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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

#241

Post by hermitcrab »

csomar wrote: post #231
i_am_a_squirrel wrote: post #178

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?

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.

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

#242

Post by hermitcrab »

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…

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

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

#243

Post by hermitcrab »

barbegal wrote: post #22

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.

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

#244

Post by defrost »

hermitcrab wrote: post #242
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…

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).
which raises questions about what kind of wave such an impact could create and what are the odds of that hitting a populated coastal town (or three) might be.

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

#247

Post by coderenegade »

NL807 wrote: post #230
coderenegade wrote: post #222

Earlier quoted context omitted.

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 t…

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.

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

#248

Post by baq »

VierScar wrote: post #137
renjimen wrote: post #123

Earlier quoted context omitted.

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?

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

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

#250

Post by baq »

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…

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…
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