New Horizons

[Mr Shifty]

So it is going to be facing Pluto's dark side as it flies by? Couldn't they have aimed it so it passes the day side instead?

It, of course, will approach from the day side. The geometry of the situation is inevitable. It's approaching from the inner solar system, i.e. the direction of the sun. Pluto's full, illuminated face will be facing NH as it approaches. It will fly directly across the terminator at closest approach (with Charon almost directly opposite), then face Pluto's dark side as it departs. You can see all this in NASA's Eyes free visualization tool:

What's really cool is that, starting a couple weeks before the Pluto encounter, NASA's Eyes shows the fields-of-view of NH's instruments and communication dish. You can see it continuously re-orienting itself (according, presumably, to the mission's planning) first to observe Pluto and its moons, then to transmit back to Earth.

[Meithan]

What's really cool is that, starting a couple weeks before the Pluto encounter, NASA's Eyes shows the fields-of-view of NH's instruments and communication dish. You can see it continuously re-orienting itself (according, presumably, to the mission's planning) first to observe Pluto and its moons, then to transmit back to Earth.

Yep, there's a cute almost-conscious feeling to that behavior: <observe something> "You have to see what I just saw, guys!" <turns towards Earth and transmits>

[Camacha]

What's really cool is that, starting a couple weeks before the Pluto encounter, NASA's Eyes shows the fields-of-view of NH's instruments and communication dish. You can see it continuously re-orienting itself (according, presumably, to the mission's planning) first to observe Pluto and its moons, then to transmit back to Earth.

It somewhat surprised me that orienting the whole craft is preferable over targeting instruments individually, though I can see some engineering issues with the latter. It seems so wasteful on the ÃŽâ€v. Then again, when done with restraint, it should take not much fuel.

[Kryten]

NASA have announced a media conference on June 3rd about recent Hubble observations of the Pluto system, in preparation for the flyby. Apparently they've noted something 'surprising' in the behaviour of the moons, and it must indeed be pretty surprising to warrant a press conference.

[smjjames]

NASA have announced a media conference on June 3rd about recent Hubble observations of the Pluto system, in preparation for the flyby. Apparently they've noted something 'surprising' in the behaviour of the moons, and it must indeed be pretty surprising to warrant a press conference.

Some sort of complex orbit synchronation?

[Streetwind]

Small update:

According to mission scientists, things look like a smooth, hazard-free cruise right now. (But of course, the search will be ongoing. Safety first!)

[Pluto100]

Do you mean that you work in New Horizons project? Please explain, downgraded from being a huge project?

Seriously i'm interested, or at least my Engineer side and astronomer geek is.

- - - Updated - - -

The only thing better is the real deal in couple of weeks and yeah probably better with music and easier to watch instead of running the nasa app

Ahh, so sorry for such a late reply! I'm hardly ever on here. But I remember watching some sort of documentary a bit ago (a long bit ago at that) that mentioned something about a lander, an orbiter, and microprobes. I believe it was part of the Pluto Express mission, which was of course scrapped. Of course, I may be remembering this wrong, but I'm pretty sure that's what it was!

Edit: Naw, sadly, I am not. I would love that though!

[Mitchz95]

NASA have announced a media conference on June 3rd about recent Hubble observations of the Pluto system, in preparation for the flyby. Apparently they've noted something 'surprising' in the behaviour of the moons, and it must indeed be pretty surprising to warrant a press conference.

Mass relay?

[Camacha]

Small update:

According to mission scientists, things look like a smooth, hazard-free cruise right now. (But of course, the search will be ongoing. Safety first!)

That would be a good ol' smack.

[Nikolai]

It somewhat surprised me that orienting the whole craft is preferable over targeting instruments individually, though I can see some engineering issues with the latter. It seems so wasteful on the ÃŽâ€v. Then again, when done with restraint, it should take not much fuel.

Having individually-targeted instruments is not without its delta-v costs. As the camera is trained to stay on objects, the entire spacecraft rotates in the opposite sense, and corrections need to be made to keep the high-gain antenna pointed at Earth. (Remember, nothing can be considered "stationary" except the center of mass of the system.) It gets surprisingly complicated rather quickly.

Then there are the problems of making sure everything deploys correctly, and that everything points just the right way during a mission that is over relatively quickly.

Since storage space is abundant, it's relatively easy to optimize pointing and then point back at Earth when we have to. That, and the simplicity of building a solid-block spacecraft over many independently-articulated platforms that might or might not go through different amounts of wear on a spacecraft that had to be constructed relatively quickly, meant that a single-block spacecraft won out.

[Kryten]

Also, the long length of the cruise phase and severe conditions at Pluto meant moving parts were deliberately kept to a minimum. For example, the colour portion of the main camera (Ralph) uses filters that are physically attached to portions of the CCD, rather than the standard system of a filter wheel at the aperture.

Edited May 31, 2015 by Kryten

[pincushionman]

NASA have announced a media conference on June 3rd about recent Hubble observations of the Pluto system, in preparation for the flyby. Apparently they've noted something 'surprising' in the behaviour of the moons, and it must indeed be pretty surprising to warrant a press conference.

The article noted "possibly a sixth moon."

With respect to steerable instruments, fixed components are also less massive than those with mechanisms.

[peadar1987]

It somewhat surprised me that orienting the whole craft is preferable over targeting instruments individually, though I can see some engineering issues with the latter. It seems so wasteful on the ÃŽâ€v. Then again, when done with restraint, it should take not much fuel.

Yeah, moveable parts tend not to do particularly well in space. Bearings especially, any sort of lubricant deals with the vacuum poorly, and the fine tolerances required don't really mesh with big thermal variations. Spacecraft try and minimise them as far as is possible, although there are success stories (I'm thinking Opportunity, for one)

[Ralathon]

Yeah, moveable parts tend not to do particularly well in space. Bearings especially, any sort of lubricant deals with the vacuum poorly, and the fine tolerances required don't really mesh with big thermal variations. Spacecraft try and minimise them as far as is possible, although there are success stories (I'm thinking Opportunity, for one)

Opportunity isn´t in a pure vacuum though. The thin atmosphere of Mars dampens temperature fluctuations which helps immensely.

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.

[SelectHalfling0]

Mass relay?

Yes!!!

[smjjames]

Mass relay?

Whats a mass relay?

[Motokid600]

Whats a mass relay?

http://masseffect.wikia.com/wiki/Mass_Relay

[Mitchz95]

Whats a mass relay?

In the Mass Effect video games, Pluto's moon Charon was found to be a massive alien artifact called a mass relay.

[Meithan]

Dammit, Steve.

[Kryten]

http://www.nasa.gov/press-release/nasa-to-hold-media-call-to-discuss-surprising-observations-of-pluto-s-moons

Announcement in a couple of hours or so. Most common rumour is chatoic rotation of the smaller moons.

[Frida Space]

So, to summarize:

- The minor moons (Styx, Nix, Kerberos, Hydra) probably all share an oval shape (football-like) due to gravitational stress

- Their rotation is absolutely chaotic and unpredictable. As Showalter said, "if you had an estate on Nix north's pole, you could suddenly find yourself at the south pole. You would never know when the Sun would rise and set: one day it could rise from the west and set on the north, and the following day it might not rise at all".

- Nix & Hydra reflect 40% of the incoming light (did I hear that correctly?), so they're like dirty snowballs, whilst Kerberos is very different, as it reflects only 4% and is much more similar to charcoal. That suggests it could be a fragment produced during the Charon-forming collision, although "that's just pure speculation", as Showalter said.

- New Horizons should be safe: there is physically no space in between the moons to add any other objects in stable orbits. (although, if I may add, we already knew that, and the real hazard isn't an undiscovered moon, but rather a debris cloud/stream/material exchange between moons and Pluto)

- Nix, Styx & Hydra are in an orbital resonance: "If you were sitting on Nix, you would see that Styx orbits Pluto twice for every three orbits made by Hydra," to quote Hamilton. Orbital resonances greatly prevent collisions (see Pluto itself and Neptune's resonance), so that's probably why a tiny world like Pluto has so many moons.

- Refined sizes: Nix (35 x 16 miles), Kerberos (19 miles), Hydra (36x21 miles), Styx (too small to tell with Hubble's vision).

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An animation of Nix's rotation:

Edited June 3, 2015 by Frida Space

[Mitchz95]

Wow, that's really interesting. Can't wait to see what else we learn from New Horizons.

[Moon Goddess]

Nix is making me sick looking at it, can you imagine standing there.

[Motokid600]

Are those pictures/textures just place holders for the demonstration? And are they really that oval?

[Frida Space]

Are those pictures/textures just place holders for the demonstration? And are they really that oval?

At least in the case of Nix, I believe yes, because they said: "the texture (the surface) is purely an artist representation, but the shape and the rotation are the result of a numerical model we developed" or something like that.

On a side note, am I the only one that thinks that for the Hydra texture they just stretched a photo of Mimas?