Suppose a meteor, the same size and scope as the Chicxulub impactor, came barreling upon the modern Gulf of Mexico. Could modern society survive? How much advance notice would our astronomers give us? Would we try to divert it or destroy it, or would we just adapt to the changes in the climate its debris would cause? Or would it be as cataclysmic as last time, when its crater was apparently the trigger to dinosaur extinction.
There is zero we could do this year to affect an impact this year. In 50 years we’ll probably be able to both detect it and deflect it away so there’s no impact.
A lot depends on how much warning we have. If we saw it today but the projected impact date was 100 years from now we could probably deal with it. But if we saw it 100 years from today but only a month before impact, we’d be powerless.
An identical repeat of Chicxulub would kill modern society and the vast majority of humanity. Maybe not in the first week, but certainly in the first year.
It would depend on both the amount of advance notice, and on the competence of the leadership in power at the time, both of which are unpredictable. It would be possible for us to detect something like this a century in advance, and it would also be possible for us to literally not detect it at all until it hit (there have been some close calls that were only detected after they were past).
Given a decade or two of warning, we could probably stage a Manhattan Project-like initiative to divert it. Given two or three years, we could probably stockpile enough food, seeds, etc. to ameliorate the worst of the effects of an impact. Given no warning at all, some people would still survive because they’ve been stockpiling supplies anyway, probably for other purposes, but most of the population would be goners.
We could develop the means to deflect a sub-1 km diameter object with entirely conventional propulsion and nuclear weapon technology ‘today’, given the political will and about a decade lead time. However, there is no extant system to do so and no apparent impetus despite the fact that we are statistically overdue for a meteorite impact large enough for regional or continental devastation.
Keep in mind that the last time this happened it didn’t wipe out all life on the planet. Far from it. Some early mammals survived and that’s why I’m typing this today. Large modern cities would be devastated, but some people live far from large modern cities. Humans live in the far reaches of the planet, and while climate change would be fairly dramatic for at least a few dozen years, people living in Antarctica, assuming they had some kind of food supply, could probably survive for at least a few years by rationing. Lots of animals survived the last one even if the dinosaurs didn’t, and they didn’t have underground bunkers and storage facilities with food and fresh water to survive on.
Lots of species survived. But even among those land species that survived, most of the individuals died.
Humanity, as a species, would almost certainly survive. We’re too widespread and too adaptable to wipe out entirely. But most of us would still die.
Your best bet, and the most likely seed to restart civilization, would be either Iceland or New Zealand, depending on what hemisphere the meteor hit in.
It seems that no land animal larger than a cat survived the event. However, the bigger ones were probably more vulnerable because they needed more food and starved to death. The impact winter would have lasted several years when no plants could grow.
Some humans could survive if there were enough time to build bunkers and store enough food to last several years, or grow it under artificial light. After that it might be possible to start growing crops again.
Not quite. The largest terrestrial survivors were around 25-kilos. Cite.
However, the bunkers would have to be pretty big.
An MVP of 500 to 1,000 has often been given as an average for terrestrial vertebrates when inbreeding or genetic variability is ignored.[6][7] When inbreeding effects are included, estimates of MVP for many species are in the thousands. Based on a meta-analysis of reported values in the literature for many species, Traill et al. reported concerning vertebrates “a cross-species frequency distribution of MVP with a median of 4169 individuals (95% CI = 3577–5129).”[8]
Not understanding the pessimism. IF detected far enough away THEN altering its course only very slightly would result in a miss, wouldn’t it? The issues are having technology to detect the threat while far away, the means to have something capable of altering the course that slight amount while it is still far away, and the calculating power to know what needs to done.
Do we have any of that technology today? No. But none of that seems unachievable in a reasonable future.
How far away can lasers focus and deliver energy through space? Heating up one side to emit could do it even from some distance theoretically yes?
Perhaps the very distant future where large fleets of nuclear fusion-powered thrusters could provide continuous thrust for a long duration. The problem here is that while a ~1 km asteroid could be deflected to a significant enough degree to cleanly miss the Earth using our most powerful momentum transfer systems (e.g. nuclear detonations used to create a directional impactor that would push on a lateral aspect of the body evenly to prevent it from fracturing or dispersing) something on the order of 15 km has so much mass that even using the energy released by the detonation of every nuclear weapon ever built would not significantly alter its course, even if you could contrive to release it in such a way to impact the body without simply breaking off a piece or causing it to fracture into multiple hazardous objects. With enough time and propulsive capability, you could alter the course of a potentially threatening object with almost any arbitrarily low amount of momentum but the general assumption here is that you would need to alter the course of an object within a few years or a couple decades at most.
If you had hundreds of thousands of years this could potentially be sufficient; in the period of dozens of years, just radiative heating would be wholly insufficient to make any perceivable alteration in the course of a really massive body. I’ve worked on studies of various notions on asteroid redirection, and there are a large number of concepts that are often promoted in the popular science press that have little practical validity. Both the size of a really large object and the scale of energy required to alter its course are just beyond normal conception, and the intuition of what seems like it could work is often just completely wrong.
That would be six and a half orders of magnitude less than the hypothetical 15 km diameter Chixulub impactor, notwithstanding the problem of firing a laser indefinitely. Just scaling the estimate of 30 years by that exponent, it would take over 4 billion years to redirect a 15 km object by the same degree. As I said, there are are a lot of concepts out there that seem superficially plausible until you get into the actual details of what would be required to make them work.
The hypothetical given in the article states that with a 30 year warning using lasers far below power levels those currently used by the military. Is it theoretically impossible to scale up lasers by those orders of magnitude?
A spherical asteroid (which we’ll assume for the sake of simplicity) has a surface area that increases as a square of the diameter, but a volume–and therefore mass–that increases as a cube of diameter. The lasers current “in use” (that is, in limited experimental field deployment) fire for at most a few seconds at a time and a few hundred seconds before requiring refurbishment. Scaling up lasers by orders of magnitude was the essential premise of the Strategic Defense Initiative “Star Wars” program, and despite decades of development since has not produced a laser that can actually destroy an ICBM at hundreds of miles distance, much less vaporize an asteroid millions of miles away. Again, these are concepts that are easily presented in cartoon fashion but an evaluation of hard numbers and fundamental limits shows how unworkable they are in reality on the scale under consideration here.
Having “a few rockets on standby” would be far too little and much too late. To have a realistic possibility of redirecting even a ~1 km diameter object would require intercepting it months out in its trajectory and using many individual impulses which need to be delivered in such a way to push the entire mass instead of striking in one concentrated area where it just fractures or cleaves off a chunk of material leaving the rest to continue on its way with trajectory not significantly altered.
For clarification, by ‘standby’ I don’t mean something like 24-hour notice, but more like 24-week notice - since if we only got a few months or a year notice that a Earth-extermination asteroid was coming, it would be a very compressed and nerve-wracking timetable to try to create a suitable interceptor from scratch at that point. So it might be better to have “anti-asteroid ICBMs” preppred in advance.