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Asteroid Impact on Earth 2032 with Probability 1% and 8Mt Energy

cneos.jpl.nasa.gov

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Re: Asteroid Impact on Earth 2032 with Probability 1% and 8Mt Energy

#221

Post by jaggederest »

NL807 wrote: post #164
VierScar wrote: post #137

Earlier quoted context omitted.

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 an…

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

Re: Asteroid Impact on Earth 2032 with Probability 1% and 8Mt Energy

#222

Post by coderenegade »

NL807 wrote: post #164
VierScar wrote: post #137

Earlier quoted context omitted.

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 an…

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.

Re: Asteroid Impact on Earth 2032 with Probability 1% and 8Mt Energy

#223

Post by eddieh »

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.

Re: Asteroid Impact on Earth 2032 with Probability 1% and 8Mt Energy

#224

Post by coderenegade »

ddahlen wrote: post #176
slackerIII wrote: post #102

Earlier quoted context omitted.

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 t…

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.

Re: Asteroid Impact on Earth 2032 with Probability 1% and 8Mt Energy

#225

Post by slashdev »

mmooss wrote: post #188
SR2Z wrote: post #156

Earlier quoted context omitted.

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.

> 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 traje…

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

Re: Asteroid Impact on Earth 2032 with Probability 1% and 8Mt Energy

#226

Post by energy123 »

dylan604 wrote: post #185
indigodaddy wrote: post #171

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. ma…

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

Re: Asteroid Impact on Earth 2032 with Probability 1% and 8Mt Energy

#227

Post by [deleted] »

NunoSempere wrote: post #116

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/blo…

[deleted]

Re: Asteroid Impact on Earth 2032 with Probability 1% and 8Mt Energy

#228

Post by justinclift »

sharpshadow wrote: post #104
DennisP wrote: post #67

Earlier quoted context omitted.

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.

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?

Re: Asteroid Impact on Earth 2032 with Probability 1% and 8Mt Energy

#230

Post by NL807 »

coderenegade wrote: post #222
NL807 wrote: post #164

Earlier quoted context omitted.

>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 an…

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 tr…

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).
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