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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

#41

Post by dylan604 »

alkyon wrote: post #30
prewett wrote: post #24

Earlier quoted context omitted.

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?

Maybe if this was a Michael Bay movie, but real scientists know that an Earth ending level event would just laugh at your nukes as it just flew on by. In the grand scheme of the cosmos, man made nukes are but a mere gnat at the picnic nuisance.

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

#42

Post by dylan604 »

ant6n wrote: post #33
SoftTalker wrote: post #26

Earlier quoted context omitted.

> 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?

If the asteroid was gonna be like a large nuclear explosion, perhaps one could evacuation the directly affected areas.

Maybe, if you could pin point where that would be, but that's much more difficult than people give it credit. Margin of errors means thinking it will hit the east coast of the US, but wind up hitting the west coast. So you've evacuated for nothing, and didn't evacuate where it counts.

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

#43

Post by mjcohen »

EA-3167 wrote: post #16
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…

What you're describing is known as Constant Bearing, Decreasing Range (CBDR), https://en.wikipedia.org/wiki/Constant_bearing,_decreasing_r... and generally doesn't apply to to the case of a nearby asteroid on a collision course with Earth. For the parallax created by our orbit to be negligible, the object would have to be very distant.

The way I heard this is, at a military site, "No change in azimuth. No change in elevation. Let's get the hell out of here!"

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

#44

Post by throwawaymaths »

dylan604 wrote: post #41
alkyon wrote: post #30

Earlier quoted context omitted.

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

Maybe if this was a Michael Bay movie, but real scientists know that an Earth ending level event would just laugh at your nukes as it just flew on by. In the grand scheme of the cosmos, man made nukes are but a mere gnat at the picnic nuisance.

This particular asteroid is the size of a jet plane, so a nuke would probably have an effect.

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

#45

Post by delta_p_delta_x »

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…

Firstly, the several different unit systems in this comment give me a headache.

Next,

> 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.

Not really. The important variable is not distance, but rather the mass and velocity vector.

There could exist an asteroid that is currently barely 1 moon orbit away (~400 000 km), but has a velocity vector almost equal to that of Earth's. This asteroid could then be predicted to impact upon the next close encounter with Earth.

In general, the more distant the predicted impact date, the less the delta-v required to push the asteroid off its current path and avoid an impact in future.

> Now keep in mind that at that distance you are looking for something as "tiny" as 60 miles across

NASA and ESA have databases of some 35000 near-Earth asteroids, and many of them are orders of magnitude smaller than 100 km[1]. Our detection capability has significantly improved since efforts first started in the 1980s.

Asteroid impact avoidance is amongst the few natural disasters humanity has the technological, financial, and engineering capability to completely avoid.

We have both the firepower and the lift capability (if not now, then in the near future, dictated by the urgency of the asteroid impact) to deflect even a 12 km, Chicxulub-size impactor if detected sufficiently early. About 5-10 years' warning would be enough time for a large nuclear device to deflect such an asteroid, which would be a major achievement for humanity.

[1]: https://cneos.jpl.nasa.gov/sentry/

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

#46

Post by delta_p_delta_x »

johnnyanmac wrote: post #11
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...…

well the Chicxulub impactor (The one that ended the Cretaceous Period) was estimated to be 10-15km. on the other end, the largest recorded asteroid in Siberia was 50-60m in size and did local but very noticeable damage[1], apparently 4x as powerful as the nuclear bomb that hit Hiroshima. So 260m would be absolutely devastating, but wouldn't end civilization as we know it. it would absolutely destroy any state or smal…

> So 260m would be absolutely devastating, but wouldn't end civilization as we know it

It really depends. A ~100 m asteroid is roughly as energetic as some of the largest nuclear weapons ever detonated (~10¹ to 10² megatons).

As an example... It'd destroy London, and maybe some of its satellite cities like Luton, Oxford, and Cambridge, but the effects would be significantly diminished by the time the fireball radiation and the blast got to Nottingham.

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

#47

Post by squigz »

SoftTalker wrote: post #26
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…

> 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?

> 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?

Assuming 'they' knew it was a world-ending event... good luck getting everyone involved to not say anything to anyone, including their loved ones. I also imagine there are several agencies doing asteroid detection, so it's not like it's just NASA personnel we have to worry about.

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

#48

Post by adamredwoods »

The biggest takeaway is that a former Queen member turned astrophysicist, Brian May. Rock on!

>> Asteroid Day, sanctioned by the United Nations, was started in 2014 by astrophysicist and former Queen musician Brian May along with Apollo 9 astronaut Rusty Schweickart along with a few others. The goal is to inform the public about asteroids and their potential threats as well as calling on governments to work on asteroid detection programs.

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

#49

Post by phkahler »

EA-3167 wrote: post #16
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…

What you're describing is known as Constant Bearing, Decreasing Range (CBDR), https://en.wikipedia.org/wiki/Constant_bearing,_decreasing_r... and generally doesn't apply to to the case of a nearby asteroid on a collision course with Earth. For the parallax created by our orbit to be negligible, the object would have to be very distant.

CBDR only requires constant velocity. Similar triangles are all you need. On short time scales even orbits are approximately straight. It still applies and may well be the reason this one was missed until so close.

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

#50

Post by Mistletoe »

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…

>to have enough time to do anything about it

Do we have a real plan for what we would do? What can we do? Do we even have nuclear weapons that can target outer space etc.?

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