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I work on the Near Earth Object Surveyor space telescope (NEO Surveyor) writing simulation code which predicts which objects we will see. This one has drummed up a bit of interest due to its (relatively) high chance of impact. I actually spent quite a bit of time yesterday digging through archive images trying trying to see if it was spotted on some previous times it came by the Earth (no luck unfortunately). Since we saw it so briefly, our knowledge of its orbit is not that great, and running the clock back to 2016 for example ended up with a large chunk of sky where it could have been, and it is quite small. We will almost certainly see it again with NEO Surveyor years before its 2032 close encounter. I have not run a simulation for it, but I would not be surprised if LSST (a large ground telescope survey which is currently coming online) to catch it around the same time NEO Surveyor does.

Our knowledge of the diameter of this object is a bit fuzzy, because of surface reflectivity, small shiny things can appear as bright as dark large things. This is one of the motivations of making the NEO Surveyor an IR telescope, since IR we see black body emission off of the objects, which is mostly size dependent, and only weakly albedo dependent.

There is an even tinier chance that if it misses the Earth in 2032, it could hit the moon. I haven't run the numbers precisely for that one, but it impacted a few times in some monte-carlo simulations.

If anyone is interested in orbit dynamics, I have open sourced some of the engine we are using for observation predictions: https://github.com/Caltech-IPAC/kete

It is relatively high precision, though JPL Horizons has more accurate gravitational models and is far better suited for impact studies. My code is primarily for predicting when objects will be seen in telescopes.

Great post, thank you!

Where does the uncertainty (1%) come from? For example, is it more from our ability to precisely determine the orbit based on limited observations, or is it because orbits for objects like this just aren't predictable years out, or something else?

It's a bit of both, observing has uncertainty in a lot of places, if you are on the ground you get atmospheric effects, imprecision of timing, imprecision of optics, etc etc. You are also observing an object where you dont know how far away it is. That distance has to be solved by basically doing a sort of triangulation, which requires either the observer or the object to move enough. So if you observe over a short time (hours for example), you can see it is moving, but it is hard to tell distance.

Once you have an estimated orbit, if it has any interactions with planets (IE: flyby of Earth), small differences in positions during the close encounter make LARGE differences decades later. Add to this the effects of photons from the sun pushing on the smaller asteroids or dust, or out-gassing /dust from comets cause these objects to slightly drift from just the basic gravitational forces. Generally inner solar system asteroids (inside mars) are very chaotic over hundreds of years, though typically predictable less than a century.

Note that I am not an expert on impact calculations, I just know a bit about and and can do back of the envelope ones. There are a number of ways to get to the ~1%, the orbit fits have uncertainties on them and those can be propagated forward in time. However there are all sorts of complexities with doing that, and often the easiest method is to sample the uncertainty region a few hundred thousand times (Monte-carlo), and propagate those and see what hits.

Very cool. How are samples drawn from the uncertainty region? MCMC or does it simplify down? I'm guessing that this would drive the final percentage values that you guys determine, since the orbital dynamics would be deterministic.

I can tell you how I do it, but again I am not an impact study person. It helps to understand a bit of the background of how we fit orbits in general:

1) someone with a telescope sees something moving (typically these days these are bigger surveys)

2) These observations are submitted to the Minor Plant Center (MPC), the clearinghouse of all asteroid/comet observations.

3) Several groups pull observations from the MPC to fit orbits, including JPL Horizons (MPC also fits orbits)

4) You now have a pile of observations which you have to figure out which observation links to other observations, which is a complex math problem on its own. Solve that.

5) JPL Horizons for example then fits the orbits to the observations, and since the observations may be 100 years of data of wildly varying quality, from hand written notes in the 1920s through to modern data, this is very difficult. They publish a covariance matrix with the associated fit (IE: basically a gaussian error fit for the parameters).

6) I grab that covariance matrix and sample from it using some pretty vanilla statistics to build orbits.

7) Propagate and see what happens.

Here is an example of an observation from 1950: https://caltech-ipac.github.io/kete/tutorials/palomar.html The image was developed on a glass plate, this one was never even sent in to the MPC, the guy taking the observation just wrote down "Asteroid" on the cover slip for the image. It was not formally discovered until the 1980s. We now know its orbit very well, so this particular observation is not that interesting other than as a curiosity.

Here is an example of an orbit fit by JPL Horizons: https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=c%2F2...

Note the "condition code" on the right, which is a score of how good their orbit fit matches the data, 0 means we know the orbit with high precision. This one is an 8, meaning we have a fit, but its not that great. Most likely because we only have 31 days of observations.

Parent mentioned Monte Carlo simulations, which allow you to simulate across a range possible scenario parameters and see what % result in some outcome (like a collision with Earth or the moon).

I'm sure there's a reason, but it seems like an unusual use of Monte Carlo - it's all deterministic and there is no opposing player making choices. Must have something to do with uncertainties in projected orbits or imperfect simulations maybe?

>it's all deterministic and there is no opposing player making choices

It's not deterministic, it's chaotic. That is the nature of the N-body problem. We can only approximate trajectories in such a system using numerical methods, within a certain margin of error. In principle, the object is gravitationally interacting with everything else in the solar system. But for the most part, most interactions are negligible and could be ignored (eg, other small objects far away), except of the large bodies. But there are many unknowns (as stated before), where initial conditions will affect the outcome of the trajectory simulation, and errors will certainly amplify over time. I'm guessing Monte Carlo is used to "fuzz" the simulations with randomised initial conditions to account for the range of unknowns, and see what the outcome is under these different scenarios.

Chaotic doesn't mean non-deterministic, it just means that small changes in initial conditions result in a large change in the trajectory. The system itself can be both chaotic and deterministic.

It's also a reasonable question to ask, because the simulations are deterministic. It's just that because the system is also chaotic and there's noise in the measurement, that can result in a large spread of deterministic trajectory simulations.

It's only deterministic in the sense of the mathematical constructs that models the system, like differential equations that drive the simulations at each finite time step. But the information or the state which the simulation is applied on is always chaotic. That is because delta at each time step is an approximation with some error. It's impossible to make the state in the system behave deterministically, because that requires time deltas to approach to zero (or infinite amount of infinitely small differential steps).

Energy drift doesn't make the system non-deterministic, it just means that the time evolution has some error. The error is still deterministic. If you simulate a deterministic but chaotic system like n-body orbitals with a non-symplectic integrator, you'll always get the same result for the same initial conditions. The drift created by the finite timestep will also be the same.

It’s the error with the ground truth that you can’t predict. Otherwise you would just be able to cancel it out. You can only predict probability distributions..

If you're saying that it's the uncertainty in the initial measurement, then we're in agreement. If the initial measurement were perfect, the only source of error would be the finite timestep. N-body simulation itself is deterministic, and so the only source of randomness is our uncertainty about the object's true mass, size, shape, position, velocity, etc.

The N-body _reality_ _might_ be deterministic. The N-body simulation using digital computers will technically still introduce errors because of the time steps even if you had perfect knowledge of initial conditions.

The errors are deterministic. Determinism has nothing to do with the existence of errors, it's about uncertainty. They're different things. A system that is deterministic will produce the same results every time given the same initial conditions. If there are numerical errors, they will be identical for each run. A non-deterministic system will give you different results every time given the same initial conditions, with some variance. You can still have numerical errors in such a system.

Ironically, reality probably isn't deterministic. It definitely isn't at small scales (e.g. radioactive decay). If it's non-deterministic at a macro scale, the effect is small enough that we don't see it.

We don't know the configutation it's in precisely. We don't know the initial conditions. Small unobservable differences will lead to large difference in outcome. That's the chaotic part.

I get that. I'm pointing out that these are separate factors. Chaotic does not imply non-deterministic, and vice versa. The only source of randomness here is the uncertainty in the observation of the object, because (as you point out) multiple combinations of parameters could produce the same observation, and each one will have a different trajectory. The randomness doesn't come from the chaotic nature of the system, it comes from noise in our measurements. It also doesn't (as other posts are claiming) come from energy drift in the simulation, because that's also deterministic.

At the very least you can use monte carlo to provide examples from the expected distribution. It's hard to visualize a probability cloud.

The observations are not 100% certain. There are a variety of body states and configurations that might result in the same (few) pixels being lit up in the few measurements collected so far. As additional measurements are collected, some possibilities may be eliminated and the uncertainty of the trajectory can be reduced. This usually results in the impact probability converging toward 0%.

...or 100%. But yeah, the MC comes in this way. You have a current most probable value for the position and some distribution around it, depending on the precision of the measurement device etc. That can be a high-dimensional space. You draw some (many) random points from this space and propagate them all deterministically. Taking into account how likely a certain random point was in the first place, you can then estimate the hit probability.

MC is numerically approximating an integral. Here it replaces the high-dim integral over the start parameters.

Looks like alpha zero stole the original meaning of Monte Carlo… it is not required to have players, or a game, to use the method: https://en.m.wikipedia.org/wiki/Monte_Carlo_method

It wasn't stolen, it was a well-established particular case well before alphago

https://en.wikipedia.org/wiki/Monte_Carlo_tree_search

I only meant the total mind share :) looks like folks have never heard of MC in other contexts than game bots.

I would assume that it is because we have imperfect knowledge of the state of the asteroid (i.e. mass and current position/velocity/...). This imperfect knowledge is characterised by a probability distribution. Similarly the state of all other objects in the solar system is only known up to some distribution. To propagate the information forward in time to impact requires a complicated function f(state of solar system; state of asteroid). If all of the data was known (and expressible numerically) with perfect accuracy, and f were computable with perfect accuracy then all would be good. But as noted, (state of solar system; state of asteroid) is a probability distribution, and there are very few distributions and very few types of maps f that are amenable to analytic transformation. For example if the state was a normal distribution with mean x and covariance P, and f were a linear transformation, then x,P mapped through f is also normally distributed with mean y and covariance P_y, you can get the mean of the transform as y=fx, and P_y = fPf' (where ' indicates transpose). Needless to say our knowledge of the state of the asteroid and the solar system is probably a rather complicated distribution, and the n-body problem is not a linear transformation. Monte-carlo simulation is often used to propagate probability distributions through non-linear transformations.

It is very common to use Monte Carlo for deterministic problems. It's just an integral over complicated PDFs

The guesswork is uncertainity about the object's exact paraneters. Because of this they have to use informed estimates (scientiffic guesswork).

Uncertain observations, I'm sure

It's "deterministic" the same way the weather is.

Right - we only got a short glimpse of it, not enough to get a high confidence of its trajectory.

Right:

- "Since we saw it so briefly, our knowledge of its orbit is not that great"

- "[for example, in 2016 the data shows] a large chunk of sky where it could have been, and [the object is quite small."

- "Our knowledge of the diameter of this object is a bit fuzzy, because of surface reflectivity,"

My guess is that small objects like this suffer greatly from the 3-body problem, and multiple trajectories are generated from various starting points inside our measured error bars for the current states of these objects. Small inaccuracies compound over the years.

n-body problem.

The planets, sun and all planetoids orbit the barycenter of the solar system, which in our case happens to be inside the sun. They all affect each other, making more than 3 bodies problematic.

> My guess is that small objects like this suffer greatly from the 3-body problem

What bodies? My impression is that the only objects around Earth with enough gravity to significantly impact trajectories are the Earth and Moon. Will the other small objects have any significant gravitational impact on this body?

I also understand that in cislunar space, the Earth-Moon dynamic does create a three-body problem and trajectories are fundamentally unpredictable, with some exceptions. I wonder how that affects objects such as this one if they pass through the Moon's gravitational well.

Even if you're just doing a 2-body problem around the moon you'll get wildly wrong orbits over a timespan of just months if you treat the moon as a point mass (the way that's relatively safe to do with Earth, in comparison). Lunar mascons are so strong you can't even rely on a plumbob to point straight down if you want just tenth-of-a-degree accuracy. These perturbations are so severe there are only effectively only four (instead of 90) stable inclinations for low lunar orbits.

Literally every body in the solar system acts on every other body at all times. All asteroids in the asteroid belt are perturbed by Mars and Jupiter, right? Except if you recognize the need to include Mars in calculating their trajectories, you need immediately to at least also account for the 4 Gallilean moons, who sum to about the same mass as Mars, and now you have a 7-body problem. You won't get correct results on trajectories of Earth approaches if you discount the mass of our moon, nor if you discount the rest of the asteroid belt (4% of our moon's mass)... etc.

Clicking the link, I found this visualization of the approximate orbit:

https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2024%...

This orbit is around the sun (as asteroids tend to) and the apoapsis is closer to Jupiter's orbit than Mars.

Also, the gravity of asteroids or small planetary bodies like moons that it passes close to will have some small effects that can add up over a long time period.

Gravity has unlimited range, the patched conics method you think of is a good approximation on short time spans, but breaks down surprisingly quickly. Keep in mind the Sun moves all the water in Earth’s oceans all the time…

The Sun, Jupiter, Saturn are the main ones. Depends on the orbit as to how much influence they have.

There's going to be some degree of measurement error, which will likely be greater for objects which have not been observed many times. Multiple observations should allow both better estimation of the object attributes (average out the noise), and allow some judgement of the quality of predictions given what you think you know about it.

Mesurement uncertainty when propagated over long periods of time leads to very large uncertainties, imperfect gravity models, space weather

Thank you. Why I read HN!

Could we stick an rtg-powered tracking beacon on it during its next flyby so that we can better calculate its orbit?

If in 2032 an impact did occur, how much time before that impact would be able to ascertain over 50% probability of impact? hypothetically.

That is, does the certainty increase steadily or non-linearly over time? Does near certainty of an impact occur from measurements taken just minutes before the impact, or hours, days, years?

We would see it years before, and we would know with certainty years before.

If the object really looked like it might impact I'm sure someone would get time on a powerful telescope to lock in the orbit.

How far in advance would we know exactly _where_ on the Earth it will hit? If, say, New York is going to be destroyed, it makes a big difference if we know that a year in advance vs. a day.

Knowing if it will hit is a lot easier than knowing where.

Knowing where, will depend on the angle of impact - if came basically straight in (tangent to the surface) we can be pretty accurate, but the more shallow the angle the harder it will be.

With a shallow angle, we'll probably be able to tell the latitude pretty well, but not the longitude.

It must be easy to determine which face of the earth it strikes though...?

Nitpick: normal to the surface.

Oops! Yes, I meant to say perpendicular (or normal).

Does it though? People don't leave hurricane zones. People don't heed tornado warnings. I just have very little faith in humanity, and fell like "Don't Look Up" would be not too far off.

Also, if you evacuate New York a year in advance, who's to say that the prediction isn't just a skosh off so that New York is left untouched but the real impact location was hit unprepared?

A lot of people do evacuate hurricane zones, even when death and destruction are not absolutely guaranteed. If we knew with certainty that a particular place was going to be hit by an asteroid, and we had time to evacuate, I am confident most people would do so.

The accuracy issue is the thing. I’d venture a guess that our prediction of the path of a hurricane 7 days out is more accurate than predicting where an impact will be.

It's actually the opposite. Calculating an asteroid impact is much easier because it primarily involves basic Newtonian physics. In contrast, the climate is a chaotic system, making long-term predictions far more complex.

I don't know how it's opposite. There's some complex guesstimating on where an asteroid will hit. We roughly know its size. We roughly know its composition. We roughly know its speed. We can give a +/- range where the impact area will be. That's not any different than how hurricane spaghetti models do.

Having lived through a bunch of hurricanes in south Florida I can very confidently say people absolutely evacuate when given the order to.

There's always a few holdovers, but my experience living in disaster prone areas is that people evacuate when evacuation orders are given. Literally nobody is going to come help you if you don't.

What was the compliance rate in evacuating parts of LA for the recent fires?

[flagged]

Please don't do this here.

Sorry, will do better.

> how much time before that impact would be able to ascertain over 50% probability of impact? hypothetically.

I understand it's hypothetical, but even a 10% chance of hitting a city, for example, would be a crisis.

They didn't say anything about 50% being the minimum level for a crisis. There is no "but" because they are two different topics. One is "how far out could an impact be predicted at 50/50 probability" and the other is "at what probability of impact would it become a serious issue/crisis".

I wonder if we have a chance to catch it still on radar this pass. I know Arecibo used to do that and is now sadly gone, but Goldstone also has capability. Anyone know more?

FAST [0] in China maybe?

[0] https://fast.bao.ac.cn/

FAST also doesn't have transmitters, unlike Arecibo. So you cannot do radar observations of radio-reflective but not emitting objects with it in the same way.

> JPL Horizons

A slight tangent.. but my favorite thing about Horizons is that they still maintain a telnet interface to their system. Once you learn to use it it's quite a bit of fun to play around with it.

That warms my heart on a winter night.

What are the implications of a moon impact? Would it affect life on Earth?

Would Earth see on-again, off-again random showers of rocks of various sizes ?

> if it misses the Earth in 2032, it could hit the moon.

Oh, that's not so ba--- Wait, isn't that what happens in Seveneves?

I think that was supposed to be some kind of small black hole passing through the solar system or something more exotic. Maybe I'm misremembering. Great book though and still haunts me sometimes when staring up at the night sky:)

He never actually said what it was. I think some people floated theories, but the book never reveals the answer.

I had also interpreted it as a small solo black hole. Which it itself a scary concept.

Especially if it was a member of a band before going solo.

An 8 MT impact on the Moon is what the Moon calls "Tuesday." It has dealt with far, far worse.

The impact probably wouldn't even be visible with the naked eye unless it hits a part of the Moon not then illuminated by the Sun -- in which case one might see a brief flash of light.

Because I was curious and had no idea about the relative size of meteors that hit the moon, the one that hit the moon in 2013 and was captured by Spanish astronomers was traveling at 65k KPH and weighed about 400kg. That had an impact energy of 15 tons of TNT (https://www.youtube.com/watch?v=perqv4qByaI&t=1s)

Safe to say, an 8 megaton impact from one that weighs 220,000,000kg would be a bit more substantial! Apparently that would be roughly the size of the Meteor Crater in Arizona (https://en.wikipedia.org/wiki/Meteor_Crater).

> traveling at 65k KPH

You could say 65 MPH (megametres per hour) ;-). Or more formally: 65 Mm/h or 18 km/s.

Yes. Similar to hundreds of other craters on the Moon.

SE leaves the question of exactly what impacted the Moon unspecified, referring to it as the "agent". Both narratively and in-story, the question of what the ramifications of the event are is far more significant than its origin. It's not possible to change the past, nor does an understanding (narratively or in-story) have any appreciable impact on what transpires as a consequence.

As others have noted, an 8 MT impactor on the Moon would be a quite minor event. It would likely be visible to terrestrial observers (if on the near-side) and leave a visible crater. Might generate ejecta which itself could enter the Earth's atmosphere over time, though likely with little effect on the ground.

This happens in the YA book Life As We Knew It. A really great book (for a YA audience). I still feel cold remembering it.

it's the agent...

Read that book over a year ago and it's still eating at me.

Do you know people worrying about supervulcano erruptions?

https://www.usgs.gov/observatories/yvo

https://en.wikipedia.org/wiki/Yellowstone_Volcano_Observator...

How concerned? https://www.agiweb.org/geotimes/june05/feature_supervolcano.... not very.

Very interesting. How can we get rich from this?

I’m not saying this is a good idea, but conspiracy/prepper YouTube channels seem to be thriving off ad revenue these days.

There's too many of those, you'll never stand out from the crowd. Instead, you could make a channel where you react/review to specifically asteroid impact related books and media. It could be very low effort, but topical enough to gain traction as people search and watch other asteroid videos.

This is not an increase over baseline risk (as its Palermo scale[0] indicates, being a negative number, -0.56).

I think there's going to be a crisis of media going forwards, because with the very awesome new telescope[1] that's going online this year, the number of these detections is going to drastically go up. The number of objects isn't going up—they've always been there, we just didn't know—but I think the media coverage is not going to absorb that nuance very well.

[0] https://en.wikipedia.org/wiki/Palermo_Technical_Impact_Hazar... ("A rating of 0 means the hazard is equivalent to the background hazard (defined as the average risk posed by objects of the same size or larger over the years until the date of the potential impact)")

[1] https://www.technologyreview.com/2025/01/01/1108643/vera-c-r... ("With its capacity to detect faint objects, [Vera] Rubin is expected to increase the number of known asteroids and comets by a factor of 10 to 100")

HOWEVER this is an excellent time to review https://en.wikipedia.org/wiki/List_of_impact_structures_on_E... in particular the S2 to S8 spherule beds found in South Africa (AKA "the big one(s)" or "we are less than dust in the eyes of the gods").

The universe is a big place with some big rocks in it. There are also some !!fun!! simulations of things like the Vredefort impact on YouTube.

See also: https://en.wikipedia.org/wiki/Australasian_strewnfield (debris over 10% to 30% of the Earth's surface from an impact ~788,000 years ago). Smaller, for sure, but very recent and large enough for "nuclear winter" type scenarios.

(I worked tangentially on software for analyzing data that will come from the Vera Rubin telescope, and) yeah, while it was designed for spotting weird supernovae and such, the first half of its operation is expected to be dominated by the discovery of near earth objects.

So you're calling it a "crisis" that people will be better informed of the risk they've always faced? Seems to me we should use that media coverage to build political support for a real asteroid defense system.

If the media does not contextualize risks correctly, as it never does, it's absolutely a crisis—a crisis of a poorly-informed, panicked society lashing out and doing irrational things.

It's not a costless error if a warped illusion of risk drives countries to, i.e., deploy nuclear-tipped space weapons for asteroid defense, which then precipitate a genuine crisis. It's not obvious that having more defenses is obviously safer than having less; some thoughtful people have argued the opposite:

>"In our view, development of this asteroid-deflection technology would be premature. Given twentieth-century history and present global politics, it is hard to imagine guarantees against eventual misuse of an asteroid deflection system commensurate with the dangers such a system poses. Those who argue that it would be prudent to prevent catastrophic impacts with annual probabilities of 10^-5 would surely recognize the prudence of preventing more probable catastrophes of comparable magnitude from misuse of potentially apocalyptic technology."

https://sci-hub.se/https://doi.org/10.1038/368501a0 ("Dangers of Asteroid Deflection" (1994), Carl Sagan & Steven Ostro)

In this case, the context is "we face the same risk all the time, from asteroids we don't see." I'm not convinced that's reassuring.

The Sagan paper concerns much larger asteroids, which are correspondingly more rare. For asteroids in the 8MT impact range, it doesn't make much military sense to launch deep space missions to divert them years in advance, rather than delivering nukes directly with ICBMs in minutes. Given any competent asteroid defense system, an asteroid diversion would be detected immediately and countered, and the perpetrators would face consequences.

In fact, since we already have rockets that can reach asteroids, I'd say the possibility of malicious diversion makes a defense system more important.

- "The Sagan paper concerns much larger asteroids, which are correspondingly more rare."

That's a fair distinction—the paper predates the modern telescope surveys that are discovering all the small ones.

- "rather than delivering nukes directly with ICBMs in minutes"

You'd still need multiple years for those nukes to have a useful effect. (The change in velocity is instant; the change in position is not). They wouldn't be ICBM's, either: we'd need a new type of deep-space delivery vehicle, far larger than a suborbital ICBM. That'd probably trigger a new type of nuclear arms race.

Sorry, what I mean is: why would I use my rocket and nuke to divert an asteroid years in advance, when I can drop an 8MT nuke on you directly in 30 minutes with much more accurate targeting?

One possible reason is plausible deniability, but that goes away if we have a good asteroid defense system with an emphasis on early detection.

Ah, I understand now.

For one thing, you could weaponize asteroids as a second-strike response, if there's an imbalance where one superpower has asteroid deflection and one does not. Even if it's delayed by months, the certainty that the asteroid will eventually hit establishes a deterrent against attacking the asteroid-controlling country. If there's defenses against ballistic missiles, this circumvents those.

For another, the asteroid-deflecting nukes are dual-use as weapons themselves. A nuclear warhead in deep space defeats conventional ballistic missile defenses. If that warhead is turned towards Earth, that (first-strike) attack's not visible to the adversary until a few seconds before impact—unlike an ICBM launch, which has tens of minutes of warning, enough to launch (conventional) interceptor missiles.

I don't think a second strike from asteroids would work. You can't just arbitrarily redirect an asteroid towards Earth whenever you want. You need one that's already going to pass nearby. You might have to wait decades for it to hit, and during that time your enemy can send their own nuke and nudge it away.

But if you could do second strikes with asteroids, that would be a good thing. Second strike capability helps prevent nuclear war. Effective first strikes are what's destabilizing.

Which brings us to your second point. I agree that stationing nuclear warheads in space is a bad idea. But we don't have to do that. With years or decades of advance warning, we can just launch them from Earth.

- "Second strike capability helps prevent nuclear war. Effective first strikes are what's destabilizing."

I don't disagree!

- "You need one that's already going to pass nearby."

There's a very large number of these already, within a small delta-v of Earth. We don't know where they are yet (it was a show-stopping issue with NASA's Constellation (?) program, when they wanted to demonstrate capturing an asteroid, but couldn't find one), but that's going to rapidly change.

- "and during that time your enemy can send their own nuke and nudge it away"

That's pretty useful: that brings it to a point where the defender has to invest an amount of resources comparable to the attacker. That's a win for the economically stronger country. If the difference grows large enough, they can simply overwhelm them with numbers.

That's even before opening the technological possibilities of stealth asteroids.

Eh, we already have steath aircraft that could slip in past air defenses and drop a nuke with next to no warning. We probably have a stealthy hypersonic that can also do so. That doesn't negate a nations second strike ability.

Part of the reason the US, Russia and China have vast land based missile fields is to visibly show the enemy that they're gonna have to wipe out huge swaths of land with hundreds of nukes (and THEN sink our boomers) to have a successful first strike.

Right; but if the enemy thinks that's likely to happen, it'd only take them 15 minutes to nuke that one airbase that stores all the B-2's. Strategic bomber aircraft aren't very useful weapons for superpowers fighting each other (or else we'd have a lot more B-2's).

Space-based weapons (which are banned by treaty) are more like submarine-basing, in that the enemy isn't necessarily sure where they are; but, in addition to that, they have potentially very short warning times before a strike. No one actually wants that unstable dynamic, with the short/no-warning; which is why all the nuclear powers have (so far) agreed by treaty not to build any.

edit: But if someone were to build a civilian spaced-based asteroid defense, which involved sending nuclear weapons into space... that could get destabilizing fast. Whether or not Sagan can predict specifics, the big-picture idea of humans not trusting each other with apocalyptic weapons is not wrong. (Worth recalling the USSR genuinely mistook the civilian US Space Shuttle for a nuclear weapons platform).

Forgive my naivete, but do we really have the precision measurements and kT payload calibration needed to alter an asteroid's trajectory and speed to the point that we can target specific (even very large) country landmasses as the Earth's rotation exposes them to the oncoming projectile?

No, nothing about asteroid deflection is precise; the physics are messy and we know little about them.

...boomer submarines exist.

Nuclear second strike has always been from the submarines, which guarantee a response within minutes.

Versus your proposal here of launching a highly visible rocket, to manipulate a highly visible object, with a flight time measured in days to weeks that's mostly ballistic.

Frankly: this is strategic nonsense.

It's nonsense today, but technical factors change over time. It's unsafe to try to predict too far ahead.

The physics of tomorrow though will be the physics of today however: a many months flight time out to an orbital object to affect trajectory change is a response time so far away as to be meaningless: any opponent with an ICBM strike capability on Earth could happily blast away your entire civilization, and reasonably expect to use the same technology that enables that ICBM capability to blast away (or deflect) your asteroid.

Put it another way: for considerably less expenditure of effort, you could just build a hydrogen-bomb large enough to obliterate Earth's biosphere completely[1]

[1] https://en.wikipedia.org/wiki/Doomsday_device

Consider that ICBM's might not work forever. If e.g. new types of anti-ballistic missile defenses were to become cheap and reliable, then ICBM/SLBM's could even become obsolete (say, within the century). If that happened, there'd be a slew of new arms races, which are unimaginable to us, being beyond our technology horizon.

Physics isn't changing over time, but engineering is.

>we'd need a new type of deep-space delivery vehicle, far larger than a suborbital ICBM.

Like...starship?

> That'd probably trigger a new type of nuclear arms race.

Why on earth would there be an arms race on something designed to deliver nuclear payloads to deep space? The only way I could see that happening is if we had nuclear armed deep space colonies? (See, the expanse)

This. It’s a crucial step for our civilisation to be able to protect earth from any incoming dangers be it asteroids or Umuamua type objects. There must be a global effort with all countries to build such a system.

> There must be a global effort with all countries to build such a system.

That bit doesn't really seem necessary though?

Good luck with that... currently we are failing to muster a global effort for tackling climate change, which is a much more pressing issue than an asteroid which may or may not hit us. I know https://en.wikipedia.org/wiki/Don%27t_Look_Up is satirical, but reality often outdoes satire, so I wouldn't be surprised if things would play out exactly like in that movie...

This pessimism has its place, but in this specific case, it is not accurate.

Congress did decide that NEO's are an important problem, and eventually money was appropriated to address it, and a technical solution to the detection problem has been found. (https://en.wikipedia.org/wiki/NEO_Surveyor)

There is open doubt as to whether climate change, as presented, is truly a near-term existential issue.

There is no doubt that an asteroid hitting earth is.

There is an open doubt whether a fully functional coffee machine is currently orbiting Venus, however one of these hypotheses is different than the other.

Hint: expertise matters, evidence matters, and in a field where buildings/laws/fields of study get named after successful contrarians, a long streak of effectively unanimous consensus should not be undervalued.

The good news is that the near-unanimous consensus among experts is that climate change is not an existential issue. Almost no climate scientist thinks that climate change could wipe out the human race. (That's compatible with it having very large effects on human welfare, substantial percentages of global GDP.)

Existential to our way of life. That humans will survive in caves, and maybe even a few million, is cold comfort.

The coffee machine has no implications on my current life span. It may be true, but who would waste their time caring about this?

Show me the /unanimous/ consensus that this is an immediate /existential/ issue. I don't believe such a thing exists. When attempting to understand the difference between those who care about an asteroid and climate change, which was the question, this is the critical point to concern yourself with.

Unanimous consensus is an impossible goal.

Overwhelming agreement among experts is as gold as standards get.

But FWIW, I don't think anyone believes that climate change is a quick duration species-existential event. Massive slow-roll geopolitical destabilization leading to societal collapse? That's definitely on the table.

> Unanimous consensus is an impossible goal.

I know this. I was responding to the OPs appeal to authority.

> Overwhelming agreement among experts is as gold as standards get.

What is this agreement? That it will eventually happen? That's not much of an agreement.

> I don't think anyone believes that climate change is a quick duration species-existential event.

Among those who "agree" is there a common timeframe that they estimate? Or do they all have varying opinions on this?

> That's definitely on the table.

We have nuclear weapons. In bunkers. Aimed at "targets." Everything is on the table. This isn't useful.

I don't believe you would have any trouble answering these questions for yourself, and I do not have any confidence that you are engaging earnestly.

Hmmm… what level of agreement would constitute sufficient cause for massive change?

Eventually happen? What percentage of the Great Barrier Reef is gone?

How about this every single climate change skeptic I have offered this wager to has declined to take me up: if in the next calendar year, the average global temperature for a given month is below the average global temperature of that month in the year you were born I will pay you 10 times the amount you are willing to wager. If the opposite is true, that the month this year is warmer than the same month in the year you were born you must pay me the amount you are willing to wager.

Care to take that bet? Didn’t think so.

by doubting, you've already ruled it out, haven't you? 95%+ is as good as it gets probably.

For starters, we know corals will be dead in the next few decades, home of 25% of all oceanic species.

The mass extinction event is underway and we aren't doing enough to stop it.

> by doubting, you've already ruled it out, haven't you?

So you are attempting to create an environment where reasonable doubt is impossible. This behavior is actually part of the reason I have doubts.

> we know corals will be dead in the next few decades

Do we?

> The mass extinction event is underway and we aren't doing enough to stop it.

This is a clever dodge of the original question. Can you explain to me when our current inaction reaches a point where no response will ever be able to overcome the drivers of this mass extinction? Do you have an estimate you can share?

Gotta be the acme of pedantic behavior to say "there's no proof climate change will kill ALL of us".

> I think there's going to be a crisis of media going forwards

I take that as meaning a crisis of traditional media. But most of our false-positive and false-negative crises are crises of social media. Look at climate change, vaccines, ethnic hatred, pizza gate, every crazy rumor ...

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What is it with people like you's selective memory? People were dying in droves in places like India or China, scroll down about halfway to see the funeral pyres: https://www.buzzfeednews.com/article/piapeterson/covid-pande...

They were even just dumping bodies in their holy river because they couldn't afford proper funerals.

Congrats for living (I assume) in a modern world with good health and clean air where you were just "inconvenienced" by shut restaurants and having to wear a mask, but hey, MAGA is fixing that too, let them "doge" your life into poorer air quality and less health protections! Winning!

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1 million Americans died in the first 4 months of the COVID epidemic. That was not normal, nor anywhere close to normal.

You're undercalling it, that would actually be completely normal. About 1 million US citizens die every 4 months (technically the number of American deaths would be quite a bit higher). The anomaly was that there were about 0.7 million surprise deaths over 12 months (some minority of which would have been caused by the COVID response itself, mind)

You can look it up here - https://ourworldindata.org/grapher/number-of-deaths-per-year... - the COVID death rate is going to be a pretty good year in the 2030s. It is a statistically significant blip but ultimately the vast majority of deaths were already locked in. It was always going to be about 3 million people each year.

The hospitals were at their breaking point in 2022, many of my family were there. If we would have had the normal 1 million flu deaths + car accidents etc on top of the 1 million COVID deaths the health care system would have completely broken down and we would have had a couple more million deaths of things that would normally have been treatable but weren't because the health care system was broken.

That is also underselling the situation because that observation is pretty normal too. Typically hospitals are at breaking point, they're funded to roughly match demand. If anything unusual happens then they reach breaking point. In my experience in Australia we get a "hospitals at breaking point" announcement every bad flu season because they are funded to just-about cope with a bad flu season.

COVID was worse than a bad flu season by a big margin, but that doesn't change the fact that the blip was relatively small. You're going to see hospital capacity being forced to expend to more-than-COVID levels just to deal with the baseline number of oldies in the next decade.

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Family members that worked in a hospital.

2020 COVID and 2022 COVID were very different things. Few people got COVID in 2020, but a high fraction of those who did got hospitalized. Pretty much everybody got it in 2022, and a low fraction of those who did got hospitalized. But a small fraction of "pretty much everybody" is still a large number.

And yes, the hospitals are full right now. Flu, RSV, COVID & norovirus all going around. One is bad, 2 at the same time can be really bad. Good thing lock downs prevented that scenario from happening in 2022.

Lockdowns didn't prevent anything that would have justified the harm they brought on society, culture and politics.

I know you don't like Russell Brand and he's definitely not doing well ... nonetheless this interview with Tim Robbins basically summarizes my personal experience to the t:

https://www.youtube.com/watch?v=uMdOesJo4h8

also many people died due to restricted access to medical services and simply stress from the panic that was spread.

About 1% of the US population dies every year even without COVID. This is around three million.

Let's not observe false vacuum.

Why crisis? People should simply not look up.

On the other hand, if people are told constantly to look up, eventually they stop looking.

Or maybe we just build a system that can reliably detect and deflect asteroids and resolve the concern.

Obviously we should build a system which can reliably detect and correct people looking up and resolve the concern.

> Why crisis? People should simply not look up.

I don't understand why this apt pun on that movie is being downvoted.

Would anyone of the downvoters of parent care to explain?

Puns are for Reddit, not HN.

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HN's value proposition is high signal-to-noise discussion. Jokes and meme comments work against that.

A lot of people think off-topic puns and jokes are annoying, and HN has a much higher concentration of such people than most of the internet.

That's part of why discussion on HN tends to be much higher-signal than Facebook or Reddit.

Working link: https://cneos.jpl.nasa.gov/sentry/details.html#?des=2024%20Y...

8.1 megatons of kinetic energy. According to the Torino rating, only risk of “localized destruction” (less than “regional devastation”): https://cneos.jpl.nasa.gov/sentry/torino_scale.html

Those numbers were a bit abstract to me, so to get an idea: Tungunska event (1908) is estimated between 3 and 5 [1], and the Chelyabinsk (2013) at 0.5 [2]

[1] https://en.wikipedia.org/wiki/Tunguska_event [2] https://en.wikipedia.org/wiki/Chelyabinsk_meteor

The ESA's estimate is a bit lower, at 0.1 MT: https://neo.ssa.esa.int/search-for-asteroids?tab=possimp&des...

I'm guessing there's still a lot of uncertainty.

Comparable in energy to a B-53 nuclear bomb, minus the radiation.

https://en.wikipedia.org/wiki/B53_nuclear_bomb

So a 14 km blast radius it seems.

Unless it lands in the ocean in which case tidal waves, and if on land, probably an earthquake/shockwave.

A comparable ocean impact would be the 2004 Indian Ocean earthquake, which was about 3x more energetic.

I'd assume quakes transform much more energy into tsunami waves than meteorite hit does.

That is not correct.

Earthquakes' energy doesn't all go to displacing water and hence generating tsunamis. An ocean impact is significantly more efficient at transferring energy into tsunamis.

https://www.sciencedirect.com/science/article/abs/pii/B97804...

Interesting, I would assume surface wave dissipation to counteract that compared to seabed origin.

2004 Indian Earthquake was 9.1-magnitude, so it was about 150 megatons of TNT.

The USGS estimated 1.1×10^17 Newton-Meters of energy, which converts over to ~26Mt TNT.

https://web.archive.org/web/20100404013939/http://neic.usgs....

What I just learned from ChatGPT…

Asteroids mostly contain the same naturally radioactive elements we find in Earth's rocks - mainly potassium, uranium, and thorium in very small amounts. When they hit Earth, they don't typically create radiation hazards. Scientists have checked out famous impact sites like Meteor Crater in Arizona and found normal radiation levels. While impacts can briefly create some radioactive isotopes through the collision process, it's really the impact's explosive force that does the real damage, not radiation.

*megatons of TNT. 1 MT of TNT = 4.14*10^15 joules

So you wouldn't want to be under it, but a good-sized hill would be enough cover?

Yes, deep underground shelter planned for nuclear attack will be enough to survive, as damaging mechanisms, are mostly same - short but very powerful infrared flash and deadly shockwave (better to consider it as very fast pressure grow and then pressure drop).

Just staying behind hill, will be not enough cover from shockwave, so people will suffer from fast pressure changes.

But shockwave quickly weakened as square of distance, and hill will make it's path longer. So, something like 100m hill could be considered as moving border of deadly zone 100m closer to epicenter.

Link fixed now. Thanks!

imagine if you could channel that much kinetic energy into a propulsion system for interstellar travel

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I don't want to come off too harsh here -- not a personal attack -- but I genuinely don't understand why folks are sharing the output from LLMs. It's usually too long, it's not written by a human (which is why I came to HN), and I could have trivially asked an LLM myself!

I've been ongoingly baffled by the phenomenon as well. Like it's a new technology and all, but it seems incredibly obvious to me that copy and pasting output like that is adding nothing to the conversation (and the hallucination factor makes it, well, worse then useless IMO).

Some people are literally just that out of touch.

Imagine if every forum was just screenshots of google search results.

Yeah it is bad and a lot of damage if it hits somewhere populous but my understanding is we've tested nukes that powerful

Largest was the Tsar Bomba at > 50 megatons! https://en.wikipedia.org/wiki/Tsar_Bomba

Two terms I never heard in the table for the asteroid:

Parlermo Scale https://en.wikipedia.org/wiki/Palermo_Technical_Impact_Hazar...

Torino Scale https://en.wikipedia.org/wiki/Torino_scale

For reference the Tunguska event, which was projected to be a 5MT explosion on the low end, flattened about 2000 square kilometers when it airburst. If this hits the ocean it would no doubt cause some large tsunamis.

https://en.m.wikipedia.org/wiki/Tunguska_event

Only very locally, the Japan tsunami was an order of magnitude more energy and aiui earthquake tsunamis happen particularly with certain kinds of seafloor displacement. It's not just about the amount of energy but how that energy is applied, impact energies dissipate quickly with distance.

This one could be like Tunguska, an air bust maybe around 10km high. Would that cause a large tsunami?

It depends, on where exactly will hit. Similar to nuclear explosions, if one happen over sea or ocean near coast, it will cause extremely large wave, which will be similar to tsunami. If it will hit land, will be small earthquake.

This is why nearly all nuclear explosions was over land or far from coast. Few experiments near some coast or island, created tsunami-like wave on those coast (island), which considerable widen polluted territory (ocean is usually considered as self-cleaning).

Bookmarked - I don't want to miss a thing.

I see what you did there :)

Completely out of my domain and seat of pants rationing here, but although the impact probability is 1%, aren't we far far more certain about the /time/ at which it would strike earth? Could humanity collectively just migrate to the side of the world that will be shielded for a day?

Even if we had the infrastructural capacity to move hundreds of millions or billions of people for that amount of time (how many airplanes would you need? where would they all stay?) the political considerations would never be feasible. Think if the asteroid would hit Central America/Mexico, and think of the politics of moving them further north into North America.

I don't see why you'd make that assumption.

If we run a simulation forward to, say, Jan 1 2032, our uncertainty about where the asteroid will be is not only in, let's call it, the X and Y axes, describing a flat circle of where the asteroid might be (see [1]), but also in a Z axis.

That is, our uncertainty of where the asteroid will be can be described as a 3D shape. And if it's further "behind" or "ahead" in its trajectory, then it would be passing through Earth's orbit behind or ahead of time.

1. https://en.wikipedia.org/wiki/Torino_scale#/media/File:Apoph...

The bad news is no, we have nothing even remotely close to the infrastructure necessary to move half the world's population. We don't have the transport, being limited to planes and boats mostly.

The good news is that, worst-case scenario, this is going to wipe out a city. And cities and their surrounding areas can absolutely be evacuated. We definitely have the cars and buses necessary for that.

But in any case, we certainly have the logistics to move populations given the timeline. Not everyone has to evacuate and return within a 3 day window.

Even without incentives, in all likelihood, those who can will evacuate early for peace of mind, and as the prediction becomes more certain on its approach through measurement, individuals will I'm sure even start to return /before/ the pass. You know everyone has their own set of 9s to chase

No, we don't.

Even if we had three years to move everyone from one side of the earth to the other and could handle the transportation, and then another three years to move them back, how are you going to keep them fed? We're just going to double our food infrastructure on half of the world?

Where do we house them for several years? We're going to double our housing?

How are we going to find all those people jobs to sustain them for the several years they're spending on the other side of the world?

All those things would have to be part of the logistics too. Energy usage. Health care. The list goes on.

It would be a logistical and economic upheaval the likes of which the world has never seen. It would lead to political chaos and massive wars over suddenly incredibly limited resources.

Humanity would survive, but a lot of people wouldn't. It wouldn't be a question of logistics, but a complete and increasingly violent reconfiguration of society in all spheres.

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My mistake, my understanding was that an event of this magnitude could cause seismic/volcanic activity. Didn't realize it was so localized

Just moving a city or two 100 miles away would be sufficient, see: https://news.ycombinator.com/item?id=42864509

Supposing we had a good estimate about time and place, it would be similar in scope to evacuating for a hurricane.

XCKD has a grim and humorous breakdown of the logistics of moving billions of people: https://what-if.xkcd.com/8/

Spoiler: It's an XKCD What If, so lots and lots of people die.

Knowing humanity and its ability for planetary level solidarity, its more likely that the most powerful nations would simply displace the weaker ones. "No offence bro, but we are the salt of the Earth, so get out of here and good luck".

What about empty places? Luckily for Greenland, the calculations predict that the flux of impacts to the poles for Earth is 22% greater than the flux at the equator [1]. So nobody (in their right mind) would want to annex it as an asteroid survival backup site.

[1] https://iopscience.iop.org/article/10.3847/PSJ/abefda/pdf

2032 Mayan prophecy + 2024 YR4 = prime fuel for internet-born doomsday cults.

"The final katun in the sequence that must happen before the new cycle of the katuns begins again is 13 Ahau. This starts in 2032 and ends in 2052. It is the time from 2032 to 2052, that great earth changes may take place.

The translation from the codices about 13 Ahau that starts in 2032 is ‘Famine, plagues of locusts, and loss of rulers. The judgment of God’ Mr. Scofield goes on to elaborate on this katun.

‘This is a time of total collapse where everything is lost. It is the time of the judgment of God. There will be epidemics and plagues and then famine. Governments will be lost to foreigners and wise men and prophets will be lost.‘

It is my perception that the great crisis that many fear in 2012 may well start after 2032. An interesting note to this time period is that it did bring great revolution and change during the time period from 1776 to 1796."

https://www.tokenrock.com/mayan-astrology/2012-mayan-prophec...

Mayans did not follow the Gregorian Calendar so our yearly dates don't match they already had their apocalypse in 1500s

" This is a time of total collapse where everything is lost. It is the time of the judgment of God. There will be epidemics and plagues and then famine. Governments will be lost to foreigners and wise men and prophets will be lost.‘"

Hilarious. That article was written in 2021. We call that moving the goalposts.

Less exceptionalist American: the Maya predicted the Declaration of Independence

https://en.wikipedia.org/wiki/2024_YR4#2032_potential_impact

Perhaps this would be a good opportunity to test out asteroid deflection technologies? We've got multiple orbital refueling architectures (New Glenn, Starship...) slated to come online in the next few years, so it should be easier to pack more oomph.

Is there a "sweet spot" for asteroids where they don't impact the earth, but come within like 20 meters of it?

Like is it possible for an asteroid to give a city a "buzz cut" and then continue on into outer space?

> but come within like 20 meters of it?

like is doing some heavy lifting here. We have had asteroids pass by at a distance closer than the moon. That's pretty damn close in my book relative to the size of the cosmos. At that scale, that's pretty much a ringer in horse shoes.

The buzzcut is a very strange question though. If the thing enters the atmosphere and does not burn up, it is hitting the ground.

You are slightly mistaken. There have been hit-and-run asteroids that entered the upper atmosphere and skipped through. https://en.wikipedia.org/wiki/1972_Great_Daylight_Fireball The Grand Teton Meteor / The Great Daylight Fireball of 1972 came within 35 miles of the surface. A huge iron meteor might survive a low pass but this would be a very rare event.

https://en.wikipedia.org/wiki/Category:Earth-grazing_firebal...

In 1972, someone happened to have a camera when this passed by and captured an absolutely gorgeous shot with the Tetons in the backdrop.

https://www.gardenofmemory.net/the-great-daylight-fireball-o...

video: https://www.youtube.com/watch?v=4WlCfuPrszU -- https://www.youtube.com/watch?v=G4nP9jcFBJQ

35 miles is hardly a 20 meters' "buzzcut". The odds of that happening are probably worse than winning the lottery seventeen years in row

I don't think a 20m buzz cut and back to space is possible. To get back to space you need at least low earth orbit velocity which is about 16,000 mph and stuff going that speed low in the atmosphere gets very hot and would probably melt and break up. Maybe if it was a big one some would break off and some make it back.

Anything that comes closer than the ISS (give or take) is going to interact with the atmosphere which is going to change the dynamics considerably. Generally something with the right orbit to pass 20m above the earth's surface is going to burn up in the atmosphere or hit the surface. The drag is going to kill its orbit fairly quickly.

To have enough energy to come that close without doing so means it has enough energy that superheating the atmosphere or generating nuclear events through impacts with air molecules starts to become a problem (or both: first one then the other). This is the "baseball at the speed of light" type problem from XKCD.

If you come in at exactly the right angle (because you'll skip off the upper atmosphere if you come in too flat) and if you're fast enough, it's entirely possible to enter the atmosphere but fail to complete the aerobreaking maneuver, resulting in an exit from the atmosphere at above escape velocity.

The stress of this maneuver is considerable, especially if you get as low as 20m above ground, so the object would need considerable shear strength and yield strength. Also high density and high thermal capacity. But not unrealistic, I think a tungsten ball (or better yet, a solid tungsten lifting body with aerodynamic steering authority) should make it through.

You can even exit the atmosphere but not have escape velocity, effectively using the aerobreaking maneuver to assist in the gravity capture of your object. But you'd better circularize the orbit shortly after, otherwise your next pass through the atmosphere is going to be terminal.

Relativistic baseball effects aren't very relevant yet, I'm talking about objects hitting the upper atmosphere with around 20-50 km/s. Enough to leave again, not enough to start a fusion reaction.

I am not that good in physics so someone should probably correct me but if an object comes at such a speed that it escapes earth gravity, it'll probably eject us from our solar path into the unknown.

The mass of such an object is likely be miniscule compared to the mass of the earth. So even a very close approach isn't likely to make much difference to the earth's orbit.

E.g. an asteroid 100m across with the same density as the earth is going to have ~0.0000000000001 the mass of the earth.

Mass is relative to speed. If the object has a very high speed, it can reach the mass of the earth or even higher. That's why my understanding is that if it can escape the gravity of the earth, it means its own gravitational field is as or more powerful.

That's only relevant at relativistic speed, an Asteroid isn't going to come in at 10% of the speed of light.

An Asteroid is going at most about 70 km/s:

https://astronomy.stackexchange.com/questions/20805/what-are...

That's 0.02% of the speed of light (300 000 km/s).

The mass of an object increases appreciably with velocity only at relativistic velocities. This is completely irrelevant at the speed an asteroid is likely to be travelling.

If an asteroid travelling at relativistic velocity passed through the atmosphere, a change in the earth's orbit would be the least of our worries!

realistically any scenario is possible if the asteroid is going fast enough

...and dense enough and with enough shear strength and yield strength. Air blast disintegration is making a lot of scenarios impossible.

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If it is determined years ahead that it will hit, will there be a months to years ahead period where we will know the exact target/landing spot, eg so we can have evacuations of the impacted area and surrounding areas?

at those scales, the off by a degree type errors make a huge difference. if you're off by a small margin so that a direct impact to NYC is off to the east, then you still have tsunami issues coming to NYC. so that might not be a direct hit, it's still within blast radius.

with the earth's surface being 70% water, that means a greater chance of a water impact. so there's hope there, except that damn tsunamis again. maybe we can convince the asteroids to hit the spacecraft cemetery

The errors should be a function of time until impact. I'd like to know what that error variance vs time plot looks like.

Wouldn’t blowing it up into smaller pieces reduce the overall risk by having more of the bolide’s original mass consumed in the atmosphere?

It's 1.2% cumulative over 6 passes that begin in 2032.

1.3e-2 on the first pass, e-6 range and smaller on the following ones

I have an article looking at similar probabilities here: <https://blog.sentinel-team.org/p/how-likely-are-various-prec...>; for asteroids we gave 0.02% per decade of killing >= 1M people.

One thing to consider is that for a 55m asteroid like this one to do a lot of harm, it not only has to hit the earth, it has to hit it somewhere very populated. (only about 0.3% of the earth is very urban https://nunosempere.com/blog/2024/10/16/urban-share/)

Or hit the sea, which covers ~70% of the earth?

That's an interesting one, from the comment above yours linked article

  The Tugunska event of 1908 instead had 50-60m, but caused only three deaths because it was over a sparsely populated area; it still affected 2.1K km2 (or about two NYCs worth). 

I suppose the dust cloud from impact could take care of global warming for us, assuming it impacts land.

This article (despite the click-bait headline) has some interesting background on asteroid risk in general and 2024 YR4 in particular:

https://starwalk.space/en/news/should-you-worry-about-an-ast...

Woah. A 1% probability is a lot higher than I expected and am comfortable with (not that I can do anything about it)

Urban areas are only about 0.5% of earth surface, so rough approximation of a catastrophic hit chance is around 0.005%. The chance of you specifically being affected by this asteroid is vanishingly small.

You should personally be more worried about crossing a road or plugging in an electric appliance or being hit by a lightning. For others there's a lot more devastation going on globally that you could even do something about.

Depends if it causes tsunamis

An asteroid that size doesn't cause a very far reaching tsunami.

Not really worried that it'll impact me directly, but rather the damage that it could cause if an urban area anywhere in the world.

8 megatons is like the Tunguska impact, so not planet-destroying.

That risk corridor covers the many of the highest populated areas of Africa... and ends in India.

The impact to society would be much greater on a sociological scale then on a physical scale, many nukes are more than 8Mt, the likelihood of it hitting a highly populated area is lower still.

I don't think I understand your comment. The yield of nukes is of no consequence if they're not being used, so I don't think the comparison stands?

My point is, we have used nukes, so we know exactly what the worst case scenario is, and that’s about 20-50 million lives(hitting Tokyo or NYC). Equal to the number of deaths during the Spanish flu or half of world war 2. I think the comparison helps us understand what the risk truly is. I think the world would panic and likely loose more lives through chaos than the actual impact.

3.8m for NYC , 3.1m for Tokyo

https://nuclearsecrecy.com/nukemap/?&kt=8000&lat=40.72422&ln...

https://nuclearsecrecy.com/nukemap/?&kt=8000&lat=35.6889853&...

Losing 20-50 million lives through "panic" seems like a crazy estimate. What are you basing this on?

Do not panic, I've rolled a 1d100 and got a 42, we are safe.

About 16x the energy of the Chelyabinsk meteor.

2024 YR4 isn't that great of a name. I'm guessing the discoverer gets to name it. Is there a more human-friendly name?

So is anyone working on increasing those odds?

They're already workshopping how to blame the impact on DEI.

Since it's now okay to discriminate based on race and sex companies can put in their jobs ads 'no white men or Irish need apply'

Come friendly bombs and fall on Slough

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8Mt would be on par with a major nuke, right? Or will it become more energetic? or did I get it wrong?

I guess the probability of impact won't reach the >50% level until a few months before impact due to variations in earth's orbit and by that point the ability to do anything about it is limited.

I think the uncertainties are down to not precisely knowing:

-the size of the object

-the orbit of the object

-the velocity of the object

-effect of outgassing and solar wind on the object (as mentioned in the top comment)

Rather than uncertainties in the earth's orbit.

> due to variations in earth's orbit

I don't see how this could possibly be correct. Earth's orbit is very precisely known.

It needs a pictogram to help understand how destructive 8Mt of energy is. Is this a cool light show? Worldwide extinction?

https://nuclearsecrecy.com/nukemap/?&kt=8000&lat=40.72422&ln...

Medium scale nuclear test. Largest was 50Mt

Doesn't sound like a huge problem unless we get the size of the asteroid wrong. Won't we have a year or more of notice on where and when it will impact? Plenty of time to evacuate in a worst case scenario.

When there are hurricanes there are often holdouts that don't abide by the evacuation order. I wonder if there would be holdouts if an asteroid were coming.

Just over half of Castle Bravo. Not the end of the world. And the Earth's surface is 71% water.

With the cheap kg to orbit heavy lift systems coming online, these near misses are becoming opportunities for vast riches if they can be captured and mined. Less massive making the orbit easier to change.

Why change the orbit? Just lift off way in advance, land on it, mine it, then when the orbit is close just lift off at closest approach

The mined material (ie the entire asteroid depending on its composition) would still require delta v to a suitable orbit.

you have to have delta v regardless. enough for your mined material, or the entire mass of the asteroid. i seriously doubt we'd ever approach ability of completely mining the whole of the asteroid.

however, if you removed enough mass from the asteroid, would you end up screwing yourself by now changing the orbit so that the next time it swings by it's more of a direct trajectory?

Given the predicted time, could we calculate which hemisphere is most likely for it to impact?

It has already been calculated: https://en.wikipedia.org/wiki/File:2024_YR4_risk_corridor.pn...

It is listing 6 possible impacts.

But not the location.

Probability 1% percent with a 50% margin of error

Will the guess of an outcome improve over time?

It will converge to 0% or 100% with more observations. With 0% more likely.

In terms of the general topic of asteroid impact and risk, here is a highly informative reference.

https://cneos.jpl.nasa.gov/pd/cs/pdc25/ImpactRiskIntro-ATAP-...

> Uncertainty region (3 sigma): 1.65 million km

fingers crossed!

Giant meteor for President! Finally!

Any idea which hemisphere is going to be exposed to the (low) risk of impact?

With the size of the asteroid, is this one where we could use the gravity tractor[1] or the Yarovsky Effect[2] techniques for deflection, or is there not enough lead time?

1. https://en.wikipedia.org/wiki/Gravity_tractor 2. http://ui.adsabs.harvard.edu/abs/2021plde.confE.119A/abstrac...

To change orbit of so large asteroid, need huge amount of energy.

Unfortunately, humanity now have only small power ready, for such far things just about 50kW, it will need decades to transfer so large energy.

Russians claimed to create nuclear reactor for space with somewhere near 200kW, but unfortunately, now these are just words, very far from real hardware.

If Mt of asteroid impact roughly equates to a nuclear weapon, then this is pretty bad for a metropolitan area but not enough to put a big dent in humanity.

There's a 3 in 4 chance an asteroid hitting the earth will hit water, and of the remaining change about 50/50 it hits a desert or ice sheet (Antarctica, Greenland).

The stripe where this object could hit is mostly at low latitude.

Sorry could you expand / clarify this comment? What would make this more likely to hit near the tropics?

The risk corridor calculated here https://en.wikipedia.org/wiki/File:2024_YR4_risk_corridor.pn...

Hitting an ice sheet might be worst case scenario for global impact.

Depending on the amount, if landing on solid earth, the effect of dust ejected into the atmosphere might be critically significant in terms of energy dynamics and solar energy production.

I think it if it's far enough out you only need to change it's trajectory only very slightly to reduce to the probably of impact to something much less

It would have been scary even 2 years ago but by that time AI would solve that, maybe even turn it into some sort of mining operation

By 'solve' do you mean 'write a limerick about'?

You don’t think we will have AGI or even ASI by then to have significantly improved tech? I would be we will

An AI that can save us from an asteroid hitting earth in 2032? I think that is highly unlikely.

what the fuck are you fucking talking about

Thatll be dpn jrs first term so expect a "dont look up" sequel

What can be done to increase the asteroid impact probability?

And can we speed up the timeline? 2032 is too far away.

Can we also add mass to the asteroid?

And speed

We're gonna need a bigger rock.

Monke, smash!!

The best way I can think of is similar to what I heard from Jaron Lanier (he may not be the first person to explain this). Basically what you do is send something massive out there that will gravitationally tug it into a collision course with Earth. Obviously this will take quite a bit of time but if your calculations are correct it will pretty much guarantee impact.

Waiting. In general the probability increases as more data is gathered, and the error ellipse shrinks with the Earth still inside. Then is suddenly drops to zero in the overwhelming majority of cases, when the Earth finally gets out of this shrinking error ellipse.

The precision (of the observed trajectory) increases. If the probability increased in general we should recalibrate our probability estimates.

Get a lot of people to jump at the same time to nudge us into the path.

This would move the Earth by less than the width of an atom: https://what-if.xkcd.com/8/

So, we all have to just skip for a while ?

There's a Sci-Fi Plot in there somewhere:

A hero tries to and succeeds in persuading govts to organize a planet scale skipping effort to get earth closer to a passing by rock and escape an impending disaster on earth.

GP didn’t specify Earth.

God I love HN.

that's a beautiful idea. it will only work if we act together as one human race. this is the moment where we have to put political conflicts aside and commit collective suicide.

We can land on it, drill and plant nukes inside to shatter it

Can't tell why I'm hearing "I could stay awake just to hear you breathin" in my head when reading the above

That's not what they asked

That would create far more objects, many on the same rough direction, thus increasing the chance of an impact

Only if you managed to leave the trajectory the same if it was already on a collision course or change the direction to a collision course. Do you think you can control that with a nuclear explosion? You probably don't know enough about to the system to make a high confidence prediction of the new outcome.

Not really, blowing it up is going to create a lot of fragments with slightly different orbits, and some are going to have practically the same as the whole Asteroid had before. So the chance of anything at all hitting earth will increase, but the parts will be smaller. It would be like a bullet turning into buckshot during flight.

If we were talking about a projectile fired at relatively close range on the surface of the Earth I would agree with you. But we are talking about a very small object very far away with already only a 1% chance of impact. Buckshotting the object with a random explosion is unlikely to change the dynamics of system to point where you say with high confidence the chance of impact is much higher. Some fragments might hit but it's very difficult to predict.

As long as some part of the asteroid keeps the old trajectory, the chance can only increase because you’re adding particles with slightly different trajectories.

It would definitely increase impact probability though.

Not necessarily. See my new comment above. In addition, depending on how far out you do it, gravity will allow it to reform. And if it never reforms because you blew it to dust headed out to interstellar space you wont get an impact either. It's not at all a simple problem.

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Don't become the very thing you claim to hate!

Been rooting for Asteroid/Meteor in the recent presidential elections.

Full link: https://cneos.jpl.nasa.gov/sentry/details.html#?des=2024%20Y...

You can email hn@ to ask them to fix a link.

The title bot likes to strip URL parameters.

In this case it changed the link because https://cneos.jpl.nasa.gov/sentry/details.html was listed as the canonical URL on the page. We've reverted that now.

Fixed now. Thanks!

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I don't know, i think we needed some precious minerals

Is that probability of an impact 1% or 1 = 100%????

it says 1% in the title, what's there to misunderstand?

1% is tiny, really small.

In my experience, commonly orbits in the solar system are astoundingly accurate over centuries. This prediction is relatively soon, 2032.

So, we have (A) a crude orbit and only 1% prediction of hitting Earth or (B) an accurate prediction of 100% = 1. Between these two, (A) seemed too small and (B) too large. So, I asked.

This question seemed appropriate enough.

Reading the paper, sure, they have a lot of predictions for several decades to come with all the probabilities close to 1% and far from 100%. The paper gives some details on the difficulty of getting a very accurate orbit for the object. So, apparently the 1% is what they have in mind and their title, accurate.

So, if it hits, what might be the damage?

And it it does hit, what would be the probability of it hitting a densely populated area instead of ocean, desert, mountains, ...? Net, with the 1%, the risk of major damage seems quite small.

Hmm, what would the insurance industry think? Vegas?

1% is 1 in 100.

If you detected 100 objects with a 1% chance to hit, you're actually very likely to be hit by more the 1. There's a lot of objects up there, fortunately the chances they hit us are a lot lower then that so far.

1%

Don't Look Up Vibes

Maybe it will start climbing in probability, giving us a chance to reflect, and to improve our ways.

Since, if we're already doing Nazi salutes at a US Presidential inauguration, less than 100 years after we'd learned that Nazis are pure evil, then I'd understand if some higher power was ready to hit the reset button. Maybe tardigrades would evolve better.

(ProTip: Be sure to send a second asteroid, to Mars, ahead of the Nazi escape ship.)

You just Godwin'ed the crap out of this thing. Congratulations, I guess.

https://en.wikipedia.org/wiki/Godwin%27s_law#:~:text=Godwin'...

In a time when, apparently, it needs to be said that "Nazis are bad", that's the best way I can imagine to spend hard-earned HN Internet Points.

Alternatively, perfect timing for a "US saves the world" moment.

That salute stuff is just to distract people, maybe it was even carefully planned.

I'd rather focus on Bitcoin, AI and Blockchain scams as well as nepotism. The official excuse for Ramaswamy's DOGE exit is that Musk has a tech approach to solving (?) the efficiency problems:

https://www.newsweek.com/vivek-ramaswamy-asked-if-elon-musk-...

Expect a lot of blockchain nonsense infiltrating the government, perhaps even a digital currency. That must be avoided at all costs.

Basically the same odds of dying in a car crash over your lifetime. So unless you give up on driving or being a passenger of a car—this is a meaningless risk, and besides that, it is even less likely to hit land, let alone a populated area. The chance that this will impact you is unbelievably low.

This is so below the threshold of worry, I’m shocked by the points and comments.

Schedule a colonoscopy, quit drinking, resign from your high stress job, drive less, get your moles checked; all better mitigation for prolonging you life than worrying about this.

I used genAI to help me understand the Palermo scale number seeming low.

The 2032 asteroid does warrant tracking, but the Palermo Scale remains below a critical level because:

The impact probability (1.2%) is not high enough to trigger a stronger alarm. The background frequency of 8 Mt impacts is relatively high, making this event less statistically exceptional. The event is still 8 years away, so uncertainties in orbital prediction remain.

I asked a parrot about quantum physics and it told me I’m a pretty bird.

Could be LLM generated spam post to promote LLM generated spam?

I find it fascinating that some people may brag about not using their brain like that…

Asking a LLM about topics you have no idea about it a great way to be misled by hallucinations, don't do that.

It's actually a great way to find concepts to verify and ask questions about. You will often find out about tangential topics you otherwise would not have.

I find it fascinating that people brag about refusing to even try to learn to use new tools just because they don't know how to use them effectively.

> I find it fascinating that people brag about refusing to even try to learn to use new tools just because they don't know how to use them effectively

Interesting how you jump to conclusion based on nothing. Had you checked my profile (even though it's even more obvious from my Reddit one) you'd have seen that I'm actually pretty savvy when of comes to language models.

But knowing your tools also implies knowing their limits.

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Yet you behave the exact same way …

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Rules For Thee but Not for Me

My comment was illustrative and was intended to mock your insult. If you can't see that I suspect you are either not being genuine, or just generally have trouble with social clues.

In any case, this discussion has devolved too far into bickering and tone policing, so I concede; you're right, I shouldn't have mocked you.