Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

cneos.jpl.nasa.gov

Post reply on HN
Print view View original

331–340 of 374 posts

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

#331

Post by tofof »

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…

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.

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

#332

Post by SamBam »

me-vs-cat wrote: post #195
ddahlen wrote: post #84

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 w…

> 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?

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.

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

#333

Post by mongol »

ars wrote: post #198
School-Cotton wrote: post #174

Earlier quoted context omitted.

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...?

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

#334

Post by SamBam »

elif wrote: post #291

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?

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...

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

#335

Post by Ajedi32 »

layer8 wrote: post #20

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

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.

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

#336

Post by ddahlen »

coderenegade wrote: post #224
ddahlen wrote: post #176

Earlier quoted context omitted.

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.

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.

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

#337

Post by lupusreal »

grapesodaaaaa wrote: post #325
AISnakeOil wrote: post #324

Earlier quoted context omitted.

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.

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

#338

Post by gWPVhyxPHqvk »

elif wrote: post #291

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.

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

#340

Post by m3kw9 »

hermitcrab wrote: post #246
m3kw9 wrote: post #142

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
Post reply on HN