NASA's DART spacecraft changed an asteroid's orbit around the sun
sciencenews.org
sciencenews.org
It's also the best planetary terrorism, going by the plot of The Expanse
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.
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.
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.
We feel safe here on earth but it's really a giant graveyard trap - that so effectively exerts control over life on it, that it made all living mammals out of mice - we may actually be safer on almost any other planet.
All life on earth has eventually died out so far, we are the 1st species that could stop the most likely extinction level event - but this DART is the closest we ever got to actually taking up that responsibility - the preservation of our species and whatnot, thats just 1 minor reason.
The most important tho, given how much we have example of people "getting theirs" at all other peoples expense - this is much worse if a non-state actor gets there 1st.
Lastly, I do have to clarify the American position - we run the world, or there will not be one to run. Nobody alive today made that decision - it changes nothing, once that choice was made, we are locked into it. Did you think we are only an economic power? That is the front. We can always pivot to actual power - the kind that can destroy all cities above a certain size - we have never hid this fact, the whole world knows of MAD. That is what power is.
What is American power if someone can destroy the US and we can't destroy them?? That doesn't work for the US - nothing at all changes if the US gets that spaceship first.
You can call this ugly - there were more modern wars before we started running things, from the looks of things - the whole world will go to war the moment we are out of the picture.
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.
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...
I mean, you did say:
> space battleship - one that never comes down to the surface, just sits in orbit.
So I think it's understandable for people to take that at face value.
Furthermore, if it isn't in orbit, then where would it be?
> 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.
From an orbital mechanics standpoint I don't think there's actually a difference. You're changing an orbit either way.
What if I make that the space battleship's job? What if a drone can do that?
Im not really worried about resupplying the space battleship holding earth hostage -> someone will "volunteer" to do that, bc they want to live life.
Ah, so by "orbit" you were talking about orbit around Earth specifically?
> why cant I just throw a tow strap on that, accelerate, and park it an area that only has to be accurate enough for a planet to hit it - I dont need to stop it, or have it flying at the earth, it only needs to be in the way, moving a little slower than the earth.
Again, from a high-level orbital mechanics perspective there is little difference between the two. You start with two non-intersecting orbits and you're changing one orbit to intersect the other at the same time and place. How you go about doing so is just a question of how much time/fuel you're willing to expend, for various values of "just".
That being said, assuming I'm interpreting you correctly what you propose is probably technically possible (e.g., change an asteroid's orbit to a slightly-larger-than-Earth-sized one), but it's also very fuel-intensive compared to skipping the "parking"/"in the way" part.
If you haven't tried it already I can't recommend Kerbal Space Program enough for experimenting with this kind of thing, especially if you are alright with playing with mods. Real Solar System (changes the in-game solar system to match the our real-life one) and Principia (replaces the simplified patched conics system KSP uses for orbits with n-body gravity) would be particularly relevant here.
I may be confused but I dont mean a "larger orbit than the earth" -> I mean the exact identical orbit, the exact path that earth takes around the sun -> ahead (or behind, it does not matter) of where we are and instead of 365 days to circle the sun, the asteroid is moving at a rate that will take MORE days -> so the earth will smash into the asteroid, bc it can't do anything else. I dont mean "park" in the sense that I stop its movement, nor would I select an asteroid that has such an orbit that it couldn't be manipulated into position with little difficulty.
Like, imagine the solar system was a record on record player (I've never used one either) and the earth is on a line/groove - a choice asteroid is moving in the same direction on an immediately adjacent line/groove - the asteroid only needs to move onto the earth's groove (anywhere on that specific groove the earth occupies on the record works) and then the asteroid is then sped up or slowed down (not much tho) on that exact orbit -> either will result in a collision with earth.
The only real way to stop such activities is with spaceships. That is my entire argument - you are saying that is less feasible than making a missle out of an asteroid? I appreciate the explanation fr
Tbh, it wasn't until the game Terra Invicta that I really considered the solar system, as it actually is. That game has no other relevance to this particular conversation - good game, very different kind of 4x that I recommend but unrelated.
Unfortunately that's not really possible. To a first approximation, Earth's orbit is a circle with the Sun at its center, and the size of that circle is determined entirely by Earth's orbital speed around the Sun. Assuming you're also in a circular orbit, if you move at Earth's speed, the size of your orbit will be the same as that of Earth's. If you move faster or slower, your orbit will be smaller or larger, respectively, unless you wish to continuously burn fuel to maintain your distance from the Sun. That's why I said the asteroid's orbit must be slightly larger than that of Earth's for an Earth-catches-up-to-asteroid-in-similar-orbit scenario.
Obviously things get more complicated once you consider non-circular orbits, but the end result is similar - you can't continuously hang out in Earth's path while moving slower than the Earth around the Sun without burning a stupendous amount of fuel.
> you are saying that is less feasible than making a missle out of an asteroid? I appreciate the explanation fr
I think it's more that I think that "making a missile" is likely to require less fuel since you only need to adjust the asteroid's orbit ~once (only need to get it on a collision course) instead of ~twice (get the asteroid on a near-collision course, then adjust it again for the "right" kind of collision).
The speed doesn't have to be much different - 366 days and earth will eventually hit asteroid - 364 days and it will eventually hit the earth.
Ahh, Im still having a hard time figuring out why that would take more energy - I'm going to be researching this all morning tomorrow.
Thanks for the help!
Kind of? An object moving in a circular motion at a constant speed must have an acceleration towards the center of the circle of (velocity^2)/(radius). This means that two objects in the same circular orbit moving at different speeds must be experiencing different accelerations towards the center of the circle.
In the simplified case of orbits around the Sun, that acceleration towards the center of the orbit is due to the Sun's gravity. However, gravity accelerates everything at a given distance at the same rate. As a result, you can't have two objects solely influenced by the Sun's gravity that orbit around the Sun with the same orbital shape but moving at different speeds. You'd need something in addition to the Sun's gravity to pull that off.
> The speed doesn't have to be much different - 366 days and earth will eventually hit asteroid - 364 days and it will eventually hit the earth.
Sure. When I said slightly-larger-than-Earth-sized orbit, I really meant it. Kepler's third law of planetary motion states (approximately) that (orbital period)^2 is proportional to (radius)^3. Assuming I did my math correctly, if your orbital period goes from 365 to 366 days your orbital radius gets ~0.18% larger, which is roughly 274000 km increase over the radius of Earth's orbit. That would fit inside the Moon's orbit (~385000 km from the Earth)!
> Ahh, Im still having a hard time figuring out why that would take more energy
At least the way I was thinking, the short answer is that one alteration to an orbit is likely to be cheaper than two, especially if you aren't particularly concerned in what manner the asteroid eventually collides with Earth.
You will need to replenish from somewhere & that somewhere might as well get nuked instead of the ship, rendering it useless.
Can you say more on this? Thanks!
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
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
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.
And yeah, it is perhaps the most extremely imbalanced strategic advantage that can be attained.
There are ways to battle that - balistic missile submarines for one and then "Project Michael" which would be a massive spoiler to elaborate on. ;-)
Before?! We're already doing a great job at it!
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.
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.
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.
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.
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.
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).
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.
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.
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.
Or in other words, 1 meter per day
Why not say that?
I found the meter per day conversion helpful. Through another lens, it's about 0.000036 km/hour (or about 1.5 inches per hour).
Multiplying/dividing by 1 million is way easier than by 86400 though.
Obviously there was the kinetic energy transfer but the impact ejacted some of the asteroids mass opposite to it's trajectory further increasing it's trajectory change.
Cool demonstration, hopefully not needed one day.
Rockets are using mass loss but there's more going on with the rapidly expanding gas causing the increased impulse.
If you think about it that's how a cannon works. The projectile gets pushed forwards and the barrel gets pushed in the opposite direction. Some of the larger ones can push their launcher back quite a bit more than you might expect.
My point is that this is actually a common failure of intuition. We tend to think of larger objects on earth as fixed and in our day to day life on dry land they often are (at least more or less) due to static friction.
A slightly more interesting observation (I think) is that if the bodies don't achieve escape velocity relative to one another then the forces all cancel out in the end. It just might take an arbitrarily long time in the case of similarly sized masses.
You build a little factory and use chunks of the asteroid itself as thrust.
That's valuable not only for versatility, but also because it would really suck to send a spacecraft on a redirect mission only to find out that our assumptions about the asteroid's composition were wrong
Instead of pointing out that exact measurements finally came in (of long term movement change), journalist instead focused on the obvious outcome that everyone expects and knows
The nitty-gritty details are what the article is for, not the title.
However, the most efficient method would be actually land (I know - maybe even impossible?) on it, and use propellers to change its trajectory. We don't have too much throwaway high-tech to crash it on asteroids...
It was in the context of hydrogen and I could have sworn it was flammable. But here is this encyclopedia telling me it's INflammable. It's... not flammable? Looked it up in the school library.
Thank you, that memory came up from the depths of time. Probably haven't thought about that in 30 years. Funny how we sometimes just didn't know stuff, and couldn't find out back then.
The only logical way out of the flammable/inflammable mess is to use 'flammable' and 'non-inflammable', which makes me so mad.
There are many counter-examples to your examples, such as “direct” and “indirect”, “humane” and “inhumane”.
The words used should be clear in their meaning. “Inflammable” is ambiguous, and it makes a great deal of difference which meaning is intended.
Flammable is unambiguous, as is non-inflammable. I’m forced to use these. Personally, I’m more in favour of flammable (able to catch fire) and inflammable (not able to catch fire).
The historically correct term would be non-inflammable. The modern variant is non-flammable.
Similarly, inflammable is the historic term and flammable is the modern variant.
The confusion arises when people are exposed to the word flammable and then attempt to apply the usual rules to construct a word they've never actually used before.
This isn't the usual sort of inconsistency introduced by our fusing multiple incompatible languages. It's from the original Latin and I'm unclear what led to it. For example consider inflammable versus inhumane. It seems Latin itself used the prefix to mean different things - here on(fire) versus not(human). But confusingly it's ex to indicate location, despite ex also being the antonym of in. So ex equo means you are on horseback, not off it as I would have guessed.
They are not counter-example. You use the other "in-" prefix that take an adjective and give the opposite adjective, not the one that create a verb from a noun.