A First for Humanity Confirmed: NASA's DART Mission Slowed the Asteroid's Orbit (sciencenews.org) 54
NASA heralded a new study published Friday documenting a first for humanity — "the first time a human-made object has measurably altered the path of a celestial body around the Sun."
It was 2022's DART mission where NASA crashed a spacecraft into an asteroid — and the experiment "could have implications for protecting Earth from future asteroid strikes," writes ScienceNews: A spacecraft slowed the orbit of a pair of asteroids around the sun by more than 10 micrometers per second... Within a month, researchers showed that the impact shortened Dimorphos' 12-hour orbit by 32 minutes. Some of the rocks knocked off of Dimorphos fled the vicinity completely, escaping the gravitational influence of the Dimorphos-Didymos pair, says planetary defense researcher Rahil Makadia of the University of Illinois Urbana-Champaign. Those rocky runaways took some momentum away from the duo and changed their joint motion around the sun.
To figure out how much that motion was affected, astronomers watched the asteroids pass in front of distant stars, dimming some of the stars' light like a tiny eclipse. These blinks, called stellar occultations, can be visible from anywhere on Earth and are predictable in advance... Calculating how far off occultation timings were from predictions revealed that the asteroids' orbit around the sun was about 150 milliseconds slower than before the DART impact...
Didymos and Dimorphos are not a threat to Earth, Makadia says, and weren't before DART. But knowing how a deliberate impact changes one asteroid's orbit can help make defense plans against another, "in case we need to do a kinetic impact for real."
The researchers spent nearly two and a half years to collect 22 measurements of the asteroid's post-crash position, relying on amateur astronomers "to go out into the middle of nowhere and observe the necessary stellar occultations," acvcording to their paper. Planetary defense researcher even tells ScienceNews "There was an observer who drove two days each way into the Australian outback to get these measurements."
It was 2022's DART mission where NASA crashed a spacecraft into an asteroid — and the experiment "could have implications for protecting Earth from future asteroid strikes," writes ScienceNews: A spacecraft slowed the orbit of a pair of asteroids around the sun by more than 10 micrometers per second... Within a month, researchers showed that the impact shortened Dimorphos' 12-hour orbit by 32 minutes. Some of the rocks knocked off of Dimorphos fled the vicinity completely, escaping the gravitational influence of the Dimorphos-Didymos pair, says planetary defense researcher Rahil Makadia of the University of Illinois Urbana-Champaign. Those rocky runaways took some momentum away from the duo and changed their joint motion around the sun.
To figure out how much that motion was affected, astronomers watched the asteroids pass in front of distant stars, dimming some of the stars' light like a tiny eclipse. These blinks, called stellar occultations, can be visible from anywhere on Earth and are predictable in advance... Calculating how far off occultation timings were from predictions revealed that the asteroids' orbit around the sun was about 150 milliseconds slower than before the DART impact...
Didymos and Dimorphos are not a threat to Earth, Makadia says, and weren't before DART. But knowing how a deliberate impact changes one asteroid's orbit can help make defense plans against another, "in case we need to do a kinetic impact for real."
The researchers spent nearly two and a half years to collect 22 measurements of the asteroid's post-crash position, relying on amateur astronomers "to go out into the middle of nowhere and observe the necessary stellar occultations," acvcording to their paper. Planetary defense researcher even tells ScienceNews "There was an observer who drove two days each way into the Australian outback to get these measurements."
redunancy is solid engineering (Score:4, Funny)
while we don't really need the asteroid's help, it is nice to have a backup plan.
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While, if they had left it alone, it would have missed us completely. Good job, NASA!
Sure, it's good to know that it worked in case we need it in the future, but screwing with something like that can have consequences.
Leave it to the humans to bang rocks together (Score:1)
I remember being told more times than I can remember by more exceptionally credentialled people than I can count that nuking an asteroid wasn't going to do jack squat and a more subtle and controllable approach was called for in case an asteroid *needed* redirecting.
Well here we've got a split verdict at best. Yes momentum change did occur, but it was a messy and chaotic affair since this (like many if not most) was a rubble pile and the momentum exchange wasn't a clean pure inelastic or pure elastic collis
Re:Leave it to the humans to bang rocks together (Score:5, Interesting)
Yes, but... They used the craft itself. Your proposal of a nuke would give a strong, uniform push to the target. But to get it there would cost a LOT more. Nukes are heavy. Very heavy. If the target is legitimately threatening Earth, sure, throw all the money we have at it. For an experiment looking for data, this is fine.
Re: Leave it to the humans to bang rocks together (Score:2)
The smallest fissile bomb weighed about 51lbs and yielded 20kt. https://en.wikipedia.org/wiki/... [wikipedia.org] (DART impact was about 3kt).
I expect you could find room in the weight budget in the 1340lb DART for that by cutting some of the secondary stuff (liciacube on its own was 31lbs).
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Ah Grasshopper, you recall those fetching movies of nukes going off and get all Hegsethian about it: "Wow!! One of these would surely do the trick." In typical Hegethian fashion, you forget that a stand-off nuke means the nuke stands-off (hint: the name). It will go off in a more or less spherical explosion. A tiny fraction of that explosion will impact the asteroid. Most will go off into space. And the mass of the explosion is quite small. So you can not count on the mass.
You are counting on the shock wave
Re: Leave it to the humans to bang rocks together (Score:1)
Shockwaves don't exist in space, genius. They are pressure waves that propagate through air.
The energy to drive them comes from xrays and gamma rays released in a nuclear blast. Those propagate fine through empty space. And while most of them would go off to nowhere, the energy flux through the asteroid would be more than enough to ablate away material to impart an impulse to the whole side of the asteroid, not just at one impact point.
Pro tip: a Team Blue membership card is not the same thing as technical
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Shockwaves don't exist in space, genius. They are pressure waves that propagate through air.
He knows that. He was accusing you of not knowing that.
The energy to drive them comes from xrays and gamma rays released in a nuclear blast. Those propagate fine through empty space. And while most of them would go off to nowhere, the energy flux through the asteroid would be more than enough to ablate away material to impart an impulse to the whole side of the asteroid, not just at one impact point.
Ehhh, a fucking microscopic amount of energy compared to a kinetic impactor.
Yes, the "rubble pile" is a problem, but a nuclear weapon is still a terrible energy transfer mechanism.
Pro tip: a Team Blue membership card is not the same thing as technical expertise in whatever topic is being discussed, be it epidemiology, celestial mechanics, or nuclear weapons.
Undeniably the case.
But you lost all credibility when you talked about nuking an asteroid.
Re: Leave it to the humans to bang rocks together (Score:1)
Like I said... a lot of received wisdom. Wisdom predicated on assumptions that have been demonstrated to be only partly true.
It's the absolute amount of energy and momentum transfer, not the efficiency that matters. And ablation by high power xrays from an upclose nuke is a whole hell of a lot of energy and momentum, even if orders of magnitude more go off into 4pi minus epsilon.
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It's got the surface area to make a pretty significant rocket motor.
For smaller objects, a kinetic impactor is going to transfer far more momentum than any nuke will ever be capable of- at least in standoff configuration.
That goes right out the window if you actually embed the weapon within the asteroid or something like that, but afaik, that's generally considered A Bad Idea.
Size of the effect (Score:5, Interesting)
But before the Slashdot snark kicks in, keep in mind that this whole experiment was aimed principally at changing the orbit of the minimoon (Dimorphos) , rather than altering the orbit of the pair around the sun. That effect - the subject of this article - is a side effect of the main event. If they'd instead smashed into the main body (Didymos), the effect on the heliocentric velocity would be larger.
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Nobody saw any of the sci-fi movies that dealt with this exact thing?
So... you slowed it a tiny, tiny, fraction of a millimeter (like taking a sheet of paper and slicing a sheet of paper down the broadside... a micrometer of a micron)... good job deflecting it! Are you gonna launch one of those asteroid-orbital knockers for everything that comes too close? Are you going to tie the launch to some sh**y AI? Do we have a thousand rockets ready to go exactly now to combat all the natural things heading for u
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All this proves is we can force an asteroid to divert a millimeter further away. What did this cost? What were the chances this would smack into us? Was it worth it?
Do you understand that one way how people find out whether a technique is effective is by trying them it out and seeing what happens?
Can you think of a scenario where having some real-world data on how a spacecraft alters the trajectory of a projectile might be useful?
Do you think remaining ignorant and inexperienced is an effective way to save money?
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Sure... experientialism. I'm extremely familiar with the concept. I used to work at a place that built a whole thing that shrunk a quarter to the size of a dime (1,800 volts, over 100,000Amps, dumped into a coil of wire wrapped around the quarter a dozen times... no loss of mass at all). It started with a few microwave caps, grew to a bunch of electrolytics, and ended with three big Aerovox caps.
Sure, send up a thing and blast it to pieces... what about when those pieces get directed towards you instead
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Well,
do you think in a normal society, people lern those physics in school?
You do not need to fire a projectile at an asteroid to see "for real" if it works.
You only need pen and paper. I would bet second year physics you have a question in your test asking exactly that.
Hope that helped your hypocrite arrogance.
P.S. you need only two laws: conservation of energy and conservation of momentum, under the condition of an "inelastic collision".
If you do not know how to to that: google it. The AI will not be scol
We can do it! (Score:4, Funny)
This implies that given the proper care, we should be able to put 2024 YR4 [slashdot.org] back on track to impact the Moon! Humanity has really been half-assing this destroying the ecosystem [slashdot.org] and I feel like we can do better by annihilating with a well placed asteroid.
How do you "slow an orbit"? (Score:2)
An appropriate headline for DevianArt perhaps, but here?
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Physics isn't your strong suit is it? Maybe you should go hang out on DeviantArt. Or learn some basic physics.
>How do you "slow an orbit"?
Oh, I don't know, maybe:
1: Make the orbit a larger circumference without adjusting the speed. This will slow the orbit until equilibria is re-achieved and the object gets pulled back to the original circumference over time.
2: Slow the object itself, and the orbit will be slower and maintain being slower once the smaller circumference orbit is achieved.
3: Do the opposit
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Congrats... you just made it your kids' problem (or made it tomorrow's issue)!
Slow the orbit... instead of tomorrow, it's two days from now! Awesome!
Make the orbit larger... push it an inch beyond what the orbit was originally (to make it orbit around our huge planet, which will attract it back in a wild orbit that we'll have to compensate for)
Inertia... requires clamping onto the thing, just nuzzling against it, or some combo that can be done in space... whatever it is has to have fuel
Whatever route you t
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>Congrats... you just made it your kids' problem (or made it tomorrow's issue)!
Uh, yeah, that's kind of the whole point...
If you've done the math and find out that objects A and B are going to meet at a point in space in the future, and it takes an hour for A to fully be outside of the point of intersection so no part of it will be touched when B gets there, you slow down or speed up object B just enough so that there's no intersection.
That doesn't mean you stop tracking the object and forget about it ei
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Solution: https://slashdot.org/comments.... [slashdot.org]
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Well, of course, NORAD and Space Force track everything possible, and all the global observatories will notice it, I'm sure (unless we hate a country... easy way to clean house). :-) bonus, strap some radioactive waste to the thing).
Launching a VW Bug at it won't do much... a grabby thing with some rocket engines and a massive gas tank might do better... just keep nudging it at the right points and guide it toward the Sun (more fuel for the fire
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Unless you can think of a way to eject it from the solar system, or move it into a significantly different solar orbit, that's how it works.
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An unmanned craft that clamps onto the thing, lights an engine or three and shoves it into the sun, same thing we could do with the nuclear waste (strap a few barrels to the craft).
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Hence the "It can't be eliminated."
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Applying even 12km/s of delta-v to something with tens of thousands- up to millions of metric tons of mass would require more thrust than all rockets mankind has ever launched, ever.
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So, change it's orbit enough that it'll avoid Earth, Venus, and Mercury (and the moons and the other junk piles), so that it's orbit will take it into the big ball of fusion nearby.
It doesn't have to be rocket's firing all the way... just shove it far enough that it's orbital trajectory will smack it into the big ball of fusion. It can be the size of Starship, just a gas tank with a computer and comms, with a grabber thingy to clamp onto the object and get it far enough out to do the job. Or, leave the cr
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So, change it's orbit enough that it'll avoid Earth, Venus, and Mercury (and the moons and the other junk piles), so that it's orbit will take it into the big ball of fusion nearby.
I explained this to you.
It requires more energy to make it intersect with the sun (over twice as much) that it does to make it leave the solar system.
And even the amount that it takes to leave the solar system is more than all of the rocket fuel mankind has ever used for even a small space rock.
It doesn't have to be rocket's firing all the way... just shove it far enough that it's orbital trajectory will smack it into the big ball of fusion. It can be the size of Starship, just a gas tank with a computer and comms, with a grabber thingy to clamp onto the object and get it far enough out to do the job. Or, leave the craft attached with a fullish tank, and give it an occasional "gentle nudge" as far as you can afford.
Delta-v is the measurement of how much change of velocity is required to transition one orbit to another.
To create any orbit that impacts the sun, it requires a minimum of 30km/s of delta-v.
To create an orbit tha
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Large rock in the pond in the back forty versus a dozen timed rocks in the same pond... which gets
I know stopping a Foucault Pendulum totally takes a good amount of energy... that's why you nudge it the same amount each time it passes the same point; just keep pushing it a bit further out (so, you'd have to plot all the course out and time everything right)... you don't have to burn your whole fuel load in one go.
Put it in the sun = most likely (because we don't know the end result truly, but material shoul
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You're also talking speed...
Correct. Because it's all that matters when computing an orbit.
12.3km/s.
12 to leave the solar system. 30 to reach the sun.
Force moves thing... not speed. Speed would be the big rock (big splash, little waves).
No, speed is a reaction to force. I can give you the values in force if you like, but they're less helpful. Orbital parameters care not what amount of force it took to move something (which is dependent upon the mass of the thing you're moving), only its velocity.
I'm not getting through to you, but you fundamentally misunderstand how orbital mechanics work.
You can't "drop" something into the s
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You are daft, right?
Your parent told you already two times how and why this is kind of impossible.
The only way to do it, would be a sling shot maneuver around another plant, and even that is far sketched,
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One, my "parents" didn't tell me anything about this kinda thing... I'm the geek in the family (156 laptops built out of like 300s worth of parts when I worked for the non-profit science lab, we also had a Foucault pendulum in a stairway). Or, are you referring to someone else who commented, who I've never met outside of here as my parent?
A nudge (kick the thrusters for 30 seconds or less) at the right time, you can change the orbit far enough that we don't have to worry... shoot your whole load at once an
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and the orbit will be slower
What is the speed of an orbit, which happens to be an abstract circle that we draw in the sky to visualize the motion of a celestial object?
Words have meanings, and these are sometimes very specific. It is good to know them before you stick your neck out, dear.
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Yeah, you need to go take some physics classes, "dear".
Speed is distance over time.
Orbital speed is the time it takes to reach the same point on "the abstract circles drawn in space" when an object is traveling through space while captured by a gravity well. Earth is roughly 29.8km/s OR 365.25 days.
Now what happens if you change the speed or the distance? Hmmmm? You either get a positive or negative number from the reference point of 1 where the object would be if unaffected. We call that either slowing dow
Re: How do you "slow an orbit"? (Score:2)
aggressive ignoramus day on slashdot today, just like every day :)
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Oh please, use your towering intellect to point out what's wrong in the posts of someone who actually knows what they are talking about.
This should be amusing considering your prior posts. My prediction? It will probably be zero substance again, maybe with personal attacks thrown in for good measure. Because you fundamentally seem incapable of understanding basic physics principles and the terms used in orbital mechanics.
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There is nothing abstract about it, and it's not drawn in the sky.
An orbit is the path a celestial object in freefall.
orbit (n):
the curved path of a celestial object or spacecraft around a star, planet, or moon, especially a periodic elliptical revolution.
Given the nature of orbital parameters, the path can be said to sped up, or slowed down, lengthened (in space), or shortened (in time).
These are all valid descriptors.
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Ah, we're pretending to be "smart" again. An orbit has 6 degrees of freedom and is therefore described by 6 independent parameters. There are several different incarnations of these, but the typical is this one: https://www.astronomicalreturn... [astronomicalreturns.com]
Which orbit is "fast", which is "slow" and why?
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Ah, we're pretending to be "smart" again.
No, we're demonstrating that we're more knowledgeable than you, not that that's a high bar or anything.
An orbit has 6 degrees of freedom and is therefore described by 6 independent parameters.
Correct.
There are several different incarnations of these, but the typical is this one: https://www.astronomicalreturn... [www.astron...lreturn...] [astronomicalreturns.com]
Also a factual statement.
Which orbit is "fast", which is "slow" and why?
That's the wrong question to be asking, and it shows definitively that you have no fucking idea what you're talking about, or what your link even says, lol.
The question you need to be asking, is how does the "faster" orbit affect its orbital parameters.
If you had pointed out the problem with ambiguity, you'd have demonstrated that you had any idea what you were talking a
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So, which parameter of the six is "faster" or "slower", smartypants?
I get the attempted sarcasm, but why is there no answer to such a simple question from a simpleton like myself?
How did the "DART mission slow the asteroid orbit" as the headline claims, in terms of the orbital definition that you accept as "correct"?
Enlighten me :)
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So, which parameter of the six is "faster" or "slower", smartypants?
The question you mean to ask, is which of them are factors for the orbital velocity.
Speed is not one of the parameters, because speed is determined by the parameters.
If you alter the speed, you alter the parameters. It's not like a spacecraft engages its eccentricity drive or its inclination motivator to change its orbit.
I get the attempted sarcasm, but why is there no answer to such a simple question from a simpleton like myself?
Because you asked the wrong question.
How did the "DART mission slow the asteroid orbit" as the headline claims, in terms of the orbital definition that you accept as "correct"?
It transferred the momentum from the impactor into the orbiting body, slowing its orbital velocity, via a retrograde impulse.
The result on the orbita
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So, how is the orbit itself, as claimed by the moronic headline, "slowed down"?
Your fail of an explanation has no relation to the orbit, you're discussing a transfer of an object from one orbit to another, and not "slowing" or "speeding up" of an orbit.
So, tell me, how do you slow down an orbit - you have the parameters that describe one, show us how it is done using them. Ought to be easy :)))
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So, how is the orbit itself, as claimed by the moronic headline, "slowed down"?
Because the mean orbital velocity was decreased (slowed) by the impact.
Your fail of an explanation has no relation to the orbit, you're discussing a transfer of an object from one orbit to another, and not "slowing" or "speeding up" of an orbit.
This is some idiotic reasoning, right here.
You seem to be arguing that to alter your orbit at all, you have "transferred" to a new orbit, as if an orbit were a quantum energy level.
"The car didn't move left, it transferred to a new lane."
So, tell me, how do you slow down an orbit - you have the parameters that describe one, show us how it is done using them. Ought to be easy :)))
I literally already explained that. I don't know how to help you understand it- your head is buried too far up your ass, I fear.
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Because the mean orbital velocity was decreased (slowed) by the impact.
What does the velocity of an object have to do with the orbit as such? The object slowed, and moved to a different orbit.
as if an orbit were a quantum energy level.
Concepts have precise definitions for a reason. I'm sorry you're unable to grasp a simple concept like that, but an orbit can't be "slowed" or "accelerated", it is just there.
I literally already explained that.
No, you literally didn't, you explained something else. Like I said, if you could "slow down" or "speed up" an orbit, you'd be able to express it in orbital parameters only.
You still haven't :)
"The car didn't move left, it transferred to a new lane."
You're argument that an
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Your.
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What does the velocity of an object have to do with the orbit as such? The object slowed, and moved to a different orbit.
That is equally as valid as saying, "The object's orbit slowed."
You're coming at this from a bizarre semantic direction where orbits cannot be modified, only swapped with a new one.
You have used the term "transferred to a new orbit", which I assume was you mixing up a Transfer Orbit with the modification of one's orbit to a transfer orbit.
This is incorrect usage of the word.
Do you think NASA refers to station keeping as "transferring to a new orbit?"
Of course not.
Concepts have precise definitions for a reason. I'm sorry you're unable to grasp a simple concept like that, but an orbit can't be "slowed" or "accelerated", it is just there.
This is a linguistic nonsense.
It's equ
Re: How do you "slow an orbit"? (Score:2)
That is equally as valid as saying, "The object's orbit slowed."
Except it hasn't, as it would be a different orbit, described by different orbital parameters.
I know physics is hard and that you're struggling, but believe me, removing that friction force from the lane breaks all traffic analogies.
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Yes, dear
In this case, the speed of the orbit is whatever it was cruising at before it caught a whiff of this little blue marble's gravity and got pulled closer towards us.
We launched a tin can at it and nudged it a little bit, so now, it's orbit is a little wider and it's speed is slowed by a few feathers... wow, that $500 billion launch really saved us! Oh, wait... what's that heading straight for ---- (dead air)
Couldn't we, with all our global engineering knowledge, build a flying gas tank with a claw m
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How do you shorten one (in time)?
How do you lengthen one (in distance)?
How would you like a modification to the orbital parameters given?
Didn't it speed up the orbit? (Score:1)
who pays (Score:2)
Who pays if they accidentally *cause* an asteroid to collide with Earth?