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Now on to Saturn


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After the unbelievable success of the Mars Exploration Rover missions, you might be asking yourself, 'how can that be topped?' - well, look no further than the Cassini-Huygens mission to Saturn, and Saturn's largest moon, Titan.


Right now the Cassini orbiter, and the Huygens probe it carries, is only about 2 months from entering into orbit around Saturn...here's the latest picture taken with it's narrow-angle (aka telephoto) camera:




The images returned should only get more impressive as it gets closer. On July 1st, Cassini will go into orbit around Saturn, amazingly it will pass through a gap in the rings as it approaches Saturn. I can only imagine what kinds of images it will return during this part of the mission. After it makes this first, and closest pass, of Saturn, Cassini will settle into orbit and prepare for what may be the coolest part of the mission, the launch of the Huygens probe which will try to land on Titan!


While Cassini is a NASA-built orbiter, Huygens was built by the ESA (European Space Agency) ? I tried to link to the ESAs Huygens site, but it seems to be down. It will separate from Cassini on Dec 25th and coast toward Titan, the only moon in our solar system that has an atmosphere, for a rendezvous on January 14th, 2005. Unlike the Mars rover missions, the majority, if not all, of the Huygens probe mission will take place during it's 2.5 hour descent into the atmosphere of Titan. Although there is a chance that the craft will land and continue to send back data, the battery-life of the probe will limit any such surface mission to about 30 minutes. There is a surface-science instrument (one of 6 instruments total) on board in case it lands intact.


Cassini's mission will last 4 years. It's orbit will repeatedly bring it close to the planet and then back out past the orbits of various moons, so over the years it should return some amazing images and data from a number of Saturn's 31 moons.


In some ways this mission is more exciting than the Mars rovers missions, it will be the farthest planet to which we have sent an orbiting craft (AFAIK) by a longshot. Galileo orbited Jupiter, but Saturn is nearly twice as far from the sun than Jupiter is (850 million miles and 450 million respectively). Compare that to 128 million for Mars. The rings of Saturn alone should be amazing to get an up-close look at.


In any event, it's going to be a really great year for space science. July 1st, mark your calendar ;)

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Originally posted by iCamp

How long has the trip to Saturn taken?? That stuff just blows my mind. Thanks for the link Mike, and thanks for posting the topic Ed.



Quite a while. The mission was launched in Oct 1997! That's before the current Mars Rover mission was even conceived of.


They did some very fancy maneuvers to get it to Saturn, including 4 'gravity assists' - where they use the gravity of another planet to slingshot the craft toward Saturn. First Earth was used, Venus was used twice, then Jupiter. I believe they did this in part because Cassini is huge, it's the 3rd largest craft ever launched into space. But the maneuvers take time, which is why it'll be almost 7 years from launch to the time it gets there.

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  • 2 weeks later...

A new image was posted today:


Click on the image to see the full-res version, or click here to see the full description and a link to the full-res.


Dark regions are generally areas free of high clouds, and bright areas are places with high, thick clouds which shield the view of the darker areas below. A dark spot is visible at the south pole, which is remarkable to scientists because it is so small and centered. The spot could be affected by Saturn's magnetic field, which is nearly aligned with the planet's rotation axis, unlike the magnetic fields of Jupiter and Earth. From south to north, other notable features are the two white spots just above the dark spot toward the right, and the large dark oblong-shaped feature that extends across the middle. The darker band beneath the oblong-shaped feature has begun to show a lacy pattern of lighter-colored, high altitude clouds, indicative of turbulent atmospheric conditions.


This is going to be FUN!


EDIT: Note this from the description:


Contrast has been enhanced to aid visibility of features in the atmosphere.


Which is why the image looks funny around areas of high-contrast.

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Another nice image:



click on the image to see the big version

The high clouds of Saturn's bright equatorial band appear to stretch like cotton candy in this image taken by the Cassini narrow angle camera on May 11, 2004. The icy moon Enceladus (499 kilometers, or 310 miles across) is faintly visible below and to the right of the South Pole.


More information on it here, plus other stuff about Cassini's first encounter on June 11th with the moon Phoebe.


EDIT: I guess it's the same image I posted a few weeks ago, only without the sharpening applied to it...I think it looks nicer without the post-processing.

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I read the article about Phoebe the other day. I always thought that Titan would have been the focal point of any voyage to Saturn, but it seems like Pheobe has a great deal to offer as well. Plus, being able to get as close to it as they are going to should be terrific. Astronomy geeks must be in heaven this year.



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Those photos are amazing. The thing I don't understand is Saturn's rings. Are those photos time-lapse images? Otherwise, how do the rings look so perfect? Are the bits that make them up so small and so numerous that they just look smooth like that all the time?


Forgive me for asking, I'm an arts/humanities person.

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Originally posted by ChoiceStriker@Jun 9 2004, 07:23 PM

Are the bits that make them up so small and so numerous that they just look smooth like that all the time?

I think that about sums it up. Although I'm sure this mission itself will give us more insight into their actual structure :)

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One thing to note is that the smallest thing the above image (if you look at the full-size version) resolves are 97 miles across (it says that in the caption). The rings themselves are probably less than a mile thick, so nothing in the rings is anywhere near 97 miles across.


They will look quite smooth until you get very close to them.


What I find amazing is the bands that clearly do show up from far away (and may contribute to your question). If you can't see any individual chunks in the rings, how do you see such clear banding? And what about the empty spot (the "Cassini Division")? What the heck creates that space?


My feeling is that it's a very complex sifting out of different-sized objects by gravity, like-sized objects group together because they are balanced by the gravity of objects toward the inside and outside of the rings. It probably took hundreds of millions of years, or more, to settle into the state they are in now.

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Images of the Phoebe flyby are coming in, I think you could put this into the dictionary next to desolate:


you can click on each of these for a hi-res version







The last one was taken near the closest part of he flyby, only 1,200 miles away! The crater is 8 miles in diameter.

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Well, tomorrow is the big day! Cassini will pass through a gap in the rings and use Saturn's gravity as a brake (along with a 90 minute burn of its engines) to slow itself down enough so it falls into orbit. This will be the closest pass to the planet of the entire mission.


For science geeks (like me), NASA TV will cover JPL mission control starting tomorrow at 6:30PM pacific:




They say if all goes well, the first images from this maneuver, and probably the closest images ever taken of the rings, will be returned around 11PM pacific.

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Originally posted by Derrik Draven@Jun 30 2004, 03:09 AM

I hope that probe doesn't run into a monolith floating out there around Io. ;)

I'll be a smart ass and say that if it does, NASA might as well give up trying to look at Saturn, since Io's a moon of Jupiter ;)


..but I'll also be a purist and say if they find a monolith around Iapetus (one of Saturn's moons) then they'll be in line with what Clarke wrote in the book version of 2001. :)

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