex STRONGLY argues against a human approach.
Doing real science at an asteroid can be argued to be a task that humans in situ might well be needed for. Even that is something that planetary scientists argue about. But deflection is comparatively easy.
Hmm. Can we harpoon them and then have the robot reel itself in?
Déjà vu.
Helen,
I have to marvel at your consistency. Yet again, you’ve read my post without reading it. Then, once again, you proceeded to “correct” me for what I didn’t say. In response to Tinker’s arguments for HSF, I did say about HSF vs. robotics that:
“Each needs to be used where it is the best answer (while still being practical) on a case by case basis“
And then further down I expanded on this by saying:
“the argument for “both” needs to specify “or” vs. “and” as well. Any mission that employs both, together, at the same time, is logically going to provide the most and best results, but that comes, quite literally, at a price“
In summary (between HSF and robotics):
• There is no unconditional best choice; it comes down to the requirements for a given task (case by case).
• The argument for any given case (task) has to decide between 1) HSF AND robotics, or 2) HSF OR robotics.
• Having both HSF and robotics available for any given task will give us the best odds of better succeeding, but is going to be more expensive.
Further, I stated that the “unknowns” were an argument against Tinker’s “we gotta get there first” assertion for HSF. However, you shot me down for saying that we should do both because we’re not sure what we’ll need — which is not at all what I said — and labeled it “a bit simplistic.” What appears simplistic to me is your reading skills.
And I’m going to stop there because the rest of your post goes in another direction. But I would offer two ideas for consideration:
1) We’ve both identified cost as a factor to be considered, but I think you put much more weight on cost as a decision factor, relative to best satisfying the requirements of a task, than I do; and
2) Although I am not overly pessimistic by nature, you seem to put much more faith in untested technology than I do. I believe we need to test new technologies/science to their limits until we can comfortably call them proven, particularly when a wrong assumption or lack of precision has the potential to harm people and/or the Earth.
The HSF and/or robotics argument is one that I suspect we’ll never get general agreement on. Too many people argue in favor of the one they know (or enjoy) the best, as opposed to looking at how to best satisfy requirements. I recognize that I am personally guilty of this when I argue for “both,” given that I’m a long-time fan of HSF but recognize the unique capabilities of robotics.
Steve
Mr. Whitfield, you said …
“As for ‘getting there’, when it comes to the HSF vs. robotic question, I
am firmly committed to the ‘both’ vote.”
I interpreted that to mean that you were firmly committed to developing
“both” options for “getting there”. I’m sorry, but that’s what those
words strongly imply. I said ONCE, at the beginning of my post, what I
thought you said. That was it.
If that’s not what you meant, then perhaps it should have been phrased less ambiguously.
If you meant that you’re firmly committed to being open minded about
using both robots and humans for asteroid mitigation, because you
yourself don’t have much of a clue about the relative importance of
each, that’s one thing, and it’s a perfectly defensible thing to say,
and I respect it. But my argument was simply that there is no evidence I
can see that human space flight even needs to be considered to mitigate
asteroid impacts. An astute NRC committee considered asteroid impact
mitigation with some care, a few years ago, and concluded that human
space flight didn’t clearly offer value in doing so. They did this after evaluating a multitude of what appeared to be technically feasible concepts for robotic mitigation.
I’m not saying that human space flight is bad. Just that for this
application there is no evident reason it would offer significant value.
If you want to change your mind, or clarify your words, that’s fine. If
you want to argue with my argument, then have at it. But please don’t
continue to play the tiresome and slightly paranoid game of accusing me
of not reading your words, and posting anguished remarks about how I
misinterpreted you. If you can’t take the heat, then get out of the
kitchen.
FWIW, here is the *entire* verbiage about the potential role of human space flight in the NRC 2010 report on asteroid detection and mitigation. This is out of a 150 page report that took more than a year and almost forty committee members to produce..
“During its deliberations, the committee was briefed on the possibilities of human missions to near-Earth objects. This subject also received attention during meetings of the Human Space Flight Review Committee and was mentioned as part of its ‘Flexible Path’ option in its final report. In the future, NASA’s Exploration Systems Mission Directorate may conduct human missions to one or more near-Earth objects. The committee identified no cost-effective role for human spaceflight in addressing the hazards posed by NEOs. However, if human missions to NEOs are conducted in the future, the committee recommends that their scientific aspects be maximized to provide data useful for their characterization.”
I agree relative cost dictates the role of humans in space. In LEO there is at least the prospect of reducing the cost of human flight to a level at which humans can be productive, particularly with fully reusable launch systems. For deep space missions where it is not practical to send humans, NASA should be investing in exploration-focused artificial intelligence systems that can carry along our accumulated human experience to deal effectively with situations that were not anticipated but have parallels in past experience, just as humans would. Machine intelligence is rapidly evolving (so to speak) and for specialized situations like exploration there is no reason it could not soon approach or equal the real-world performance of human intelligence.
In a “completely” unexpected situation, like the monolith in “2001”, even humans are pretty much just along for the ride.
Helen – you’re skewing it a little bit, aren’t you?
All the risk assessments for asteroids are made with the atmosphere in mind. Otherwise we’d have been worried about 2 pound asteroids as well.
This latest event only demonstrated that small objects are indeed nothing to worry about. Some broken glass, very local damage – nothing that threatens the survival of the human race or even a single nation.
But it’s a good reminder that the risk of a major impact is real, and human space flight with the eventual goal of solar system habitation is the only remedy that I know of.
Nope. I’m exactly right. I said that the Earth’s atmosphere protects us from MOST space objects. It’s the very few that it doesn’t protect us from (the big ones) that are the ones we need to worry about.
As to those big ones, it is amusing to think about such an asteroid being hit by an air defense missile. Of course, such a missile would do largely nothing to the rock, assuming it could hit it. Except maybe break it into pieces, whereby a shower of high velocity pieces would come raining down on us on trajectories almost identical to the original. That’s what Henry Stamper did in Armageddon.
The reason air defense missiles work when they do hit a ballistic missile is that the power contained in what they’re trying to hit is not the kinetic energy of the incoming vehicle. For a ten-ton asteroid, what hurts is the kinetic energy, and an air defense missile doesn’t get rid of that.
I havent read the data (and couldnt interpret it if I did) but didn’t this one come in at an oblique angle, essentially slicing through the atmosphere “the long way?” What I mean is, from views and some reports it appears as if this object, had it not exploded, might have just sailed right on through and out again like the 1972 fireball, without hitting earth?
If that’s the case, wouldn’t a more direct approach from this same object possibly be much worse?
(Then again, perhaps it would just mean it would heat up and explode more quickly?)
I hope after some number crunching someone will have some animations somewhere of different possible outcomes from different angles of approach.
A meteor with a steeper entry angle would have been subject to even higher dynamic pressure and would likely have exploded at about the same altitude.
Assuming the body was not particularly coherent and only about 15-30M in diameter a missile strike could have fractured it, which would have reduced the peak shock wave overpressure and probably resulted in more of the mass being dissipated in the upper atmosphere.
That’s not a contrail, the engines are on fire!
i’m wondering how a meteorite supposed destroyed by missles impacts a factory wall ? i reckon the meteorite exploded, of it’s own accord, and the shock wave did the rest.
surprised i haven’t seen something from NASA. wouldn’t they detect an atmospheric explosion like this ? in today’s world i’m suspicious of news, reported at multiple sites, that tracks back to one original source (like eagles carrying away babies).
Just a little reminder the planet is undefended.
Agree! How about using Mars as a base camp to study its moons and the asteroid belt, instead of just going there “because it’s there?”
How does being on Mars help with that?
It would be much easier to get real support for missions with the asteroid belt as primary obective. Figuring out techniques and technologies needed to divert i.e.move one out of its collision course with Earth. That’s in case out of nowhere a comet nucleus (for example) came straight toward Earth.
{Comet nuclei, unlike asteroids, can appear out of nowhere, like one in the early 1990s. It broke into 23 huge chunks before falling into Jupiter’s atmosphere in July 1994. The pockmarks in the clouds, even without a solid planetary surface, were so large they could be seen from Earth using just amateur telescopes.}
Mars could be a base camp for training and learning missions to the asteroids, or both of Mars moons. And astronauts would rather take a break on solid ground, rather than spend their whole missions (how many months, years?) inside a spaceship.
Moreover, their bodies could use a break from zero gravity and heir bones would regain some of the density lost during a long inteplanetary voyage.
Obviously, while other astronatus would tend to the Martian base camp, they will have the opportunity of conducting studies and search for possible signs of life (past or present) on the planet.
A mission to Mars just reach the Red Planet would be much harder to sell to Congress etc. My assumption comes from simple logic…
If the meteorite shower in Russia has no effect on the decision-makers, we could end up like the dinosaurs. The only difference would be knowing something is going to wipe us out in a couple of years, or months, and all we could do would be kneel and pray in hopes of a very unlikely miracle.
“Moreover, their bodies could use a break from zero gravity and heir bones would regain some of the density lost during a long inteplanetary voyage.”
You assume. We actually have no idea what is the minimum gravity to prevent (or repair) bone loss. And we won’t know until we can explore multiple g’s with a variable gravity facility, such as a centrifugal space station module. And if you can build that… again what does Mars add?
“A mission to Mars just reach the Red Planet would be much harder to sell to Congress etc. My assumption comes from simple logic…”
Everything except flags’n’footprints on Mars will be stripped away as the barest minimum of reaching Mars inflates in cost to consume the entire budget. Congress happily starving and mismanaging the program as long the bare minimum criteria they need to continue their district’s pork continues.
My assumption comes from 40 years of history of the US space program.
A mission to test techniques and technologies, and
learn how to move an asteroid from a collision course
with Earth would have much more support than one to
explore Mars. At least in the eyes of the decision
makers.
Using Mars as a base camp would be a break for
astronauts who have flown for months or years and
would help their bones recover some of the density
lost during their interplanetary voyage. (Zero-gravity
causes bone density loss, as you may know.)
The Martian moons could be a starting point. Then
would come the missions to the asteroid belt.
Meanwhile, astronauts at the basecamp could carry
out all the scientific research, including the search for
forms of life on the planet.
That would be particularly useful in case of a potential
impact by a cometary nucleus which, unlike asteroids,
can appear out of nowhere. The most famous example
is the one that fell into Jupiter atmosphere in 1994.
It was first spotted one year, if not two (?) the impact,
and it turned into 23 huge chunks that left marks on
Jupiter’s clouds shroud visible from Earth even using
rather modest scopes.
Can you imagine if that happened on Earth? We would
be all gone, but it would have been an agonizing long
time before the end came… compared to us, the
dinosaurs would have been lucky.
It’s a matter of logic and time for decision-makers to
start moving. The meteorite that fell in Russia should
be a wake-up call for each one of them.
If Merlin Olsen (A Fire in the Sky) taught me anything, take cover in a sleeping bag!
“Seemingly there is no reason for these extraordinary intergalactic upsets. Only Dr Hans Zarkov, formerly at NASA, has provided any explanation… This morning’s unprecedented solar eclipse is no cause for alarm.”
How did our radar geeks miss this one?
Too small; far too small
Oh…and the NEO community…amateur or otherwise…
After a couple minutes saying WOW at the videos of the boom, and lamenting the state of out space program, I’m now thinking this should have shown as a pretty big flare on the Russian infrared early warning satellites… How long did they take to identify it as a natural object? The trajectory was a reentry over russian territory, after all, and I’m sure there are manuals that deal with not detecting an ICBM until later in the flight. So, to put it in other words, how close to WWIII were we?
I’m pretty sure that it was obvious that this was a meteor because of its tremendous speed. I’m guessing that they pick up meteors all the time and this would have looked similar – except of course for being larger than a typical meteor.
And spectroscopic analysis would have shown large quantities of metal alloys not typical of a natural body.
You sure it’s possible to run such an analysis on the time this took to reenter? Totally serious here, I have no idea how long such a thing takes (the analysis). But knowing nothing on the subject, I would have said going by gut that would more time than available.
Fair question. I’m pretty sure it comes down to mass and size. No one has any space asset that, upon reentry, would produce anything close to the power of the sonic blast that this thing did. You’ll get sonic booms, but you won’t get the earth shaking and lots of windows breaking.
Anyway, early warning IR satellites are looking for launches, not reentries. By the time you see a reentry, it’s pretty much too late.
As to metallic spectroscopic signatures, most meteorites are “stony” — basically basaltic material. They wouldn’t show any kind of exceptional metallic signature. That’s something you don’t hear about a lot in mining asteroids. I believe that most asteroids are likely pretty worthless, with regard to heavy and refractory elements. By the same token, I suspect a satellite reentering would show highly metallic signatures.
But the extent to which such an event can get the military excited is something that I’d like to believe has been considered in great detail. Large meteors enter the Earth’s atmosphere all the time, and are routinely detected by IR recon satellites. They don’t often happen over populated areas, though. The DoD has by far the best statistics on large meteor falls.
That’s way better answer than “spectroscopic analysis”, and in retrospective, I should have thought of it. They do have to have this kind of event fairly regularly (especially on Russia!), so if we’re still here I must assume it’s ’cause whatever they use works.
As to how, of all the stuff you have pointed out, I find the magnitude argument the most believable… a reentry vehicle is designed to slow down as less as possible, after all, and hit the ground shedding as little energy as possible. Different trajectory, too… I gues unless the perfect meteor showed up?
And even then, I imagine you would hold down the counterstrike until you detected the blast, if it’s a single one, because frankly people aren’t that crazy. You would have to conjure up a perfect meteor over a veeery sensitive place. Let’s hope either I’m again wrong (likely) or that doesn’t happen over the Kremlin/White House/Forbidden Palace/Champs elysees…
Definitely should have thought the stuff out more… but it’s more fun the other way, right? Gives us stuff to talk about.
I was thinking… do the Russians have a Bruce Willis type of their own?
Vladimir Putin. There were early rumours that the object was in fact Putin reentering Earth’s atmosphere from a trip to space to rescue that Iranian monkey, with his shirt off to better deflect the plasma off his bare chest. (Artists Impression: http://cdn0.dailydot.com/up… )
OK rocket scientists, here’s a question to ponder — if this meteorite had stayed intact all the way to the ground, what sort of damage/crater/newslines would we be reading today?
My guess is that the impact would not have been all that spectacular. The trajectory was obviously at a high angle, and the rock dissipated most of it’s energy in the stratosphere in the form of heat, light, and sound waves. Once it slowed down, it pretty much just fell. So it would hit the ground at a terminal velocity of several hundred mph. (I think Felix managed to achieve a terminal velocity of 800 mph.)
So what do you get when you drop a few dozen tons from altitude? Well, take the wings off a Boeing 737 and drop it from altitude. That’s what you get. Maybe a ten or twenty meter crater. In fact, that looks to be about the size of the hole in that ice-covered lake.
Now, if there had been no atmosphere, no energy dissipation, and a vertical impact, we’d probably be talking about a crater a few hundred meters or so across, and damage from everything that got flung out of it. That would be a lot more exciting. See
http://www.lpl.arizona.edu/…
I sort of know how those people felt. Many years ago I had a terrific explosion at 8PM. The loudest I had ever heard. A single explosion,not a sonic boom double. It was not directional. No thunderstorms.I also ran out to the street. Nothing. A neighbor 1/4 mile N. came out. Never heard anything in the news. May not been a meteor of course,but I think it was.
“we have the knowledge and technology to do that“
To the best of my knowledge, we have some theories, tested only at small scale in labs at best, and only a half dozen groups in the world are even working on this (I don’t count the blogs; they don’t test, just talk). In effect, we currently have no means preventing an impact.
“So we are capable of defending against certain objects given early enough warning.“
There’s a big catch. We don’t get early warning. Only for the known repeaters of significant size do we get much warning (I know in the movies it’s always days or weeks or even months, or else they can mobilize their defenses in hours, but that’s not reality). Also, while comets are long-period and predictable, asteroids are less forgiving. With all of the mass in the inner solar system, spread all over the place, an asteroid’s orbit can be perturbed, even several times, and we wouldn’t know it until it didn’t show up when/where expected, leaving relatively little time to find it again and assess the situation.
I have to agree with James.
“Also, while comets are long-period and predictable, asteroids are less forgiving.”
I would suggest the opposite is true.
Periodic comets are periodic (duh), but large new comets can and do emerge from out there with no prior warning. And you’ll have only the time from detection to impact to prepare a defence. An example being Comet ISON, discovered in September last year, will pass Earth’s orbit by October this year. If it was going to hit us on the inward leg, I doubt we could do anything about it, by the time it is close enough to be reached, nothing we can do would be big enough to divert it. Likewise, if it was deflected enough by outgasing during perihelion to turn a spectacular near-miss into a civilisation ending hit, we’d have just a couple of weeks warning from perihelion to impact.
By contrast, once you’ve mapped the larger asteroids in the inner solar system, you’ve got them all. No new major asteroids are going to suddenly appear. It feels more chaotic today, because we’re still mapping and modelling them, so we’re only just discovering the near-misses and getting excited over each one, which is happening more often than new large comets. But once we’ve finished mapping them, we will have centuries of warning of any high-risk objects.
[Some might come close enough to other bodies be perturbed, but even that is predictable (the encounter, at least. You might not know exactly where it will end up, but you can predict that encounter and you can watch the outcome.)]
Small asteroids are nastier. Too small to track, too easy to be perturbed from predictable orbits. So like the Russian asteroid, you get no real warning. However, those are city killers, not civilisation enders, and most of them won’t end up anywhere near a city. (And as bad as it sounds, we can and do recover fairly easily from losing a city. It’s an human-scale natural disaster, we deal with those all the time. Earthquakes, tsunamis, hurricanes, volcanoes.)
I often scan NASAWatch, including the posted comments from readers. In the case of this NASAWatch story on the Chelyabinsk meteor, I am amazed at the number of misconceptions. Here is a quick list of some of these (mostly unchallenged) misconceptions”If it had not entered the atmosphere obliquely, it would have reached the surface and made a crater.It did reach the surface and hit a building.It was shot down by the Russian missile defense system.The trail was a vapor trail from the ice in the impactor.It is easier to predict comet impacts than asteroids because comets have periodic orbits. Asteroid impactors come from the main belt beyond Mars.Small asteroids are more easily affected than large ones by gravitational interaction with planets.Orbits of small asteroids are shuffled so they can not be predicted.Human space missions would be needed to divert an asteroid or comet.To defend our planet we need human missions to the main asteroid belt.The best way to deflect an asteroid would be with a rocket engine landed on the surface.