2004 MN4, Even Higher Probability

phreakuencies writes "Worried since the recent post about the MN4 2004 asteroid, I added a bookmark to its 'impact risk' section at NASA. The asteroid started as having a 1/233 probability of hitting earth. Later it raised to 1/63. Daily computations made on 25 Dec raised its chances up to 1/45. Optimists can now say it has a 97.8% probability of missing earth." And Veteran writes " NeoDys offers the 'Orbfit' software package (source code released under the GPL) which can be used to get a pre-release view of the situation with Asteroid 2004MN4."

Comments

Party like it's 2099

[IO ERROR]

And now it's 4 on the Torino Impact Hazard Scale.

The way I see it, we've got about 24 years to party before the world ends. Have another glögg!

Seriously, if it hits 5 or greater on the scale, then we'll have reason to really worry. In the meantime, it's sufficient to just watch and see what happens. As phreakuencies pointed out, right now there's a 97.8% chance of absolutely nothing happening.

Re:Party like it's 2099

[TimToady]

Sorry, it's aimed mostly at the eastern hemisphere. If it hits, it'll be at about 9:22pm in London (.89 of a day at UTC), and since the rock is coming in almost directly from the night side of the planet, it's mostly aimed about 3 zones east of London plus or minus 6 hours. Or were you thinking that Iraq would have been renamed "Texas" by then?

Re:Party like it's 2099

[Zocalo]

Talking of the Torino scale, does anyone have any idea at what percentage probablility of impact it would move up to the orange (threatening) section of the scale? As far as I can tell, both the orange and red (impact!) sections are based more on the predicted amount of damage rather than likelihood of a collision, so I'm guessing it's pretty high. Also, assuming that the estimated size and consistency of the object don't change, it looks like an object would not be given two separate orange or red scores. If that's the case then I'm guessing that if MN4 is going to hit us it'll go to five, then eight based on a play with the damage predictor.

In any case, we have 24 years and it's not *that* big. Plenty of time to nudge it off course with some of those surplus nukes we have lying around if it is going to hit...

Re:Party like it's 2099

[MoonBuggy]

Seriously, if it hits 5 or greater on the scale, then we'll have reason to really worry.

Even if it does hit 5, it's worth noting that the probability estimation has changed twice in the space of a day. That's no insult to the mathematicians - I can't begin to grasp the variables involved here, but if the numbers can change that fast I think it's safe to assume that there's going to be more fiddling of the statistics needed in the next 24 years before we get an acurate projection.

Re:Party like it's 2099

[NockPoint]

When it is going to hit (if it does) is known down to minutes NOW. That and knowing which way it is coming from allows us to exclude half the planet from worries other than climatic. As someone has already pointed out, that means both NY city and Texas are safe from this rock.

The uncertainty is a long strip that is 0.018 (see NEODyS) of the Earth's radius wide, and many times the Earth's radius long. Go look at:

http://neo.jpl.nasa.gov/images/2004mn4b.gif

If the odds don't go down to zero soon, someone will calculate where the stripe of uncertainty is on the globe. It wouldn't be hard to do.

Re:Party like it's 2099

[Scarblac]

Of course the statistics change - more measurements are being done, so the error margin on the estimate goes down. There is a band of possibilities, a bunch of possible trajectories, and more measurements make that band smaller.

Currently Earth is still within that band, and Earth's diameter is about 1/45th of the width of the band, so that's the probability of a hit.

Since more measurements are being done, we'll see this for a few more days - either the band is smaller and Earth is still within it, which raises the probability, or the band is smaller and Earth isn't in it anymore, and the probability drops to 0.

Saying this is "fiddling of statistics" is an insult to the mathematicians involved.

(Story above is simplified, by making it 2D instead of 3D, and by ignoring the fact that it's probably not some fixed area but the probabilities of the thing going outside the area are smaller and it's some weighted average, and I don't really know anything about the maths, I just think it's obvious that the probability would change quickly).

Impact calculator

[Nine Tenths of The W]

Just to reassure you
http://janus.astro.umd.edu/astro/impact/
The impact comes out as somewhere between 450MT and 1.6GT, depending on speed and composition

10 Bucks on Florida

[GeekDork]

'nuff said

Re: Seriously, you might as well relax.

[Black Parrot]

> You know in all those movies where some guy, sometimes just an amateur scientist, sees something in his telescope/seismograph/thermometer/disease-modeling -software that all the high-up professionals miss, and rushes in to warn the government?

> That doesn't happen.

You're with the agency that makes those guys disappear, aren't you.

Exciting!

[DogDude]

Am I just sick, or do other people find the possibility of this thing hitting to be pretty damn exciting? The chaos, the devestation, the panic, the collapse of all social systems... jeez, that would honestly be one of the coolest (And last) things to ever happen in most of our lives. The timeframe is nice too... many of us that are currently in our late 20's, early 30's will be wiped out before things start going really downhill for us (physically), but we'll have enough time to get a decent bit of fun stuff done too. Bring it on!

Re:Exciting!

[fionbio]

It's hard to find such thing exciting if you have children.

Re:Exciting!

[zmooc]

One more reason for not having kids:)

Common mistake in press coverage

[AxelBoldt]

Many press reports essentially say "the chances of impact is relatively high with 1 in 45, but don't worry since it is almost certain that future observations will exclude the possibility of impact." Even the original NASA report contained a sentence like that.

It's important to note that if the chances of impact are 1 in 45, then the chances that future observations will exclude the possibility impact are 44 in 45.

The two events "asteroid hits us" and "we can never exclude the possibility of it hitting us" are equivalent: the first happens if and only if the second happens. Therefore the two events have the same probability.

So the "don't worry" part of the above sentence is pointless: the second half sentence is a mere reformulation of the first; there is no reassuring "extremely high" probability that future observations will correct the number downward.

Re:Common mistake in press coverage

[angel'o'sphere]

Well, seems you don't get the problem.

Simple map of the Earth moon Sysstem:

1 _ _ _ 10 _ _ _ 20 _ _ _ 30 _ _ _ 40 _ _ _
E ... m

Simple map of the path of the asteroid:

/ / / ... ... / / /

That should be 42 stripes but the junk char filter ....

As you see, the first stripe hits earth, the other 41 don't hit. Well, moon is in fact at opposite position when the asteroid comes in, but it was difficult to "draw" that. So, remember moon wont be hit.

Further observations of the asteroid will give us more data to determine wether the asteroid will travel stripe number 1 or 2, or wether it will travel stripe number 20 or 30 or whatever.

If we figure the asteroid is traveling NOT stripe 1 we are 100% certain that it will miss us.

If we figure the asteroid will not travel stripes 31 to 42, the likelyhood of an impact increased to 1:30.

Both calculations are "100%" certain. OTOH, your parent was right. The likelyhood that the chance of getting hit decreases is high. You have 42 draws ... and in 41 draws you have the chance that stripe number 1 -- the stripe which hits earth -- is removed from the set or possible pathes. Because more accurate measurement shows that the asteroid wont go that path/stripe.

angel'o'sphere

Re:Something to bear in mind

[barawn]

That's not necessarily true. It depends on the characteristics of the error.

If the errors are Gaussian, if the nominal trajectory (i.e. "it misses the Earth by X+/-Y km") is accurate, but imprecise (that is, X is correct, but Y is large compared to X) then the probability of impact will decrease as the precision is improved (i.e. as Y decreases) because the "Earth impact" possibility moves farther out on the fringes of the observation, and the area doesn't shrink fast enough to compensate for this.

Of course, if the errors are flat (all solutions are equally likely - actually, if the PSF falls off slower than the area shrinks) then you're correct. I'm pretty sure that they're Gaussian, or approximately Gaussian, though. So the only way the probability could be increasing is if the nominal trajectory's impact parameter is decreasing - that is, closer impact.

Not too big a deal, I think

[philovivero]

From the last post about this, I went and read up on the whole thing. I went to the beautiful CGI script where you input asteroid size and velocity and all that, and assumed I was 100km from the impact.

I had to up the asteroid size to 1300 metres and a velocity of 14kps of dense rock colliding with porous rock before I could interpret the results as something that would suck for me (2nd degree burns on my body from the fireball).

There would be no major earth effects of such an asteroid hitting Earth, so it said.

Compare these stats against our current fearsome asteroid.

In one thread I saw someone refer to this as possibly a human-extinction event. I have a hard time believing that once I actually bother to go check this out. It'd sure suck for everyone within 100km of the impact site but for everyone else, I guess we'd have about the same effects as a major earthquake to deal with.

Re:Not too big a deal, I think

[coyote-san]

Maybe you'll "only" get second-degree burns from the fireball, but what about everything else in your vicinity exposed to the same energy?

Anyway, for large nuclear explosions radiation isn't an immediate concern. If you're close enough to catch much radiation you're already dead from the other effects. What kills you at distance is the overpressure wave and the radiant energy. The former knocks down structures and the second ignites fires that grow into firestorms.

If you think back to those early films of atomic bomb tests, that's why the paint on the house smolders (radiant energy) before being blown to kindling (overpressure wave). Terminator 2 showed the same sequence.

You might think you're safe from 2nd degree burns if you hang out side during the initial flash, but that won't do you much good if the house is blown down around you.

P.S., before somebody mentions it a nuke's nuclear reaction has stopped long before the fireball is a foot or so across - the size of the original warhead. Afterwards everything else is a case of extreme thermodynamics, the origin of the energy is irrelevant.

An impact's fireball is far more spread out, but it ultimately comes down to a very large fireball and local seismic effects.

it actually can be a good thing

[BigGerman]

you know.

Imagine how much technology boost all the related stuff will receive. If the Moon shot (the pure publicity stunt) generated so much progress, imagine this.

By the time we will know it is going to miss by 500km, we will already have cheap reliable interplanet travel and will be able to melt/mine/whatever the asteroids. Cool.

Maybe I'm a sick puppy..,

[TLLOTS]

...but I sort of hope it is found to have a much, much higher likelyhood of hitting earth, so much so that's it's almost certain to occur.

Why? Simply because it would post such a great challenge for humankind. It could well bring much greater cooperation between countries, cooperation of a level presently unheard of.

Certainly, I'm not hoping it actually strikes earth, merely that people work together in order to stop it.

Just be glad that Bush won't be the president at the time. If it did hit, in US soil no less, then he'd start pouring billions per month into NASA for the development of spacecraft to fight the alien 'terrorists' who threw that asteroid at America.

Let's say that the thing will hit

[ArcticCelt]

Let's say for a moment it is confirmed that the thing will hit. Then we will have to determine where its going to hit. We know that damages will only be localized so if it is calculated that the asteroid will fall on an area populated by not so industrialized countries I am really curious how the world will react.

Do powerful countries will prefer to do nothing to avert making a mistake that could possibly send the asteroid on their head?

What could possibly do a small country in africa if nobody wants to help them?

Re:Let's say that the thing will hit

[Zocalo]

Or another possibility: what if it turns out that an impact will be on an industrialised country "Gog", sufficiently far from a political/economic rival "Magog" to offer no real threat to "Magog"? Would Magog dare to offer less than 100% of what it can offer to preventing the disaster, either publically or otherwise?

To get a clue as to the answers, look at the recent devastating earthquakes in Iran - even though Iran was on his "Axis of Evil", Bush was offering aid almost immediately. Sure, besides the humanitarian side, there is also political capital to be made on such a gesture, but that's by the by. I have absolutely no doubt that if this, or any other asteroid, is going to hit us then every capable nation will be working 100% to prevent the impact, no matter where it might be.

Re:Whew

[momerath2003]

At first I thought it says " it has a 97.8% probability of hitting earth"

Good thing i read it over again.

Good thing! If you hadn't, we'd be in some big trouble.