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Thread: NASA’s Double Asteroid Redirection Test (DART)

  1. #21

    Default Re: NASA’s Double Asteroid Redirection Test (DART)

    Nasa's Dart spacecraft 'changed path of asteroid'
    The experiment took place some 11 million km (7 million miles) from Earth.

    It saw the 750kg Dart spacecraft drive straight into Dimorphos, destroying itself in the process.

    The space rock orbits a much larger (780m wide) object called Didymos. Before impact, the time taken for Dimorphos to make one circuit of its sibling was 11 hours and 55 minutes.

    The telescope evidence now indicates this orbital period has been reduced to 11 hours and 23 minutes - a change of 32 minutes.

    "This is a 4% change in the orbital period of Dimorphos around Didymos. Dart just gave it a small nudge. But if you wanted to do this in the future, you'd want to do it years in advance," commented Dr Nancy Chabot from the Johns Hopkins University Applied Physics Laboratory, which led the mission for Nasa.


    Beyond being a proof of concept, this mission allowed scientists to test out observing and detecting objects in space and how their trajectory change with kinetic factors.
    The Armenian Issue

  2. #22

    Default Re: NASA’s Double Asteroid Redirection Test (DART)

    I must say that I shared the skepticism of Flinn in this matter and I am quite surprised that the small object had that great of an impact on Dimorphos. I guess this is one of those times when one is happy to have been wrong.

    Also, the up-close imagery of a celestial object like Dimorphos sent by Dart in the brief moments before the impact is very impressive and alone a scientific victory in a sense. I watched that over and over again, amazed that we can get that kind of footage of a relatively small object that far away in the vastness of space.

  3. #23
    Flinn's Avatar His Dudeness of TWC
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    Default Re: NASA’s Double Asteroid Redirection Test (DART)

    I never doubted the possibility that they could modify the orbit of an asteroid, but the actual usefulness of the whole project.

    And to be honest, expecting a modification of 73 second and instead obtaining one of 32 minutes is a huge failure, in scientific terms, because that means that they largely underestimated what was going to happen. Considering that what we are talking about are objects that do not disappear once hit, making a miscalculation of 25 times () can cause serious consequences. Also, this is an asteroid orbiting another larger body, so they were expecting it to go no where far from it, doing the same with an independent orbiting body, with that rateo of error, could lead to a disaster.

    https://www.nasa.gov/press-release/n...otion-in-space

    Let ne stress that again, it's more about politics than science.

    This mission shows that NASA is trying to be ready for whatever the universe throws at us. NASA has proven we are serious as a defender of the planet. This is a watershed moment for planetary defense and all of humanity, demonstrating commitment from NASA's exceptional team and partners from around the world
    Last edited by Flinn; October 13, 2022 at 07:35 AM.
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  4. #24

    Default Re: NASA’s Double Asteroid Redirection Test (DART)

    Quote Originally Posted by Flinn View Post
    I never doubted the possibility that they could modify the orbit of an asteroid, but the actual usefulness of the whole project.
    And to be honest, expecting a modification of 73 second and instead obtaining one of 32 minutes is a huge failure, in scientific terms, because that means that they largely underestimated what was going to happen. Considering that what we are talking about are objects that do not disappear once hit, making a miscalculation of 25 times () can cause serious consequences. Also, this is an asteroid orbiting another larger body, so they were expecting it to go no where far from it, doing the same with an independent orbiting body, with that rateo of error, could lead to a disaster.
    That makes this test even more crucial. They are doing what they should do, what we always do about any process.
    The Armenian Issue

  5. #25
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    Default Re: NASA’s Double Asteroid Redirection Test (DART)

    And to be honest, expecting a modification of 73 second and instead obtaining one of 32 minutes is a huge failure, in scientific terms, because that means that they largely underestimated what was going to happen. Considering that what we are talking about are objects that do not disappear once hit, making a miscalculation of 25 times () can cause serious consequences. Also, this is an asteroid orbiting another larger body, so they were expecting it to go no where far from it, doing the same with an independent orbiting body, with that rateo of error, could lead to a disaster.
    Interesting explanation of why you want to small controlled tests no? I really don't see a basis for your forced nihilism on this point. Now thay have actual data they can than revisit models and figure out why the change was more than they anticipated. But also I do believe you are misreading the statement you are comparing what was the stated minimum expected alteration to be a success to the actual result. Not they calculated that the result would be only that minimum.
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  6. #26
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    Default Re: NASA’s Double Asteroid Redirection Test (DART)

    The issue at hand is that they have promptly demonstrated that any attempt at modifying the orbit will be very random, that is. Dimorphos is a well know object, and yet the results have been 25 times (let me stress the point again, 25 times) greater than expected. This opens up the matter about why there was such a huge difference, which is a valid point to discuss.

    Basically, it's a matter of combining all the different parameters, is to say: speed (also including any rotational speed, if present), size, composition. Of the three, speed (atl orbital speed) is the easiest to measure, while precise size can only be measured after long observations (depending on the albedo, too). The real problem comes with the composition, which in turns determines the mass and the "weight": of the three parameters that's the one that will affect mostly any precision attempt to modify the orbit, and that's basically impossible to establish it in advance with a decent precision (atl with our actual means).

    One ought to keep in mind this small fact about orbiting objects: you just don't have to "push them away and the farther the better", but you rather have to move them into a "safe orbit, which will not interfere with other objects, smaller or larger, and that can possibly cause any unpredictable and uncontrollable consequence". Being of extreme precision, is a must. It's not nihilism, it's looking at facts with actual knowledge of the matter discussed.
    Last edited by Flinn; October 13, 2022 at 09:26 AM.
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  7. #27

    Default Re: NASA’s Double Asteroid Redirection Test (DART)

    If the intention is to knock off the course an object about to hit Earth (the feasibility of which I remain skeptical to), I don't see the problem with knocking it 25 times more off the course than waht would be minimally needed. With the distances in space it would have to astronomically bad luck for that object to then hit something else that will in turn hit Earth.

    In many other scenarios, I would agree with Flinn that more precision is needed. Our intuition easily fails when trying to grasp the vastness of space. Some astronomer claimed that if two galaxies collide, as sometimes happen, it is unlikely that any star systems within those two collide. Quite mind-blowing to me, at least.

  8. #28

    Default Re: NASA’s Double Asteroid Redirection Test (DART)

    The 73 seconds figure is not an expected outcome. It's a threshold figure. Since NASA doesn't know exactly the make up of the asteroid and how its distributed within, they had no way of accurately knowing the result of an impact.
    The Armenian Issue

  9. #29
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    Default Re: NASA’s Double Asteroid Redirection Test (DART)

    Sounds like they hit a rock and it deflected, good result?
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    Default Re: NASA’s Double Asteroid Redirection Test (DART)

    Quote Originally Posted by Cyclops View Post
    Sounds like they hit a rock and it deflected, good result?
    Apparently not according to Flinn perfect pre devised AI based uber simulation work should have resulted in a forgone conclusion of something never done so it did not need to be done and was thus a waste of time. But clearly NASA is full of government hacks just fishing for job security. Presumable Flinn also imagines new cooking recipes can be made on a scratch pad and work the first time all time everywhere.
    Last edited by conon394; October 15, 2022 at 10:51 PM.
    IN PATROCINIVM SVB Dromikaites

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    But if the cause be not good, the king himself hath a heavy reckoning to make, when all those legs and arms and heads, chopped off in battle, shall join together at the latter day and cry all 'We died at such a place; some swearing, some crying for surgeon, some upon their wives left poor behind them, some upon the debts they owe, some upon their children rawly left.

    Hyperides of Athens: We know, replied he, that Antipater is good, but we (the Demos of Athens) have no need of a master at present, even a good one.

  11. #31
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    Default Re: NASA’s Double Asteroid Redirection Test (DART)

    Since it seems impossible to have a reasonably well knowledgeable discussion, due to the ignorance in the matter of some of those partaking into the discussion, I'll answer for the simplest point, or about the fact that not being extremely precise when modifying an orbit is not an issue: it is, because as I tried to explain various times, all the objects orbiting in our Solar System (and the Sun itself) are gravitationally interconnected, so it's not just about "pushing it farther away" but "putting it into a safe orbit". Imagine you planned to change an orbit by 1° and it ending up being modified by 25°, I fail to see how this is not going to be an issue. I dunno how to explain the concept better, so I have to give up if someone simply wants to reject it.

    Quote Originally Posted by PointOfViewGun View Post
    The 73 seconds figure is not an expected outcome. It's a threshold figure. Since NASA doesn't know exactly the make up of the asteroid and how its distributed within, they had no way of accurately knowing the result of an impact.
    Thanks for making my point. As I explained above they will never be able to determine the composition and distribution of mass of an asteroid unless they will be studying it extensively before, something which is not practical and probably impossible for any foreseeable future, so I remain that the whole Dart mission is moot in its own premise. The more if we keep in mind, as I told, that it is completely useless against all those smaller asteroids that are more likely to impact the Earth and that could cause local wreckage.

    As far as I know the original concept of the mission was not to simply "hit an asteroid and let's hope we didn't make it worse", but to actually attach some sort of "motor" to the asteroid/comet and use it to control, as precisely as possible, the modification of the orbit. I don't know why they gave up on that idea, I can assume that the failure of Philae (Rosetta's lander) to properly attach on 67P/Churyumov-Gerasimenko comet played and important role, once again the variables are so many that's impossible to be sure of how to proceed (keep in mind that it's somewhat counter-intuitive, since the larger the object, the easier is to calculate the mass, for instance), even though the Hayabusa probes have been successful in recovering samples.. it's pretty ramdom, atl for what are the standards applied by Nasa and other space agencies when it comes to spending billions to send spacecrafts flying around our system.

    Quote Originally Posted by Cyclops View Post
    Sounds like they hit a rock and it deflected, good result?
    For what it costed? Not really. We have been "hitting" asteroids and comets for over 4 decades now, so there's nothing special about that, and no one ever doubted that a strong enough impact could have modified the orbit of that asteroid. It is scientifically relevant for any future mission? Possibly, even though if they don't determine, again, how the asteroid is composed and its mass distribution, knowing that 600 kg projectile have pushed it "that far away" is a useless info, since it's completely partial.

    We'll see if in the future more similar missions will be set up, I honestly doubt that.
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  12. #32

    Default Re: NASA’s Double Asteroid Redirection Test (DART)

    Quote Originally Posted by Flinn View Post
    Imagine you planned to change an orbit by 1° and it ending up being modified by 25°, I fail to see how this is not going to be an issue.
    Is there a particular reason why you insist on repeating the same fallacious argument?


    Quote Originally Posted by Flinn View Post
    Thanks for making my point. As I explained above they will never be able to determine the composition and distribution of mass of an asteroid unless they will be studying it extensively before, something which is not practical and probably impossible for any foreseeable future, so I remain that the whole Dart mission is moot in its own premise. The more if we keep in mind, as I told, that it is completely useless against all those smaller asteroids that are more likely to impact the Earth and that could cause local wreckage.
    It doesn't make your point as it doesn't stop there. Not knowing exact composition of an asteroid does not stop us from understanding it better based on our observations and come up with feasible models. That's how science works for most things. It doesn't stop us for other fields. Why should it for this particular one?


    Quote Originally Posted by Flinn View Post
    As far as I know the original concept of the mission was not to simply "hit an asteroid and let's hope we didn't make it worse", but to actually attach some sort of "motor" to the asteroid/comet and use it to control, as precisely as possible, the modification of the orbit. I don't know why they gave up on that idea, I can assume that the failure of Philae (Rosetta's lander) to properly attach on 67P/Churyumov-Gerasimenko comet played and important role, once again the variables are so many that's impossible to be sure of how to proceed (keep in mind that it's somewhat counter-intuitive, since the larger the object, the easier is to calculate the mass, for instance), even though the Hayabusa probes have been successful in recovering samples.. it's pretty ramdom, atl for what are the standards applied by Nasa and other space agencies when it comes to spending billions to send spacecrafts flying around our system.
    Have you read their mission report?
    The Armenian Issue

  13. #33

    Default Re: NASA’s Double Asteroid Redirection Test (DART)

    It makes no sense mathematically that deflecting a small object from a collision course would not be worth it because we cannot guarantee a safe orbit. As it whizzes past Earth and starts to gain distance from us, it is almost unthinkable it could cause a worse outcome than the original, undeflected collision would have. Almost any orbit is relatively safe in the vastness of space. Gravitational connectivity does not imply that a small individual rock changing it's course a little would have any catastrophic consequences in a solar system where equilibrium is maintained by objects such as Jupiter.

    According to Nasa there are 1.1 million known asteroids and almost 4,000 known comets, but NASA suspects there might be billions of the latter orbiting the sun. Objects like that frequently change their orbits when they get too close to planetary bodies, and that is no great concern to Earth. We are a tiny little speck in a lot of nothingness.
    Last edited by Septentrionalis; October 19, 2022 at 01:53 PM.

  14. #34
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    Default Re: NASA’s Double Asteroid Redirection Test (DART)

    Since it seems impossible to have a reasonably well knowledgeable discussion, due to the ignorance in the matter of some of those partaking into the discussion, I'll answer for the simplest point, or about the fact that not being extremely precise when modifying an orbit is not an issue: it is, because as I tried to explain various times, all the objects orbiting in our Solar System (and the Sun itself) are gravitationally interconnected, so it's not just about "pushing it farther away" but "putting it into a safe orbit". Imagine you planned to change an orbit by 1° and it ending up being modified by 25°, I fail to see how this is not going to be an issue. I dunno how to explain the concept better, so I have to give up if someone simply wants to reject it.
    While technically I agree you presenting a fact. But deflecting even a larger dangerous asteroid is unlikely perturb any major body in a meaningful way. I mean Oumuamua is exogenous to the system and it does not in fact seem to causing a massive collapse of the the orbits of objects in the solar system.

    As far as I can tell your basic complaint is this is wasteful busy work because we always knew we could hit an asteroid.
    IN PATROCINIVM SVB Dromikaites

    'One day when I fly with my hands - up down the sky, like a bird'

    But if the cause be not good, the king himself hath a heavy reckoning to make, when all those legs and arms and heads, chopped off in battle, shall join together at the latter day and cry all 'We died at such a place; some swearing, some crying for surgeon, some upon their wives left poor behind them, some upon the debts they owe, some upon their children rawly left.

    Hyperides of Athens: We know, replied he, that Antipater is good, but we (the Demos of Athens) have no need of a master at present, even a good one.

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