Pluto Atmospheric Observations: NH Post-Encounter Phase, 1 Aug 2015- TBD Options

[Ron Hobbs]

This morning New Scientist pinged me about an article: Exclusive photos: Clouds seen on Pluto for first time

It is a short article, but an interesting insight into a discussion that has been occurring between members of the NH team and people at New Scientist. It also looks they might be releasing a new photo through them.

Pluto: Curiouser and curiouser!

[MOD NOTE]: Interesting article, but reminder to all to consider rule 1.9 during discussion. Thanks!

[fredk]

It should be simple to look at the putative cloud locations in other images to check whether they might be stationary surface features rather than clouds. Of course even the lack of a feature in a different image doesn't prove it's a cloud if the lighting is very different, since we've seen what look like specular-ish reflections from smooth surfaces already.

[alan]

Pluto's hybrid interactions with the solar wind:

Previously, most researchers thought that Pluto was characterized more like a comet, which has a large region of gentle slowing of the solar wind, as opposed to the abrupt diversion solar wind encounters at a planet like Mars or Venus. Instead, like a car that’s part gas- and part battery-powered, Pluto is a hybrid, researchers say.

Like Earth, Pluto has a long ion tail, that extends downwind at least a distance of about 100 Pluto radii (73,800 miles/118,700 kilometers, almost three times the circumference of Earth), loaded with heavy ions from the atmosphere and with “considerable structure.”

Pluto’s obstruction of the solar wind upwind of the planet is smaller than had been thought. The solar wind isn’t blocked until about the distance of a couple planetary radii (1,844 miles/3,000 kilometers, about the distance between Chicago and Los Angeles.)

Pluto has a very thin boundary of Pluto’s tail of heavy ions and the sheath of the shocked solar wind that presents an obstacle to its flow.

http://www.nasa.gov/feature/pluto-s-intera...que-study-finds

[elakdawalla]

New Horizons has been downlinking lots of departure phase 1 images recently, showcasing the shrinking "O" of the atmosphere. It'll make a nice animation, something I plan to do....unless someone else beats me to it

http://planetary.s3.amazonaws.com/data/nh/dp1.html

(New items downlinked in May are highlighted in yellow)

[Astroboy]

Aligned on the stars:

[Explorer1]

Astounding work!
Charon is an invisibly thin crescent at this angle without any atmosphere, correct? Or is it just out of frame?

[wildespace]

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.

[fredk]

Aligned on the stars:

Stunning.

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

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.

[elakdawalla]

I was puzzled about the curve in Pluto's path too. Does it have to do with Pluto's rotation about the system barycenter?

[ugordan]

If the timespan of those images matches up (around 3 days) I think you've nailed it, Emily.

[elakdawalla]

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

[ugordan]

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!

[Saturns Moon Tit...]

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.

[Astroboy]

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!

[tasp]

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.