Impact visible from Shpherd video

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Brian

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Oct 10, 2009, 12:18:26 AM10/10/09
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Looking at the video stream from the shpherd raft, the impact appears
to be visible in the near-infrared section at the time of impact.

On the small crater is a lighter spot (green) at 6 o'clock. Pay close
attention to the area just past halfway from the green to the section
of blue below it. Also a couple of degrees to the left.

Pause the video at 1:17. Then advance slowly. You will see a small
blue dot just before the flight director announces the impact. I have
posted a power presentation showing the sequence and highlighting the
possible impact. Centaur Impact.ppt. A quick and dirty layout but it
appears to show the event. Total duration was about 2 seconds.

Now to find information on the size of the crater to get a sense of
the size of the plume and figure out how far away the camera was at
this point.

Jake Burkart

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Oct 10, 2009, 1:11:03 AM10/10/09
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I thought I heard the crater was clearly visible in infrared and
measured 24 meters in diameter.

Jake Burkart

Tom Munnecke

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Oct 10, 2009, 12:56:31 AM10/10/09
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what's the URL of the video?

canopus56

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Oct 10, 2009, 1:56:44 AM10/10/09
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The impact video is:

http://www.youtube.com/profile?v=VVYKjR1sJY4&user=NASAtelevision

The press conference is:

http://www.youtube.com/profile?v=MEV4IoUh_Gk&user=NASAtelevision

I suggest skipping the front part of the conference and watching
beginning at around minute 50 of the 1 hour 9 minutes broadcast.
That's where the meat starts.

Colaprete seems prettty confident that they got good spectral data
from the side looking spectrometer. It's still a mystery why there is
an impact crater that glows in the infrared, but no detection of the
predicted dust cloud ejecta curtain. There's any of number scenarios
that might explain the result. It will take a couple of weeks to work
it out.

Clear Skies - Kurt

P.S. - A bit of speculation - what if instead of a rock shelf, they
hit a thinly buried ice shelf and the water went straight to a gas?
Hence, crater but no plume?
> > this point.- Hide quoted text -
>
> - Show quoted text -

Brian

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Oct 10, 2009, 10:08:12 AM10/10/09
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24 meters is feasible for the crater. Centaur wasn't that big
relative to the size of the crater. The analogies I saw were similar
to a large SUV. Sadly the impact appears to have been in the shadow
of the crater so it can't be observed in the photos. But the infrared
plume (assuming that is the impact) having a diameter of 1-2 miles
seems plausible. With the Centaur hitting at 5600 mph, much of the
energy would be transferred to the surface and it seems reasonable
that the soil would quickly reach a velocity of 3-4000 mph. 3600 mph
translates to 1 mile per second which is about how long the plume of
that size is visible, with the size of about 1-2 miles. Then factor
in there is no atmosphere entraining the ejecta up and outwards as it
would be displaced from the impact, or to hold it in suspension for a
short time afterwards.

It would be interesting to see the temperature scales for the infrared
image then determine if the kinetic energy converted during the impact
is consistent with the infrared signature of the plume. And if the
loss due to radiative cooling would be that sudden.

As an aside, I went back and watched a few videos of the moonwalks to
get a sense of how the lunar soil responds to disturbances. Certainly
not the same scale as a Chevy Suburban crashing into the surface at
5600 mph, but the soil kicked up by the astronauts' feet seemed to
travel farther horizontally than vertically, though this may be due to
the kicking action. By contrast, if one goes to a baseball field and
kicks the dirt, a fair amount of dust flies into the air and stays
aloft, bouyed by the atmosphere. With no atmosphere the soil on the
moon would seem to fall much faster, even with the smaller
gravitational force.

Hopefully NASA releases some images from the data recorders soon.

On Oct 10, 12:11 am, Jake Burkart <jake.burk...@gmail.com> wrote:
> I thought I heard the crater was clearly visible in infrared and  
> measured 24 meters in diameter.
>
> Jake Burkart
>
> On Oct 9, 2009, at 9:18 PM, Brian <zlow_h...@yahoo.com> wrote:
>
>
>
>
>
> > Looking at the video stream from the shpherd raft, the impact appears
> > to be visible in the near-infrared section at the time of impact.
>
> > On the small crater is a lighter spot (green) at 6 o'clock.  Pay close
> > attention to the area just past halfway from the green to the section
> > of blue below it.  Also a couple of degrees to the left.
>
> > Pause the video at 1:17.  Then advance slowly.  You will see a small
> > blue dot just before the flight director announces the impact.  I have
> > posted a power presentation showing the sequence and highlighting the
> > possible impact.  Centaur Impact.ppt.  A quick and dirty layout but it
> > appears to show the event.  Total duration was about 2 seconds.
>
> > Now to find information on the size of the crater to get a sense of
> > the size of the plume and figure out how far away the camera was at
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