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Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

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Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#21

Post by mike_d »

s1artibartfast wrote: post #15
phkahler wrote: post #4

"Maybe the big take-home point on this one is it's a pretty big object and it was only found 10 or 12 days before closest approach," I've said this before. The way they find these things is looking for movement against the distant background / starfield. That works pretty well for finding things, but there is one problem. Any object on a collision course with earth will NOT be moving across the background in the days…

>It will appear stationary against the stars, so will not be detected by these systems. To some extent it also doesn't matter that we are orbiting the sun because while near, earth and asteroid will be in the same accelerating reference frame. I dont think that is true aside from the case where the asteroid vector is the exact opposite of the earth. Even if the earth and the asteroid are in the same accelerating refe…

> If you have two race cars going in around a track and at one from the other, it still appears to be moving relative to the stands.

Right. Now put the stands on another planet and you start to understand the problem.

We need to be able to see an asteroid at a minimum of of 3-4x the distance between the earth and the sun to have enough time to do anything about it based on the average speed of 40k mph.

Now keep in mind that at that distance you are looking for something as "tiny" as 60 miles across, the accepted size that would unquestionably end life on earth. Something ~1km across would cause mass famine. In 1908 an asteroid less than 200 feet across flattened 80 million trees over an 830 square mile area.

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#22

Post by whycome »

metadat wrote: post #2

Was funding for the Asteroid Watch program drastically reduced, or why did the detection come in so late? https://www.jpl.nasa.gov/asteroid-watch

Because they had to time the asteroid to show up for World Asteroid Day obviously.

https://asteroidday.org/about/

(June 30th, since 2014)

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#23

Post by throwthrowuknow »

biot wrote: post #13
dylan604 wrote: post #9

Earlier quoted context omitted.

I'm surprised there's no TNT equivalent comparing it to the biggest weapons humans have created. That always seems like a data point used when showing destructive forces.

From the article: > "This is a big object. An object of this size is going to have the equivalent impact energy in the hundreds of megaton approaching a gigaton," Brown said. "That'd be a regional impact. It's the sort of thing that if it hit the east coast of the U.S., you would have catastrophic effects over most of the eastern seaboard. But it's not big enough to affect the whole world."

Not very comfortable with how much that sounds like downplaying the effects. It would be the largest disaster in all of human history. For reference the estimated strategic nuclear arsenal of the United States is about 820 megatons and the largest US test detonation was 15 megatons so an impact of this size would be on par with or possibly worse than an all out nuclear war between the US and Russia. God knows what kind of effects that kind of blast would have, it would probably kill half the US population on impact and light the entire east coast on fire. No idea what would happen to the rest of the world after that but the supply chain “disruption” alone would mean millions starving and without fuel or medicine.

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#24

Post by prewett »

dylan604 wrote: post #10
iam-TJ wrote: post #8

Earlier quoted context omitted.

I'm confused about the late warning quote because the data page for MK2024 shows the first observation for the orbit fit was 2024-05-07. https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2024%...

So even if they announced on the day of the first observation, that's not really much notice to do anything about it other than start prepping for accepting of loss of life. I would seriously hope it took some amount of time for other people to verify/validate trajectory than the first person that observes it. At this point, we're still at the point of needing years if not decades notice for us to even have a chance…

I figure we could get a Falcon Heavy filled with rocks or something launched in a hurry. But, I did the math, and like you say, all we could do is watch.

Assuming the standard asteroid density of 2000 kg/m^3 [1], a 260 m diameter asteroid has a volume of 4/3 * pi * 130^3 = 1.84e10 m^3. Falcon Heavy can lift 16818 kg to a transfer orbit to Mars [2], which I assume is basically what it can do to reach an asteroid coming at us. A normal speed of space probes (without gravity assists) seems to be about 25,000 mph = 11600 m/s. Thus, it has a momentum of about 1.95e8 kg*m/s.

Assuming we hit the asteroid perpendicular to its motion, transferring all our momentum into transverse velocity, that is 1.95e8 / 1.84e10, or approximately 0.01 m/s. To ensure a miss, it would need to travel the whole diameter of the earth, 6.378e6 m, which would take 6.378e8 seconds, or about 20.2 years, which is the amount of time before impact we would need to hit the asteroid.

We would probably have more success hitting it head on. Since the earth is moving at about 3e4 m/s, we only need to delay the asteroid by 213 seconds. The minimum speed of an asteroid impacting Earth is 1.1e4 m/s, so we would need to move it backwards 2.343e6 m. This allows us to hit it slightly later, only 7.3 years ahead of time (in the best-case scenario). Assuming it could vary by a factor of two, we would need up to about a 14 year lead time.

[1] https://en.wikipedia.org/wiki/Standard_asteroid_physical_cha...

[2] https://en.wikipedia.org/wiki/Falcon_Heavy

[3] https://en.wikipedia.org/wiki/Impact_event

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#25

Post by throwthrowuknow »

rich_sasha wrote: post #14

My physics might be wrong, but with Earth's radius at 6500km and Lunar orbit radius around 350,000km, probability of a collision course given asteroid being within a lunar orbit distance is only (6.5/350)^2 or 0.03%, or maybe even cleaner, 1 in 3000. So it's not that close a miss.

Cool but what’s its orbital period and how does this close pass effect future crossings?

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#26

Post by SoftTalker »

dylan604 wrote: post #10
iam-TJ wrote: post #8

Earlier quoted context omitted.

I'm confused about the late warning quote because the data page for MK2024 shows the first observation for the orbit fit was 2024-05-07. https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2024%...

So even if they announced on the day of the first observation, that's not really much notice to do anything about it other than start prepping for accepting of loss of life. I would seriously hope it took some amount of time for other people to verify/validate trajectory than the first person that observes it. At this point, we're still at the point of needing years if not decades notice for us to even have a chance…

> start prepping for accepting of loss of life

If they knew it was going to hit, but not be an extinction event, maybe that makes some sense but realistically what kind of "prepping" can reasonably be done? Stock up on toilet paper?

If they knew it was going to hit and incinerate the surface of the earth, would they even say anything? Why create worldwide panic for no purpose?

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#27

Post by hyperpape »

jfengel wrote: post #5

How large? "anywhere from 120 metres to 260 metres in diameter". Is that bad? According to NASA, "If a rocky meteoroid larger than 25 meters but smaller than one kilometer ( a little more than 1/2 mile) were to hit Earth, it would likely cause local damage to the impact area. We believe anything larger than one to two kilometers (one kilometer is a little more than one-half mile) could have worldwide effects." So...…

I can't vouch for this being perfectly accurate, but it's appeared here on HN before: https://neal.fun/asteroid-launcher/

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#28

Post by s1artibartfast »

mike_d wrote: post #21
s1artibartfast wrote: post #15

Earlier quoted context omitted.

>It will appear stationary against the stars, so will not be detected by these systems. To some extent it also doesn't matter that we are orbiting the sun because while near, earth and asteroid will be in the same accelerating reference frame. I dont think that is true aside from the case where the asteroid vector is the exact opposite of the earth. Even if the earth and the asteroid are in the same accelerating refe…

> If you have two race cars going in around a track and at one from the other, it still appears to be moving relative to the stands. Right. Now put the stands on another planet and you start to understand the problem. We need to be able to see an asteroid at a minimum of of 3-4x the distance between the earth and the sun to have enough time to do anything about it based on the average speed of 40k mph. Now keep in mi…

Even if the stands are far away, even light years away, you pan through 360° every year. The fact that the background is far away means that it moves even quicker relative to a nearby object in a rotational frame.

If you spin around in a circle, hold your hand out and look at it, it will be moving very quickly against a distant background, like the horizon.

My point is that the distance to the background helps detection, not hurts it. If the background was nearby and co-rotating around the Sun, detection would be a near impossible.

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#29

Post by CaptainOfCoit »

jfengel wrote: post #5

How large? "anywhere from 120 metres to 260 metres in diameter". Is that bad? According to NASA, "If a rocky meteoroid larger than 25 meters but smaller than one kilometer ( a little more than 1/2 mile) were to hit Earth, it would likely cause local damage to the impact area. We believe anything larger than one to two kilometers (one kilometer is a little more than one-half mile) could have worldwide effects." So...…

The amount of "suckage" in case it would hit Earth is mentioned in the article:

> Fortunately, it won't impact Earth. But it would be a bad day if it did. "This is a big object. An object of this size is going to have the equivalent impact energy in the hundreds of megaton approaching a gigaton," Brown said. "That'd be a regional impact. It's the sort of thing that if it hit the east coast of the U.S., you would have catastrophic effects over most of the eastern seaboard. But it's not big enough to affect the whole world."

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#30

Post by alkyon »

prewett wrote: post #24
dylan604 wrote: post #10

Earlier quoted context omitted.

So even if they announced on the day of the first observation, that's not really much notice to do anything about it other than start prepping for accepting of loss of life. I would seriously hope it took some amount of time for other people to verify/validate trajectory than the first person that observes it. At this point, we're still at the point of needing years if not decades notice for us to even have a chance…

I figure we could get a Falcon Heavy filled with rocks or something launched in a hurry. But, I did the math, and like you say, all we could do is watch. Assuming the standard asteroid density of 2000 kg/m^3 [1], a 260 m diameter asteroid has a volume of 4/3 * pi * 130^3 = 1.84e10 m^3. Falcon Heavy can lift 16818 kg to a transfer orbit to Mars [2], which I assume is basically what it can do to reach an asteroid comin…

I haven't done any calculations but wouldn't they use nuclear warheads to deflect it?
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