Cassini/Huygens Mission Update Thread

[backspace]

Thanks, Alex! I knew you'd have it!<br /><br />Now, the 64-thousand dollar question.... if this is the Sequence 0-1 outline... are the others avaliable to us?

 

[alexblackwell]

<i>Now, the 64-thousand dollar question.... if this is the Sequence 0-1 outline... are the others avaliable to us?</i><br /><br />I'm not sure what you're asking for, though the types of information I <i>think</i> you are referring to are for internal use only. In fact, some of the information is ITAR-protected and cannot be released, for legal reasons. Also, some of the information isn't even ready yet. Mission and science planning for the tour is an ongoing process, and most of the sequences are still being finalized.<br /><br />At any rate, if you are referring to documents similar to the SOI document, apparently the Cassini Project plans to provide ones to the public shortly before all of the <i>targeted</i> encounters in the tour (<i>e.g</i>., Ta, Tb, Tc, T3, E1, T4, etc.). Non-targeted flybys, such as Iapetus tonight, are too numerous, so I don't expect the Project to provide the public with documents covering each and every one.<br /><br />Having said that, however, one will note the Project <i>is</i> releasing some mission and science planning products to the public (<i>e.g</i>., flyby animations, timelines, etc.), which is more than I've seen with prior space missions.

 

[backspace]

Thanks Alex! That's the best answer I could have hoped for.<br /><br />The ITAR bit puzzles me.. I wonder whose equipment they're sharing...<br /><br />Anyway, glad to hear that about the targeted flybys. That'll make following it all the more fun.

 

[alexblackwell]

<i>Anyway, glad to hear that about the targeted flybys. That'll make following it all the more fun</i>.<br /><br />Well, I should have issued a caveat. I <i>think</i> the Cassini Project will do this based on the recent pattern but I'm certainly not promising it. It's entirely conceivable that once the initial public interest in the mission has died down, the Project may scale back on the types of detailed, technical information they're currently making available to the public. For instance, there may not be enough differences between, say, Titan-11 and Titan-12 to justify separate mission description documents for each. Then again, there may well be. We'll just have to wait and see.<br /><br />Internally, though, the Project provides a great deal of technical information for the scientists and engineers for <i>each</i> flyby, both targeted and non-targeted. In fact, the best and most detailed information can be found in the presentations made by the various instrument teams at meetings (usually telecons) of both the Titan Orbiter Science Team (TOST) and the Satellites Orbiter Science Team (SOST). Unfortunately for the public, these presentations are for internal use only, though they do form the basis for the mission description summaries that have been released to date.

 

[Leovinus]

<i>This image of Iapetus was taken on Dec. 31, 2004 at a range of about 71,978 kilometers (44,725 miles) from the icy moon. It is one of several recently uploaded into the Cassini Raw Image Gallery.</i> <div class="Discussion_UserSignature"> </div>

 

[thinice]

So Cassini Regio is this huge ancient impact crater filled with some dark material (probably a mixture of brighter ice from the outer crust and debris of the impact body)?

 

[backspace]

I find the marked difference in topology coupled with changes in the surface composition (basing this on color) very interesting... as though there was a significant geological event following the heaviest period of cratering...<br /><br /><br />

 

[larper]

It looks like it melted a little, smoothing the terrain. What could melt just one side, though, and just the "leading" hemisphere? <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

 

[Leovinus]

Maybe that leading hemisphere swept up a now-absent ring. <div class="Discussion_UserSignature"> </div>

 

[larper]

Could a ring have formed that far out? <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

 

[Leovinus]

I don't know. It just reminds me of would happen if you threw a ball through a mist of paint -- the leading side would be painted the new color. <div class="Discussion_UserSignature"> </div>

 

[bobvanx]

On another thread, the "faces of Iapetus" one, I've posted a pic of the equatorial ridge that also suggests a ring got swept up.

 

[Leovinus]

I saw that pic. It's hadn't occurred to me when I saw it that the ridge could have been formed from sweeping up a ring. <div class="Discussion_UserSignature"> </div>

 

[bobvanx]

Leo,<br /><br />I worked out that if Iapetus does show us where a ring was, that from Earth this ring would have been at least 2/3 the apparent diameter of our moon.<br /><br />Since (to my knowledge) there are no ancient astronomical descriptions of such a thing, we can be sure there hasn't been a ring there for at least recorded history.

 

[Leovinus]

<i>This Cassini image captured Saturn's moon Pan (25 kilometers, or 16 miles, across) just after the little moon emerged from Saturn's shadow. Pan orbits within the narrow Encke Gap (300 kilometers, or 186 miles, wide).<br /><br />A faint hint of the narrow ringlet within the Encke Gap in earlier Cassini images (see PIA06534) is visible here.<br /><br />Saturn¿s rings appear extremely overexposed due to the enhancement used to make Pan visible, but the processing technique also makes other faint features stand out. In addition to the bright, knotted core of the F ring, two faint nearby ringlets can be seen. At right, this view of the Cassini Division shows that there is actually a great amount of material embedded within it.<br /><br />The image was taken in visible light with the Cassini spacecraft narrow angle camera on Dec. 1, 2004, at a distance of approximately 4.1 million kilometers (2.5 million miles) from Saturn. The image scale is 25 kilometers (15 miles) per pixel. </i><br /><br />I have yet to see a single image of spokes in any Cassini image. <div class="Discussion_UserSignature"> </div>

 

[Leovinus]

2/3? Are you sure? That seems a bit big for so far away. <div class="Discussion_UserSignature"> </div>

 

[douglas_clark]

I'm starting to get excited about the Huygens probe. Any news?<br /><br />Douglas

 

[bobvanx]

Yep. Here, I can give you a visual, using the 1 degree field of view option (from the Solar System Simulator).<br /><br />If Iapetus did in fact orbit within a ring, it probably made a gap like the Encke gap. So the ring system could have been staggeringly wide.

 

[bobvanx]

>>spokes<br /><br />I recall the spokes were later (quietly) explained as an imaging artifact.

 

[thalion]

I'm pretty sure the spokes weren't imaging artifacts, for two reasons:<br /><br />1.) Time-lapse Voyager movies show the spokes clearly orbiting along with the rings.<br /><br />2.) There have been a few Earth-based observations of the spokes, before the Voyagers visited Saturn.<br /><br />I'm inclined to think that the spokes are a function of viewing geometry--maybe the low angles characteristic of the Voyager encounters made viewing them more favorable. Or, perhaps they're simply time-dependent phenomena.

 

[backspace]

Correct me if I'm wrong, but GRAVITATIONALLY, spokes are both plausible and make sense, if you think about the fields involved... Consider the chaos of the ring system however and it is understandable that "spokes" may be periodic events...

 

[Leovinus]

Might it have something to do with the Sun's 11-year cycle? Maybe Cassini and V2 are visiting at different points in the cycle. We all know how solar wind affects planetary magnetic fields. <div class="Discussion_UserSignature"> </div>

 

[claywoman]

Okay...I know I'm old, and not very good at this and I'm going to show my ignorance but I've just got to say this...what spokes? am I missing something in that picture? I know drum me out of SDC....

 

[mah_fl]

There are no spokes in the above picture, but there are some in the Voyager images.<br />http://www.nasm.si.edu/research/ceps/etp/saturn/satringspok.html<br /> <br />http://www.solarviews.com/raw/sat/spoke.mov

 

[retro555]

I noticed from reading the Huygens Probe mission description report that 3 parachutes are deployed during the descent phase. This seems overly complex and risky. I am wondering why and when it jettisons the main 8.3m chute and deploys the 3m drogue. How much data could be lost if the last chute does not deploy?