Accounting for violent conflict risk in planetary defense decisions (2020) | Hacker News Reader

Accounting for violent conflict risk in planetary defense decisions (2020)

gcrinstitute.org

67 pointspmoriarty24 comments

Tangentially, Carl Sagan wrote a column (one of the earliest?) identifying asteroid defense as an existential risk:

https://sci-hub.se/https://doi.org/10.1038/368501a0 ("Dangers of Asteroid Deflection", Carl Sagan & Steven Ostro)

This is slightly expanded in Pale Blue Dot, though maybe half of the rest of the book serves as an interesting comparison of what Sagan thought might happen and what actually happened with space missions that were not complete at the time of book publication. Disappointingly, the audio book only has portions narrated by Sagan probably due to his cancer.

'Chapman describes a “giggle factor” and a “Chicken Little” dynamic. That was ultimately changed by a mix of scientific progress, policy outreach, writing for the general public, and the major Hollywood films Armageddon and Deep Impact'

-Good to hear that Armageddon may actually have done something good then..

You might even say they had a positive impact

You might, but probably shouldn't :)

> when an [sic] NEO collision on Earth is mistaken for a violent attack, prompting an actual attack that the attacker believes to be a retaliation but is in fact a first strike

Oof, never thought about this one. Do we have systems in place that would quickly and reliably differentiate an unexpected asteroid impact from a nuclear strike?

> > an [sic] NEO

That's perfectly correct grammatically. It just means whoever wrote that pronounces it N-E-O rather than "neo".

As to your question, I think yes since I expect the trajectory would be very different.

Nuke strikes have a distinctive double flash that I don’t think asteroids or meteorites do.

I think they’re more referring to ‘if an asteroid hits Washington DC, Moscow, or Beijing in the middle of what is going on now, will everyone check their satellites for it before they launch a retaliatory strike?

> Nuke strikes have a distinctive double flash that I don’t think asteroids or meteorites do

The concern raised in the paper, which I now share, is that in the time between initial detection and someone running the tape to count the flashes, nukes could be launched. Particularly for powers who have invested heavily in use-it-or-lose-it land-based missiles. You need that differentiating infrastructure and protocol in place ex ante if it's going to prevent false retaliation.

Arguably, the best strategy for mitigating existential risk and responding to a NEO collision event is a diversity of populations, civilizations, economies, and governance on the planet, so that as a species we are more resilliant to such an event takes out one or some of us.

Proposals that end in creating a single planetary policy source, and single global coordination and governance scheme to "fight" it necessarily reduce to dumbness because they create an economics that optimizes for reinforcing it over the interests and aggregate desires of individual organisms. Removing the diversity of governance alternatives means you have to optimize for that single solution, which in any complex system is essentially risk convergence, collapse, and death.

We are much more likely to die off of a confluence of starvation, war, disease, and non-replacement birth rates wrought by the risk correlation of central policymaking before a meteor hits or some other global catastrophe is actually realized. It's so much easier to make humans fear the same thing than to get us to all believe in it, and once you get your hand on that lever, does it matter what the threat is? The lever is narrative. I'd be skeptical of people indexed on planetary defense, because it's just a proxy and pretext for another centralization agenda. Just like when everyone is responsible, nobody is - when a solution is for everyone, it's pretty much also guaranteed to be for almost nobody as well.

It seems that you always want to use deflection, despite what they did in the movies, and it is doubtful whether a nuclear explosion would be better than attaching something to the object and generating enough thrust to alter its path, possibly using some of the mass of the object itself (stupid way: land a trebuchet, toss enough rocks into space to move it).

Nuclear detonations would also use the mass of the object itself. The short radiation pulse ablates material off of the surface, and that's what provides most of the impulse. Vaporized rock is the reaction mass.

I wonder. Is ablation better than having the warhead in the center of some mass, detonating the warhead to drive some of the mass at very high velocity into the target?

Considering that any mass as part of the launch vehicle will have a major trade off in time to intercept?

It’s way better to use the asteroid or comet itself. Every bit of mass (or second of delay to launch) you add to the intercept vehicle allows the bolide to get that much closer, requiring that much more escalating delta-v be added to it to clear the planet in time.

If the object is caught and intercepted far away, it may take only the slightest nudge. Up close and personal, it might require almost vaporizing it.

Fair. Or, you could use the same boost capacity to send more warhead, instead of more inert mass.

Yup, though time to intercept is a huge part of this. Optimizing anything about the strike itself (more powerful warhead, or whatever) is rarely as useful as getting there sooner, which is usually done by using what we might already be able to get there and doing it as quickly as possible.

Adding in that practically, we have no idea how to detect and intercept/prevent an actual issue in practice right now.

All actual hits have hit. We have never successfully stopped a hit yet. We had zero warning either, or awareness it was happening until they blew up in the sky somewhere.

We already know of a number of near misses that are large, but that is generally because they are near misses and not hits, so we have time to plot orbits, think about it, they are generally recurring so we can do this a couple times, etc.

All the comet missions have taken a very long time, literally years.

We’ve never actually tried to intercept an object on a short time line like we would with a surprise object and do anything to it. So it’s all still theoretical.

Some of this is pretty basic stats - if large objects came about frequently, we’d all be dead. But because large objects don’t come about frequently, we have no real experience handling this.

I think in terms of force:mass you can't beat nukes. We know how to make them, we know how to put them on rockets, and we can can line them up to detonate a little away from the asteroid, while a landing would need to match velocity. Probably the best would be nuclear shaped charges a la Project Casaba-Howitzer, which I believe were initially explored as a vehicle propellant.

The nuclear weapon is a very high power trebuchet.

I think (you read it here first) that the first step towards actual planetary defense will be the moon. That is: humanity's first, actual, somewhat working system realistically able to defeat an incoming asteroid will consist of moving the moon. Not that that is easy - absolutely not. But it is genuinely something that we can prepare for. We can start building an infrastructure on the moon for vaporising moon rocks, providing thrust. Energy can come from sunlight. You could well argue that moving the moon is nigh impossible. It probably is. But it is (1) feasible and (2) an engineering challenge. The most daunting one ever faced by humanity, but the pay off is equally great: we get to save the planet.

The key point is that the moon can easily stop incoming asteroids. It reduces the entire problem to "simply" moving the moon. Which is something I think is achievable with roughly today's tech.

The moon is integral to many of lifes rhythms and processes, it would be better if possible to find a way that doesn't have a chance of follow on system risk to us which interfering with the moon does.

This is one of the functions of the new James Webb telescope right? From what I remember planetary defence was one of the few recent things a lot of countries agreed upon to mutually fund as well

I think the JWST is to far-sighted to be very useful for spotting something in an Earth intercept orbit. For one, it is to the outside of Earth's orbit and its instruments work in infrared bands requiring extreme cooling--it can't be aimed at angles towards Earth's orbit because of solar radiation. The shield at the "bottom" of the telescope allows for some inclination but not a tremendous amount.

https://webb.nasa.gov/content/about/orbit.html

No, it can watch asteroids, kupier belt objects, etc. Sure, not ones already near earth orbit, but most objects are further out at least at some point.

However as far as I know it's unlikely to actively survey them. It's expensive and limited time, so it'd focus will be on what can only be seen in infrared, like the early universe and exoplanet spectra. But who knows what the scientists will decide look at.

Hum... I don't think anybody expects objects on an orbit near or more internal than the Earth's one to intercept us. The Solar System is quite old, and any nearby object would have already hit us.

All the remaining objects that can intercept us stay far away most of the time.

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