|
|
 |
Imaging Diary - Cassini
Newsroom - Press Releases
Newsroom - Special Events
Home - Captain's Logs
Newsroom - Looking Ahead
Alliance Member Comments
Coming to Light |
Mercury_3488 2008-02-27 17:24:34 | View all member's comments | Hi DEChengst,
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
Thanks Carolyn,
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.
Andrew Brown. | |
Epimetheus Revealed |
Mercury_3488 2008-02-03 11:59:29 | View all member's comments | 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. | |
Epimetheus Revealed |
Red_dragon 2008-01-25 15:50:34 | View all member's comments | Yes, it may be so; I think now I can see the crater. It's a luck for Epimetheus to be a porous, low-density body: if it was solid, surely it would have been destroyed. | |
Saturn's Rings 3D |
Andrzej Karon 2007-07-21 09:56:08 | View all member's comments | What do you think about my 3-D anaglyphics rotating maps of a eleven Saturn's moons?
http://ksiezyce.republika.pl/mapy/3-d/prometheus-mapa_3-d.html
http://ksiezyce.republika.pl/mapy/3-d/epimetheus-mapa_3-d.html
http://ksiezyce.republika.pl/mapy/3-d/janus-mapa_3-d.html
http://ksiezyce.republika.pl/mapy/3-d/mimas-mapa_3-d.html
http://ksiezyce.republika.pl/mapy/3-d/enceladus-mapa_3-d.html
http://ksiezyce.republika.pl/mapy/3-d/tethys-mapa_3-d.html
http://ksiezyce.republika.pl/mapy/3-d/dione-mapa_3-d.html
http://ksiezyce.republika.pl/mapy/3-d/rhea-mapa_3-d.html
http://ksiezyce.republika.pl/mapy/3-d/titan-mapa_3-d.html
http://ksiezyce.republika.pl/mapy/3-d/hyperion-mapa_3-d.html
http://ksiezyce.republika.pl/mapy/3-d/iapetus-mapa_3-d.html
Yours Sincerely
Andrzej Karon
http://ksiezyce.republika.pl/index_en.html | |
Sixty for Saturn |
Andrzej Karon 2007-07-21 09:41:18 | View all member's comments | 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!)
Yours Sincerely
Andrzej Karon
http://ksiezyce.republika.pl/index_en.html | |
|
