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Comment by iam-TJ | Hacker News Reader

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%...

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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 of actually protecting from an impact in a meaningful way.

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

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.

If it isn't the Moon but an asteroid of 100m radius then deflecting or breaking it apart is feasible.

https://www.llnl.gov/article/50716/new-nuclear-deflection-si...

To estimate this order of magnitude. A typical (non MERV) 1.2Mt B83 in the active US nuclear arsenal would likely vaporize ~100m diameter hemisphere to deflect a relatively large 3km asteroid. Assuming an asteroid at 1-10 km/sec relative velocity 12 days out is 1-10M km away and earth is ~10k km across. So a deflection angle of ~1-10mrad is needed for a 3km (~10km3) spherical asteroid mass of ~10^13kg.

A 5E15 J/Mt 1000kg bomb with a half momentum of about 10^9 kgkm/sec could deflect an angle of 0.1mrad 12 days out. Half energy conservation would gives you a similar ~0.01km/sec dV, so you'd need >10x more time or >10x more 1Mt nukes for a 3km asteroid. It gets much worse for larger asteroids, but interestingly dV doesn't change quickly with relative velocity since the required angle falls as the velocity rises.

> 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.

> 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.

The record shows many long winters,4 close tree rings. Global and in same strata. about 5000 yrs. So how can we survive that 4 winters? not impossible if coms,radio, light boards ,satellite messages.. and civility are maintained.During the Black death in England, funerals,and wills kept civility.

the lunar base can provide terra firma form dropping supplies and there's startups in that. i even proposed to AIG insurance company a lunar escape resort as futures,funding miners via from invested premiums into managed derivatives and holdings.moon should be a net exporter or technology and rare earth.

i'm late to this discussion but i work on unified gravity, its close, we had it a long time but its getting to be beautiful & simple. verifiable so far. other possibility: A two burn oberth can zip a falcon heavy with high 50km/s towards a meteor if we saw it coming. this should be the 1000x higher priority over wars and genocides and pandemics and Gucci bags and mars fantasies and VR.

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