[gatreddi]

Wild that we went from "can we even deflect an asteroid" to measurably changing a solar orbit. 150 milliseconds sounds tiny until you realize compounding over decades makes that a meaningful trajectory shift. The engineering confidence this gives for actual planetary defense is massive.

[adriand]

> The engineering confidence this gives for actual planetary defense is massive.

Is it? Isn’t it the case that we can’t even detect the vast majority of objects on a potentially problematic intersection path with earth? I feel like the most likely scenario is that by the time we realize we’re about to get slammed by an asteroid, it’s way too late.

[alex43578]

Two different problems: detection, deflection.

Before this, even if we spotted one, we didn’t know if we could prevent impact.

Detection honestly feels like an easier problem, especially as networked sensors and space-lift capacity has improved.

[idatum]

Is there really better confidence we could now detect a similar 2013 Chelyabinsk meteor event?

[alex43578]

Yes? Rubin is supposed to contribute, and more broadly we have more and better "eyes" on the night's sky than ever before. There's always the opportunity for more tracking, but tracking without being able to do anything about it would've been pointless.

[gatreddi]

Detection is still the weak link, that part is true. But the equation is shifting. Surveys like NASA’s NEOWISE mission and the upcoming NEO Surveyor mission are specifically aimed at finding those missing near-Earth objects earlier.

The point of DART mission wasn’t that we can deflect every asteroid tomorrow. It was to prove that physics and guidance actually work in space. Now the playbook is clearer: detect earlier, then nudge early.

If you get even a few years of warning, a tiny velocity change compounds into a huge miss distance. That’s the real takeaway.

[phkahler]

>> The engineering confidence this gives for actual planetary defense is massive.

I've been waiting for this a long time. They initially reported significant changes to the orbit of the smaller rock around the larger one which was cool and all, but I kept wanting to hear how much it affected the whole system. I suspect it's taken several years to answer that because it's such a tiny change in velocity. Dimorphos we can deflect, Didymos not so much.

[ivanjermakov]

I find it mesmerizing how predictable orbital mechanics are. We can tell where celestial body will be years ahead with meter accuracy.

[alex43578]

I think that’s what makes the 3 body problem unintuitive, given how we can predict 2 easily.

[littlestymaar]

There's no “two body problem” here, the solar system is an n-body problem.

And the “three-body problem” is overblown in pop culture: even n-body problems are fairly predictable in the short-ish term, it's just that you cannot predict things over a long period because measurement imprecisions have a snowball effect, but it's not particularly unintuitive (I'd say it's more intuitive than the idea that we could predict things with perfect precision over billions of years).

[mkbosmans]

Well, the article says that the effect of the impact was much larger than the scientists expected. That doesn't really give a lot of confidence in how good we are at predicting these things.

[nacozarina]

Makes you wonder how many other objects were sent on new trajectories by even smaller influences

[jl6]

Or offense.

[wongarsu]

You know what they say: the best planetary offense is a good asteroid redirect program

It's also the best planetary terrorism, going by the plot of The Expanse

[m4rtink]

It only worked in the Expanse because they expertly choose a special trajectory that made the rocks hard to detect and some questionable (but plot necessary) "stealth coating".

By this point UN and MCR have been in cold war for 100+ years staring each other down with region killer nuke arsenals and an absurd amount of interceptors always ready. See than one time Mars actually fired a barrage - only like two warheads got through, only due to shitload of decoys and overall numbers.

A dumb rock would totally get vaporized without the plot armor in a safe distance.

[Ajakks]

Ok. The Expanse is a show/book - that doesn't actually portray any of this very well, but its very important to note - there are no satellites in orbit, with nukes or any kind of missiles - if you want to pretend they are, they are most definitely pointed at the earth.

I'd love to buy into that plot armor but there is too much to take seriously by S6. The reality is, the first time a colony decided to it was independent enough, to use an asteroid - they would pick one, or many, so as to to render earth uninhabitable, there is no doing what they did in the show - thats how you lose a war AFTER having already used a weapon of last resort.

Once Inoki or w/e his name decided to use an asteroid, and one hits, the ONLY choice open to Earth is an immediate unconditional surrender. The only correct choice for asteroid #2 is one that will end all life on the planet without any doubt.

What's her name? The President would have killed us all and attained nothing doing so.

[m4rtink]

I think given the technology that has been shown - a massive space and planetary infrastructure base, torpedoes with torch drives armed with nukes that would make Teller blush - I don't think you can actually use Dinosaur killer asteroid unnoticed.

That would be far too big to not be spotted by the many UN aligned sensor platforms all around Sol, well before it is actually on a collision course as changing the trajectory of something this massive could take a long time, not to mention for it to actually travel all the way to Earth on that trajectory.

I am sure that Belter Cheguevara was not the first one to get these ideas, so any major power not tracking most asteroid orbits in almost real time at this point would be stupid. The technology they demonstrated to have should easily allow that.

And by that point one of the many Ships UN has all around the system would just go there and shoot anyone working on the big rock to pieces. Possibly deploying tugs to change the trajectory to a safe one afterwards.

So I think they had to use rock small enough not to be easily tracked, that could be quickly accelerated + that special stealth coating from the Martians. Enough to kill a city and devastate a region but not much else.

[redman25]

First things first, we have to colonize the rest of the solar system before we can terrorize Earth.

[dylan604]

That totally depends on the type of super villain organization we're discussing. Some are willing to watch the Earth burn making the colonization step unnecessary. Others think humans are the problem and again would be willing to skip that step.

[vova_hn2]

It depends on the size of the asteroid and precision with which it can be aimed...

[MisterTea]

> before we can terrorize Earth.

Before?! We're already doing a great job at it!

[Ajakks]

Why exactly? I think the US ought to spend a few trillion on an actual space battleship - one that never comes down to the surface, just sits in orbit. There was a project regarding dropping telephone pole sized pieces of metal from space as an offensive weapon - put something like that on the space battleship and...

That is simply "Assured Destruction" with absolutely no mutual drawbacks or lingering consequences like radioactive wasteland. Just craters.

This is also something where the 1st country to achieve the "Space Battleship" could effectively prevent any other from also doing so...

In theory, Bezos or Musk could do it.

I don't understand why any country would bother with ground based military assets at this point.

[wongarsu]

> That is simply "Assured Destruction" with absolutely no mutual drawbacks

Nuclear countries would simply declare that they will launch nukes if any rod comes down on their territory. Even if you had thousands of projectiles in orbit (at considerable cost per projectile) this would not be significantly different from 60s-style MAD: put nukes in bunkers, in the air and in the sea to ensure they can't all be taken out. We might see the return of strategic bombers that stays in the air for weeks at a time.

Alternatively they can just shoot down your battleship with anti-satellite weapons. The risk of retaliation might be worth preventing the disadvantaged position in the long term

[Ajakks]

That reaction is not the same tho - a rod isn't even a conventional weapon, I am not certain off hand that an incredibly destructive such weapon would even be banned under current treaties. That matters bc your taking about the end of the world. Only Russia would ever shoot at the US - so, dont drop rods on Russia.

Plus - if countries don't do space wars - this will still happen 100%. It will just be a non-state actor - who do you nuke if Austin Powers is the bad guy from space?

Also, there seems to be a prevailing sense of "we'll just shoot it down" and that is actually extraordinarily unlikely - bc of all the space, in space. I wouldn't sit in orbit with my Space Battleship - maybe a lunar orbit.

Let's say I park halfway to the moon - ALL of my missiles will still hit earth, I don't think current defense systems would have any better odds - whats the difference between an ICBM that enters the atmosphere from space - shot from a silo or a spaceship?? Not much, functionally identical to the Space Battleship... missiles from earth tho, will be like in slow motion, the space battleship ought to be able to literally shoot them down with bullets - none will be able to surprise the space battleship, how do you even do a missle defense overwhelm tactic in such a situation - I can move the spaceship you know.

I may sound like I'm being unserious, but in reality, this is absolutely the future of warfare 100% - I can't be more serious, the humor is bc this topic makes me legitimately nervous.

[bdamm]

You've described a space station, which three countries have already done independently (Mir, SkyLab, Tiangong).

But dropping rods from an orbiting platform makes no sense. There's a reason that "Rods from God" didn't pan out, and it has to do with orbital dynamics. Neither Bezos nor Musk can do it, because it actually doesn't work.

[Ajakks]

I doubt it was seriously considered at the time it was discussed. Space Stations are in orbit - the space battleship doesn't have to be, that is very significant.

Earth is spinning in a giant circle around the sun. Thats facts. "aiming an asteroid" is less of making a rock a missile - and a lot more of tug-boating it into the exact right spot, in the way of earth, so that earth hits the asteroid - not anything complicated like the asteroid hitting earth.

There are a lot of little things like that...

[ryan_j_naughton]

> There's a reason that "Rods from God" didn't pan out, and it has to do with orbital dynamics. Neither Bezos nor Musk can do it, because it actually doesn't work.

Can you say more on this? Thanks!

[MisterTea]

> . There was a project regarding dropping telephone pole sized pieces of metal from space as an offensive weapon

I remember it was nicknamed "Rods From God". Kinetic energy weapon using 9 ton tungsten rods dropped from an orbiting platform. https://en.wikipedia.org/wiki/Kinetic_bombardment

[bhhaskin]

The technology doesn't exist and it would be a huge waste of money.

How heavy would a telephone pole sized tungsten rod be?

What happens when China, Russia, India or Pakistan find out you are building this (cause you can't hide it if it's in near earth orbit)? They would either knock it out of the sky or hit you with everything they have. We would do the exact same if anyone else was developing such a weapon.

[Ajakks]

I personally would get whatever metal in space, so weight is not the issue - solving this problem would also create almost immediately chunks of rocks that could also be dropped. In all reality, anything can be "setup" to be a weapon - many ways have been identified here.

All required innovations - of which, most are not out of reach in the slightest, all of that tech would be immensely valuable, literally everything we do to secure space superiority will be actual gains - not smaller microchips equivalent innovations - entirely new machines, entirely new economies of scale - there is no equivalent military tech that we can develop on earth.

Not only is there really no conceivable way to ignore the strategic advantage once considered, the long-term economic payoff is actually reason enough alone to pursue the radical idea of a "space battleship" - I can think of about 20 ways to cause significant global issues with one measly space battleship.

As a hypothetical alone, it has reason enough to warrant a substantial amount of the 1.5 trillion defense budget the Pentagon plays with.

[m4rtink]

The story of Footfall is basically about that - and alien space invasion force with torch drive powered space battleship in orbit.

There are ways to battle that - balistic missile submarines for one and then "Project Michael" which would be a massive spoiler to elaborate on. ;-)

[ge96]

queue the neurodivergent mech pilot

[nashashmi]

Slight changes can cause such impacts? Now imagine how many other meteors and comets also will be adjusting because of this. Will one of them once on a course to never hit earth suddenly shift to hit earth in a thousand years time? The confidence i get is the opposite

[tgv]

I don't think asteroids (like the target) have influence on others. There's so much space between them, and their mass is almost neglible.

[nashashmi]

Oh no. I was not talking about the other objects that float through space influenced by such a small object so far away.

I was talking about the sun shaking in its orbit because high velocity objects are now pulling at it differently causing other objects to be influenced by the new position of the sun.

I read the parent comment as “solar orbit change” meaning the sub was changing position.