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Pluto Atmospheric Observations: NH Post-Encounter Phase, 1 Aug 2015- TBD
Explorer1
post Jun 2 2016, 06:24 AM
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Astounding work!
Charon is an invisibly thin crescent at this angle without any atmosphere, correct? Or is it just out of frame?
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wildespace
post Jun 2 2016, 08:48 AM
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Sorry if I'm posting this in the wrong thread, but I've just had a question about the backlit shots of Pluto. Has the Sun ever appeared in LORRI's field of view, and are there any images of it there?

I'm asking because LORRI doesn't have a shutter, and a NASA video shows the CGI Sun going behind Pluto and out again: http://www.dailymail.co.uk/sciencetech/art...lyby-Pluto.html

On a related topic, has anyone made timelapse videos out of the "sun glare" LORRI images, like this one? http://pluto.jhuapl.edu/soc/Pluto-Encounte...mgType=approved

Thank you.


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fredk
post Jun 2 2016, 02:53 PM
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QUOTE (Astroboy @ Jun 2 2016, 06:03 AM) *
Aligned on the stars:

Stunning.

Averaging the frames together you can easily see the path of Pluto relative to the stars:
Attached Image

If the path of NH was straight, Pluto's path would look (esssentially) straight relative to the stars. So presumably we're seeing the gravitational effect of Pluto bending NH's path, although the effect seems surprizingly large to me.
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elakdawalla
post Jun 2 2016, 03:44 PM
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I was puzzled about the curve in Pluto's path too. Does it have to do with Pluto's rotation about the system barycenter?


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ugordan
post Jun 2 2016, 04:30 PM
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If the timespan of those images matches up (around 3 days) I think you've nailed it, Emily.


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elakdawalla
post Jun 2 2016, 04:35 PM
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It's 7 days, or one Pluto rotation period, which makes sense (curve goes out and back). Cool.

Now I want a similar V2 Neptune departure sequence aligned on background stars to contrast that with smile.gif


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ugordan
post Jun 2 2016, 04:38 PM
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Heh, it looked like half a rotation to me, but now that you mention it I can make out a full sine curve. Cool stuff!


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Saturns Moon Tit...
post Jun 2 2016, 04:43 PM
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New NASA article- Secrets Revealed from Pluto's 'Twilight Zone'

https://www.nasa.gov/feature/secrets-reveal...s-twilight-zone

potential cloud spotted!

Has anyone tried to match up the nightside terrain silhouette with the low resolution maps of Pluto's far side? I see some rugged, mountain-looking terrain and some very smooth regions.
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Astroboy
post Jun 2 2016, 04:48 PM
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I'm glad everyone enjoyed that! Yeah, the timespan is from 7/15 at 15:21 to 7/21 at 04:24, so that's almost a full rotation of Pluto and Charon. Judging by the Nasa Eyes simulation, Charon would probably only appear in a few of the frames at the end. I tried stacking multiple frames from individual later observations and still couldn't find her. I was pretty tired while doing that, though.

I really want to do some star-aligned Voyager animations too, now!
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tasp
post Jun 2 2016, 05:35 PM
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Appreciate Emily noting the barycenter effect!

As I recall, the NH camera pixels are around 1 arc second in size (smallest yet flown beyond LEO), would the Plutonian system gravitational deflection of NH be superimposed on the barycenter curve as shown, and therefore visible as a slight 'deformation' of the curve, or is the deflection small enough it can only be discerned through the radio science experiment ??

It would be exciting if the effect was large enough to be 'teased' out of the images too.
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fredk
post Jun 2 2016, 05:51 PM
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Doh - barycentre motion must be it. I mentioned that the effect was surprizingly large if due to the deflection of NH's path by Pluto, tasp - given the speed of the encounter and how far from Pluto we were at the start of this sequence I'd guess that this effect would be very small. But this could easily be confirmed by plotting the barycentre (and Pluto and Charon) positions from the point of view of NH against the fixed stars using some orbital software...
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mcaplinger
post Jun 2 2016, 06:03 PM
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QUOTE (tasp @ Jun 2 2016, 09:35 AM) *
As I recall, the NH camera pixels are around 1 arc second in size (smallest yet flown beyond LEO), would the Plutonian system gravitational deflection of NH be superimposed on the barycenter curve as shown, and therefore visible as a slight 'deformation' of the curve, or is the deflection small enough it can only be discerned through the radio science experiment ??

http://www.unmannedspaceflight.com/index.php?showtopic=5079

If the deflection angle is about 2 arc-min per that thread (assuming I haven't made a units conversion mistake), then that would be about 100 LORRI pixels, so yeah, it should be in there somewhere, though there would be some motion of Pluto against the star background even if there was no deflection and even without the barycenter thing.

BTW, MOC and HiRISE have smaller IFOVs than LORRI, so your "smallest yet flown beyond LEO" is wrong.


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fredk
post Jun 2 2016, 07:20 PM
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QUOTE (mcaplinger @ Jun 2 2016, 07:03 PM) *
If the deflection angle is about 2 arc-min per that thread

That 2' deflection is the change between the incoming and outgoing directions. Most of that will be incurred very close to closest approach (CA) (I'd think within a few hours). That sequence starts about a day after CA, so the remaining deflection during the sequence will be considerably smaller than 2'.
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