[X] My Assistant

[alan]

Cassini will leave the ring plane on this orbit. It will be nice to see the rings again.
The view from Solar System Simulator on July 24
http://space.jpl.nasa.gov/cgi-bin/wspace?t...=1&showsc=1

[Guest_AlexBlackwell_*]

The T16 Mission Description document is now online (1.2 Mb PDF).

[Guest_AlexBlackwell_*]

The T16 flyby page is now online.

[NMRguy]

This T16 flyby is scheduled to have an altitude of only 950km, which is markedly lower than previous ones. In the past, the Cassini team has been reluctant to perform such a low pass due to fears of friction and drag from Titan’s enormous atmosphere. I haven't been following the "Significant Event Reports" page on the Cassini website lately--are they no longer concerned with these possible effects?

[Guest_AlexBlackwell_*]

This T16 flyby is scheduled to have an altitude of only 950km, which is markedly lower than previous ones. In the past, the Cassini team has been reluctant to perform such a low pass due to fears of friction and drag from Titan’s enormous atmosphere. I haven't been following the "Significant Event Reports" page on the Cassini website lately--are they no longer concerned with these possible effects?

There will always be a little apprehension at the lower altitudes but, among other things, T16 is a near-polar pass, which mitigates the risk somewhat. There was some discussion of this in another thread ("Cassini Tour Tweaks - Titan >950 Km").

[Guest_Sunspot_*]

Pictures are up......

[volcanopele]

ummmm...not good...

http://saturn.jpl.nasa.gov/multimedia/imag...eiImageID=79647



We are also a bit into unchartered territory here. This is our first Titan flyby with the illuminated view visible after the flyby. This was just the first of the two Titan-dedicated downlinks so hopefully the rest of our outbound mosaic will be returned, but as I noted above, the over-exposure of the mt1 frames is a tad worrisome...

Also, since we are seeing our outbound frames, this does bode well for RADAR, so hopefully they got their data.

[djellison]

Almost certainly just crap processing of the JPG's before going on line. Jason will be able to give us more details ( maybe ) but they're likely to be able to pull something out of that lot.

Doug

[The Messenger]

ummmm...not good...

http://saturn.jpl.nasa.gov/multimedia/imag...eiImageID=79647



We are also a bit into unchartered territory here. This is our first Titan flyby with the illuminated view visible after the flyby. This was just the first of the two Titan-dedicated downlinks so hopefully the rest of our outbound mosaic will be returned, but as I noted above, the over-exposure of the mt1 frames is a tad worrisome...

Also, since we are seeing our outbound frames, this does bode well for RADAR, so hopefully they got their data.

Yes, there should be good radar, and it may explain some of this imaging. The closest image I could find was ~26,000 km, and the first release jumps from ~30km to over 100,00km. There were some scheduled gaps, and the Cassini Event log said that the data was being transmitted on a priority bases.

[ugordan]

Almost certainly just crap processing of the JPG's before going on line.

I'm not so sure about that... There are images that have a rather large dynamic range clipped off, some are plain overexposed like come CB3 filtered frames and some are just wasted like this one. Notice it's not white so it's not due to the raw histogram stretching.

You think that after 16 flybys they'd nail Titan's brightness through various filters vs. phase angles.

[um3k]

Almost certainly just crap processing of the JPG's before going on line. Jason will be able to give us more details ( maybe ) but they're likely to be able to pull something out of that lot.

Doug

Tired, Doug? You seem to be replying to Jason.

[Phil Stooke]

Well, a bit of a mosaic (so far?)

Phil

[volcanopele]

Well, as you can see from the images Phil put together, we got some of the images right, in fact we got most just fine. But some of the images are over-exposed (meaning it isn't just a problem with the histogram stretching). Regardless, since some of the images look okay, perhaps I can do something with them.

[edstrick]

"ummmm...not good..."

Um... I think those pictures (which are only selected pics in the sequences) are intentionally overexposed so as to get good signal-to-noise in the near-terminator regions.

[ugordan]

I think those pictures (which are only selected pics in the sequences) are intentionally overexposed so as to get good signal-to-noise in the near-terminator regions.

That sounds plausible. Though, looking at the raws themselves - it only turned out useful at the upper half of the images, not that much territory. Contrast is bound to be very low anyway due to the low sun elevation there.

I'm looking forward to RADAR guys releasing bits of the newest swath. Hopefully some interesting stuff will 'crop up'

[volcanopele]

That would be my guess too... but these were meant to be very long exposures. I just wish the MT1 frames were not exposed that long...

[Guest_AlexBlackwell_*]

There will always be a little apprehension at the lower altitudes but, among other things, T16 is a near-polar pass, which mitigates the risk somewhat. There was some discussion of this in another thread ("Cassini Tour Tweaks - Titan >950 Km").

From the latest Cassini Significant Events Report:

"ACS performed nominally [during T16], but with a higher than predicted thruster duty cycle during the +/- 15 minutes around closest approach. The higher duty cycle implies a greater atmospheric density than expected. Discussions are underway between the various teams to resolve whether the Titan 16 atmospheric results, if applied to Titan 17 on September 7, indicate that changes should be made to that flyby."

[debbiek]

Cassini will leave the ring plane on this orbit. It will be nice to see the rings again.
The view from Solar System Simulator on July 24
http://space.jpl.nasa.gov/cgi-bin/wspace?t...=1&showsc=1

Thanks for that... as a newbie, this is the kind of information I find to be of real interest... great simulated picture too

[The Messenger]

From the latest Cassini Significant Events Report:

"ACS performed nominally [during T16], but with a higher than predicted thruster duty cycle during the +/- 15 minutes around closest approach. The higher duty cycle implies a greater atmospheric density than expected. Discussions are underway between the various teams to resolve whether the Titan 16 atmospheric results, if applied to Titan 17 on September 7, indicate that changes should be made to that flyby."

Does anyone know if the INMS mole count is consistent with the 'drag force', this time? It was off by a factor of 2-3 on the ~1200km pass.

[Guest_AlexBlackwell_*]

From the latest Cassini Significant Events Report:

"ACS performed nominally [during T16], but with a higher than predicted thruster duty cycle during the +/- 15 minutes around closest approach. The higher duty cycle implies a greater atmospheric density than expected. Discussions are underway between the various teams to resolve whether the Titan 16 atmospheric results, if applied to Titan 17 on September 7, indicate that changes should be made to that flyby."

From the Cassini Significant Events Report for August 4, 2006:

Thursday, July 27 (DOY 208):

It was reported in the Cassini Significant Events last week that the atmospheric density measured at Titan 16 was higher than expected. The Titan Atmospheric Modeling Working Group (TAMWG) met this morning to discuss this result and assess whether the altitudes selected for upcoming encounters are still acceptable. At the conclusion of the meeting, the TAMWG recommended no changes to the altitudes of upcoming encounters. The new T16 data point has not fundamentally changed our understanding of Titan's atmospheric profile, except to indicate a less steep falloff in density at high latitudes. Cassini only has one future Titan flyby at very high latitude, Titan 32. Much like T16, this encounter is at 84 deg N latitude with a closest approach at 950 km, so it should be safe as well.

This post has been edited by AlexBlackwell: Aug 5 2006, 12:55 AM

[alan]

Slushy volcanoes might support life on Titan

Dozens of structures on Saturn's moon Titan that appear to be collapsed slush volcanoes have been revealed by NASA's Cassini spacecraft. The heat and chemicals associated with these possible volcanoes could provide a niche for life on the frigid moon.

In a flyby of the moon on 22 July, radar observations revealed dozens of rounded depressions that look like volcanic structures on Earth called calderas. These depressions form on Earth when the ground collapses after lava has drained out from under it in volcanic eruptions.

http://www.newscientistspace.com/article/d...-on-titan-.html

I believe the image in the article is a new release, at least I don't remember seeing the lakes with built up rims before

http://www.newscientistspace.com/data/imag...10304-2_600.jpg

[volcanopele]

While I would love these lakes to be centered on cryovolcanic calderas, I am a bit skeptical. Like Enceladus, you would have to explain why we see these structures here, and only here. A hotspot could work, but if we find these at the south pole...

Some lakes are clearly within collapse structures. Whether this necessarily means they are calderas is a bit of a stretch for the time being.

[Thorsten]

To all SAR fans: I don’t know if this has been mentioned before, but if you look at the latest video update on Cassini's recent flybys, you can find some more previously unseen parts of the T16 radar swath (although the movie itself deals with T18 (Sept. 23)!)

http://www.jpl.nasa.gov/videos/cassini/cassini20061006/

Compare the short movie sequence with PIA0630 (Lakes on Titan). At the beginning of the sequence the right part of the lower image can be seen and at the end the left part of the upper image is visible. Together they merge into a considerable part of the T16 SAR radar swath.

[Thorsten]

Here is a crudely patched version of the "expanded T16 RADAR swath".

Attached thumbnail(s)

 

[Thorsten]

The new image "Infrared and Radar Views of Titan (PIA09035)" allows us to bring the expanded T16 RADAR swath into a really global context. BTW, is that short SAR RADAR strip just south of T16 the one from the T18 flyby?

Attached thumbnail(s)

 

[Decepticon]

Looking at this http://cassinicam.com/titanflybys/titantracks.html it seems to be T18.

Im not 100% sure.

[Ian R]

Great work Thorsten!

[ustrax]

Great work Thorsten!

I second that...
And what a great work Cassini!
Looking at this fly-overs Huygens sounds very "We got to do MUCH better next time"...

[Decepticon]

Was bored. so I made this dated sar map.

[Matt]

I've been incredibly bored lately. Feels more like a sunday today than a saturday.

I noticed Saturn in the early hours last night, quite close to Regulus in Leo.

Might have to dust off the old Dob!

[Thorsten]

And what a great work Cassini!

I couldn’t agree more, ustrax. So far we can see T16 and T18 on the map - great work, Decepticon!
But in half a year we should – hopefully – also have the SAR radar swaths from the north polar passes of T28 (April 10, 2007), T29 (April 26, 2007), and T30 (May 12, 2007) – and not to forget T19 (October 9, 2006), from which there are already two nice cut-outs released.
So I guess that by summer 2007 we should have a much more comprehensive picture of what Titan’s North Pole looks like. And we should see a lot more beautiful lakes like the ones below (their position is not too accurate, so take it with more than just one grain of salt).

Attached thumbnail(s)

 

[Decepticon]

Nice!