5 ms·

We hit a thing with another thing which imparted a force on it so by the most fundamental laws of physics it's trajectory was effected.

hypertele-Xii 4y ago
If it's so fundamental and obvious, then why wouldn't these world-class astroscientists say anything about any estimations of deviation after such surprising success? Your toenail is affecting the asteroid's trajectory, by laws of physics. That adds nothing to this conversation.
- cjensen 4y ago
  They don't have a radar gun pointing at the asteroid which measures velocity. Instead, they have to measure position after a period of time to measure velocity. The smaller the change in velocity -- and this is a very tiny change -- the longer the time needed to measure the change.
  - hypertele-Xii 4y ago
    > this is a very tiny change There! That's what I was looking for. So they were expecting a miniscule change, and instead they were pleasantly surprised by the evidence and are now expecting a very tiny change?
    - bmlzootown 4y ago
      I mean, they quote Ian Carnelli in the article, saying that he expects a "much bigger deflection than (he) had planned". That said, the article also mentions that it will take Earth-bound telescopes/radars at least a week to get initial estimates in regard to the change of the asteroid's orbit, and then three to four weeks before getting precise measurements. I think the real takeaway here is just that something unexpected happen. They're monitoring as they would have regardless, and results will come in time. Expecting results and/or a conclusion this early is, well, jumping the gun.
    - shagie 4y ago
      The orbit of Didymoon around around its primary is about 4in/s or 10cm/s. Wolfram gives its comparison to the speed of a garden snail. They are hoping to see a change in its velocity of a fraction of a mm/s. https://youtu.be/U0nZvOm3bNs?t=415 https://youtu.be/U0nZvOm3bNs?t=415 It is a small value, but its a measurable fraction of the the velocity of its orbit around the primary (about 12h). They know the momentum that the impacter had. They had an estimate of the mass of Didymoon and its velocity. They are interested in how much of that momentum was transfered to Didymoon and how much was carried away from ejecta.
  - hotpotamus 4y ago
    > They don't have a radar gun You know, I have my doubts about the practical benefits of this whole operation given that there aren't any planet killers lurking in the asteroid belt for at least a century, and so I suspect this was sold with a planetary defense angle because a bit of a scare is a good way to loosen the pocket book. That said, maybe we could justify rebuilding Arecibo along similar lines. I believe they were in fact using it as a near Earth radar gun and it was even initially constructed as a defense project.
    - shagie 4y ago
      The original budget for it was on the low side. It's launch budget went to the lowest bidder - SpaceX at $69m ( https://www.nasa.gov/press-release/nasa-awards-launch-services-contract-for-asteroid-redirect-test-mission https://www.nasa.gov/press-release/nasa-awards-launch-servic... ). The mission as approved 3 years before Arecibo collapsed and final assembly of the spacecraft was done half a year before. https://cosmosmagazine.com/space/dart-timeline-from-build-to-spacex-to-impact/ https://cosmosmagazine.com/space/dart-timeline-from-build-to... The loss of Arecibo was a loss to the mission as the pictures that you most often see of Didymos were from Arecibo. The mission itself was also a technology demonstration of a camera, autonomous navigation using that camera, solar arrays, new antenna, and ion thruster design. https://en.wikipedia.org/wiki/Double_Asteroid_Redirection_Test#Spacecraft https://en.wikipedia.org/wiki/Double_Asteroid_Redirection_Te...
    - ncmncm 4y ago
      1. We have absolutely no certainty that no planet-killers are there. All we know is that none mapper are. 2. China has an Arecibo-class device. Actually bigger than Arecibo. Do we need two? Considering that the whole Free World could not scratch together enough money just to maintain Arecibo, building it again seems beyond possibility.
      - hotpotamus 4y ago
        The astronomers I've seen lecture say that they have a pretty good mapping of the asteroid belt and they know that there are no planet killers in there anytime soon which seems to intuitively make sense since we only get planet killers on the order of every 100 million years or so. Of course there are tons of smaller asteroids out there that can be problematic as well. I wouldn't want to be around when Berringer Crater was created, but that was still a few 10's of thousands of years ago if I'm remembering right. (I'd recommend stopping by if you're ever in the American Southwest). I'm not all that familiar with any of the big radio telescopes, but I thought that China's didn't have the active radar capabilities that Arecibo did. That said, I find it sad that something like Arecibo was possible to build and maintain in the 60's but not now. I suppose that has to do with the perception of it moving from defense project to science project.
- adgjlsfhk1 4y ago
  you don't need a big change to divert an asteroid if you divert it early enough. 1mm/s change a few years in advance is more than enough.
Nekhrimah 4y ago
> effected. Just FYI, this should be affected. https://www.merriam-webster.com/words-at-play/affect-vs-effect-usage-difference https://www.merriam-webster.com/words-at-play/affect-vs-effe...
- heavyset_go 4y ago
  This drives me nuts because 'affect' as a verb means something closer to causing an 'effect', while 'affect' as a noun doesn't. Because of that, on the surface, it feels like 'effect' as verb would make more sense than 'affect' when describing the action of causing an effect on something.
  - bee_rider 4y ago
    In a language full of stupid footguns, affect/effect has got to be one of the worst.
    - mwcremer 4y ago
      Your right, its definately a loosing battle.
      - andrewinardeer 4y ago
        Did you do that on purpose?
        deleted 4y ago
        [deleted]
        dredmorbius 4y ago
        For all in tents and porpises, surly yes.
        bee_rider 4y ago
        Should have gone with "intensive purposes," it would be plausible enough to continue the confusion.

hypertele-Xii 4y ago

If it's so fundamental and obvious, then why wouldn't these world-class astroscientists say anything about any estimations of deviation after such surprising success? Your toenail is affecting the asteroid's trajectory, by laws of physics. That adds nothing to this conversation.

cjensen 4y ago
They don't have a radar gun pointing at the asteroid which measures velocity. Instead, they have to measure position after a period of time to measure velocity. The smaller the change in velocity -- and this is a very tiny change -- the longer the time needed to measure the change.
- hypertele-Xii 4y ago
  > this is a very tiny change There! That's what I was looking for. So they were expecting a miniscule change, and instead they were pleasantly surprised by the evidence and are now expecting a very tiny change?
  - bmlzootown 4y ago
    I mean, they quote Ian Carnelli in the article, saying that he expects a "much bigger deflection than (he) had planned". That said, the article also mentions that it will take Earth-bound telescopes/radars at least a week to get initial estimates in regard to the change of the asteroid's orbit, and then three to four weeks before getting precise measurements. I think the real takeaway here is just that something unexpected happen. They're monitoring as they would have regardless, and results will come in time. Expecting results and/or a conclusion this early is, well, jumping the gun.
  - shagie 4y ago
    The orbit of Didymoon around around its primary is about 4in/s or 10cm/s. Wolfram gives its comparison to the speed of a garden snail. They are hoping to see a change in its velocity of a fraction of a mm/s. https://youtu.be/U0nZvOm3bNs?t=415 https://youtu.be/U0nZvOm3bNs?t=415 It is a small value, but its a measurable fraction of the the velocity of its orbit around the primary (about 12h). They know the momentum that the impacter had. They had an estimate of the mass of Didymoon and its velocity. They are interested in how much of that momentum was transfered to Didymoon and how much was carried away from ejecta.
- hotpotamus 4y ago
  > They don't have a radar gun You know, I have my doubts about the practical benefits of this whole operation given that there aren't any planet killers lurking in the asteroid belt for at least a century, and so I suspect this was sold with a planetary defense angle because a bit of a scare is a good way to loosen the pocket book. That said, maybe we could justify rebuilding Arecibo along similar lines. I believe they were in fact using it as a near Earth radar gun and it was even initially constructed as a defense project.
  - shagie 4y ago
    The original budget for it was on the low side. It's launch budget went to the lowest bidder - SpaceX at $69m ( https://www.nasa.gov/press-release/nasa-awards-launch-services-contract-for-asteroid-redirect-test-mission https://www.nasa.gov/press-release/nasa-awards-launch-servic... ). The mission as approved 3 years before Arecibo collapsed and final assembly of the spacecraft was done half a year before. https://cosmosmagazine.com/space/dart-timeline-from-build-to-spacex-to-impact/ https://cosmosmagazine.com/space/dart-timeline-from-build-to... The loss of Arecibo was a loss to the mission as the pictures that you most often see of Didymos were from Arecibo. The mission itself was also a technology demonstration of a camera, autonomous navigation using that camera, solar arrays, new antenna, and ion thruster design. https://en.wikipedia.org/wiki/Double_Asteroid_Redirection_Test#Spacecraft https://en.wikipedia.org/wiki/Double_Asteroid_Redirection_Te...
  - ncmncm 4y ago
    1. We have absolutely no certainty that no planet-killers are there. All we know is that none mapper are. 2. China has an Arecibo-class device. Actually bigger than Arecibo. Do we need two? Considering that the whole Free World could not scratch together enough money just to maintain Arecibo, building it again seems beyond possibility.
    - hotpotamus 4y ago
      The astronomers I've seen lecture say that they have a pretty good mapping of the asteroid belt and they know that there are no planet killers in there anytime soon which seems to intuitively make sense since we only get planet killers on the order of every 100 million years or so. Of course there are tons of smaller asteroids out there that can be problematic as well. I wouldn't want to be around when Berringer Crater was created, but that was still a few 10's of thousands of years ago if I'm remembering right. (I'd recommend stopping by if you're ever in the American Southwest). I'm not all that familiar with any of the big radio telescopes, but I thought that China's didn't have the active radar capabilities that Arecibo did. That said, I find it sad that something like Arecibo was possible to build and maintain in the 60's but not now. I suppose that has to do with the perception of it moving from defense project to science project.
adgjlsfhk1 4y ago
you don't need a big change to divert an asteroid if you divert it early enough. 1mm/s change a few years in advance is more than enough.

Nekhrimah 4y ago

> effected. Just FYI, this should be affected. https://www.merriam-webster.com/words-at-play/affect-vs-effect-usage-difference https://www.merriam-webster.com/words-at-play/affect-vs-effe...

heavyset_go 4y ago
This drives me nuts because 'affect' as a verb means something closer to causing an 'effect', while 'affect' as a noun doesn't. Because of that, on the surface, it feels like 'effect' as verb would make more sense than 'affect' when describing the action of causing an effect on something.
- bee_rider 4y ago
  In a language full of stupid footguns, affect/effect has got to be one of the worst.
  - mwcremer 4y ago
    Your right, its definately a loosing battle.
    - andrewinardeer 4y ago
      Did you do that on purpose?
      - deleted 4y ago
        [deleted]
      - dredmorbius 4y ago
        For all in tents and porpises, surly yes.
        bee_rider 4y ago
        Should have gone with "intensive purposes," it would be plausible enough to continue the confusion.