CICLOPS: Cassini Imaging Central Laboratory for OPerationS

Sector 6

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At Last ... 'Star Trek' Opens!
TomMadigan      
12-24-2009  20:48:07

correction...that would be "moot".
TomMadigan      
12-24-2009  20:32:21

The special effects and visuals were great, especially the Enterprise/ Saturn sequence. However, growing up watching the original cast and crew, collecting all bound volumes of all the episodes, attending one or two Star Trek conventions, taking in every previous Hollywood major motion picture, I find the "rewriting of history" offensive to the memory and legacy of the original concept, to put it mildly. By destroying Vulcan in the Prequel, all future episodes, stories and plots are now mute. The Vulcan race, a race now removed retroactively, figured large in many episodes and story lines. This is not simply just another episode - it is an anomaly produced in an alternative universe. They crossed the "artistic license" line with this one and I'm not so sure Gene Roddenberry would be as gleeful as some have suggested. Some things are better left alone and to make a movie simply because you can is one thing but to do so and rewrite 50 years of history is quite another. In short, this movie was all show, no substance and (hopefully) will soon be forgotten.

Cassini's Holiday Greetings!
TomMadigan      
12-24-2009  08:28:40

Brilliant, as usual! An appropriate audio track for these superlative clips would be Tschaikowsky's "Dance of the Sugar Plum Fairy"!

Thanks, Carolyn, for another great year of science, discovery and a treasure trove of unforgettable images!

Best to all for the holidays and the coming New Year

Tom

Targeting the Jet Sources
TomMadigan      
08-26-2008  14:21:50

Andrew Brown (3488) and NeKto:
Thank you for the affirmation. You’re absolutely correct concerning the mass of Saturn vs. Jupiter. I was speaking in “Powers of Ten” and had probably taken undue license with the values (Saturn: 5.7 x 10^26 kg and Jupiter: 1.9 x 10^27 kg) as they are not that dissimilar. As far as answering your questions, Carolyn did a fine job ;)

Carolyn; thank you.
Re: Roche Limit; Rather than overcomplicate my answer, I deliberately neglected to mention that the strict formulation of the Roche limit only applies if gravity is the sole force binding the moon together. A newly formed moon or planet that has just coalesced from smaller planetesimals would be a good candidate for breakup if it came too close to a larger body. Aside from internal cohesiveness, another possibility could be a range of densities among the various moons. Since the Roche limit reduces to the cube root of double the ratio of the densities of the greater (more massive) body vs the lesser (less massive) body multiplied by the radius of the greater body, those moons of Neptune that are within the Roche limit of Neptune for one moon may lie outside their own Roche limit for Neptune if they have a higher relative density. An interesting scenario would be one where there is a large relative disparity of densities among the moons. The Roche limit of one may lie outside the Roche limit of another of greater density.
TomMadigan      
08-20-2008  02:28:43

Pipipot and NeKto:


When trying to answer questions such as these, it occurs to me that we should first look for similarities between Saturn and any interactions with its satellites and similar interactions between its larger sibling, Jupiter and its entourage of satellites. It’s well documented that the lion’s share of the energy that fuels Io’s active volcanoes is derived from tidal heating. Because of its proximity to Jupiter and its orbital eccentricity, Io endures continued tidal flexing from Jupiter’s exceedingly strong gravity. Explained differently, the force that Jupiter’s gravity exerts on Io changes significantly from one point to another (a differential change) along a line connecting the two centers of mass. This differential force is the same “tidal force” that gives us the tides here on earth and is responsible for the harmonious gravitational interplay between the earth and the moon. This tidal flexing induces internal frictional heating and is the primary cause for Io’s active volcanism.

When you consider that Enceladus has an orbital eccentricity almost identical to Io’s and, like Io, is in close proximity to its host planet (Io is the closest of the major Jovian satellites; Enceladus is the second only to Mimas), its no accident that we see evidence of internal heating, heating no doubt caused by tidal flexing. It is quite possible that the Cryovolcanism we observe on Enceladus is caused by very similar processes as that which produces Io’s volcanism. Although the tidal force endured by Enceladus is more than ten thousand times less than that endured by Io, it should be noted that Saturn has only 10% the mass of Jupiter with a density less than that of water. Another factor that figures in significantly here is that Enceladus is at an orbital distance from Saturn that is only 4 times the Roche distance (for Enceladus and Saturn). Any two bodies where the lesser of the two goes inside the Roche limit, that body will be disrupted as the tidal force exceeds the self-gravitation of the body, resulting in its destruction or material disassociation. The closer to the Roche distance, the greater any tidal effects will be.
TomMadigan      
08-20-2008  00:43:20

Gruapma:
Historically (c 800-1050), Baghdad was the intellectual capital of the world while the supposedly enlightened clerics and thinkers of western Europe, up through the mid-17th century, were disemboweling heretics, burning them at the stake or placing them under house arrest for publishing such heresies as heliocentrism and the wild notion that the earth orbits the sun and that we’re not the center of the cosmos (if you think what they did to Galileo was bad, look up Giordano Bruno when you have a spare moment). Among the disciplines the ancient Persians (the people of Iraq and Iran) studied, Astronomy and Mathematics (Algebra was first developed by them as was the numbering system we use today) were first and foremost with Baghdad being the center of learning and study. Its no accident that 2/3 of all stars with proper names have Arabic roots. Because the scientists, thinkers and philosophers of this culture did most of the work they got to name the stars and influence the study of that discipline going forward. Baghdad remained the center of science and learning up through the late 11th century until an influential Muslim cleric, Al-Ghazali, determined that mathematics was the work of the devil (sound familiar?) and, unfortunately, Baghdad and the enlightened culture that it represented never recovered.

Historically (at least from a Western perspective), the languages of science were Latin and Greek. You’ll note the names on all the published maps of the terrestrial planets are in Latin (ex. Olympus Mons – Latin for the mythological Greek mountain that was home to Zeus, Mount Olympus). These ancient languages, along with the Arabic tongues, have been the languages of science. This brings me to your question; as an American, I don’t take it as an insult that Arabic names are used but more as a continuation of the scientific tradition of old.

As an aside, a little known casualty of the ongoing conflict in the Middle East was the near destruction of the Iraqi National Observatory on Mount Korek, first by the Iranians and then by the USAF during GW-II – look it up.

Enceladus Rev 80 Flyby
TomMadigan      
08-07-2008  15:23:22

>>lsteward
08-07-2008 11:13:19

How does the Cassini avoid being sucked into the gravity of Enceladus when it is so close to it?<<


Cassini's orbital velocity exceeds the escape velocity of Enceladus. The escape velocity of any body depends on its mass. For example, the Earth's escape velocity is 11.2 Km/Sec which means to say that any spacecraft that can be accelerated to this velocity or greater will escape Earth's gravitiation pull. In order for the vaunted Cassini spacecraft to begin its epic journey of exploration and discovery, it would have necessarily have to escape the gravitational pull of the earth. By equating the kinetic energy (the "energy of motion") to the gravitational potential energy of the planet or body under consideration, we can compute the escape velocity. Another example worthy of mention would be the launch of the Space Shuttle. Following the launch of the Space Shuttle, specific attention has to be given to the throttle settings of the vehicle's boosters and main engine. If allowed to accelerate for too long, the orbiter *would* escape the earth's gravitational pull. The shuttle is "falling" around the earth just under the escape velocity of the earth (11.2 Km/sec) at 7.7 Km/sec.