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."

Comments

Re:This is simple

[Anonymous Coward]

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

Re:This is simple

[GigsVT]

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".

When I'm not kicking ass, I'm studying saturn

[H4x0r Jim Duggan]

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.

Re:Spokes?

[Queuetue]

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.)

Magnetic field not coherent?

[Saltation]

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

Re:Magnetic field not coherent?

[Waffle Iron]

So if the spokes aren't visible now, maybe Saturn's magnetic field is fluctuating/less coherent than normal.

The Saturnians have taken notice that this vessel is on a trajectory to permanently enter their planetary system, with the apparent further intention of penetrating one of their moons. They have therefore diverted the entire force of the giant planet's magnetic field into charging the energy banks of their weapons systems. If the spacecraft does not alter its course soon, they will no recourse but to unleash a devestating counterattack on the inner planet that initiated hostilities.

They're not taking the pictures the same way...

[bc90021]

From the second link:

In order to bring out the very faint detail in the B-ring, the image was specially processed for the spokes and thus does not show the true relative brightness of the other rings.

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.

Re:Spokes?

[eddie can read]

Google it.

Here

Here

Here (scroll down to find a movie)

Re:visual astronomers...

[Tablizer]

Here is a link to Voyager spoke images

Single Image

Gallary

Re:Spokes?

[Anonymous Coward]

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 remember when...

[rotenberry]

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.