Starship Asterisk*

Flying Past Pluto

Explanation: What would it look like to fly past Pluto? The robotic New Horizons spacecraft did just this in late July and continues to return stunning pictures of the dwarf planet. Some well-chosen flyby images have now been digitally sequenced to create the featured video. The animation begins by showing New Horizon's approach to the Pluto system, with Pluto and its largest moon Charon orbiting a common center of mass. As the spacecraft bears down on Pluto uniquely, surprising surface features are nearly resolved that, unfortunately, quickly rotate out of view. New Horizons then passes just above and near a large, fascinating, light-colored, heart-shaped, and unusually smooth region now known as Tombaugh Regio. The spacecraft then pivots to look back at Pluto's night side, seeing an encompassing atmospheric haze. Finally, Pluto fades away in a final sequence illustrated with the orbits of many of Pluto's smaller moons. Although humanity has no current plans to return to Pluto, the New Horizons spacecraft may well be directed next to fly past an asteroid currently known only as 2014 MU69.

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thanks for including the moons and sun, thus enhancing the sense of flying by enormously.

That is strange. I assume the smaller bright dot is Charon. Now I have always read that Charon and Pluto are tidally locked and always present the same face to each other. In this video you can see a dark spot on Charon's right side. As Charon rotates counterclockwise on the screen with Pluto at the center of the clock, you can see the dark spot is facing right at 3 o'clock. It is facing right at 12 o'clock and it is facing right at 9 o'clock. This means that the dark spot is facing away from Pluto at 3 o'clock and is facing head-on to Pluto at 9. How can this be, if they are tidally locked? (Pausing the video at 4 and 5 seconds helps.)

Is there a very faint ring system around Pluto? It could be an aberration in the optics.

I get the impression from both the video and the text that New Horizons didn't really "fly past" Pluto but rather looped around it, using Pluto's gravity, or even went into orbit. Most news reports seem to indicate that the spacecraft just flew by and got a quick glance in passing, then headed on further into space.

Sure looks like a planet to me .

Great subject. Thanks for the video and adding orbit lines for the smaller moons. Would have missed them otherwise.

De58te wrote:
That is strange. I assume the smaller bright dot is Charon. Now I have always read that Charon and Pluto are tidally locked and always present the same face to each other. In this video you can see a dark spot on Charon's right side. As Charon rotates counterclockwise on the screen with Pluto at the center of the clock, you can see the dark spot is facing right at 3 o'clock. It is facing right at 12 o'clock and it is facing right at 9 o'clock. This means that the dark spot is facing away from Pluto at 3 o'clock and is facing head-on to Pluto at 9. How can this be, if they are tidally locked? (Pausing the video at 4 and 5 seconds helps.)

The dark spot on Charon's right side at 3 o'clock essentially represents Charon's north pole.

Rusty Brown in Cda wrote:I get the impression from both the video and the text that New Horizons didn't really "fly past" Pluto but rather looped around it, using Pluto's gravity, or even went into orbit. Most news reports seem to indicate that the spacecraft just flew by and got a quick glance in passing, then headed on further into space.

New Horizons essentially passed through the Pluto system in a straight line. The gravity of the pair was insufficient to significantly deflect the spacecraft. It did not loop at all, it did not enter a closed orbit.

neufer wrote:

[b][color=#0000FF]A composite of enhanced color images of Pluto (lower right) and Charon (upper left), taken by New Horizons on July 14, 2015. This image highlights the striking differences between Pluto and Charon. The image combines blue, red and infrared images taken by the spacecraft's Ralph/Multispectral Visual Imaging Camera (MVIC). NASA / JHUAPL / SwRI / Planetary Society[/color][/b]

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Thanks for posting that image, Art. I have been very interested in the color difference between Pluto and Charon. The image you posted shows that Pluto has a much higher albedo than Charon, but also that Charon appears quite gray, and not reddish at all, apart from its red polar region. Pluto, of course, is part bright, part dark, and mostly reddish from reddish ice.

Ann

Chris Peterson wrote:

Rusty Brown in Cda wrote:
I get the impression from both the video and the text that New Horizons didn't really "fly past" Pluto but rather looped around it, using Pluto's gravity, or even went into orbit. Most news reports seem to indicate that the spacecraft just flew by and got a quick glance in passing, then headed on further into space.

New Horizons essentially passed through the Pluto system in a straight line. The gravity of the pair was insufficient to significantly deflect the spacecraft. It did not loop at all, it did not enter a closed orbit.

Pluto has an escape velocity (V_e) of 1.212 km/s at a radius of 1,186 km.

The local escape velocity at New Horizons at closest approach (i.e., 12,500 km from the surface)

• was (V_enh) ~ 0.357 km/s ~ 1.212 / sqrt(1 + [12,500/1,186]).

At that time New Horizons was traveling at (V_nh) = 13.78 km/s

• or ~38.6 times the local escape velocity (V_enh)

The deflection angle = sin^-1(V_enh/V_nh)² ~ sin^-1(1/38.6²) radians ~ 2 arc minutes.

It would be interesting to know what was the actual time elapsed of the video. Did it travel that far in 23 seconds?

mnolin7055 wrote:
It would be interesting to know what was the actual time elapsed of the video. Did it travel that far in 23 seconds?

You can count for yourself almost 2 orbits of Charon ...so roughly 10 days.

Lovely video, Thanks for posting it! Nevertheless it leaves me with the question whether there are even images (e.g. radar) of Pluto's dark side?

Uwe wrote:Lovely video, Thanks for posting it! Nevertheless it leaves me with the question whether there are even images (e.g. radar) of Pluto's dark side?

New Horizons doesn't carry a radar imager. It only has optical imagers covering wavelength ranges where there is no significant reflection or emission from regions not lit by sunlight. So no, don't expect any image data from hemispheres in shadow.

Damn, this means I shall never see the Dark Side of Pluto before I die. I shall simply have to petition NASA to send another probe that can image the Dark Side

BMAONE23 wrote:Damn, this means I shall never see the Dark Side of Pluto before I die. I shall simply have to petition NASA to send another probe that can image the Dark Side :mrgreen:

And allowing for funding, mission design, and travel time, hope you don't die in the next 20 years or so.

And even then... only if the Force is with you.

Rusty Brown in Cda wrote:I get the impression from both the video and the text that New Horizons didn't really "fly past" Pluto but rather looped around it, using Pluto's gravity, or even went into orbit. Most news reports seem to indicate that the spacecraft just flew by and got a quick glance in passing, then headed on further into space.

Consider as part of your interpretation that Pluto isn't a stationary object. Pluto is orbiting the sun at a varied rate, faster when nearer the sun (at permission) and slower at aphelion, but a averaging 4.67km/s. This means that as New Horizons passes through the Pluto/Charon system, Pluto also moves at 1680kph or 40320k per day. New Horizons is still traveling in a straight line, it is Pluto that is moving

BMAONE23 wrote:

Rusty Brown in Cda wrote:
I get the impression from both the video and the text that New Horizons didn't really "fly past" Pluto but rather looped around it, using Pluto's gravity, or even went into orbit. Most news reports seem to indicate that the spacecraft just flew by and got a quick glance in passing, then headed on further into space.

Consider as part of your interpretation that Pluto isn't a stationary object. Pluto is orbiting the sun at a varied rate, faster when nearer the sun (at permission [sic]) and slower at aphelion, but a averaging 4.67km/s. This means that as New Horizons passes through the Pluto/Charon system, Pluto also moves at 1680kph or 40320k per day. New Horizons is still traveling in a straight line, it is Pluto that is moving

I.e., New Horizons has been traveling in a near radial straight line,
it was Pluto that moved angularly to pass between New Horizon & the Sun.

http://asterisk.apod.com/viewtopic.php? ... 37#p248821

Uwe wrote:Lovely video, Thanks for posting it! Nevertheless it leaves me with the question whether there are even images (e.g. radar) of Pluto's dark side?

Calm down, guys; just asking . Thanks for the reply. But isn't that some lost opportunity? Going billions of kilometers and on arrival not taking anything you could get? Well, on the other hand, the dark side will probably not display (even more) spectacular new features.

Uwe wrote:

Uwe wrote:Lovely video, Thanks for posting it! Nevertheless it leaves me with the question whether there are even images (e.g. radar) of Pluto's dark side?

Calm down, guys; just asking :wink: . Thanks for the reply. But isn't that some lost opportunity? Going billions of kilometers and on arrival not taking anything you could get? Well, on the other hand, the dark side will probably not display (even more) spectacular new features.

That's the reality of budgets. You can only take so much, you can only put so many instruments on a spacecraft. I wouldn't be surprised if some kind of imaging radar was on the table during the early parts of the program design. But eventually, you end up with compromises. The amount of money. The mass budget. The power budget. Questions of technology and reliability. And of course, the lack of knowledge about what we might find and what the best instruments might turn out to be.

Uwe wrote:

Uwe wrote:
Lovely video, Thanks for posting it! Nevertheless it leaves me with the question whether there are even images (e.g. radar) of Pluto's dark side?

Calm down, guys; just asking . Thanks for the reply. But isn't that some lost opportunity? Going billions of kilometers and on arrival not taking anything you could get? Well, on the other hand, the dark side will probably not display (even more) spectacular new features.

The Magellan spacecraft, a.k.a. Venus Radar Mapper, required 1,792 orbits to do a radar survey of Venus.
Not sure that a radar flyby would have been worth the extra weight.

The lost opportunity was, perhaps, in not allowing Voyager 1 to
continue on to Pluto by simply making a more distant pass of Titan:

http://asterisk.apod.com/viewtopic.php? ... 37#p248712

neufer wrote:

BMAONE23 wrote:

Rusty Brown in Cda wrote:
I get the impression from both the video and the text that New Horizons didn't really "fly past" Pluto but rather looped around it, using Pluto's gravity, or even went into orbit. Most news reports seem to indicate that the spacecraft just flew by and got a quick glance in passing, then headed on further into space.

Consider as part of your interpretation that Pluto isn't a stationary object. Pluto is orbiting the sun at a varied rate, faster when nearer the sun (at permission [sic]) and slower at aphelion, but a averaging 4.67km/s. This means that as New Horizons passes through the Pluto/Charon system, Pluto also moves at 1680kph or 40320k per day. New Horizons is still traveling in a straight line, it is Pluto that is moving

I.e., New Horizons has been traveling in a near radial straight line,
it was Pluto that moved angularly to pass between New Horizon & the Sun.

http://asterisk.apod.com/viewtopic.php? ... 37#p248821

I do so dislike the autocorrect feature on my Kindle

DGSmith wrote:Is there a very faint ring system around Pluto? It could be an aberration in the optics.

I noticed the rings as well. I believe I noticed small objects in the second and fourth rings as well.

Ogdru wrote:

DGSmith wrote:Is there a very faint ring system around Pluto? It could be an aberration in the optics.

I noticed the rings as well. I believe I noticed small objects in the second and fourth rings as well.

There are no rings. There are paths drawn around Pluto to illustrate the orbits of its moons, though.