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.
>> 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.
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.
> 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 the strategic bomber 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
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.
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.
> Space Stations are in orbit - the space battleship doesn't have to be
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.
> 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.
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.
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.
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.
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
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.
I'm genuinely curious whether there are a substantial number of people out there who deal on a regular basis with dV's on such a minute scale. Who would that be, outside an asteriod-redirect program such as this? Satellite operators doing precision trajectory correction?
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).
That's interesting news. I wonder how much kinetic energy it had. This accumulation of information might be useful if an asteroid were to hit the Earth someday. At the very least, it's more realistic than sending oil drilling experts to an asteroid.
Interesting. I'd not considered the loss of mass as a means of propulsion.
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.
When the impact happened the news articles seemed to imply some surprise about that as well which seemed strange to me. I just wrote it off to the journalist just not being up to speed on the subject matter. The size of the debris field trailing also seemed to be a surprising result.
It's the butterfly effect. After the momentum exchange (the rocket slamming, stuff being ejected in the impact, etc), the entire system was left with different properties. From now on, the equation F=Gm1m2/r^2 will have a different m1, and you can sum the equation over all m2 (literally every other massive object in the universe).
Yeah, I sort of meant in the context of an object losing its mass, it's seldom used on earth as the effects are small but on the timescale/distance/speeds of an asteroid it could have noticeable effects.
Rockets are using mass loss but there's more going on with the rapidly expanding gas causing the increased impulse.
Rockets are able to optimize due to dealing with a gas. It's still just pushing off of a disconnected mass. You go one way the lost mass goes the other.
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.
A lot of asteroids are much less solid than we used to think. Some of them are big rocks, but many of them are just piles of sand- and gravel-sized material loosely held together by gravity. Clamps work great on the solid rock type, but many of the alternative methods - including smashing into it - work on asteroids of any composition
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
Some have suggested attaching a solar shield to objects to add drag to alter the course. However, that would require a much more precise landing and some sort of drilling/anchoring effort. A kinetic impact like this is always going to be more efficient.
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
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...
I'm not sure this is actually a necessary explanation...but while propellers technically COULD function in space (not a perfect vacuum, right?)...they're basically going to be useless.
He probably misuses "propeller" which is strangely restrictive to "rotative blade propulsion" in English whereas "to propel" is generic in its meaning.
Inflammable made me so angry as a child/teen when I found out. I read it in our encyclopedia set but we didn't have a dictionary, and this was pre-internet.
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.
It's just a parsing error. "in-" is also a prefix to create verbs from a name or another verb like inhume, inflame, induce, incite, inject, infiltrate. Inflammable is (inflame)-able and not in-(flammable)
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).
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.
Makes you wonder how many other objects were sent on new trajectories by even smaller influences
>> 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.
I find it mesmerizing how predictable orbital mechanics are. We can tell where celestial body will be years ahead with meter accuracy.
Or offense.
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
First things first, we have to colonize the rest of the solar system before we can terrorize Earth.
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.
> 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 the strategic bomber 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
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.
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...
> Space Stations are in orbit - the space battleship doesn't have to be
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.
> 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!
> . 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
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.
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.
If this is satire, it's not that funny. If you're serious, it's a good example of 'the ugly American.'
> before we can terrorize Earth.
Before?! We're already doing a great job at it!
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.
It depends on the size of the asteroid and precision with which it can be aimed...
queue the neurodivergent mech pilot
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
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.
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.
> slowed the orbit of a pair of asteroids around the sun by more than 10 micrometers per second
Or in other words, 1 meter per day
Why not say that?
Because the SI unit is meters per second, so maintaining the “second” gives people with that understanding a basis in which to compare the delta-V.
I'm genuinely curious whether there are a substantial number of people out there who deal on a regular basis with dV's on such a minute scale. Who would that be, outside an asteriod-redirect program such as this? Satellite operators doing precision trajectory correction?
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).
One would think that any nerds that knowledgeable could divide by 86400 to make the article more accessible for the rest of us though.
1.22337962962963e-21 light years per second!
That's interesting news. I wonder how much kinetic energy it had. This accumulation of information might be useful if an asteroid were to hit the Earth someday. At the very least, it's more realistic than sending oil drilling experts to an asteroid.
>it's more realistic than sending oil drilling experts to an asteroid
Mandatory sharing of Ben Afleck commentary speaking for all of us.
https://youtu.be/-ahtp0sjA5U
> ...I wonder how much kinetic energy it had...
Since kinetic energy is proportional to v squared, that highly depends on how you measure v...
Interesting. I'd not considered the loss of mass as a means of propulsion.
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.
When the impact happened the news articles seemed to imply some surprise about that as well which seemed strange to me. I just wrote it off to the journalist just not being up to speed on the subject matter. The size of the debris field trailing also seemed to be a surprising result.
It's the butterfly effect. After the momentum exchange (the rocket slamming, stuff being ejected in the impact, etc), the entire system was left with different properties. From now on, the equation F=Gm1m2/r^2 will have a different m1, and you can sum the equation over all m2 (literally every other massive object in the universe).
That's how rockets work.
Yeah, I sort of meant in the context of an object losing its mass, it's seldom used on earth as the effects are small but on the timescale/distance/speeds of an asteroid it could have noticeable effects.
Rockets are using mass loss but there's more going on with the rapidly expanding gas causing the increased impulse.
Rockets are able to optimize due to dealing with a gas. It's still just pushing off of a disconnected mass. You go one way the lost mass goes the other.
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.
Is this a surprise?
That's amazing
Is debris a problem? I think the ideal would be to embed or clamp a rocket on the target.
A lot of asteroids are much less solid than we used to think. Some of them are big rocks, but many of them are just piles of sand- and gravel-sized material loosely held together by gravity. Clamps work great on the solid rock type, but many of the alternative methods - including smashing into it - work on asteroids of any composition
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
https://en.wikipedia.org/wiki/Mass_driver
You build a little factory and use chunks of the asteroid itself as thrust.
Some have suggested attaching a solar shield to objects to add drag to alter the course. However, that would require a much more precise landing and some sort of drilling/anchoring effort. A kinetic impact like this is always going to be more efficient.
I'm annoyed at these nothing-burger titles...
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 top comment in this thread calls this "wild" and expresses amazement that this is possible; clearly it's not what "everyone expects and knows".
The nitty-gritty details are what the article is for, not the title.
Well done, DART, which country did you aim it to?
India
Wow, that's the first step!
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...
Impact is actually a more efficient method, as it avoids the fuel consumption required for deceleration and soft landings.
I'm not sure this is actually a necessary explanation...but while propellers technically COULD function in space (not a perfect vacuum, right?)...they're basically going to be useless.
He probably misuses "propeller" which is strangely restrictive to "rotative blade propulsion" in English whereas "to propel" is generic in its meaning.
Be careful about how you store those inflammable propellers.
Inflammable made me so angry as a child/teen when I found out. I read it in our encyclopedia set but we didn't have a dictionary, and this was pre-internet.
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.
Inflammable means flammable? What a country!
It is logical: to inflame means to set on fire. Though, I agree, confusing.
Exactly!
The only logical way out of the flammable/inflammable mess is to use 'flammable' and 'non-inflammable', which makes me so mad.
It's just a parsing error. "in-" is also a prefix to create verbs from a name or another verb like inhume, inflame, induce, incite, inject, infiltrate. Inflammable is (inflame)-able and not in-(flammable)
I agree, but it’s ambiguous, hence the problem.
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).
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