New Horizons

[Camacha]

Actual space pancakes and space potatoes. How wonderful!

- Their rotation is absolutely chaotic and unpredictable.

I never quite got how this works. If a body has little to no forces acting upon it (other than Pluto's and Charon's gravity), how could it move in unpredictable ways? Would that not mean it actually and actively changes direction? If it tumbles over multiple axis, it seems to be that this is essentially a complex but predictable motion.

[Frida Space]

I never quite got how this works. If a body has little to no forces acting upon it (other than Pluto's and Charon's gravity), how could it move in unpredictable ways? Would that not mean it actually and actively changes direction? If it tumbles over multiple axis, it seems to be that this is essentially a complex but predictable motion.

Yes, I believe that with "chaotic motion" they're referring to rotation only, revolution should be pretty normal, as in they should follow normal orbits around the system's barycenter. What they mean by "unpredictable" is that it's always changing because of Charon's and Pluto's orbital motions around the common baricenter. As there is no resonance between Charon/Pluto and Nix, for example, at one point in the orbit Nix might have a certain inclination, and then a full, exact orbit later it might have a completely different inclination. Sure, it's physics, so once you know the various forces etc. at work you can predict anything, so "unpredictable" is kinda misleading, although not 100% in my opinion.

Plus, the interactions with Kerberos and Styx should be pretty meaningful, since the system is so tiny and squeezed. In the talk they said that if all the satellites were aligned a huge mess would happen.

[Camacha]

Yes, I believe that with "chaotic motion" they're referring to rotation only, revolution should be pretty normal

I figured as much, though I see no reason the physics of the rotation should be any different than those of the orbital mechanics. Rotation, though chaotic, should be predicable without clear and significant forces acting upon a body, right?

[Frida Space]

I figured as much, though I see no reason the physics of the rotation should be any different than those of the orbital mechanics. Rotation, though chaotic, should be predicable without clear and significant forces acting upon a body, right?

Yes, I figured that with "unpredictable" they meant "very complex and not straightforward", as in there are a lot of changing forces interacting with each other (even if we leave out Styx because it's so tiny and consider the influence of the minor moons on Pluto negligible, we see that Nix is influenced by 4 bodies (Pluto, Charon, Hydra, Kerberos) which in turn are influenced by respectively 1 body (Pluto, that's Charon), 4 bodies (Charon, that's Pluto, Hydra, Kerberos and Nix itself), 4 other bodies and 4 other other bodies and so on...) Now this example I just made is kinda stupid but you can easily see how things get dramatically complex very quickly as you need to consider 5/6 bodies and you have to know a lot about each of them (position, rotation, period, mass, momentum etc). I suspect that even New Horizons' great data won't be enough to allow us to predict Nix's rotation.

[epoca]

That makes sense, thank you.

[Frida Space]

So, I was making an updated plot for the trajectory of New Horizons through the Pluto system and things are a bit out of my reach. (I know that the trajectory might be changed if the current one becomes unsafe, but that's a whole other story).

My main source was this plot, however it's (relatively) very outdated: Kerberos and Styx weren't even known at the time.

For the positions of Pluto and moons, I used this other plot, where you can just see the positions:

For the timings... well, that's a big problem. My main source in this case is an email conversation I had with the atmospheric studies lead scientist for New Horizons. This is what he told me regarding timing (I didn't directly ask him for timing, I just asked him about the occultation science). In bold​ I wrote my comment:

(please note we had this conversation between Feb-March 2015, so it's very recent)

- The solar and radio occultations mostly overlap in time (since the Earth and Sun are very close together as seen from Pluto); the Pluto occultations are about an hour after closest approach (e.g., we will observe the solar ingress at Pluto from 12:16-12:49 UT on July 14th, and expect the Sun to set at about 12:47 UT; closest approach to Pluto is expected at 11:50 UT).

According to most sources (see 1st plot above and this other one), the encounter will be at 11:47 and not at 11:50 (I know it's not a huge difference, but as the flyby will be extremely quick it kinda is). For the occultation I decided, for the sake of semplicity, to consider only egress, so: Pluto-Sun occultation is 12:47 according to him, and 12:48 according to the first plot, which is acceptable. Not really sure when the Pluto-Earth radio occultation is, the 12:49 on the first plot seems realistic.

Other sources (both are NASA documents):

This is my preliminary design. Please note that the position of Pluto is intentionally wrong (or else it would have messed up everything else), and again, as I discussed above, the whole timing thing is very difficult to get your head around.

I'm not sure how anyone could help, I was thinking that maybe someone had some official sources or anything like that? Thanks.

- - - Updated - - -

And yea, I just realized that the Charon C/A point is completely in the wrong position. I'll have to change that. But the timing is more important for me at the moment than the exact positions

[epoca]

That's awesome, man! I'd love to see an updated plot with New Horizons' current trajectory, but I'm really not sure whether I could be of any help in making such a thing. Please keep us up to date here if you find any new information! I'd be very interested in seeing the final result. Thanks a lot, really.

[Frida Space]

That's awesome, man! I'd love to see an updated plot with New Horizons' current trajectory, but I'm really not sure whether I could be of any help in making such a thing. Please keep us up to date here if you find any new information! I'd be very interested in seeing the final result. Thanks a lot, really.

Thank you! I've started working with a few members of the New Horizons team on an updated and far more informative version, it's coming on pretty well.

[Camacha]

A better example would be the imaging platform of the Voyager probes. Sure, it got stuck once for Voyager 2 right after Saturn. But next to that little hiccup it worked beautifully for more than a decade.

There are more moving instruments in there. The charged particle instrument also has a stepper motor in it and despite some criticism back then, it is still going strong today - over 11 times its originally rated steps later.

:

[Mr Shifty]

Just to note: this isn't an event that will be happening live. The flyby, as we can see from Frida's awesome graphs, will be over in just a couple hours. But, we won't even get confirmation that it occurred successfully until signals from the probe reach Earth, which will take more than 4 hours. The signal from New Horizons is so weak that it can only transmit about 125 bytes/second, so it take more than 40 minutes to transfer a single image from NH's long range imager. (Emily Lakdawalla ran down the whole communications infrastructure/technology paradigm in January. It's fascinating reading, check it out!) So, we might know the fly-by went fine a few hours after it occurs, but we probably won't see images from closest approach until days or weeks afterwards (though we'll be getting better and better images as the probe approaches.) Don't hold your breath.

[Candlelight]

Ok people, 1 more month to go!

And we are already getting some good pics of Pluto's moons!

[Frida Space]

Just to note: this isn't an event that will be happening live. The flyby, as we can see from Frida's awesome graphs, will be over in just a couple hours. But, we won't even get confirmation that it occurred successfully until signals from the probe reach Earth, which will take more than 4 hours. The signal from New Horizons is so weak that it can only transmit about 125 bytes/second, so it take more than 40 minutes to transfer a single image from NH's long range imager. (Emily Lakdawalla ran down the whole communications infrastructure/technology paradigm in January. It's fascinating reading, check it out!) So, we might know the fly-by went fine a few hours after it occurs, but we probably won't see images from closest approach until days or weeks afterwards (though we'll be getting better and better images as the probe approaches.) Don't hold your breath.

Yes, during the actual flyby we will be getting only 1% of the data obtained, mostly images to satisfy our curiosity needs The last drop of Pluto science will fall on Earth in something like 9 months time.

[epoca]

Yes, during the actual flyby we will be getting only 1% of the data obtained, mostly images to satisfy our curiosity needs The last drop of Pluto science will fall on Earth in something like 9 months time.

:-( Guess the wait is a bit longer than a month then...

[Frida Space]

(PLEASE NOTE I updated the image with the newest version)

Original text: I'm happy to say I finally finished what should be the final version of my New Horizons flyby-trajectory thing. This was produced along with the New Horizons team, which were kind enough to give me all the data and help me sort out a few things. Everything here was provided to me directly by the New Horizons team (timing, distances, sizes), the only thing which isn't 100% perfect is the visual representation: obviously I had to make the bodies much bigger than they actually are to make them visible etc. I hope you enjoy.

Edited June 9, 2015 by Frida Space

[epoca]

I'm happy to say I finally finished what should be the final version of my New Horizons flyby-trajectory thing. This was produced along with the New Horizons team, which were kind enough to give me all the data and help me sort out a few things. Everything here was provided to me directly by the New Horizons team (timing, distances, sizes), the only thing which isn't 100% perfect is the visual representation: obviously I had to make the bodies much bigger than they actually are to make them visible etc. I hope you enjoy.

WOW, thank you so much for this! It's really great to have such materials on this forum, and on the whole Internet in general. I guess this is how a Mariner or Voyager flyby would have been if we had internet back in the days!

[PB666]

There are more moving instruments in there. The charged particle instrument also has a stepper motor in it and despite some criticism back then, it is still going strong today - over 11 times its originally rated steps later.

The problem is that the craft has lost almost all of its power, its only capable of running a few instruments now.

This is something folks should think about, why the pluto mission is a fast flyby, on of the limitations is to get there and get the data while it still has enough on-board power to do stuff. At sun-ship distances greater than Mars electricity is a major limitation, we are very fortunate that these two craft have enough power to communicate back to Earth.

[peadar1987]

So excitement!!

[Frida Space]

If anyone's interested, I made an updated version of my encounter diagram which fixes a few minor mistakes, mainly the fact that the New Horizons team told me they use the IAU diameter of Pluto (2390 km) and not 2368 km as shown in the previous version.

The newest version can be found here: http://s22.postimg.org/mhnb6c5nj/new_horizons_eng_1.png

I'm also happy to say Emily Lakdawalla of the Planetary Society has contacted me to use the image in a future blog post. She's currently hosting the now-outdated version at: http://www.planetary.org/multimedia/space-images/charts/diagram-of-new-horizons-pluto-trajectory.html

EDIT: She has now updated the version. The planetary.org link now displays the latest version

Edited June 9, 2015 by Frida Space

[Robotengineer]

Only a little more than a month... Are you hyped?

[Mitchz95]

Only a little more than a month... Are you hyped?

So hyped. Even though the data won't really come through for a while after it.

I'm also kind of terrified that something will go wrong during the flyby and we'll never regain contact with the probe. Just imagine how devastating that would be.

[TythosEternal]

I'm also happy to say Emily Lakdawalla of the Planetary Society has contacted me to use the image in a future blog post. She's currently hosting the now-outdated version at: http://www.planetary.org/multimedia/space-images/charts/diagram-of-new-horizons-pluto-trajectory.html

Very cool! She's awesome.

[Frida Space]

Very cool! She's awesome.

I know! That's why I'm very happy

[viktor19]

So hyped. Even though the data won't really come through for a while after it.

I'm also kind of terrified that something will go wrong during the flyby and we'll never regain contact with the probe. Just imagine how devastating that would be.

Although I doubt something that serious might happen, it would be a disaster - 14 years of hard work down the drain.

[Elthy]

How long would we have to wait for a first high resolution picture?

[Frida Space]

How long would we have to wait for a first high resolution picture?

Depends on what you mean by high-res. We should start seeing the first geological features any time now. If you mean really high-res imagery, then that will be available only during the encounter itself. New Horizons is travelling fast - 24 hours prior to Pluto closest approach, it will still be almost 1.3 million kilometers (800 thousand miles) away!