What will it take to get observation satellites in place to try to spot these things when they are far away enough to do something about them? There’s not much chance we’ll spend a lot of money on asteroid killer/deflection tech if we can’t even find one to worry about.
Not all that much. We have a current program utilizing ground based observatories for asteroid detection and tracking which JPL has already been studying for a long time but they are obviously limited by the amount of sky they can observe. The WISE satellite [NEOWISE program] was deployed to search for and catalogue minor planets missed by ground surveys (though not potentially hazardous objects in particular) and was revitalized for the (NEOWISE, studying near-Earth asteroids | The Planetary Society) as a proof of concept for a dedicated asteroid hunter. The Planetary Society has long advocated for a follow-on program of observation satellites dedicated to planetary defense:
I once worked on an unsolicited proposal for an interplanetary telemetry and positioning system which as a secondary capability would have hosted small body observatories capable of imaging everything 10 meters and larger within the orbit of the Earth including all Aten, Atira, Amor, Apollo group objects that could pose a hazard. Unfortunately, like most such proposals it went nowhere which is unfortunate because it is a capability needed to expand interplanetary space exploration as well as the benefits for planetary defense.
Stranger
Another approach but one that would require the lead time to get it into place and the ability to autotrack -
Meanwhile at least NASA is working on something for the more common threats! DART. The Double Asteroid Redirection Test.
This video (skip to1:35) says the dino killer hit at almost the perfect spot to do the most damage. They suggest hitting in deep ocean would have been much less damaging globally.
Didn’t watch the vid. But Chicxulub was 15km in diameter. The central oceans are 3 or 4 km deep. Leaving the top of the impactor still in the stratosphere above 90% of teh atmosphere as the bottom is hitting, well, bottom in the central Atlantic or Pacific.
Viewed at the correct scale, the Earth is a very big rock with a very thin wrapper of air and an even thinner coating of slightly lower wet spots called “oceans” here and there. Impactors deeper than the oceans & atmosphere put together are out there.
Comets are the real problem.
We can see asteroids decades, centuries in advance. It is unlikely that there are any 15km asteroids that we are unaware of.
Comets, however, if they are long period, we may not know more than a few months ahead. If they come in at a bad angle, where we are blinded by the sun, we may have even less.
AIUI we also tend to focus what little effort we’re spending looking mostly along the ecliptic. Comets have a lot more freedom to approach from high angles than do other objects.
Oumuamua and brethren would like a word with you.
was discovered Oct. 19, 2017 …
While originally classified as a comet, observations revealed no signs of cometary activity after it slingshotted past the Sun on Sept. 9, 2017 at a blistering speed of 196,000 miles per hour (87.3 kilometers per second). It was briefly classified as an asteroid until new measurements found it was accelerating slightly, a sign it behaves more like a comet
We didn’t see it until it was headed out. I will grant 2/3km is harder to see than 15km but except for luck we won’t see a 15km interstellar object decades or centuries in advance.
There are a couple of ideas on why that area was so damaging. One says that because the rocks were rich in gypsum the would have released a lot of sulfur. The other says it was because the rocks contained oil-rich sediments that produced a lot of soot when vaporized (however, drilling has not confirmed this).
In contrast, the floor of the deep ocean is made up mostly of basalt, which would not have produced these substances when vaporized. And there are similar-sized craters on the continents that don’t seem to have produced equivalent extinction events.
The damage done by an impactor is basically proportional to its energy. Whether that energy is deposited in atmosphere, water, or rock, and whether it’s all in one spot or spread out, makes very little difference.
Though of course, breaking up an object could mean that some of the fragments miss. You could even try to break an object in half, to use the two halves as reaction mass for each other.
It’s been almost 40 years since I read Carl Sagan’s Cosmos, so I may have this wrong. But one thing that stuck with me is his assertion that the event killed everything above 50 pounds mass. I don’t think modern society would survive something like that.
I suspect the odds of being hit by an big asteroid may be higher than by a big comet or interstellar object - the latter usually get one pass (and we’ve seen most big comets) Haley’s comet is about 11km diameter and by density, appears to be mostly assorted ices. An decent sized Interstellar object with one pass actually impacting earth sometime in the next million years would be a remarkable coincidence. The risk I assume with asteroids is that some might be gravitationally perturbed to put them on an eventual collision course, particularly if the orbital disturbance is regular and progressive. but for those - we should be able to see them coming decades in advance. IIRC we’ve identified some that come too close for comfort already, and the closer they get, the more earth influences their orbit. If we have decades of warning, presumably someone will do something. Presumably…
The main issue with any CT event is the resulting environmental disruption - yes, tiny animals may survive - but what do they eat during a global winter if no plants grow? Considering some advanced animals survived (and plants) presumably there were pockets of life that were relatively only partly scathed? Plants can survive as dormant seeds, but I doubt that assorted reptiles or amphibians could hibernate for years. Perhaps rat-like creatures could live off frozen plant material long enough to wait out an extended winter, or maybe there was a warm enough habitable zone near some geological active areas.
The biggest fallout from chicxulub seems to be the destruction of plant life, leading to starvation down the food chain, but isn’t that a problem that modern humanity could overcome? We have access to artificial light, so we could still produce crops. I mean, I can see devastation at the location of impact, and perhaps a shortage of food that causes social strife, but it’s not like humanity would die out a la the dinosaurs, right?
I’ve heard that the bulk of the deaths came from the worldwide wildfires spawned in the immediate aftermath of the collision, from debris from the impact coming back down. The creatures that survived might have been in ponds, or perhaps on small islands that were sufficiently isolated from the surrounding fires, and chanced not to get hit by any of the debris directly.
Though, yes, those few that survived the immediate calamity might have had a hard time finding food in the subsequent few years of winter.
We’re better at digging holes and building hardened shelters than the mammals 60 million years ago were. I suspect the resources and planning needed to build an asteroid killing/diverting system might be better utilized building an infrastructure that could survive the strike.
We would do so much better that I suspect the number of dinosaurs lost if such a meteor hit today would be close to zero.
Well, non-avian dinosaurs.
Building a shelter system that would keep a few thousand humans alive for a century until stuff settled down on the surface would be logistically simple.
Building a political system to pay for that shelter and select its lucky inhabitants while consigning the rest of humanity to certain death is a taller order.
As per many SF stories, having the group’s 2nd-4th generation offspring keep the colony surviving politically and socially for the whole 100 years and emerging as anything but a gang of crazed nutters is also a tall order.
Which, by the way, is something I’ve pondered for a while: what if the reason why humanity has survived and expanded from its humble beginnings was because there was so much excess arable land to expand to?
If tribes, or even people within a tribe, were having conflicts in the middle of Africa in 100,000 BC, they could just up and leave the area and migrate somewhere else, then settle down and form a new colony. Hell, it doesn’t have to be Africa, we’ve seen this pattern of migration play out all over the world (e.g. Pilgrims, the Kuomintang fleeing to Taiwan, etc) throughout history.
This wouldn’t be possible in an underground shelter, and I highly suspect that any society forced to be cooped up in such a shelter will end up with the people all killing each other before the outside world is safe to re-inhabit.
This is also why I am not optimistic about the success of a long-term colony on Mars, because due to the weak atmosphere and lack of natural resources, any disgruntled colonists will find it practically impossible to just “up and leave” without technological support from the preexisting colony.
I seriously doubt our ability to stockpile enough food for a few thousand people for 100 years. If they are not in a part of the world or can reach a part of the world that allows a return to agriculture within a year or two it’s all over anyway.