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Saturn Rings But No Spokes
An anonymous reader writes "Scientists continue to ponder why images of Saturn's rings today lack the 'spokes' or dark radial bands radiating outward and first observed on the Voyager flyby. The Boulder-based Cassini Image Team describes 5 visible moons, plans for the descent probe going into the Titan moon's hydrocarbon-rich atmosphere and the expected orbital entry around Saturn less than 4 months from now."
If only NASA would bring the success of this mission into the public spotlight as a way to raise awareness as to its more successful programs.
That's absolutely true. After what happened with the Columbia, NASA really needs to boost public support for their programs. People see the 2 shuttle disasters that have occured as being the bulk of what they accomplished, and that is just wrong.
And of course, I'm not saying what happened isn't tragic. But people dont understand that many astronauts understand that disaster is a possibility, and they're willing to take that chance in the pursuit of the Greater Understanding.
NASA really has to get the PR machine in motion
Are you sure it would send the right message?
It sort of seems to me like saying "unmanned exploration is really successful, but look at how many people we killed with stupid manned exploration, that could have easily been done unmanned".
I've had enough abrasive sigs. Kittens are cute and fuzzy.
There were no real current Astonomy Picture of the Day references so I linked to a search on Saturn. This gives quite a few different views of Saturn and some other related material as well.
Use your head, can't you, use your head,
You're on earth, there's no cure for that - S. Beckett
By the way, next summer NASA's Cassini spacecraft, launched in 1997, is scheduled to go into orbit around Saturn and its moons for about four years.
The piggybacking Huygens probe is scheduled to go into the hazy Titan atmosphere and land on the moon's surface (if all goes well). The Huygens probe is geared primarily towards sampling atmosphere. The probe is equipped to take measurements and record images for up to 30 minutes on the surface. But the probe has no legs, so when it sets down on Titan's surface its orientation will be random. And its landing may not be by a site bearing organics.
Please help publicise swpat.org - the software patents wiki
Obviously the Fithp has already left Saturn and is headed to Earth.
Time to start studying those old Orion plans...
I think they mean the itty-bitty breaks in the rings that you can see if you look very close. (There's one just about in the very center of the image.)
The "spokes" are odd disruptions in the rings caused by Saturn's magnetic field rotating through them. They show up as dark patches radiating directly away from Saturn or occasionally arching, and they travel like a wave around Saturn in time with its rotation. It was this timing/speed that tipped astronomers off as to what was causing them, incidentally.
So if the spokes aren't visible now, maybe Saturn's magnetic field is fluctuating/less coherent than normal. It's a gas giant so its field could be less stable than the denser planets. There may be some low-level eg mid-atmosphere storm disrupting the normal field-generating circulations.
Just a thought. IANAA
cheers, Sal
--
Sal
Writings: saltation.blogspot.com
Wravings: go-blog-go.blogspot.com
Perhaps the spokes don't show up because they're not applying those same techniques? I certainly don't see any mention of those techniques in the article in the first link.
libertarianswag.com
This is an offtopic comment: offtopic because it was stolen verbatim from a totally unrelated story:
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.sig modded up
http://science.slashdot.org/comments.pl?sid=793
It's just an excuse to get the
Okay, I was wondering... although it looks like it could easily be something on the lens. Heck, it almost looks like what we call a 'density dot' at work. (Explanation: I work at a copy shop, and when doing colour copies, sometimes the toner will not be applied evenly, leaving small blank or lighter shaded dots in the middle of coloured areas.)
But it couldn't be a density dot because the imaging would have been sent back from the probe using radio signals, right? It's not like a radio signal gets a bad spot on a belt.... and interference would have produced a much more distorted image....
Hrm...
Kierthos
Mr. Hu is not a ninja.
Google it.
Here
Here
Here (scroll down to find a movie)
Perhaps it is just a bad picture, Nasa has a much clearer one. I don't see anything like that on the picture linked in the article, but maybe I'm just missing it.
Here is a link to Voyager spoke images
Single Image
Gallary
Table-ized A.I.
But the spokes were first observed with the CCDs on Voyager. Also, no astronomer actually looks through an eyepiece any more, its all CCDs or other detectors. All of the ground-based spoke observations (could you provide a source for such images?) are thus not going to be subject to the Percival Lowell wishful thinking effect.
It's more likely to be due, as other posters have suggested, to be due to variations in Saturn's magnetic field. It would seem that Cassini is already producing interesting science before it goes into Saturnian orbit.
In all the APOD picture of Saturn I found a reference to Spokes and a picture that contains them.
Use your head, can't you, use your head,
You're on earth, there's no cure for that - S. Beckett
Agreed.
I think that a well-trained geologist/astronaut could pull far more information from a short walk on mars than those rovers could their whole time on the surface. Besides being infinitely more maneuverable than any robot, living astronauts can devise new experiments and fix things when they go wrong. Anything a robot can do, an astronaut in a space suit can do BETTER by several orders of magnitude.
Now, when things go wrong, it is much less tragic to lose a robot than it is to lose a space crew. However, any crew embarking on such an expedition will be fully cognizant of the risks, and I am sure that even if the trip was a guaranteed one-way ticket to mars that qualified volunteers could still be found.
To all,
I am the leader of the Cassini Imaging Team, and came upon the discussion all of you are having about spokes. The image that you have linked to does not clearly show spokes -- so it's not a good example -- and the caption at JPL is wrong: it was *not* the first time spokes were seen by Voyager. Voyager 1 first saw spokes on approach to Saturn, when the resolution was comparable to what Cassini is seeing now.
We're not sure if spokes are a seasonal phenomenon, or their visibility is very sensitive to viewing geometry. We will find out though, since Cassini will remain in orbit and make observations for 4+ years.
So stay tuned.
- Carolyn Porco
Cassini Imaging Team
I was a young engineer at JPL when Voyager 2 encountered Saturn, and I remember when the first photos of the spokes in the rings were displayed in real time on the monitors in the cafeteria. The work on other projects had pretty much ground to a halt while everyone watched the data come in.
Of course, the real time data had no captions, no explanations of what we were seeing, so we had all sorts of guesses - density waves, camera artifact, etc. Once it was apparent that the waves were holding together as the rings rotated and were not being sheared apart, it was clear they were not due to any gravitational effect. Since they moved with the rotation of the planet, the accepted explanation is the magnetic field of Saturn causing the charged dust in the rings to concentrate into visible spokes. As I understand it, the spokes are not a wave phenomenon at all.
I for one welcome our new Cassini Imaging Team overlords...
About 30 seconds after posting the above I found this link, to an abstract of a scientific paper detailing Hubble observations of the spokes.
We're not sure if spokes are a seasonal phenomenon
Just to clarify what he means here:
When the Voyagers were imaging the spokes in about 1980, the Saturnian ring system was nearly edge-on to the Sun. Now that Cassini is approaching Saturn, the ring system is wide open. It is natural to suppose that the edge-on rings made the spokes visible with long shadows, and the face-on rings make the spokes less visible.
The only thing necessary for the triumph of evil is for good men to do nothing. - Edmund Burke