... encounter with Saturn's icy moon Helene, beaming down raw images of the ... 4,330 miles (6,968 kilometers) of Helene's surface. It was the second closest approach to Helene of the entire mission.Cassini ...
Myself I would rather use any excess fuel for a close pass of fascinating Dione or Mimas or one of the lesser known inner moons like Prometheus, Pandora, or a co orbital like Helene, Ploydeuces, Telesto or Calypso. We have had loads of Titan & Enceladus, so a close pass of one of the lesser known ones would be nice. Shame we cannot do Iapetus or Phoebe again, as far too far out.
Hyperion's ultra low density amazes me. 0.55 g cm3, the least dense solid object known in the solar system.
The deep craters certainly looked like punched in material, although IIRC many are thought to have burned into the ice with dark floors absorbing the little solar radiation this far from the Sun.
I am aware that there are no further very close passes planned for Hyperion, but are any decent further passes possible, lets say less than 100,000 KM? Or for that matter, any of the other minor moons other than the close Helene pass planned? A closeish pass of Mimas would also be quite interesting, particularly with density measurements & to see whether or not the surface is peppered with smaller & smaller craters, or they cut off below a certain size, as with Jupiter's Callisto?
Saw this once before as a shadowy noisey raw image. It's great to see that some of the smaller moons are also being researched like Hyperion, Janus, Epimetheus, Helene, Telesto, Phoebe, etc.
Wonder if Janus is like Epimetheus, an icy rubble pile held together by gravity?
Does anyone know when the Helene encounter will be? Is there any chance of a close passes of Calypso, Telesto (again) Polydeuces, etc?
I've sometimes wondered about this also.
Hyperion is the least dense of the known solid bodies in the entire solar system, only 0.55g cm3. This suggests a rubble pile held together by gravity & / or a more coherent body with huge internal voids.
My bet is the rubble pile. Like polystyrene, it is possible to punch deep but narrow holes in it. We see similar here on Hyperion.
I had seen one suggestion bantered about elsewhere (not my idea), that Titan formed in a heliocentric orbit at one of Saturn's lagrange points & over time, Titan was drawn towards Saturn. Hyperion was suggested to be Titan's former moon.
The mass ratio between Hyperion & Titan is identical to that of Dione with Polydeuces & Helene as well as Tethys with Telesto & Calypso. These facts were part of a thought exercise elsewhere.
Hyperion being a former comet is an interesting idea. Remember that Phoebe is almost certainly a captured comet / KBO.
Also remember the floors of these deep craters are dark, so they absorb the very little solar energy there is & can burn through the ice.
I am sure there are a whole multitude of reasons for Hyperion's weird situation. A most fascinating object.
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.