On 10/13/2022 9:04 AM, Paul S Person wrote:
> On Wed, 12 Oct 2022 21:45:51 -0700, Robert Woodward
> <robertaw@drizzle.com> wrote:
>
>> In article <aordkhd6kbl77elr1ahd8fe2vh2eilvd9s@4ax.com>,
>> Paul S Person <psperson@old.netcom.invalid> wrote:
>>
>>> On Tue, 11 Oct 2022 12:19:41 -0700 (PDT), "pete...@gmail.com"
>>> <petertrei@gmail.com> wrote:
>>>
>>>> On Friday, October 7, 2022 at 12:03:57 AM UTC-4, pete...@gmail.com wrote:
>>>>
>>>> NASA in the last hour has announced the first results.
>>>>
>>>> The asteroid's orbit around its primary, 11 hours and 55 minutes, has been
>>>> shortened by 35 minutes. A 10 minute change would have been regarded as
>>>> a success.
>>>
>>> So now we know it /can/ be done.
>>>
>>> Of course, the target has to be fairly solid. A bunch of loosely-bound
>>> rubble might not produce the same happy result.
>>
>> I believe that Dimorphos is a loosely-bound rubble pile. There was,
>> after all, a plume over 1000 kilometers long. AFAIK, the observed effect
>> was significantly larger than the pure momentum transfer. I suspect that
>> the kinetic energy of the impact resulted in ejecta that increased the
>> amount of deceleration.
>
> The article I read also points to the plume as helping explain the
> better-than-expected result.
>
> But it also contained a statement that this might not work if the
> whole thing was just rubble: nothing to push on!

Or too many individual things to push on.

--
I've done good in this world. Now I'm tired and just want to be a cranky
dirty old man.

On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:

> But it also contained a statement that this might not work if the
> whole thing was just rubble: nothing to push on!

And that is quite a reasonable argument, despite the wording having
an unfortunate resemblance to a fallacious argument that rockets
can't work. (You know, the one which requires never having heard of
Newton's Third Law.)

John Savard

On Friday, October 14, 2022 at 3:40:10 AM UTC-4, Quadibloc wrote:
> On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
>
> > But it also contained a statement that this might not work if the
> > whole thing was just rubble: nothing to push on!
> And that is quite a reasonable argument, despite the wording having
> an unfortunate resemblance to a fallacious argument that rockets
> can't work. (You know, the one which requires never having heard of
> Newton's Third Law.)

No.

If there was 'nothing to push on' the probe would pass through the asteroid
without slowing.

I note that the Wikipedia article on the target 'Dimorphos' characterizes it as
a 'low-density rubble pile'.

Even a rubble pile provides resistance, and kinetic energy is transferred from
the probe to the material of the asteroid, similarly to how mere air can slow
a bullet.

Dimorphos is only about 170 meters across (hitting it at >4 miles/sec is quite
a feat). The impact was the equivalent of several tons of TNT, and is though to
have blown a crater 150 meters across - ie, it blew out a whole side of the asteroid.
We'll get photos in a few years on a follow-up mission.

Blowing stuff out in the opposite direction of the probe's path increased the
amount by which the asteroid's velocity changed, over what would happen
if the probe just entered the asteroid without kicking stuff up.

pt

Quadibloc <jsavard@ecn.ab.ca> writes:
>On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
>
>> But it also contained a statement that this might not work if the
>> whole thing was just rubble: nothing to push on!
>
>And that is quite a reasonable argument,

Is it? What is the effect of the rubble flying off in all
directions on the orbit of the object?

On Fri, 14 Oct 2022 13:43:51 GMT, scott@slp53.sl.home (Scott Lurndal)
wrote:

>Quadibloc <jsavard@ecn.ab.ca> writes:
>>On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
>>
>>> But it also contained a statement that this might not work if the
>>> whole thing was just rubble: nothing to push on!
>>
>>And that is quite a reasonable argument,
>
>Is it? What is the effect of the rubble flying off in all
>directions on the orbit of the object?

If it is /really/ "all directions", it might well net out to ... none
at all.

An actual space scientist/physicist made the statement, BTW.
--
"In this connexion, unquestionably the most significant
development was the disintegration, under Christian
influence, of classical conceptions of the family and
of family right."

In article <7b3c4a88-31ae-431c-83cd-e960c2560cd2n@googlegroups.com>,
pete...@gmail.com <petertrei@gmail.com> wrote:
>On Friday, October 14, 2022 at 3:40:10 AM UTC-4, Quadibloc wrote:
>> On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
>>
>> > But it also contained a statement that this might not work if the
>> > whole thing was just rubble: nothing to push on!
>> And that is quite a reasonable argument, despite the wording having
>> an unfortunate resemblance to a fallacious argument that rockets
>> can't work. (You know, the one which requires never having heard of
>> Newton's Third Law.)
>
>No.
>
>If there was 'nothing to push on' the probe would pass through the asteroid
>without slowing.
>
>I note that the Wikipedia article on the target 'Dimorphos' characterizes it as
>a 'low-density rubble pile'.
>
>Even a rubble pile provides resistance, and kinetic energy is transferred from
>the probe to the material of the asteroid, similarly to how mere air can slow
>a bullet.
>
>Dimorphos is only about 170 meters across (hitting it at >4 miles/sec is quite
>a feat). The impact was the equivalent of several tons of TNT, and is though to
>have blown a crater 150 meters across - ie, it blew out a whole side of
>the asteroid.
>We'll get photos in a few years on a follow-up mission.
>
>Blowing stuff out in the opposite direction of the probe's path increased the
>amount by which the asteroid's velocity changed, over what would happen
>if the probe just entered the asteroid without kicking stuff up.

(Hal Heydt)
One might also expect there to have been considerable heating
from the impact energy, which could create a "jet" of material
adding to the delta-v.

On Friday, October 14, 2022 at 7:18:03 AM UTC-6, pete...@gmail.com wrote:
> On Friday, October 14, 2022 at 3:40:10 AM UTC-4, Quadibloc wrote:
> > On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
> >
> > > But it also contained a statement that this might not work if the
> > > whole thing was just rubble: nothing to push on!

> > And that is quite a reasonable argument, despite the wording having
> > an unfortunate resemblance to a fallacious argument that rockets
> > can't work. (You know, the one which requires never having heard of
> > Newton's Third Law.)

> No.
>
> If there was 'nothing to push on' the probe would pass through the asteroid
> without slowing.

If the "whole thing was just rubble", then there would be no way to transfer
momentum to the entirety of the asteroid in a uniform way - unless you
had a tractor beam or antigravity. So while you are correct if one takes the
wording in a precise literal sense, it is still the case that there is no convenient
handle to grab with which to move the asteroid - no place where one can push,
and push the whole asteroid as a unit as the result.

That was what was _meant_, as ought to have been obvious.

John Savard

On Friday, October 14, 2022 at 8:13:15 PM UTC-4, Quadibloc wrote:
> On Friday, October 14, 2022 at 7:18:03 AM UTC-6, pete...@gmail.com wrote:
> > On Friday, October 14, 2022 at 3:40:10 AM UTC-4, Quadibloc wrote:
> > > On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
> > >
> > > > But it also contained a statement that this might not work if the
> > > > whole thing was just rubble: nothing to push on!
>
> > > And that is quite a reasonable argument, despite the wording having
> > > an unfortunate resemblance to a fallacious argument that rockets
> > > can't work. (You know, the one which requires never having heard of
> > > Newton's Third Law.)
>
> > No.
> >
> > If there was 'nothing to push on' the probe would pass through the asteroid
> > without slowing.
> If the "whole thing was just rubble", then there would be no way to transfer
> momentum to the entirety of the asteroid in a uniform way - unless you
> had a tractor beam or antigravity. So while you are correct if one takes the
> wording in a precise literal sense, it is still the case that there is no convenient
> handle to grab with which to move the asteroid - no place where one can push,
> and push the whole asteroid as a unit as the result.
>
> That was what was _meant_, as ought to have been obvious.

A rubble pile asteroid still has self binding by its own gravity. As long as most
doesn't experience acceleration beyond its escape velocity, it will all experience
the bulk acceleration, and hang together, perhaps with a little rearrangement.

Pt

On Friday, 14 October 2022 at 17:00:29 UTC+1, Paul S Person wrote:
> On Fri, 14 Oct 2022 13:43:51 GMT, sc...@slp53.sl.home (Scott Lurndal)
> wrote:
> >Quadibloc <jsa...@ecn.ab.ca> writes:
> >>On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
> >>
> >>> But it also contained a statement that this might not work if the
> >>> whole thing was just rubble: nothing to push on!
> >>
> >>And that is quite a reasonable argument,
> >
> >Is it? What is the effect of the rubble flying off in all
> >directions on the orbit of the object?
> If it is /really/ "all directions", it might well net out to ... none
> at all.
>
> An actual space scientist/physicist made the statement, BTW.

You'd apply a force, or an impulse, that accelerates
some or all of the mass out of a collision course
with Earth (if that's what you're attempting), so it
would be different from the asteroid somehow
spontaneously exploding but, mathematically as
a whole, not accelerating.

However, you could fire a space bullet at the
flying rock heap and see the bullet and some of the
rocks fly out of the back of the heap, while the
rest of the asteroid continues in the original course.
Like cutting the core out of an apple.

So maybe we need to start thinking about wrapping
the heap in a big net, first. Or use duct tape.

On Saturday, October 15, 2022 at 3:49:39 PM UTC-4, Robert Carnegie wrote:
> On Friday, 14 October 2022 at 17:00:29 UTC+1, Paul S Person wrote:
> > On Fri, 14 Oct 2022 13:43:51 GMT, sc...@slp53.sl.home (Scott Lurndal)
> > wrote:
> > >Quadibloc <jsa...@ecn.ab.ca> writes:
> > >>On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
> > >>
> > >>> But it also contained a statement that this might not work if the
> > >>> whole thing was just rubble: nothing to push on!
> > >>
> > >>And that is quite a reasonable argument,
> > >
> > >Is it? What is the effect of the rubble flying off in all
> > >directions on the orbit of the object?
> > If it is /really/ "all directions", it might well net out to ... none
> > at all.
> >
> > An actual space scientist/physicist made the statement, BTW.
> You'd apply a force, or an impulse, that accelerates
> some or all of the mass out of a collision course
> with Earth (if that's what you're attempting), so it
> would be different from the asteroid somehow
> spontaneously exploding but, mathematically as
> a whole, not accelerating.
>
> However, you could fire a space bullet at the
> flying rock heap and see the bullet and some of the
> rocks fly out of the back of the heap, while the
> rest of the asteroid continues in the original course.
> Like cutting the core out of an apple.
>
> So maybe we need to start thinking about wrapping
> the heap in a big net, first. Or use duct tape.

No need. We have proof of concept.

We *know* that the asteroid had its orbit changed, and
by more than expected.

The 'flying in all directions' video was taken by a cubesat
trailing behind the DART probe, so yes, it looks symmetrical.

If you look at a side view, such as that taken by to James
Webb, it's abundantly clear that most of the ejecta went
In one direction:

https://www.youtube.com/watch?v=P1zukXq4NDc

Pt

On Saturday, October 15, 2022 at 11:16:27 PM UTC+3, pete...@gmail.com wrote:
> On Saturday, October 15, 2022 at 3:49:39 PM UTC-4, Robert Carnegie wrote:
> > On Friday, 14 October 2022 at 17:00:29 UTC+1, Paul S Person wrote:
> > > On Fri, 14 Oct 2022 13:43:51 GMT, sc...@slp53.sl.home (Scott Lurndal)
> > > wrote:
> > > >Quadibloc <jsa...@ecn.ab.ca> writes:
> > > >>On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
> > > >>
> > > >>> But it also contained a statement that this might not work if the
> > > >>> whole thing was just rubble: nothing to push on!
> > > >>
> > > >>And that is quite a reasonable argument,
> > > >
> > > >Is it? What is the effect of the rubble flying off in all
> > > >directions on the orbit of the object?
> > > If it is /really/ "all directions", it might well net out to ... none
> > > at all.
> > >
> > > An actual space scientist/physicist made the statement, BTW.
> > You'd apply a force, or an impulse, that accelerates
> > some or all of the mass out of a collision course
> > with Earth (if that's what you're attempting), so it
> > would be different from the asteroid somehow
> > spontaneously exploding but, mathematically as
> > a whole, not accelerating.
> >
> > However, you could fire a space bullet at the
> > flying rock heap and see the bullet and some of the
> > rocks fly out of the back of the heap, while the
> > rest of the asteroid continues in the original course.
> > Like cutting the core out of an apple.
> >
> > So maybe we need to start thinking about wrapping
> > the heap in a big net, first. Or use duct tape.
> No need. We have proof of concept.
>
> We *know* that the asteroid had its orbit changed, and
> by more than expected.
>
> The 'flying in all directions' video was taken by a cubesat
> trailing behind the DART probe, so yes, it looks symmetrical.
>
> If you look at a side view, such as that taken by to James
> Webb, it's abundantly clear that most of the ejecta went
> In one direction:
>
> https://www.youtube.com/watch?v=P1zukXq4NDc
>
> Pt
It is possible that not the change in the orbit of Dimorphos did play the main role in the observed post-impact features of the mutual asteroid shadowing.
This role could be played by an asymmetric and optically dense near-surface "meteoroid cocoon", consisting of its recoiled debris as a part of material ejected into the hemisphere. Therefore, yet it cannot be ruled out that after the dissipation and fallback of this material onto the surface of Dimorphos, its orbit will be partially or almost completely “restored”.

On Saturday, October 15, 2022 at 11:16:27 PM UTC+3, pete...@gmail.com wrote:
> On Saturday, October 15, 2022 at 3:49:39 PM UTC-4, Robert Carnegie wrote:
> > On Friday, 14 October 2022 at 17:00:29 UTC+1, Paul S Person wrote:
> > > On Fri, 14 Oct 2022 13:43:51 GMT, sc...@slp53.sl.home (Scott Lurndal)
> > > wrote:
> > > >Quadibloc <jsa...@ecn.ab.ca> writes:
> > > >>On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
> > > >>
> > > >>> But it also contained a statement that this might not work if the
> > > >>> whole thing was just rubble: nothing to push on!
> > > >>
> > > >>And that is quite a reasonable argument,
> > > >
> > > >Is it? What is the effect of the rubble flying off in all
> > > >directions on the orbit of the object?
> > > If it is /really/ "all directions", it might well net out to ... none
> > > at all.
> > >
> > > An actual space scientist/physicist made the statement, BTW.
> > You'd apply a force, or an impulse, that accelerates
> > some or all of the mass out of a collision course
> > with Earth (if that's what you're attempting), so it
> > would be different from the asteroid somehow
> > spontaneously exploding but, mathematically as
> > a whole, not accelerating.
> >
> > However, you could fire a space bullet at the
> > flying rock heap and see the bullet and some of the
> > rocks fly out of the back of the heap, while the
> > rest of the asteroid continues in the original course.
> > Like cutting the core out of an apple.
> >
> > So maybe we need to start thinking about wrapping
> > the heap in a big net, first. Or use duct tape.
> No need. We have proof of concept.
>
> We *know* that the asteroid had its orbit changed, and
> by more than expected.
>
> The 'flying in all directions' video was taken by a cubesat
> trailing behind the DART probe, so yes, it looks symmetrical.
>
> If you look at a side view, such as that taken by to James
> Webb, it's abundantly clear that most of the ejecta went
> In one direction:
>
> https://www.youtube.com/watch?v=P1zukXq4NDc
>
> Pt
It is possible that not the change in the orbit of Dimorphos did play the main role in the observed post-impact features of the mutual asteroid shadowing.
This role could be played by an asymmetric and optically dense near-surface "meteoroid cocoon", consisting of its recoiled debris as a part of material ejected into the hemisphere. Therefore, yet it cannot be ruled out that after the dissipation and fallback of this material onto the surface of Dimorphos, its orbit will be partially or almost completely “restored”.

On Sunday, October 16, 2022 at 7:37:00 AM UTC-4, Victor Vasylyev wrote:
> On Saturday, October 15, 2022 at 11:16:27 PM UTC+3, pete...@gmail.com wrote:
> > On Saturday, October 15, 2022 at 3:49:39 PM UTC-4, Robert Carnegie wrote:
> > > On Friday, 14 October 2022 at 17:00:29 UTC+1, Paul S Person wrote:
> > > > On Fri, 14 Oct 2022 13:43:51 GMT, sc...@slp53.sl.home (Scott Lurndal)
> > > > wrote:
> > > > >Quadibloc <jsa...@ecn.ab.ca> writes:
> > > > >>On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
> > > > >>
> > > > >>> But it also contained a statement that this might not work if the
> > > > >>> whole thing was just rubble: nothing to push on!
> > > > >>
> > > > >>And that is quite a reasonable argument,
> > > > >
> > > > >Is it? What is the effect of the rubble flying off in all
> > > > >directions on the orbit of the object?
> > > > If it is /really/ "all directions", it might well net out to ... none
> > > > at all.
> > > >
> > > > An actual space scientist/physicist made the statement, BTW.
> > > You'd apply a force, or an impulse, that accelerates
> > > some or all of the mass out of a collision course
> > > with Earth (if that's what you're attempting), so it
> > > would be different from the asteroid somehow
> > > spontaneously exploding but, mathematically as
> > > a whole, not accelerating.
> > >
> > > However, you could fire a space bullet at the
> > > flying rock heap and see the bullet and some of the
> > > rocks fly out of the back of the heap, while the
> > > rest of the asteroid continues in the original course.
> > > Like cutting the core out of an apple.
> > >
> > > So maybe we need to start thinking about wrapping
> > > the heap in a big net, first. Or use duct tape.
> > No need. We have proof of concept.
> >
> > We *know* that the asteroid had its orbit changed, and
> > by more than expected.
> >
> > The 'flying in all directions' video was taken by a cubesat
> > trailing behind the DART probe, so yes, it looks symmetrical.
> >
> > If you look at a side view, such as that taken by to James
> > Webb, it's abundantly clear that most of the ejecta went
> > In one direction:
> >
> > https://www.youtube.com/watch?v=P1zukXq4NDc
> >
> > Pt
> It is possible that not the change in the orbit of Dimorphos did play the main role in the observed post-impact features of the mutual asteroid shadowing.
> This role could be played by an asymmetric and optically dense near-surface "meteoroid cocoon", consisting of its recoiled debris as a part of material ejected into the hemisphere. Therefore, yet it cannot be ruled out that after the dissipation and fallback of this material onto the surface of Dimorphos, its orbit will be partially or almost completely “restored”.

I don't think that's consistent with the two side-on views we have of the post-collision cloud.
You are, as William of Occam would say, 'needlessly multiplying entities'.
Also, a great deal of the material has exceeded the (very low) escape velocity of the Didymous/
Dimorphos system, and much that didn't will wind up on the much larger Didymous.

It will be interesting to see what actually happens.

Pt

On Sunday, October 16, 2022 at 11:21:25 PM UTC+3, pete...@gmail.com wrote:
> On Sunday, October 16, 2022 at 7:37:00 AM UTC-4, Victor Vasylyev wrote:
> > On Saturday, October 15, 2022 at 11:16:27 PM UTC+3, pete...@gmail.com wrote:
> > > On Saturday, October 15, 2022 at 3:49:39 PM UTC-4, Robert Carnegie wrote:
> > > > On Friday, 14 October 2022 at 17:00:29 UTC+1, Paul S Person wrote:
> > > > > On Fri, 14 Oct 2022 13:43:51 GMT, sc...@slp53.sl.home (Scott Lurndal)
> > > > > wrote:
> > > > > >Quadibloc <jsa...@ecn.ab.ca> writes:
> > > > > >>On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
> > > > > >>
> > > > > >>> But it also contained a statement that this might not work if the
> > > > > >>> whole thing was just rubble: nothing to push on!
> > > > > >>
> > > > > >>And that is quite a reasonable argument,
> > > > > >
> > > > > >Is it? What is the effect of the rubble flying off in all
> > > > > >directions on the orbit of the object?
> > > > > If it is /really/ "all directions", it might well net out to ... none
> > > > > at all.
> > > > >
> > > > > An actual space scientist/physicist made the statement, BTW.
> > > > You'd apply a force, or an impulse, that accelerates
> > > > some or all of the mass out of a collision course
> > > > with Earth (if that's what you're attempting), so it
> > > > would be different from the asteroid somehow
> > > > spontaneously exploding but, mathematically as
> > > > a whole, not accelerating.
> > > >
> > > > However, you could fire a space bullet at the
> > > > flying rock heap and see the bullet and some of the
> > > > rocks fly out of the back of the heap, while the
> > > > rest of the asteroid continues in the original course.
> > > > Like cutting the core out of an apple.
> > > >
> > > > So maybe we need to start thinking about wrapping
> > > > the heap in a big net, first. Or use duct tape.
> > > No need. We have proof of concept.
> > >
> > > We *know* that the asteroid had its orbit changed, and
> > > by more than expected.
> > >
> > > The 'flying in all directions' video was taken by a cubesat
> > > trailing behind the DART probe, so yes, it looks symmetrical.
> > >
> > > If you look at a side view, such as that taken by to James
> > > Webb, it's abundantly clear that most of the ejecta went
> > > In one direction:
> > >
> > > https://www.youtube.com/watch?v=P1zukXq4NDc
> > >
> > > Pt
> > It is possible that not the change in the orbit of Dimorphos did play the main role in the observed post-impact features of the mutual asteroid shadowing.
> > This role could be played by an asymmetric and optically dense near-surface "meteoroid cocoon", consisting of its recoiled debris as a part of material ejected into the hemisphere. Therefore, yet it cannot be ruled out that after the dissipation and fallback of this material onto the surface of Dimorphos, its orbit will be partially or almost completely “restored”.
> I don't think that's consistent with the two side-on views we have of the post-collision cloud.
> You are, as William of Occam would say, 'needlessly multiplying entities'..
> Also, a great deal of the material has exceeded the (very low) escape velocity of the Didymous/
> Dimorphos system, and much that didn't will wind up on the much larger Didymous.
>
> It will be interesting to see what actually happens.
>
> Pt
The specified "entity" is obvious. Please see the abrupt "swelling" of Dimorphos against the background of a smooth ejection of finer material in the video (starting from the 51st second):
https://groups.google.com/g/rec.arts.sf.written/c/nLwm0ZdZrqw

On Sun, 16 Oct 2022 04:36:57 -0700 (PDT), Victor Vasylyev
<karaforn@gmail.com> wrote:

>On Saturday, October 15, 2022 at 11:16:27 PM UTC+3, pete...@gmail.com wrote:
>> On Saturday, October 15, 2022 at 3:49:39 PM UTC-4, Robert Carnegie wrote:
>> > On Friday, 14 October 2022 at 17:00:29 UTC+1, Paul S Person wrote:
>> > > On Fri, 14 Oct 2022 13:43:51 GMT, sc...@slp53.sl.home (Scott Lurndal)
>> > > wrote:
>> > > >Quadibloc <jsa...@ecn.ab.ca> writes:
>> > > >>On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
>> > > >>
>> > > >>> But it also contained a statement that this might not work if the
>> > > >>> whole thing was just rubble: nothing to push on!
>> > > >>
>> > > >>And that is quite a reasonable argument,
>> > > >
>> > > >Is it? What is the effect of the rubble flying off in all
>> > > >directions on the orbit of the object?
>> > > If it is /really/ "all directions", it might well net out to ... none
>> > > at all.
>> > >
>> > > An actual space scientist/physicist made the statement, BTW.
>> > You'd apply a force, or an impulse, that accelerates
>> > some or all of the mass out of a collision course
>> > with Earth (if that's what you're attempting), so it
>> > would be different from the asteroid somehow
>> > spontaneously exploding but, mathematically as
>> > a whole, not accelerating.
>> >
>> > However, you could fire a space bullet at the
>> > flying rock heap and see the bullet and some of the
>> > rocks fly out of the back of the heap, while the
>> > rest of the asteroid continues in the original course.
>> > Like cutting the core out of an apple.
>> >
>> > So maybe we need to start thinking about wrapping
>> > the heap in a big net, first. Or use duct tape.
>> No need. We have proof of concept.
>>
>> We *know* that the asteroid had its orbit changed, and
>> by more than expected.
>>
>> The 'flying in all directions' video was taken by a cubesat
>> trailing behind the DART probe, so yes, it looks symmetrical.
>>
>> If you look at a side view, such as that taken by to James
>> Webb, it's abundantly clear that most of the ejecta went
>> In one direction:
>>
>> https://www.youtube.com/watch?v=P1zukXq4NDc
>>
>> Pt
>It is possible that not the change in the orbit of Dimorphos did play the main role in the observed post-impact features of the mutual asteroid shadowing.
> This role could be played by an asymmetric and optically dense near-surface "meteoroid cocoon", consisting of its recoiled debris as a part of material ejected into the hemisphere. Therefore, yet it cannot be ruled out that after the dissipation and fallback of this material onto the surface of Dimorphos, its orbit will be partially or almost completely “restored”.

That wouldn't matter ... provided the potential planet-killer missed
the planet!

Let's keep the eye on the ball here -- this isn't about changing the
orbit for All Eternity; it is about changing it on it's next pass past
our planet. So that it misses.

If it comes back on the same path in the future, we can nudge it
again.

--
"In this connexion, unquestionably the most significant
development was the disintegration, under Christian
influence, of classical conceptions of the family and
of family right."

On 10/17/2022 8:39 AM, Paul S Person wrote:
> On Sun, 16 Oct 2022 04:36:57 -0700 (PDT), Victor Vasylyev
> <karaforn@gmail.com> wrote:
>
>> On Saturday, October 15, 2022 at 11:16:27 PM UTC+3, pete...@gmail.com wrote:
>>> On Saturday, October 15, 2022 at 3:49:39 PM UTC-4, Robert Carnegie wrote:
>>>> On Friday, 14 October 2022 at 17:00:29 UTC+1, Paul S Person wrote:
>>>>> On Fri, 14 Oct 2022 13:43:51 GMT, sc...@slp53.sl.home (Scott Lurndal)
>>>>> wrote:
>>>>>> Quadibloc <jsa...@ecn.ab.ca> writes:
>>>>>>> On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
>>>>>>>
>>>>>>>> But it also contained a statement that this might not work if the
>>>>>>>> whole thing was just rubble: nothing to push on!
>>>>>>>
>>>>>>> And that is quite a reasonable argument,
>>>>>>
>>>>>> Is it? What is the effect of the rubble flying off in all
>>>>>> directions on the orbit of the object?
>>>>> If it is /really/ "all directions", it might well net out to ... none
>>>>> at all.
>>>>>
>>>>> An actual space scientist/physicist made the statement, BTW.
>>>> You'd apply a force, or an impulse, that accelerates
>>>> some or all of the mass out of a collision course
>>>> with Earth (if that's what you're attempting), so it
>>>> would be different from the asteroid somehow
>>>> spontaneously exploding but, mathematically as
>>>> a whole, not accelerating.
>>>>
>>>> However, you could fire a space bullet at the
>>>> flying rock heap and see the bullet and some of the
>>>> rocks fly out of the back of the heap, while the
>>>> rest of the asteroid continues in the original course.
>>>> Like cutting the core out of an apple.
>>>>
>>>> So maybe we need to start thinking about wrapping
>>>> the heap in a big net, first. Or use duct tape.
>>> No need. We have proof of concept.
>>>
>>> We *know* that the asteroid had its orbit changed, and
>>> by more than expected.
>>>
>>> The 'flying in all directions' video was taken by a cubesat
>>> trailing behind the DART probe, so yes, it looks symmetrical.
>>>
>>> If you look at a side view, such as that taken by to James
>>> Webb, it's abundantly clear that most of the ejecta went
>>> In one direction:
>>>
>>> https://www.youtube.com/watch?v=P1zukXq4NDc
>>>
>>> Pt
>> It is possible that not the change in the orbit of Dimorphos did play the main role in the observed post-impact features of the mutual asteroid shadowing.
>> This role could be played by an asymmetric and optically dense near-surface "meteoroid cocoon", consisting of its recoiled debris as a part of material ejected into the hemisphere. Therefore, yet it cannot be ruled out that after the dissipation and fallback of this material onto the surface of Dimorphos, its orbit will be partially or almost completely “restored”.
>
> That wouldn't matter ... provided the potential planet-killer missed
> the planet!
>
> Let's keep the eye on the ball here -- this isn't about changing the
> orbit for All Eternity; it is about changing it on it's next pass past
> our planet. So that it misses.
>
> If it comes back on the same path in the future, we can nudge it
> again.
>
Okay, there's some really bad English here. I'm not sure what Victor
Vasylyev was trying to say. Nitpick: If you change an asteroid's orbit
enough to miss a planet (or, frankly, AT ALL) when it was otherwise
going to hit it, you _HAVE_ changed its orbit for all eternity. Now,
that NEW orbit may intersect your planet next time when it wouldn't have
hit it on the next orbit before you nudged it. (At least partially
because it would have smacked into your planet and no longer be around
to have an orbit but details, details. :P ) In that situation ya,
you're going have to slap it around again.

--
I've done good in this world. Now I'm tired and just want to be a cranky
dirty old man.

Dimensional Traveler <dtravel@sonic.net> writes:
>On 10/17/2022 8:39 AM, Paul S Person wrote:
>> On Sun, 16 Oct 2022 04:36:57 -0700 (PDT), Victor Vasylyev
>> <karaforn@gmail.com> wrote:
>>
>>> On Saturday, October 15, 2022 at 11:16:27 PM UTC+3, pete...@gmail.com wrote:
>>>> On Saturday, October 15, 2022 at 3:49:39 PM UTC-4, Robert Carnegie wrote:
>>>>> On Friday, 14 October 2022 at 17:00:29 UTC+1, Paul S Person wrote:
>>>>>> On Fri, 14 Oct 2022 13:43:51 GMT, sc...@slp53.sl.home (Scott Lurndal)
>>>>>> wrote:
>>>>>>> Quadibloc <jsa...@ecn.ab.ca> writes:
>>>>>>>> On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
>>>>>>>>
>>>>>>>>> But it also contained a statement that this might not work if the
>>>>>>>>> whole thing was just rubble: nothing to push on!
>>>>>>>>
>>>>>>>> And that is quite a reasonable argument,
>>>>>>>
>>>>>>> Is it? What is the effect of the rubble flying off in all
>>>>>>> directions on the orbit of the object?
>>>>>> If it is /really/ "all directions", it might well net out to ... none
>>>>>> at all.
>>>>>>
>>>>>> An actual space scientist/physicist made the statement, BTW.
>>>>> You'd apply a force, or an impulse, that accelerates
>>>>> some or all of the mass out of a collision course
>>>>> with Earth (if that's what you're attempting), so it
>>>>> would be different from the asteroid somehow
>>>>> spontaneously exploding but, mathematically as
>>>>> a whole, not accelerating.
>>>>>
>>>>> However, you could fire a space bullet at the
>>>>> flying rock heap and see the bullet and some of the
>>>>> rocks fly out of the back of the heap, while the
>>>>> rest of the asteroid continues in the original course.
>>>>> Like cutting the core out of an apple.
>>>>>
>>>>> So maybe we need to start thinking about wrapping
>>>>> the heap in a big net, first. Or use duct tape.
>>>> No need. We have proof of concept.
>>>>
>>>> We *know* that the asteroid had its orbit changed, and
>>>> by more than expected.
>>>>
>>>> The 'flying in all directions' video was taken by a cubesat
>>>> trailing behind the DART probe, so yes, it looks symmetrical.
>>>>
>>>> If you look at a side view, such as that taken by to James
>>>> Webb, it's abundantly clear that most of the ejecta went
>>>> In one direction:
>>>>
>>>> https://www.youtube.com/watch?v=P1zukXq4NDc
>>>>
>>>> Pt
>>> It is possible that not the change in the orbit of Dimorphos did play the main role in the observed post-impact features of the mutual asteroid shadowing.
>>> This role could be played by an asymmetric and optically dense near-surface "meteoroid cocoon", consisting of its recoiled debris as a part of material ejected into the hemisphere. Therefore, yet it cannot be ruled out that after the dissipation and fallback of this material onto the surface of Dimorphos, its orbit will be partially or almost completely “restored”.
>>
>> That wouldn't matter ... provided the potential planet-killer missed
>> the planet!
>>
>> Let's keep the eye on the ball here -- this isn't about changing the
>> orbit for All Eternity; it is about changing it on it's next pass past
>> our planet. So that it misses.
>>
>> If it comes back on the same path in the future, we can nudge it
>> again.
>>
>Okay, there's some really bad English here. I'm not sure what Victor
>Vasylyev was trying to say. Nitpick: If you change an asteroid's orbit
>enough to miss a planet (or, frankly, AT ALL) when it was otherwise
>going to hit it, you _HAVE_ changed its orbit for all eternity. Now,
>that NEW orbit may intersect your planet next time when it wouldn't have
>hit it on the next orbit before you nudged it. (At least partially
>because it would have smacked into your planet and no longer be around
>to have an orbit but details, details. :P ) In that situation ya,
>you're going have to slap it around again.

I believe Valylyev was suggesting that the moonlet was not solid,
but rather had a shell of debris (cocoon) orbiting a smaller core. I can't
reconcile that idea with the photographs just prior to impact,
or the 10km trail of debris which is unlikely to re-coalesce
with the damaged moonlet.

On Monday, October 17, 2022 at 3:26:46 PM UTC-4, Scott Lurndal wrote:
> Dimensional Traveler <dtr...@sonic.net> writes:
> >On 10/17/2022 8:39 AM, Paul S Person wrote:
> >> On Sun, 16 Oct 2022 04:36:57 -0700 (PDT), Victor Vasylyev
> >> <kara...@gmail.com> wrote:
> >>
> >>> On Saturday, October 15, 2022 at 11:16:27 PM UTC+3, pete...@gmail.com wrote:
> >>>> On Saturday, October 15, 2022 at 3:49:39 PM UTC-4, Robert Carnegie wrote:
> >>>>> On Friday, 14 October 2022 at 17:00:29 UTC+1, Paul S Person wrote:
> >>>>>> On Fri, 14 Oct 2022 13:43:51 GMT, sc...@slp53.sl.home (Scott Lurndal)
> >>>>>> wrote:
> >>>>>>> Quadibloc <jsa...@ecn.ab.ca> writes:
> >>>>>>>> On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
> >>>>>>>>
> >>>>>>>>> But it also contained a statement that this might not work if the
> >>>>>>>>> whole thing was just rubble: nothing to push on!
> >>>>>>>>
> >>>>>>>> And that is quite a reasonable argument,
> >>>>>>>
> >>>>>>> Is it? What is the effect of the rubble flying off in all
> >>>>>>> directions on the orbit of the object?
> >>>>>> If it is /really/ "all directions", it might well net out to ... none
> >>>>>> at all.
> >>>>>>
> >>>>>> An actual space scientist/physicist made the statement, BTW.
> >>>>> You'd apply a force, or an impulse, that accelerates
> >>>>> some or all of the mass out of a collision course
> >>>>> with Earth (if that's what you're attempting), so it
> >>>>> would be different from the asteroid somehow
> >>>>> spontaneously exploding but, mathematically as
> >>>>> a whole, not accelerating.
> >>>>>
> >>>>> However, you could fire a space bullet at the
> >>>>> flying rock heap and see the bullet and some of the
> >>>>> rocks fly out of the back of the heap, while the
> >>>>> rest of the asteroid continues in the original course.
> >>>>> Like cutting the core out of an apple.
> >>>>>
> >>>>> So maybe we need to start thinking about wrapping
> >>>>> the heap in a big net, first. Or use duct tape.
> >>>> No need. We have proof of concept.
> >>>>
> >>>> We *know* that the asteroid had its orbit changed, and
> >>>> by more than expected.
> >>>>
> >>>> The 'flying in all directions' video was taken by a cubesat
> >>>> trailing behind the DART probe, so yes, it looks symmetrical.
> >>>>
> >>>> If you look at a side view, such as that taken by to James
> >>>> Webb, it's abundantly clear that most of the ejecta went
> >>>> In one direction:
> >>>>
> >>>> https://www.youtube.com/watch?v=P1zukXq4NDc
> >>>>
> >>>> Pt
> >>> It is possible that not the change in the orbit of Dimorphos did play the main role in the observed post-impact features of the mutual asteroid shadowing.
> >>> This role could be played by an asymmetric and optically dense near-surface "meteoroid cocoon", consisting of its recoiled debris as a part of material ejected into the hemisphere. Therefore, yet it cannot be ruled out that after the dissipation and fallback of this material onto the surface of Dimorphos, its orbit will be partially or almost completely “restored”.
> >>
> >> That wouldn't matter ... provided the potential planet-killer missed
> >> the planet!
> >>
> >> Let's keep the eye on the ball here -- this isn't about changing the
> >> orbit for All Eternity; it is about changing it on it's next pass past
> >> our planet. So that it misses.
> >>
> >> If it comes back on the same path in the future, we can nudge it
> >> again.
> >>
> >Okay, there's some really bad English here. I'm not sure what Victor
> >Vasylyev was trying to say. Nitpick: If you change an asteroid's orbit
> >enough to miss a planet (or, frankly, AT ALL) when it was otherwise
> >going to hit it, you _HAVE_ changed its orbit for all eternity. Now,
> >that NEW orbit may intersect your planet next time when it wouldn't have
> >hit it on the next orbit before you nudged it. (At least partially
> >because it would have smacked into your planet and no longer be around
> >to have an orbit but details, details. :P ) In that situation ya,
> >you're going have to slap it around again.
> I believe Valylyev was suggesting that the moonlet was not solid,
> but rather had a shell of debris (cocoon) orbiting a smaller core. I can't
> reconcile that idea with the photographs just prior to impact,
> or the 10km trail of debris which is unlikely to re-coalesce
> with the damaged moonlet.

I thought he was trying to suggest that the surface of the asteroid
was not uniform, with part of it darker, and invisible when ejected.
This means that the cloud could have been more spherically symmetrical.
He also suggested that it might later fall back to the Dimorphos,
negating most of the orbital change.

When I accused him of 'multiplying entities', I was suggesting that
this multi-toned approach was overly complicated; the straightforward
'most of the ejecta was from one side' is simpler, and consistent with all
the available evidence: the views of the impact from the side, and the change
in the orbit (which was much larger than it would be if the ejects was a
symmetric shell)

The suggestion that the ejecta will fall back on Dimorphos faces two problems
1. Some part of the ejecta is above escape velocity for the Dimorphos/Didymos
system, and isn't ever coming back. 2. A good deal of it will instead collide with the
much larger Didymos instead.

There's an intended followup mission in 2026 by ESA, "Hera", which will show us
what happened. I'm not expecting a big crater, I suspect a rubble pile will
settle and self-heal to some extent.

pt

On Monday, October 17, 2022 at 3:26:46 PM UTC-4, Scott Lurndal wrote:
> Dimensional Traveler <dtr...@sonic.net> writes:
> >On 10/17/2022 8:39 AM, Paul S Person wrote:
> >> On Sun, 16 Oct 2022 04:36:57 -0700 (PDT), Victor Vasylyev
> >> <kara...@gmail.com> wrote:
> >>
> >>> On Saturday, October 15, 2022 at 11:16:27 PM UTC+3, pete...@gmail.com wrote:
> >>>> On Saturday, October 15, 2022 at 3:49:39 PM UTC-4, Robert Carnegie wrote:
> >>>>> On Friday, 14 October 2022 at 17:00:29 UTC+1, Paul S Person wrote:
> >>>>>> On Fri, 14 Oct 2022 13:43:51 GMT, sc...@slp53.sl.home (Scott Lurndal)
> >>>>>> wrote:
> >>>>>>> Quadibloc <jsa...@ecn.ab.ca> writes:
> >>>>>>>> On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
> >>>>>>>>
> >>>>>>>>> But it also contained a statement that this might not work if the
> >>>>>>>>> whole thing was just rubble: nothing to push on!
> >>>>>>>>
> >>>>>>>> And that is quite a reasonable argument,
> >>>>>>>
> >>>>>>> Is it? What is the effect of the rubble flying off in all
> >>>>>>> directions on the orbit of the object?
> >>>>>> If it is /really/ "all directions", it might well net out to ... none
> >>>>>> at all.
> >>>>>>
> >>>>>> An actual space scientist/physicist made the statement, BTW.
> >>>>> You'd apply a force, or an impulse, that accelerates
> >>>>> some or all of the mass out of a collision course
> >>>>> with Earth (if that's what you're attempting), so it
> >>>>> would be different from the asteroid somehow
> >>>>> spontaneously exploding but, mathematically as
> >>>>> a whole, not accelerating.
> >>>>>
> >>>>> However, you could fire a space bullet at the
> >>>>> flying rock heap and see the bullet and some of the
> >>>>> rocks fly out of the back of the heap, while the
> >>>>> rest of the asteroid continues in the original course.
> >>>>> Like cutting the core out of an apple.
> >>>>>
> >>>>> So maybe we need to start thinking about wrapping
> >>>>> the heap in a big net, first. Or use duct tape.
> >>>> No need. We have proof of concept.
> >>>>
> >>>> We *know* that the asteroid had its orbit changed, and
> >>>> by more than expected.
> >>>>
> >>>> The 'flying in all directions' video was taken by a cubesat
> >>>> trailing behind the DART probe, so yes, it looks symmetrical.
> >>>>
> >>>> If you look at a side view, such as that taken by to James
> >>>> Webb, it's abundantly clear that most of the ejecta went
> >>>> In one direction:
> >>>>
> >>>> https://www.youtube.com/watch?v=P1zukXq4NDc
> >>>>
> >>>> Pt
> >>> It is possible that not the change in the orbit of Dimorphos did play the main role in the observed post-impact features of the mutual asteroid shadowing.
> >>> This role could be played by an asymmetric and optically dense near-surface "meteoroid cocoon", consisting of its recoiled debris as a part of material ejected into the hemisphere. Therefore, yet it cannot be ruled out that after the dissipation and fallback of this material onto the surface of Dimorphos, its orbit will be partially or almost completely “restored”.
> >>
> >> That wouldn't matter ... provided the potential planet-killer missed
> >> the planet!
> >>
> >> Let's keep the eye on the ball here -- this isn't about changing the
> >> orbit for All Eternity; it is about changing it on it's next pass past
> >> our planet. So that it misses.
> >>
> >> If it comes back on the same path in the future, we can nudge it
> >> again.
> >>
> >Okay, there's some really bad English here. I'm not sure what Victor
> >Vasylyev was trying to say. Nitpick: If you change an asteroid's orbit
> >enough to miss a planet (or, frankly, AT ALL) when it was otherwise
> >going to hit it, you _HAVE_ changed its orbit for all eternity. Now,
> >that NEW orbit may intersect your planet next time when it wouldn't have
> >hit it on the next orbit before you nudged it. (At least partially
> >because it would have smacked into your planet and no longer be around
> >to have an orbit but details, details. :P ) In that situation ya,
> >you're going have to slap it around again.
> I believe Valylyev was suggesting that the moonlet was not solid,
> but rather had a shell of debris (cocoon) orbiting a smaller core. I can't
> reconcile that idea with the photographs just prior to impact,
> or the 10km trail of debris which is unlikely to re-coalesce
> with the damaged moonlet.

BTW: Googling Victor Vasylyev turns up a Ukrainian astrophysicist,
along with a Russian mathematician.

pt

On Monday, October 17, 2022 at 4:08:07 PM UTC-4, pete...@gmail.com wrote:
> On Monday, October 17, 2022 at 3:26:46 PM UTC-4, Scott Lurndal wrote:

> > I believe Valylyev was suggesting that the moonlet was not solid,
> > but rather had a shell of debris (cocoon) orbiting a smaller core. I can't
> > reconcile that idea with the photographs just prior to impact,
> > or the 10km trail of debris which is unlikely to re-coalesce
> > with the damaged moonlet.

> BTW: Googling Victor Vasylyev turns up a Ukrainian astrophysicist,
> along with a Russian mathematician.

Well, there's a collaboration made in Higher Dimensions!

--
-Jack

On Mon, 17 Oct 2022 12:06:44 -0700, Dimensional Traveler
<dtravel@sonic.net> wrote:

>On 10/17/2022 8:39 AM, Paul S Person wrote:
>> On Sun, 16 Oct 2022 04:36:57 -0700 (PDT), Victor Vasylyev
>> <karaforn@gmail.com> wrote:
>>
>>> On Saturday, October 15, 2022 at 11:16:27 PM UTC+3, pete...@gmail.com wrote:
>>>> On Saturday, October 15, 2022 at 3:49:39 PM UTC-4, Robert Carnegie wrote:
>>>>> On Friday, 14 October 2022 at 17:00:29 UTC+1, Paul S Person wrote:
>>>>>> On Fri, 14 Oct 2022 13:43:51 GMT, sc...@slp53.sl.home (Scott Lurndal)
>>>>>> wrote:
>>>>>>> Quadibloc <jsa...@ecn.ab.ca> writes:
>>>>>>>> On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
>>>>>>>>
>>>>>>>>> But it also contained a statement that this might not work if the
>>>>>>>>> whole thing was just rubble: nothing to push on!
>>>>>>>>
>>>>>>>> And that is quite a reasonable argument,
>>>>>>>
>>>>>>> Is it? What is the effect of the rubble flying off in all
>>>>>>> directions on the orbit of the object?
>>>>>> If it is /really/ "all directions", it might well net out to ... none
>>>>>> at all.
>>>>>>
>>>>>> An actual space scientist/physicist made the statement, BTW.
>>>>> You'd apply a force, or an impulse, that accelerates
>>>>> some or all of the mass out of a collision course
>>>>> with Earth (if that's what you're attempting), so it
>>>>> would be different from the asteroid somehow
>>>>> spontaneously exploding but, mathematically as
>>>>> a whole, not accelerating.
>>>>>
>>>>> However, you could fire a space bullet at the
>>>>> flying rock heap and see the bullet and some of the
>>>>> rocks fly out of the back of the heap, while the
>>>>> rest of the asteroid continues in the original course.
>>>>> Like cutting the core out of an apple.
>>>>>
>>>>> So maybe we need to start thinking about wrapping
>>>>> the heap in a big net, first. Or use duct tape.
>>>> No need. We have proof of concept.
>>>>
>>>> We *know* that the asteroid had its orbit changed, and
>>>> by more than expected.
>>>>
>>>> The 'flying in all directions' video was taken by a cubesat
>>>> trailing behind the DART probe, so yes, it looks symmetrical.
>>>>
>>>> If you look at a side view, such as that taken by to James
>>>> Webb, it's abundantly clear that most of the ejecta went
>>>> In one direction:
>>>>
>>>> https://www.youtube.com/watch?v=P1zukXq4NDc
>>>>
>>>> Pt
>>> It is possible that not the change in the orbit of Dimorphos did play the main role in the observed post-impact features of the mutual asteroid shadowing.
>>> This role could be played by an asymmetric and optically dense near-surface "meteoroid cocoon", consisting of its recoiled debris as a part of material ejected into the hemisphere. Therefore, yet it cannot be ruled out that after the dissipation and fallback of this material onto the surface of Dimorphos, its orbit will be partially or almost completely “restored”.
>>
>> That wouldn't matter ... provided the potential planet-killer missed
>> the planet!
>>
>> Let's keep the eye on the ball here -- this isn't about changing the
>> orbit for All Eternity; it is about changing it on it's next pass past
>> our planet. So that it misses.
>>
>> If it comes back on the same path in the future, we can nudge it
>> again.
>>
>Okay, there's some really bad English here. I'm not sure what Victor
>Vasylyev was trying to say. Nitpick: If you change an asteroid's orbit
>enough to miss a planet (or, frankly, AT ALL) when it was otherwise
>going to hit it, you _HAVE_ changed its orbit for all eternity. Now,
>that NEW orbit may intersect your planet next time when it wouldn't have
>hit it on the next orbit before you nudged it. (At least partially
>because it would have smacked into your planet and no longer be around
>to have an orbit but details, details. :P ) In that situation ya,
>you're going have to slap it around again.

A nitpick to your nitpick: the person I was responding to was positing
that the orbit might change back as (in effect) the dust settled.

My point was that it wouldn't matter, so long as it missed this time.

And, clearly, you are correct: it also wouldn't matter if the new
orbit was a problem next time.
--
"In this connexion, unquestionably the most significant
development was the disintegration, under Christian
influence, of classical conceptions of the family and
of family right."

On 10/18/2022 9:11 AM, Paul S Person wrote:
> On Mon, 17 Oct 2022 12:06:44 -0700, Dimensional Traveler
> <dtravel@sonic.net> wrote:
>
>> On 10/17/2022 8:39 AM, Paul S Person wrote:
>>> On Sun, 16 Oct 2022 04:36:57 -0700 (PDT), Victor Vasylyev
>>> <karaforn@gmail.com> wrote:
>>>
>>>> On Saturday, October 15, 2022 at 11:16:27 PM UTC+3, pete...@gmail.com wrote:
>>>>> On Saturday, October 15, 2022 at 3:49:39 PM UTC-4, Robert Carnegie wrote:
>>>>>> On Friday, 14 October 2022 at 17:00:29 UTC+1, Paul S Person wrote:
>>>>>>> On Fri, 14 Oct 2022 13:43:51 GMT, sc...@slp53.sl.home (Scott Lurndal)
>>>>>>> wrote:
>>>>>>>> Quadibloc <jsa...@ecn.ab.ca> writes:
>>>>>>>>> On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
>>>>>>>>>
>>>>>>>>>> But it also contained a statement that this might not work if the
>>>>>>>>>> whole thing was just rubble: nothing to push on!
>>>>>>>>>
>>>>>>>>> And that is quite a reasonable argument,
>>>>>>>>
>>>>>>>> Is it? What is the effect of the rubble flying off in all
>>>>>>>> directions on the orbit of the object?
>>>>>>> If it is /really/ "all directions", it might well net out to ... none
>>>>>>> at all.
>>>>>>>
>>>>>>> An actual space scientist/physicist made the statement, BTW.
>>>>>> You'd apply a force, or an impulse, that accelerates
>>>>>> some or all of the mass out of a collision course
>>>>>> with Earth (if that's what you're attempting), so it
>>>>>> would be different from the asteroid somehow
>>>>>> spontaneously exploding but, mathematically as
>>>>>> a whole, not accelerating.
>>>>>>
>>>>>> However, you could fire a space bullet at the
>>>>>> flying rock heap and see the bullet and some of the
>>>>>> rocks fly out of the back of the heap, while the
>>>>>> rest of the asteroid continues in the original course.
>>>>>> Like cutting the core out of an apple.
>>>>>>
>>>>>> So maybe we need to start thinking about wrapping
>>>>>> the heap in a big net, first. Or use duct tape.
>>>>> No need. We have proof of concept.
>>>>>
>>>>> We *know* that the asteroid had its orbit changed, and
>>>>> by more than expected.
>>>>>
>>>>> The 'flying in all directions' video was taken by a cubesat
>>>>> trailing behind the DART probe, so yes, it looks symmetrical.
>>>>>
>>>>> If you look at a side view, such as that taken by to James
>>>>> Webb, it's abundantly clear that most of the ejecta went
>>>>> In one direction:
>>>>>
>>>>> https://www.youtube.com/watch?v=P1zukXq4NDc
>>>>>
>>>>> Pt
>>>> It is possible that not the change in the orbit of Dimorphos did play the main role in the observed post-impact features of the mutual asteroid shadowing.
>>>> This role could be played by an asymmetric and optically dense near-surface "meteoroid cocoon", consisting of its recoiled debris as a part of material ejected into the hemisphere. Therefore, yet it cannot be ruled out that after the dissipation and fallback of this material onto the surface of Dimorphos, its orbit will be partially or almost completely “restored”.
>>>
>>> That wouldn't matter ... provided the potential planet-killer missed
>>> the planet!
>>>
>>> Let's keep the eye on the ball here -- this isn't about changing the
>>> orbit for All Eternity; it is about changing it on it's next pass past
>>> our planet. So that it misses.
>>>
>>> If it comes back on the same path in the future, we can nudge it
>>> again.
>>>
>> Okay, there's some really bad English here. I'm not sure what Victor
>> Vasylyev was trying to say. Nitpick: If you change an asteroid's orbit
>> enough to miss a planet (or, frankly, AT ALL) when it was otherwise
>> going to hit it, you _HAVE_ changed its orbit for all eternity. Now,
>> that NEW orbit may intersect your planet next time when it wouldn't have
>> hit it on the next orbit before you nudged it. (At least partially
>> because it would have smacked into your planet and no longer be around
>> to have an orbit but details, details. :P ) In that situation ya,
>> you're going have to slap it around again.
>
> A nitpick to your nitpick: the person I was responding to was positing
> that the orbit might change back as (in effect) the dust settled.
>
> My point was that it wouldn't matter, so long as it missed this time.
>
> And, clearly, you are correct: it also wouldn't matter if the new
> orbit was a problem next time.

I don't see how an object could "revert" to its previous orbit after it
had been pushed into a new one absent another push.

I also don't think it is possible to have a shell of debris "orbiting"
around an asteroid. A ring, sure, but not a sphere like shell, because
different pieces would have to be orbiting at different speeds at the
same distance from the primary. Which from what I understand of physics
simply isn't possible.
--
I've done good in this world. Now I'm tired and just want to be a cranky
dirty old man.

On Tuesday, 18 October 2022 at 19:53:42 UTC+1, Dimensional Traveler wrote:
> On 10/18/2022 9:11 AM, Paul S Person wrote:
> > On Mon, 17 Oct 2022 12:06:44 -0700, Dimensional Traveler
> > <dtr...@sonic.net> wrote:
> >
> >> On 10/17/2022 8:39 AM, Paul S Person wrote:
> >>> On Sun, 16 Oct 2022 04:36:57 -0700 (PDT), Victor Vasylyev
> >>> <kara...@gmail.com> wrote:
> >>>
> >>>> On Saturday, October 15, 2022 at 11:16:27 PM UTC+3, pete...@gmail.com wrote:
> >>>>> On Saturday, October 15, 2022 at 3:49:39 PM UTC-4, Robert Carnegie wrote:
> >>>>>> On Friday, 14 October 2022 at 17:00:29 UTC+1, Paul S Person wrote:
> >>>>>>> On Fri, 14 Oct 2022 13:43:51 GMT, sc...@slp53.sl.home (Scott Lurndal)
> >>>>>>> wrote:
> >>>>>>>> Quadibloc <jsa...@ecn.ab.ca> writes:
> >>>>>>>>> On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
> >>>>>>>>>
> >>>>>>>>>> But it also contained a statement that this might not work if the
> >>>>>>>>>> whole thing was just rubble: nothing to push on!
> >>>>>>>>>
> >>>>>>>>> And that is quite a reasonable argument,
> >>>>>>>>
> >>>>>>>> Is it? What is the effect of the rubble flying off in all
> >>>>>>>> directions on the orbit of the object?
> >>>>>>> If it is /really/ "all directions", it might well net out to ... none
> >>>>>>> at all.
> >>>>>>>
> >>>>>>> An actual space scientist/physicist made the statement, BTW.
> >>>>>> You'd apply a force, or an impulse, that accelerates
> >>>>>> some or all of the mass out of a collision course
> >>>>>> with Earth (if that's what you're attempting), so it
> >>>>>> would be different from the asteroid somehow
> >>>>>> spontaneously exploding but, mathematically as
> >>>>>> a whole, not accelerating.
> >>>>>>
> >>>>>> However, you could fire a space bullet at the
> >>>>>> flying rock heap and see the bullet and some of the
> >>>>>> rocks fly out of the back of the heap, while the
> >>>>>> rest of the asteroid continues in the original course.
> >>>>>> Like cutting the core out of an apple.
> >>>>>>
> >>>>>> So maybe we need to start thinking about wrapping
> >>>>>> the heap in a big net, first. Or use duct tape.
> >>>>> No need. We have proof of concept.
> >>>>>
> >>>>> We *know* that the asteroid had its orbit changed, and
> >>>>> by more than expected.
> >>>>>
> >>>>> The 'flying in all directions' video was taken by a cubesat
> >>>>> trailing behind the DART probe, so yes, it looks symmetrical.
> >>>>>
> >>>>> If you look at a side view, such as that taken by to James
> >>>>> Webb, it's abundantly clear that most of the ejecta went
> >>>>> In one direction:
> >>>>>
> >>>>> https://www.youtube.com/watch?v=P1zukXq4NDc
> >>>>>
> >>>>> Pt
> >>>> It is possible that not the change in the orbit of Dimorphos did play the main role in the observed post-impact features of the mutual asteroid shadowing.
> >>>> This role could be played by an asymmetric and optically dense near-surface "meteoroid cocoon", consisting of its recoiled debris as a part of material ejected into the hemisphere. Therefore, yet it cannot be ruled out that after the dissipation and fallback of this material onto the surface of Dimorphos, its orbit will be partially or almost completely “restored”.
> >>>
> >>> That wouldn't matter ... provided the potential planet-killer missed
> >>> the planet!
> >>>
> >>> Let's keep the eye on the ball here -- this isn't about changing the
> >>> orbit for All Eternity; it is about changing it on it's next pass past
> >>> our planet. So that it misses.
> >>>
> >>> If it comes back on the same path in the future, we can nudge it
> >>> again.
> >>>
> >> Okay, there's some really bad English here. I'm not sure what Victor
> >> Vasylyev was trying to say. Nitpick: If you change an asteroid's orbit
> >> enough to miss a planet (or, frankly, AT ALL) when it was otherwise
> >> going to hit it, you _HAVE_ changed its orbit for all eternity. Now,
> >> that NEW orbit may intersect your planet next time when it wouldn't have
> >> hit it on the next orbit before you nudged it. (At least partially
> >> because it would have smacked into your planet and no longer be around
> >> to have an orbit but details, details. :P ) In that situation ya,
> >> you're going have to slap it around again.
> >
> > A nitpick to your nitpick: the person I was responding to was positing
> > that the orbit might change back as (in effect) the dust settled.
> >
> > My point was that it wouldn't matter, so long as it missed this time.
> >
> > And, clearly, you are correct: it also wouldn't matter if the new
> > orbit was a problem next time.
> I don't see how an object could "revert" to its previous orbit after it
> had been pushed into a new one absent another push.
>
> I also don't think it is possible to have a shell of debris "orbiting"
> around an asteroid. A ring, sure, but not a sphere like shell, because
> different pieces would have to be orbiting at different speeds at the
> same distance from the primary. Which from what I understand of physics
> simply isn't possible.

There is a ton of assorted space junk pieces orbiting
Earth closely in many random directions as I write.
I think we're meant to be imagining a cloud of stuff,
and not a "shell" such as an egg has.

And I haven't done the calculations, but the quantity of
stuff flying off the little asteroid evidently /has/ been
accelerated, I think.

On Tuesday, October 18, 2022 at 4:34:06 PM UTC-4, Robert Carnegie wrote:
> On Tuesday, 18 October 2022 at 19:53:42 UTC+1, Dimensional Traveler wrote:
> > On 10/18/2022 9:11 AM, Paul S Person wrote:
> > > On Mon, 17 Oct 2022 12:06:44 -0700, Dimensional Traveler
> > > <dtr...@sonic.net> wrote:
> > >
> > >> On 10/17/2022 8:39 AM, Paul S Person wrote:
> > >>> On Sun, 16 Oct 2022 04:36:57 -0700 (PDT), Victor Vasylyev
> > >>> <kara...@gmail.com> wrote:
> > >>>
> > >>>> On Saturday, October 15, 2022 at 11:16:27 PM UTC+3, pete...@gmail.com wrote:
> > >>>>> On Saturday, October 15, 2022 at 3:49:39 PM UTC-4, Robert Carnegie wrote:
> > >>>>>> On Friday, 14 October 2022 at 17:00:29 UTC+1, Paul S Person wrote:
> > >>>>>>> On Fri, 14 Oct 2022 13:43:51 GMT, sc...@slp53.sl.home (Scott Lurndal)
> > >>>>>>> wrote:
> > >>>>>>>> Quadibloc <jsa...@ecn.ab.ca> writes:
> > >>>>>>>>> On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
> > >>>>>>>>>
> > >>>>>>>>>> But it also contained a statement that this might not work if the
> > >>>>>>>>>> whole thing was just rubble: nothing to push on!
> > >>>>>>>>>
> > >>>>>>>>> And that is quite a reasonable argument,
> > >>>>>>>>
> > >>>>>>>> Is it? What is the effect of the rubble flying off in all
> > >>>>>>>> directions on the orbit of the object?
> > >>>>>>> If it is /really/ "all directions", it might well net out to .... none
> > >>>>>>> at all.
> > >>>>>>>
> > >>>>>>> An actual space scientist/physicist made the statement, BTW.
> > >>>>>> You'd apply a force, or an impulse, that accelerates
> > >>>>>> some or all of the mass out of a collision course
> > >>>>>> with Earth (if that's what you're attempting), so it
> > >>>>>> would be different from the asteroid somehow
> > >>>>>> spontaneously exploding but, mathematically as
> > >>>>>> a whole, not accelerating.
> > >>>>>>
> > >>>>>> However, you could fire a space bullet at the
> > >>>>>> flying rock heap and see the bullet and some of the
> > >>>>>> rocks fly out of the back of the heap, while the
> > >>>>>> rest of the asteroid continues in the original course.
> > >>>>>> Like cutting the core out of an apple.
> > >>>>>>
> > >>>>>> So maybe we need to start thinking about wrapping
> > >>>>>> the heap in a big net, first. Or use duct tape.
> > >>>>> No need. We have proof of concept.
> > >>>>>
> > >>>>> We *know* that the asteroid had its orbit changed, and
> > >>>>> by more than expected.
> > >>>>>
> > >>>>> The 'flying in all directions' video was taken by a cubesat
> > >>>>> trailing behind the DART probe, so yes, it looks symmetrical.
> > >>>>>
> > >>>>> If you look at a side view, such as that taken by to James
> > >>>>> Webb, it's abundantly clear that most of the ejecta went
> > >>>>> In one direction:
> > >>>>>
> > >>>>> https://www.youtube.com/watch?v=P1zukXq4NDc
> > >>>>>
> > >>>>> Pt
> > >>>> It is possible that not the change in the orbit of Dimorphos did play the main role in the observed post-impact features of the mutual asteroid shadowing.
> > >>>> This role could be played by an asymmetric and optically dense near-surface "meteoroid cocoon", consisting of its recoiled debris as a part of material ejected into the hemisphere. Therefore, yet it cannot be ruled out that after the dissipation and fallback of this material onto the surface of Dimorphos, its orbit will be partially or almost completely “restored”.
> > >>>
> > >>> That wouldn't matter ... provided the potential planet-killer missed
> > >>> the planet!
> > >>>
> > >>> Let's keep the eye on the ball here -- this isn't about changing the
> > >>> orbit for All Eternity; it is about changing it on it's next pass past
> > >>> our planet. So that it misses.
> > >>>
> > >>> If it comes back on the same path in the future, we can nudge it
> > >>> again.
> > >>>
> > >> Okay, there's some really bad English here. I'm not sure what Victor
> > >> Vasylyev was trying to say. Nitpick: If you change an asteroid's orbit
> > >> enough to miss a planet (or, frankly, AT ALL) when it was otherwise
> > >> going to hit it, you _HAVE_ changed its orbit for all eternity. Now,
> > >> that NEW orbit may intersect your planet next time when it wouldn't have
> > >> hit it on the next orbit before you nudged it. (At least partially
> > >> because it would have smacked into your planet and no longer be around
> > >> to have an orbit but details, details. :P ) In that situation ya,
> > >> you're going have to slap it around again.
> > >
> > > A nitpick to your nitpick: the person I was responding to was positing
> > > that the orbit might change back as (in effect) the dust settled.
> > >
> > > My point was that it wouldn't matter, so long as it missed this time.
> > >
> > > And, clearly, you are correct: it also wouldn't matter if the new
> > > orbit was a problem next time.
> > I don't see how an object could "revert" to its previous orbit after it
> > had been pushed into a new one absent another push.
> >
> > I also don't think it is possible to have a shell of debris "orbiting"
> > around an asteroid. A ring, sure, but not a sphere like shell, because
> > different pieces would have to be orbiting at different speeds at the
> > same distance from the primary. Which from what I understand of physics
> > simply isn't possible.
> There is a ton of assorted space junk pieces orbiting
> Earth closely in many random directions as I write.
> I think we're meant to be imagining a cloud of stuff,
> and not a "shell" such as an egg has.
>
> And I haven't done the calculations, but the quantity of
> stuff flying off the little asteroid evidently /has/ been
> accelerated, I think.

Vlad described his hypothetical shell as 'optically dense', ie, too thick
to see through. I don't think that's stable in the long term. I expect
it would first settle into a ring, and then into a ridge on the surface, like
Iapetus.

pt

On Wednesday, October 19, 2022 at 12:42:23 AM UTC+3, pete...@gmail.com wrote:
> On Tuesday, October 18, 2022 at 4:34:06 PM UTC-4, Robert Carnegie wrote:
> > On Tuesday, 18 October 2022 at 19:53:42 UTC+1, Dimensional Traveler wrote:
> > > On 10/18/2022 9:11 AM, Paul S Person wrote:
> > > > On Mon, 17 Oct 2022 12:06:44 -0700, Dimensional Traveler
> > > > <dtr...@sonic.net> wrote:
> > > >
> > > >> On 10/17/2022 8:39 AM, Paul S Person wrote:
> > > >>> On Sun, 16 Oct 2022 04:36:57 -0700 (PDT), Victor Vasylyev
> > > >>> <kara...@gmail.com> wrote:
> > > >>>
> > > >>>> On Saturday, October 15, 2022 at 11:16:27 PM UTC+3, pete...@gmail.com wrote:
> > > >>>>> On Saturday, October 15, 2022 at 3:49:39 PM UTC-4, Robert Carnegie wrote:
> > > >>>>>> On Friday, 14 October 2022 at 17:00:29 UTC+1, Paul S Person wrote:
> > > >>>>>>> On Fri, 14 Oct 2022 13:43:51 GMT, sc...@slp53.sl.home (Scott Lurndal)
> > > >>>>>>> wrote:
> > > >>>>>>>> Quadibloc <jsa...@ecn.ab.ca> writes:
> > > >>>>>>>>> On Thursday, October 13, 2022 at 10:04:37 AM UTC-6, Paul S Person wrote:
> > > >>>>>>>>>
> > > >>>>>>>>>> But it also contained a statement that this might not work if the
> > > >>>>>>>>>> whole thing was just rubble: nothing to push on!
> > > >>>>>>>>>
> > > >>>>>>>>> And that is quite a reasonable argument,
> > > >>>>>>>>
> > > >>>>>>>> Is it? What is the effect of the rubble flying off in all
> > > >>>>>>>> directions on the orbit of the object?
> > > >>>>>>> If it is /really/ "all directions", it might well net out to .... none
> > > >>>>>>> at all.
> > > >>>>>>>
> > > >>>>>>> An actual space scientist/physicist made the statement, BTW.
> > > >>>>>> You'd apply a force, or an impulse, that accelerates
> > > >>>>>> some or all of the mass out of a collision course
> > > >>>>>> with Earth (if that's what you're attempting), so it
> > > >>>>>> would be different from the asteroid somehow
> > > >>>>>> spontaneously exploding but, mathematically as
> > > >>>>>> a whole, not accelerating.
> > > >>>>>>
> > > >>>>>> However, you could fire a space bullet at the
> > > >>>>>> flying rock heap and see the bullet and some of the
> > > >>>>>> rocks fly out of the back of the heap, while the
> > > >>>>>> rest of the asteroid continues in the original course.
> > > >>>>>> Like cutting the core out of an apple.
> > > >>>>>>
> > > >>>>>> So maybe we need to start thinking about wrapping
> > > >>>>>> the heap in a big net, first. Or use duct tape.
> > > >>>>> No need. We have proof of concept.
> > > >>>>>
> > > >>>>> We *know* that the asteroid had its orbit changed, and
> > > >>>>> by more than expected.
> > > >>>>>
> > > >>>>> The 'flying in all directions' video was taken by a cubesat
> > > >>>>> trailing behind the DART probe, so yes, it looks symmetrical.
> > > >>>>>
> > > >>>>> If you look at a side view, such as that taken by to James
> > > >>>>> Webb, it's abundantly clear that most of the ejecta went
> > > >>>>> In one direction:
> > > >>>>>
> > > >>>>> https://www.youtube.com/watch?v=P1zukXq4NDc
> > > >>>>>
> > > >>>>> Pt
> > > >>>> It is possible that not the change in the orbit of Dimorphos did play the main role in the observed post-impact features of the mutual asteroid shadowing.
> > > >>>> This role could be played by an asymmetric and optically dense near-surface "meteoroid cocoon", consisting of its recoiled debris as a part of material ejected into the hemisphere. Therefore, yet it cannot be ruled out that after the dissipation and fallback of this material onto the surface of Dimorphos, its orbit will be partially or almost completely “restored”.
> > > >>>
> > > >>> That wouldn't matter ... provided the potential planet-killer missed
> > > >>> the planet!
> > > >>>
> > > >>> Let's keep the eye on the ball here -- this isn't about changing the
> > > >>> orbit for All Eternity; it is about changing it on it's next pass past
> > > >>> our planet. So that it misses.
> > > >>>
> > > >>> If it comes back on the same path in the future, we can nudge it
> > > >>> again.
> > > >>>
> > > >> Okay, there's some really bad English here. I'm not sure what Victor
> > > >> Vasylyev was trying to say. Nitpick: If you change an asteroid's orbit
> > > >> enough to miss a planet (or, frankly, AT ALL) when it was otherwise
> > > >> going to hit it, you _HAVE_ changed its orbit for all eternity. Now,
> > > >> that NEW orbit may intersect your planet next time when it wouldn't have
> > > >> hit it on the next orbit before you nudged it. (At least partially
> > > >> because it would have smacked into your planet and no longer be around
> > > >> to have an orbit but details, details. :P ) In that situation ya,
> > > >> you're going have to slap it around again.
> > > >
> > > > A nitpick to your nitpick: the person I was responding to was positing
> > > > that the orbit might change back as (in effect) the dust settled.
> > > >
> > > > My point was that it wouldn't matter, so long as it missed this time.
> > > >
> > > > And, clearly, you are correct: it also wouldn't matter if the new
> > > > orbit was a problem next time.
> > > I don't see how an object could "revert" to its previous orbit after it
> > > had been pushed into a new one absent another push.
> > >
> > > I also don't think it is possible to have a shell of debris "orbiting"
> > > around an asteroid. A ring, sure, but not a sphere like shell, because
> > > different pieces would have to be orbiting at different speeds at the
> > > same distance from the primary. Which from what I understand of physics
> > > simply isn't possible.
> > There is a ton of assorted space junk pieces orbiting
> > Earth closely in many random directions as I write.
> > I think we're meant to be imagining a cloud of stuff,
> > and not a "shell" such as an egg has.
> >
> > And I haven't done the calculations, but the quantity of
> > stuff flying off the little asteroid evidently /has/ been
> > accelerated, I think.
> Vlad described his hypothetical shell as 'optically dense', ie, too thick
> to see through. I don't think that's stable in the long term. I expect
> it would first settle into a ring, and then into a ridge on the surface, like
> Iapetus.
>
> pt
Trying to add some clarity to my founded hypothesis...
Most of abruptly formed asymmetric "cocoon" (consisting not of "dust", but of relatively large fragments - that's why it did not fly off so far! – see again 50+ seconds in https://www.nature.com/articles/d41586-022-03130-8) should have been concentrated on the side of the main component, where its attraction maximally contributed to the rebound of large fragments of the Dimorphos as loosely-bound rubble pile (such its internal structure was known and became evident after the impact). This asymmetry could shift the center of the summarised "albedo spot" (determined owing to eclipses) towards a shorter orbit relative to the mass center of the parent body. As a result, when interpreting, you can get the illusion of a change in the asteroid's orbit instead of its true change. Up to "cocoon" dissipation and/or fallback.