Explanation: Pluto surface is strange. As the robotic New Horizons barrels toward its closest approach to Pluto and its moons tomorrow, images already coming back show Pluto's surface to be curiouser and curiouser. The featured image, taken two days ago, shows the side of Pluto that always faces Pluto's largest moon Charon. Particularly noteworthy is the dark belt near the bottom that circles Pluto's equator. It is currently unclear whether regions in this dark belt are mountainous or flat, why boundaries are so sharply defined, and why the light regions seem to be nearly evenly spaced. As New Horizons will be flying past the other side of Pluto, this should be the best image of this distant landscape that humanity sees for a long time. Assuming the robotic spacecraft operates as hoped, images taken of the other side of Pluto, taken near closest approach, will be about 300 times more detailed.
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 5:01 am
by Wayne Jepson
So far, the images of Pluto remind me somewhat of Triton (https://en.wikipedia.org/wiki/Triton_(moon)) ... maybe some 'canteloupe terrain' nearer the north pole?
And then nearer it's equator, it reminds me more of Titan. The dark regions sure look like they could be rivers and lakes or at least the remnants of some fluid carved channels, and/or perhaps frosted areas...
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 6:35 am
by geckzilla
I feel a kind of information despair in knowing that this is the best picture we will have of this side of Pluto unless we do another run at it. Even worse, the people who keep saying this marks the end of exploration. We've still got a lot of places we can go. Even Earth is not fully explored.
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 6:58 am
by Ann
Wayne Jepson wrote:
And then nearer it's equator, it reminds me more of Titan. The dark regions sure look like they could be rivers and lakes or at least the remnants of some fluid carved channels, and/or perhaps frosted areas...
I think so, too.
Geck wrote:
I feel a kind of information despair in knowing that this is the best picture we will have of this side of Pluto unless we do another run at it. Even worse, the people who keep saying this marks the end of exploration.
Yes, there can be no doubt that the picture of the Charon-facing side of Pluto is a disappointment to many people.
I think perhaps the hopes for the pictures have been too high, and the difficulties have been underestimated. People have been getting used to seeing splendid pictures of the Saturnian moons, but that is because we have a probe in orbit there. New Horizons will never be in orbit around Pluto, and it is whizzing past at breakneck speeds.
But what about Neptune's large moon Triton? Triton is very far away, and Voyager II, which photographed it, whizzed by fast. That's true. But not all of Triton was photographed. This is, as far as I can understand, the best global map of Triton.
So our hopes for the Pluto pictures should be realistic. No, New Horizons couldn't give us a really good picture of the Charon-facing side of Pluto. Tough luck. Voyager II couldn't give us a good picture of all of Triton, either.
Ann
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
I have to say that while I do see the similarities between Pluto and Triton, I see plenty that's not the same. Those features kind of streaming toward the equator are fascinating and I want to know more about them.
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 10:45 am
by neufer
geckzilla wrote:
I feel a kind of information despair in knowing that this is the best picture we will have of this side of Pluto unless we do another run at it. Even worse, the people who keep saying this marks the end of exploration.
At least we should be able to see the dark side of Pluto that always faces Pluto's largest moon Charon thanks to Charonshine.
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 10:55 am
by Joules
I was expecting something more Vesta-like. That atmosphere has clearly been messing with Pluto's surface features.
It's probably time to start planning an orbiter mission.
That should prove quite a challenge with Charon messing up the gravity field as it does, and all those other little moonlets to avoid.
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 1:43 pm
by Dad is watching
We looked at the image and the concentration of dark areas at the equator. It occurred to us that the barycenter of the minor-planet and moon is outside Pluto. Anything falling into the gravity well of the two bodies would be drawn to the barycenter first, then (if captured) would dive onto the surface of Pluto. This would favor impacts on Pluto on the plane of the barycenter between the two objects (the equator?). Faster moving objects may just graze Pluto causing something akin to 'polishing rocks' on a planetary scale. Could this account for the differences of topology between the poles and the equator, and the rough demarcation line apparently seen? Just a thought...
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 2:32 pm
by Chris Peterson
Dad is watching wrote:We looked at the image and the concentration of dark areas at the equator. It occurred to us that the barycenter of the minor-planet and moon is outside Pluto. Anything falling into the gravity well of the two bodies would be drawn to the barycenter first, then (if captured) would dive onto the surface of Pluto. This would favor impacts on Pluto on the plane of the barycenter between the two objects (the equator?).
I don't think so. Nothing is really "drawn to the barycenter". Rather, that's the point that a body will orbit around. The probability of something actually passing through the barycenter is extremely low. And an orbiting (or nearly orbiting) body won't see its inclination changed to lie on the Pluto-Charon orbital plane.
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 2:35 pm
by Chris Peterson
Ann wrote:So our hopes for the Pluto pictures should be realistic. No, New Horizons couldn't give us a really good picture of the Charon-facing side of Pluto. Tough luck. Voyager II couldn't give us a good picture of all of Triton, either.
Let's not forget that LORRI isn't the only instrument carried by New Horizons. We all like pictures, and we can see them almost instantly. But there's a lot of other data that hasn't been released, hasn't been interpreted. When that gets laid over the imaging data, we may have a much better understanding of what we're actually seeing.
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 3:45 pm
by starsurfer
I think the best approach is to not have unrealistic expectations. I see this image and I consider it to be superb and mysterious, the southern features are very curious.
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 4:49 pm
by MarkBour
As a layman, the question that comes to mind here is: "Why would we send a spacecraft on a nearly decade-long flight to this location, and be satisfied with a mission plan that has it zip by it?" Those who are focused on Pluto would want more and better images, and even time to plan detailed imaging based on early views. Perhaps the answer is that it's just that far away and hard to reach, and also that it is beginning to be viewed as not that special of an object. New Horizons will try to capture Kuiper Belt objects as well. I suppose that was always part of what made the mission able to get funding ... barely. But at the time of launch, the Kuiper belt targets were not even known, so that doesn't seem quite right.
Is it beyond the limits of our technology (or our budget, given current technology) to send a probe to Pluto and get orbital insertion? I assume it would have taken "quite a burn" to slow down for it. And that would imply rocket engines and fuel, which would have hugely increased the launch burden from Earth.
As far as how miraculous the current mission plan was, I should not sell that short. I think we should have some of the team's engineers enter bowling competitions, but make the bowling ball and bowling pins microscopic, and make it so that the only way to get a strike would be to hit the head pin within a nanometer plus or minus, while traveling at a minimum speed of 1000 mph. Or has someone actually worked out what would be the mathematical equivalent of the precision of New Horizon's aim in bowling or billiards terms?
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 4:59 pm
by Ron-Astro Pharmacist
If an alien civilization wanted to pick a good place to leave a calling card one of the last sizable bodies within a solar system might be a good spot. By the time any developing life form had the capability to investigate that far from home "maybe" they would be ready for the knowledge other sentient beings were present somewhere in the universe.
I wonder if we are ready for that bit of information. I wonder how it would change the world. Doubt we'll find it tomorrow but it would certainly change NASA's budget. I suppose that sounds like the theme of a sci-fi novel. Probably most of them.
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 4:59 pm
by Chris Peterson
MarkBour wrote:Is it beyond the limits of our technology (or our budget, given current technology) to send a probe to Pluto and get orbital insertion?
It is certainly not beyond our technological capacity. But it would be far beyond the budget of a mission funded under the New Frontiers program. A mission designed to place a probe in orbit around Pluto would certainly cost billions of dollars. Pluto isn't a high enough interest target to justify that kind of expenditure at this time.
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 5:01 pm
by Chris Peterson
Ron-Astro Pharmacist wrote:If an alien civilization wanted to pick a good place to leave a calling card one of the last sizable bodies within a solar system might be a good spot.
I think Clarke was correct in selecting the Moon for that purpose. After all, the huge leap is to the Moon; after that, everything else is pretty unspectacular, and has followed very quickly. If you want to know when a species has left its planet, you start with the nearest body, not the farthest.
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 5:06 pm
by BMAONE23
MarkBour wrote:As a layman, the question that comes to mind here is: "Why would we send a spacecraft on a nearly decade-long flight to this location, and be satisfied with a mission plan that has it zip by it?" Those who are focused on Pluto would want more and better images, and even time to plan detailed imaging based on early views. Perhaps the answer is that it's just that far away and hard to reach, and also that it is beginning to be viewed as not that special of an object. New Horizons will try to capture Kuiper Belt objects as well. I suppose that was always part of what made the mission able to get funding ... barely. But at the time of launch, the Kuiper belt targets were not even known, so that doesn't seem quite right.
Is it beyond the limits of our technology (or our budget, given current technology) to send a probe to Pluto and get orbital insertion? I assume it would have taken "quite a burn" to slow down for it. And that would imply rocket engines and fuel, which would have hugely increased the launch burden from Earth.
As far as how miraculous the current mission plan was, I should not sell that short. I think we should have some of the team's engineers enter bowling competitions, but make the bowling ball and bowling pins microscopic, and make it so that the only way to get a strike would be to hit the head pin within a nanometer plus or minus, while traveling at a minimum speed of 1000 mph. Or has someone actually worked out what would be the mathematical equivalent of the precision of New Horizon's aim in bowling or billiards terms?
What it could take is 13 separate launchings. 12 SRB (Solid rocket boosters) launched into orbit and assembled in orbit followed by the probe to sit atop them. Then fire off 6 to gain the speed to get there, then the other 6 upon arrival to slow down back to orbit speed
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 5:34 pm
by Ron-Astro Pharmacist
Chris Peterson wrote:
Ron-Astro Pharmacist wrote:If an alien civilization wanted to pick a good place to leave a calling card one of the last sizable bodies within a solar system might be a good spot.
I think Clarke was correct in selecting the Moon for that purpose. After all, the huge leap is to the Moon; after that, everything else is pretty unspectacular, and has followed very quickly. If you want to know when a species has left its planet, you start with the nearest body, not the farthest.
I have the utmost respect for Clarke's vision and mostly agree. But the time to digest the possibilities and believe in the capabilities could be the time it would take to fully investigate the relatively near-by surroundings extending to Pluto. Of course we haven't been back to the moon to fully explore it either in about that same period of time so I wonder if Clarke chose the moon for believability, capability or suitability of alien intent. It would be interesting to know if he spoke of that choice in his life.
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 7:38 pm
by neufer
Chris Peterson wrote:
MarkBour wrote:
Is it beyond the limits of our technology (or our budget, given current technology) to send a probe to Pluto and get orbital insertion?
It is certainly not beyond our technological capacity. But it would be far beyond the budget of a mission funded under the New Frontiers program. A mission designed to place a probe in orbit around Pluto would certainly cost billions of dollars. Pluto isn't a high enough interest target to justify that kind of expenditure at this time.
A probe to Pluto would have to decelerate a whopping ~13.7 km/s to go into orbit
However, a probe to Neptune would only have to decelerate ~4 km/s to go into orbit.
This is because Neptune's escape velocity of ~23.5 km/s
well exceeds the probe's initial incoming velocity of ~13.7 km/s.
Sending the probe skimming just above the Neptunian atmosphere will result in a maximal velocity of:
27.2 km/s = sqrt[(23.5)2+(13.7)2] and retrorockets (plus some atmospheric drag)
can easily bring this down to below the escape velocity of ~23.5 km/s
Triton & Pluto are probably quite similar so it makes much more sense to fully investigate Triton first.
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 8:04 pm
by Ron-Astro Pharmacist
That's too bad. I think a lot of us would like to see some type of secondary orbiter with the ability to decelerate to orbital velocities. As long as it takes to get to Pluto, we may be in the age of the Jetsons when we get the chance to go back should something extremely curious be found there?
Click to play embedded YouTube video.
A better question might be would we have had that capability now? Say a Cube-Sat (Elroy?) with ultra-small features that could operate even in a highly elliptical orbit should that be necessary? Not second guessing an awesome mission; just imagination 10 years or so late.
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Mon Jul 13, 2015 8:42 pm
by geckzilla
Here's the latest image that's been going around. Don't see a news release article yet.
A colorized version accompanies NASA's release while individual gray-scale images are at JHU-APL.
How Big Is Pluto? New Horizons Settles Decades-Long Debate NASA | JHU-APL | SwRI | New Horizons | 2015 July 13
[img3="A portrait from the final approach. Pluto and Charon display striking color and brightness contrast in this composite image from July 11, showing high-resolution black-and-white LORRI images colorized with Ralph data collected from the last rotation of Pluto. Color data being returned by the spacecraft now will update these images, bringing color contrast into sharper focus. Credits: NASA/JHU-APL/SwRI"]http://www.nasa.gov/sites/default/files ... charon.jpg[/img3]
NASA’s New Horizons mission has answered one of the most basic questions about Pluto—its size.
Mission scientists have found Pluto to be 1,473 miles (2,370 kilometers) in diameter, somewhat larger than many prior estimates. Images acquired with the Long Range Reconnaissance Imager (LORRI) were used to make this determination. This result confirms what was already suspected: Pluto is larger than all other known solar system objects beyond the orbit of Neptune.
“The size of Pluto has been debated since its discovery in 1930. We are excited to finally lay this question to rest,” said mission scientist Bill McKinnon, Washington University, St. Louis.
Pluto’s newly estimated size means that its density is slightly lower than previously thought, and the fraction of ice in its interior is slightly higher. Also, the lowest layer of Pluto’s atmosphere, called the troposphere, is shallower than previously believed.
Measuring Pluto’s size has been a decades-long challenge due to complicating factors from its atmosphere. Its largest moon Charon lacks a substantial atmosphere, and its diameter was easier to determine using ground-based telescopes. New Horizons observations of Charon confirm previous estimates of 751 miles (1208 km) kilometers) across
LORRI has also zoomed in on two of Pluto’s smaller moons, Nix and Hydra.
“We knew from the time we designed our flyby that we would only be able to study the small moons in detail for just a few days before closest approach,” said New Horizons Principal Investigator Alan Stern of the Southwest Research Institute, Boulder, Colorado. “Now, deep inside Pluto’s sphere of influence, that time has come.”
Nix and Hydra were discovered using the Hubble Space Telescope in 2005. Even to Hubble, they appeared as points of light, and that’s how they looked to New Horizons until the final week of its approach to Pluto. Now, the latest LORRI images show the two diminutive satellites not as pinpoints, but as moons seen well enough to measure their sizes. Nix is estimated to be about 20 miles (about 35 kilometers) across, while Hydra is roughly 30 miles (roughly 45 kilometers) across. These sizes lead mission scientists to conclude that their surfaces are quite bright, possibly due to the presence of ice.
What about Pluto’s two smallest moons, Kerberos and Styx? Smaller and fainter than Nix and Hydra, they are harder to measure. Mission scientists should be able to determine their sizes with observations New Horizons will make during the flyby and will transmit to Earth at a later date.
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Tue Jul 14, 2015 12:47 am
by geckzilla
bystander wrote:A colorized version accompanies NASA's release while individual gray-scale images are at JHU-APL.
The colorized one is not the same as the grayscale one, though. It's a little farther away and rotated a little more.
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Tue Jul 14, 2015 1:36 am
by chuckster
Chris Peterson wrote:
Ron-Astro Pharmacist wrote:If an alien civilization wanted to pick a good place to leave a calling card one of the last sizable bodies within a solar system might be a good spot.
I think Clarke was correct in selecting the Moon for that purpose. After all, the huge leap is to the Moon; after that, everything else is pretty unspectacular, and has followed very quickly. If you want to know when a species has left its planet, you start with the nearest body, not the farthest.
There's always the Star Trek philosophy that it's up to Earthlings to leave thecalling card, in the form of "warp drive signatures" laced through space near Earth. We're never gonna cause trouble for other star systems with rockets or fusion drives. But if we're still addicted to "The Kardashians" and cat videos even as we hit the Fold Space button, we're nothing BUT trouble. The content of the seventy-something light year radius of our EM radiations is enough to keep even the most lonely alien race at arm's length. The supposedly "self-decoding" repetition of the Internet is an even more eloquent statement of where we're at as a species. But a derelict alien spacecraft, discovered floating among the flotsam of the Kuiper Belt, would be a wakeup call that might not be revealed to Joe Sixpack for a long time
Re: APOD: Last Look at Pluto's Charon Side (2015 Jul 13)
Posted: Tue Jul 14, 2015 1:47 am
by geckzilla
chuckster wrote:But if we're still addicted to "The Kardashians" and cat videos even as we hit the Fold Space button, we're nothing BUT trouble.
Hey now, you leave the cat videos out of this. They've done nothing but good things! Good! Cats are good people.
Last Look at Pluto's Charon Side
Probably most of them. 
