I agree with you about the nonsense regarding the Plutonium issue regarding Galileo & Jupiter. I was aware of certain elements against that plan for the fear of Jupiter becoming a second Sun due to Galileo's RTG.
It was total nonsense back then as it is nonsense that Cassini will do that with Saturn.
Gort asked a good question as he / she was not probably not aware of the non issue involved, perhaps heard scare stories from somewhere.
I responded saying that Cassini cannot initiate thermonuclear synthesis within Saturn. Cassini will not last more than seconds after atmospheric entry, will be incinerated as a shooting star in Saturn's highest atmosphere.
I was aware that Pu238 is the wrong isotope for nuclear fission. It is the heat from its natural decay that is powering Cassini. It is not even a nuclear reaction at all & that the RTGs are NOT nuclear reactors.
Remember the nonsense about the campaign to abandon the Earth encounter post launch, due to unjustified panicking over Cassini re entering Earth's atmosphere
I was not aware that even the first mission extension was not yet approved. I am sure & hope that it will be granted. The second one should also.
I agree with you 100%, that the Kronian Solstices would be of very scientific value, if Cassini is still operational & controllable then.
Like the recent Janus & Titan images. Although still iregular in shape, Janus appears more 'regular' than co-orbital / orbital swap mate Epimetheus. Wonder if Janus's larger size & mass are responsible.
Primary mission still up & Cassini still performs as well as when had just arrived. I am sure mission extension will happen.
Most of these smaller moons appear to be 'rubble piles' of ice & maybe rock. Epimetheus, Janus, Hyperion, Telesto, Calypso, Polydeuces, Helene, etc.
Phoebe appears to be more coherent, but then Phoebe most likely formed elsewhere, maybe the Kuiper Belt, got ejected & then captured by Saturn later on.
The other smaller Saturn moons & Jupiter's Amalthea, appear to be rubble piles held together by gravity.
What do you think about my 3-D anaglyphics rotating maps of a eleven Saturn's moons?
Some other interesting facts about S/2007 S4...
I can't found at the Web any information about visual brightness of S/2007 S4, but from estimation of diameter, albedo and brightness of neigbouring moons: Methone & Pallene - I thinking so S/2004 S4 has only a. +26.0 mag of visual brightness (= 100 million times fainter than the faintest stars visible to naked eye).
For comparison: Saturn's brightness (at opposition) is about 0.7 mag, so S/2007 S4 is shining fainter by about 25.3 mag. The corresponding difference in brightness is over 13 billion times!
This moon is in elliptical prograde orbit (eccentricity e = 0.0010) with a semimajor axis a = 197,700 km. At pericenter (closest to the planet) S/2007 S4 is separated from the Saturn a distance of q = 197,502 km. At apocenter (furthest from the planet) this moon is separated from the Saturn a distance of Q = 197,898 km.
Angular diameter of the Saturn's disc as observed from this moon is over 35 degrees! (or 70 The Moon's discs). Maximum brightness of the planet as observed from S/2007 S4 is -18.4 mag!
Whereas, this moon as observed near the planet (Saturn hasn't solid surface), has only 3 arcsec od diameter and +7.0 mag of brightness. Future astronauts from this place, can't see this moon! :)
And last interesting fact. These three little moons: Methone, S/2007 S4 and Pallene they have similar rotation periods - quite over 1 earthy day. Therefore the closest approach of S/2007 S4 and Pallene is possible every 10,3 days (i.e. synodic period of these moons), but the closest approach of Methone and S/2007 S4 is more rarely: only every 41,1 days!
BTW: The absolute record holders of the lenght of synodic period are Epimetheus and Janus (over 1400 days or almost 4 years!)