New moon discovered around Pluto using Hubble images!
http://www.nasa.gov/mission_pages/hubble/s...pluto-moon.html

Awesome, another target for NH

I just saw that, cool. Who would have thought it would have so many moons ?

In the search for a possible ring around Pluto in advance of the New Horizons visit, a 4th moon was discovered, more info here: http://www.physorg.com/news/2011-07-hubble-moon-pluto.html

Looks to be pretty small, less than 35km.

-kap

It's gonna be tricky to plan a close-flyby of all four of them, that's for sure. I don't envy the NH team, even with the years still left to plan.

How close would a flyby need to be to get decent science data and images on something 35km across? I'm not that familiar with the instruments on New Horizons.

-kap

In all likelihood, if they already have a good orbit fit for P4, the NH team already knows the closest approach distance and time. The actual trajectory through the Pluto system is fixed based on other requirements, neither Nix nor Hydra and certainly not P4 will have changed that. Only some observations times and targets might change a bit.

We'll likely get a fair imagery with LORRI, and crudely resolved colors with MVIC; unlikely to do more than the very crudest compositional resolution with LEISA...more once we have a good orbit fit that goes out to 2015.5.

-Alan

Back of the envelope calculation - let's say P4 is 20 km and closest approach by NH is 50 000 km. The moon would then be about 80 pixels across in LORRI images. Not bad at all.

That's about this big, although the uncertainty is obviously +/- 50% of this:
Click to view attachment

Ah, Hubble - casting off veils of mankind's ignorance since 1990. Congrats to the discoverers.

Really pleasing news! This no doubt presents a nice challenge for the re-design of LORRI pointing sequences - I imagine it's getting a little tight now around C/A.

All we need now is a background star occultation observed from Mauna Kea or elsewhere to reveal a few rings or ring-arcs.....

The "Kodak Moment" team here should probably have another stab at photo ops once the refined orbit details are available.

What would be the procedure if rings were discovered? NH would have to avoid passing through them at encounter, right? And if they're so faint that NH itself discovers them, time would be very short in making and sending commands to avoid them.

Fantastic news!
New Horizons flyby of Pluto more and more looks like Voyager's flybys of giant planets. So many targets!

Yep, five targets, minimum, plus searches for new moons and searches for rings. We're going to be busy!

I see two possibilities. Perhaps Pluto will continue to be the only object in the solar system with a number of discovered natural satellites between two and 13, a fact which might point to a particularly interesting orbital history that could be related to the presence of Charon. Alternatively, it will be joined in this distinction by some significant fraction of other TNOs as soon as a similar degree of attention is paid to them. Either way, there will be some explaining to do - and I don't know which of "Pluto is unique" and "the Kuiper belt is full of 3,4,5+-body-systems" would be easier to explain.

...and the only object in the solar system with a natural satellite discovered in an image taken on a Tuesday.

No. There's at least one asteroid with three moons - a quadruple system.

http://www.oca.eu/workshop/Pise/slides/Pisa-Colas.pdf

The NH encounter just keeps getting more & more exciting. Never wanted four years to pass so fast before in my life!

What's the general consensus (or is there any?) on whether these objects (Nix, Hydra and P4) are all moons that formed following a large impact on either Charon or Pluto? Or could all 5 objects be ones that formed alone and then Pluto/Pluto-Charon's gravity captured them?

This is answered in the article linked in the first post of this thread:

Cool, thanks.

That's a bit disappointing though from the standpoint of examining as many formationally-unique KBOs as possible.

Pluto's P4 moon is now available at SSD Horizons (body ID: 904)
NH closest approach to P4 will take place 2015-Jul-14 12:03 CT at distance of 67000 km.

So that means P4 will appear just a little smaller than the simulation on page 1; still way better then a point of light!

It would appear just a little smaller if NH were to image it exactly at closest approach. That's not likely to be the case given other observation timings and priorities.

Also, the orbit used to make that calculation may not yet be accurate enough to determine precisely where it'll be four years from now...

LOL, when the accurate orbit becomes available, I bet the savy simulation wranglers here find a stunning Kodak moment or two.

All Pluto's moons are orbiting at strongly resonant orbits. Nix, P4 and Hydra periods are multiples of the Charon-Pluto orbital period (as 1:4:5:6 to be precise) and therefore actual orbital position can not drift too much from predicted one. Actual flyby viewing geometry will be quite close to the mentioned above.

Am I right that the orbit of Pluto's fourth moon is much more elliptical and much more inclined?

More on P4 (and NH too) in this radio interview aired today: http://howonearthradio.org/archives/1092

2015 is going to be a really exciting year with the Dawn mission reaching Ceres and New Horizons exploring the Pluto system.

2015 year of the Dwarf Planet.