10 ms·

So it "looks good" but that's all we get for now. A dust plume. What they can't say yet, is if the asteroid's trajectory was effected, at all.

wolfram74 4y ago
the kinetic energy of the probe was 900 times that of the gravitational binding energy of the moonlet, there is a non-trivial chance that the main thing we'll learn from this mission is how these gravel piles are destroyed via impactors. An important process to solar system development.
- lamontcg 4y ago
  I think I worked it out that the kinetic energy is equivalent to around 2 tonnes of TNT, or of roughly a US Navy Atlanta class light cruiser doing 90 mph down the freeway.
  - burnerburnito 4y ago
    Good unit of measurement, that last one.
- andrewflnr 4y ago
  > 900 times that of the gravitational binding energy of the moonlet Wait, seriously? Maybe I should have paid more attention to the relative scale of these things. That makes it sound like the most reasonable expected outcome is total obliteration.
  - wolfram74 4y ago
    The mission was approved in 2015, which means it was designed before then, we've learned a good chunk about how smaller asteroids bind together since then, the hyabusa 2 and osiris rex missions were both after 2019, so it wasn't wholely unreasonable that some other kind of internal binding mechanism might be at play besides the piddling role gravity plays at these scales.
UnlockedSecrets 4y ago
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.
deleted 4y ago
[deleted]
heavyset_go 4y ago
This says that the trajectory was affected[1]: > On Sept. 26, DART crashed into Dimorphos at a speed of 6.6 kilometers (4.1 miles) per second. The impact should have changed Dimorphos' orbital period around Didymos from 11.9 to 11.8 hours — a difference of just 4.2 minutes. This will pull Dimorphos slightly closer to Didymos. [1] https://www.planetary.org/space-missions/dart https://www.planetary.org/space-missions/dart
- docmechanic 4y ago
  +1
- EdwardDiego 4y ago
  Got to say, love the name Didymos - twin. (Random aside, the sayings gospel Gospel of Thomas is attributed to Didymus Judas Thomas, effectively Twin Judas Twin, obviously such a twin that they named him that twice)
  - shagie 4y ago
    Informally called "Didymoon" - https://www.esa.int/ESA_Multimedia/Images/2015/03/Target_Didymoon https://www.esa.int/ESA_Multimedia/Images/2015/03/Target_Did... (which, frankly, is easier to remember which one is which)

wolfram74 4y ago

the kinetic energy of the probe was 900 times that of the gravitational binding energy of the moonlet, there is a non-trivial chance that the main thing we'll learn from this mission is how these gravel piles are destroyed via impactors. An important process to solar system development.

lamontcg 4y ago
I think I worked it out that the kinetic energy is equivalent to around 2 tonnes of TNT, or of roughly a US Navy Atlanta class light cruiser doing 90 mph down the freeway.
- burnerburnito 4y ago
  Good unit of measurement, that last one.
andrewflnr 4y ago
> 900 times that of the gravitational binding energy of the moonlet Wait, seriously? Maybe I should have paid more attention to the relative scale of these things. That makes it sound like the most reasonable expected outcome is total obliteration.
- wolfram74 4y ago
  The mission was approved in 2015, which means it was designed before then, we've learned a good chunk about how smaller asteroids bind together since then, the hyabusa 2 and osiris rex missions were both after 2019, so it wasn't wholely unreasonable that some other kind of internal binding mechanism might be at play besides the piddling role gravity plays at these scales.

UnlockedSecrets 4y ago

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.

deleted 4y ago

[deleted]

heavyset_go 4y ago

This says that the trajectory was affected[1]: > On Sept. 26, DART crashed into Dimorphos at a speed of 6.6 kilometers (4.1 miles) per second. The impact should have changed Dimorphos' orbital period around Didymos from 11.9 to 11.8 hours — a difference of just 4.2 minutes. This will pull Dimorphos slightly closer to Didymos. [1] https://www.planetary.org/space-missions/dart https://www.planetary.org/space-missions/dart

docmechanic 4y ago
+1
EdwardDiego 4y ago
Got to say, love the name Didymos - twin. (Random aside, the sayings gospel Gospel of Thomas is attributed to Didymus Judas Thomas, effectively Twin Judas Twin, obviously such a twin that they named him that twice)
- shagie 4y ago
  Informally called "Didymoon" - https://www.esa.int/ESA_Multimedia/Images/2015/03/Target_Didymoon https://www.esa.int/ESA_Multimedia/Images/2015/03/Target_Did... (which, frankly, is easier to remember which one is which)