Near Earth Asteroids

[Shadowy Man]

But is there some reason why NEOs with such orbits (year an integer multiple of Earth's year & perigee near Earth) are the most likely colliders?

is this a true statement? What statistics have you seen that suggest this?

If it is true, I’d surmise it’s that other orbits that cross earth’s, do so at greater angles to earth’s travel, giving them less time in or around earth’s orbital path.

Well, orbital resonances are a thing so it’s not impossible that there are specific periods of NEOs that are more favorable for collisions. But I haven’t seen the statistics on that specifically.

Yes, objects with periods closer to earth will be more likely than the long period objects that swing by really fast to make impact and have multiple opportunities too.

 

[Swammerdami]

But is there some reason why NEOs with such orbits (year an integer multiple of Earth's year & perigee near Earth) are the most likely colliders?

is this a true statement? What statistics have you seen that suggest this?

And once again, the ambiguity of English strikes! I wrote "Is there some reason why X?" I was NOT stating that X is true, but rather ASKING if X is true (and if so, wondering why). The JPL site you and I both linked to probably has useful data, but I am incompetent and gave up.

One thing DOES seem to be true (or do I have this wrong also?): The special orbit of 2024 YR4 led to its DETECTION 8 years before the projected near-collision. Without such a special orbit, a colliding asteroid of that size wouldn't be detected until it was nearly upon us, especially if approaching the sunny side.

 

[bilby]

Presumably the objects with the greatest chance of becoming impactors are simply those which cross Earth's orbit most often.

And such objects are, for the same reason, most likely to be detected prior to the orbit during which the impact occurs.

 

[Swammerdami]

2024 YR4 had a near collision in late December 2020 (according to the JPL orbit-viewer). Why wasn't it detected then?

BTW, it appears to me the JPL Orbit-viewer I linked to does NOT compute orbit completely, e.g. to reflect changes due to a near-Earth approach. It just moves the asteroid around and around in a fixed ellipse. (Is this correct?) That webpage shows the asteroid nearly colliding every four years in the near future and NOT the perturbed timings Bomb#20 mentioned in post #26.

 

[Swammerdami]

... 2024 YR4 currently has a 4-year orbital period; it had close approaches in 2016 and 2020, and another is scheduled for 2028. But according to this NASA website, the most likely upcoming collision possibilities are in 2032, 2039, 2043, 2047, 2074, and 2079. The ones after 2032 aren't multiples of 4 years. So NASA is evidently expecting the earth's gravity to have a huge effect on the outgoing trajectory. It could reduce the orbital period by as much as six months.

Clicking to Bomb#20's link I find the dates of the projected near-collisions

2032-12-22.59
2039-12-23.35
2043-12-23.15
2047-12-22.05
2047-12-22.05
2079-12-22.73

This seems dreadfully wrong. The 4-year cycle remains 4 years almost exactly, but one entire year is skipped! Skipping that YEAR implies a HUGE change to the asteroid's ellipse, yet there it remains, AFTER the skipped-year, in an exact 4-year cycle, still with nearest approach just before Christmas?

I'll bet there was some sort of reporting "glitch" at NASA or JPL making these dates off by one year. Any takers?

 

[bilby]

2024 YR4 had a near collision in late December 2020 (according to the JPL orbit-viewer). Why wasn't it detected then?

It was probably in our blind-spot. Large vehicles often have huge blind spots, and the Earth is just about the largest passenger vehicle I know of. It's not even fitted with reversing cameras.

 

[Bomb#20]

Clicking to Bomb#20's link I find the dates of the projected near-collisions

2032-12-22.59
2039-12-23.35
2043-12-23.15
2047-12-22.05
2047-12-22.05
2079-12-22.73

This seems dreadfully wrong. The 4-year cycle remains 4 years almost exactly, but one entire year is skipped! Skipping that YEAR implies a HUGE change to the asteroid's ellipse, yet there it remains, AFTER the skipped-year, in an exact 4-year cycle, still with nearest approach just before Christmas?

I'll bet there was some sort of reporting "glitch" at NASA or JPL making these dates off by one year. Any takers?

Well, the thing to keep in mind is that these are all million-to-one longshots. So something staggeringly unlikely could make the asteroid come back at these times; it's just that hitting us in other years is even more unlikely. So, just wildly speculating here, maybe in NASA's simulations they saw a scenario where the 2032 interaction knocked the period down to 3.5 years and then the resulting 2039 interaction kicked it back up to 4 years. And however improbable that is, other scenarios leading to collisions all turned out to be even more improbable.

As far as Christmas goes, that's pretty much inevitable, since orbits are ellipses. Whenever an asteroid orbit is altered by a close approach to a planet, the point in space where that happened is necessarily a point on the new orbit, so it's necessarily a point the asteroid will come back to. The planet will come back there too of course, so the original intersection point will continue to be the intersection point with the new orbit. And the Earth will always come to that point at the same time of year since a year is Earth's orbital period. So 2024 YR4 is never coming back except just before Christmas, unless it first has a close approach to Mars or Ceres or something to kick it onto a new orbit.

 

[Swammerdami]

This seems dreadfully wrong. ...

I'll bet there was some sort of reporting "glitch" at NASA or JPL making these dates off by one year. Any takers?

Well, the thing to keep in mind is that these are all million-to-one longshots. So something staggeringly unlikely could make the asteroid come back at these times; it's just that hitting us in other years is even more unlikely.

I'm still willing to make the bet. Gambling for money is probably against ToU. So ... Loser has to click Like (or some other icon!) on all the Winner's posts for three weeks?

 

[bilby]

Loser has to click Like (or some other icon!)

See above...

 

[Bomb#20]

This seems dreadfully wrong. ...

I'll bet there was some sort of reporting "glitch" at NASA or JPL making these dates off by one year. Any takers?

Well, the thing to keep in mind is that these are all million-to-one longshots. So something staggeringly unlikely could make the asteroid come back at these times; it's just that hitting us in other years is even more unlikely.

I'm still willing to make the bet. Gambling for money is probably against ToU. So ... Loser has to click Like (or some other icon!) on all the Winner's posts for three weeks?

How do you envision settling the bet? Suppose your hypothesis is correct. Do you have a strategy in mind for getting NASA to admit it's correct?

 

[Swammerdami]

This seems dreadfully wrong. ...

I'll bet there was some sort of reporting "glitch" at NASA or JPL making these dates off by one year. Any takers?

Well, the thing to keep in mind is that these are all million-to-one longshots. So something staggeringly unlikely could make the asteroid come back at these times; it's just that hitting us in other years is even more unlikely.

I'm still willing to make the bet. Gambling for money is probably against ToU. So ... Loser has to click Like (or some other icon!) on all the Winner's posts for three weeks?

How do you envision settling the bet? Suppose your hypothesis is correct. Do you have a strategy in mind for getting NASA to admit it's correct?

In the olden days -- e.g. 2024 -- I'd expect NASA to answer a polite e-mail and correct their webpage if appropriate.

It may be harder in 2025, with remaining NASA staff busy delivering all their secrets to Musk, and burning documents containing the word "climate."

 

[Loren Pechtel]

If they know the direction the asteroid is moving to a high degree of precision, but have more uncertainty about its speed (or its distance), then that would result in a projected impact whose location is determined by the rotation of the Earth, and whose probability of occurring is determined by Earth's movement along her orbit; Both of these vary by a FAR greater amount in the East-West direction than they do in the North-South direction.

Rotation??? Earth's rotation is on the order of 1 km/sec. Compared to the 30 km/sec of our orbit.

So what? The precise point of impact still depends on what part of the surface is pointing towards the incoming object when it arrives.

The point is the dominant force is our movement, not our rotation. We streak through the threat zone in 7 minutes plus a bit from drawing it in when it would otherwise have been a near miss. A small uncertainty on when it will arrive will produce a big streak like that plot.

 

[Loren Pechtel]

I think that's right, but here's the rest of the story. 2024 YR4 currently has a 4-year orbital period; it had close approaches in 2016 and 2020, and another is scheduled for 2028. But according to this NASA website, the most likely upcoming collision possibilities are in 2032, 2039, 2043, 2047, 2074, and 2079. The ones after 2032 aren't multiples of 4 years. So NASA is evidently expecting the earth's gravity to have a huge effect on the outgoing trajectory. It could reduce the orbital period by as much as six months.

As of February 10, 2025, the probability of asteroid 2024 YR4 impacting Earth on December 22, 2032, is 2.3%

That seems like a pretty significant chance.
I guess if we don’t look up …
If we add the chances of impact in the other 5 dates Bomb mentioned, are we above 10% yet?

Not even close, The odds for all the other dates add up to about 1 in 100,000. (And according to the site's latest update 2074 is no longer a potential collision.)

Based on how erratic the pattern of potential collision dates is, it looks to me like NASA thinks by far the most likely scenario is that the 2032 interaction will alter the period of the orbit from its current exact resonance with Earth's orbit to some random-ass period like three years and 354 days, which means 2024 YR4 is going to take up repeatedly returning to the point where our orbits cross on dates other than Dec. 22, when the Earth gets there every year, which means we probably won't see it again for maybe a thousand years.

This is an example of why the general n-body problem has no solution. Any uncertainty in it's orbit will be hugely magnified by a near enough miss, we simply can't make a realistic projection past that point.

 

[Loren Pechtel]

The asteroid 2024 YR4 has an orbital period of almost exactly 4 years and, moreover, is currently aligned to nearly collide with Earth once every 4 years. Furthermore its minimal distance to the Sun is not much less than 1 AU.

I can understand why those parameters made it so easy to detect: It came very close December 21. But is there some reason why NEOs with such orbits (year an integer multiple of Earth's year & perigee near Earth) are the most likely colliders? Is the prior orbit of the Tunguska asteroid known or guessable?

If it's in a resonance it has a chance to hit each time around. And it has come close so we have a good plot of where it's going.

An object which is not in such an orbit will be much, much less likely to be noticed and very well might go undetected until the ballistic warning radars see it.

 

[Elixir]

Vice.com reports odds of 2024-Y4 impacting earth in 2032 are now down to 1:43, from 1:87 whe it was first tracked.

If it starts creeping towards 1:2 will President Musk start talking about intercepting it?

 

[thebeave]

Vice.com reports odds of 2024-Y4 impacting earth in 2032 are now down to 1:43, from 1:87 whe it was first tracked.

If it starts creeping towards 1:2 will President Musk start talking about intercepting it?

I wouldn't be surprised if he starts talking about it long before it gets that close.

Assuming we decide to try to build an interceptor for this asteroid, there's a good chance that SpaceX will play a big role. They have the big rockets and expertise. If he ends up saving mankind from destruction, will the hard core lefties be willing to give him at least a pat on the back, or will they still find a reason treat him as a pariah? Like bringing up his bad poetry. I wonder...

 

[bilby]

If he ends up saving mankind from destruction,

By diverting an asteroid that's at most large enough to take out one city, and that almost certainly won't hit a built-up area at all?

The absolute most he could possibly do is save about one percent of mankind from destruction, because that's the maximum damage the asteroid in question is capable of inflicting, in the worst possible case of an impact directly onto a major conurbation.

That might still be worthy of a pat on the back, but it cannot in any way mitgate or redeem the harms he is currently doing.

The guy who finally managed to shoot Adolf Hitler dead doesn't get many plaudits, for much the same reason. He did the world a huge favour, but it was too little, too late.

 

[crazyfingers]

The guy who finally managed to shoot Adolf Hitler dead doesn't get many plaudits, for much the same reason. He did the world a huge favour, but it was too little, too late.

Hitler shot himself in the head

 

[Elixir]

If he ends up saving mankind from destruction, will the hard core lefties be willing to give him at least a pat on the back, or will they still find a reason treat him as a pariah?

If he can get the USA to underwrite a successful effort to avoid a collision I will give him props, AND treat him like a pariah.
Because he’s a scumbag. Even scumbags can become accidental heroes.

OTOH, if Elon himself rides a nuke into the asteroid Slim Pickens-style, I’ll give him bigtime credit whether or not it works, just for saving us from Elon Musk.

 

[Elixir]

The guy who finally managed to shoot Adolf Hitler dead doesn't get many plaudits, for much the same reason. He did the world a huge favour, but it was too little, too late.

Hitler shot himself in the head

And as bilby pointed out, he doesn’t get much credit for that.