T13 (April 30, 2006) Options

[Guest_AlexBlackwell_*]

Since Emily posted in her LPSC notes:

"So, so much for Titan. All in all, there wasn't a lot that was new, either new data or new insight. I wish now that I'd skipped the latter part of the Titan session and gone to the rovers, but it was too late for that. The radar story will get more interesting, because after a long hiatus in the acquisition of radar data they are going to be getting a lot more radar passes beginning with the T13 flyby on April 30, so there is much to look forward to there."

I guess I'll go ahead and post the science highlights for the T13 flyby:

T13 - Science Highlights

Imaging Science Subsystem (ISS) – will observe particle properties, vertical distributions (~6 km/px. 0.6 Mbit/frame with 2x2 summing). ISS will also examine wind/cloud motions; (3-12 km/px, 3 images/timestep in CB1 filter to increase SNR), and search for and monitor lightning/aurora. (high-resolution imaging, 50-200 m/px, special targets, emission angles < 45 prefer IR-polarizer (phase 45-110)).

Cassini Plasma Spectrometer (CAPS) – will investigate large-scale and distant aspects of the Titan interaction by observing during entire period around an encounter from 10 to 25 RS.

Composite Infrared Spectrometer (CIRS) –will obtain information on trace constituents in Titan's stratosphere. Integrate on limb at two positions POINTING: Obtain information on CO, HCN, CH4. Integrate on disk at air mass 1.5-2.0. POINTING: -y to Titan, x away from sun.

Ultraviolet Imaging Spectrometer (UVIS) – will observe star Beta Ori as it becomes occulted by Titan’s atmosphere.

Visible and Infrared Mapping Spectrometer (VIMS) – will obtain new high resolution images that will help understand Titan's geology and the fate of CH4.

Magnetometer (MAG) – will investigate large-scale and distant aspects of the Titan interaction by observing during entire period around an encounter from 10 to 25 RS. (23TI (T13)) T13 is an equatorial wake flyby under plasma conditions near Saturnian local midnight with 1852 km altitude at CA. Thus it is very similar to T11 even according to local time.

Magnetospheric Imaging Instrument (MIMI) – will investigate micro-scale and near aspects of the Titan interaction by observing during about one hour period around an encounter. With -Y pointed toward Titan, when within 30 minutes of the targeted flyby, optimize secondary axis for co-rotation flow as close to the S/C -X, +/- Z plane as works with the other constraints on pointing. Also, measure Titan exosphere/magnetosphere interaction by imaging in ENA with INCA (when sun is not in INCA FOV).

Ion and Neutral Mass Spectrometer (INMS) – will obtain data regarding Titan’s atmospheric and ionospheric composition and thermal structure. INMS will also observe the magnetospheric/ionospheric interaction.

Radio and Plasma Wave Spectrometer (RPWS) – will perform observations in the immediate vicinity of Titan, including thermal plasma density and temperature measurements with the Langmuir probe, search for lightning and other radio emissions, characterization of plasma wave spectrum, search for evidence of pickup ions. Langmuir probe within 90 degrees of spacecraft ram at closest approach, co-rotational ram outside of +/- 15 minutes.

RADAR – will perform low and high resolution SAR (Synthetic Aperture RADAR) imagine of Titan’s surface. Additionally, RADAR will collect Altimetry, Radiometry, and Scatterometry Data.

[JRehling]

Since Emily posted in her LPSC notes:

"So, so much for Titan. All in all, there wasn't a lot that was new, either new data or new insight. I wish now that I'd skipped the latter part of the Titan session and gone to the rovers, but it was too late for that. The radar story will get more interesting, because after a long hiatus in the acquisition of radar data they are going to be getting a lot more radar passes beginning with the T13 flyby on April 30, so there is much to look forward to there."

I guess I'll go ahead and post the science highlights for the T13 flyby:

T13 - Science Highlights

Visible and Infrared Mapping Spectrometer (VIMS) – will obtain new high resolution images that will help understand Titan's geology and the fate of CH4.

That's what the VIMS highlight always says. Rare data releases, and the ones that do come out are always huge discoveries. Is that an ESA-run instrument?

[Guest_AlexBlackwell_*]

That's what the VIMS highlight always says. Rare data releases, and the ones that do come out are always huge discoveries. Is that an ESA-run instrument?

Bear in mind that these are the highlights for public release; indeed, I believe they're the same ones used in the mission description document that's posted on the flyby page. The really detailed goals are discussed during the closed TOST/SOST telecons.

Notice that RADAR seems to always have a sort of generic description, too. And yes, their description used the word "imagine" instead of "imaging." I didn't want to be cruel and include a [sic].

[volcanopele]

I can try to fill in some of the gaps in the info for ISS and RADAR. There will be a long E-W SAR swath through central Xanadu. Xanadu's geology continues to be a puzzle, though we maybe making some headway, if you believe Barnes et al.'s cryovolcanism model for western Tui Regio in SW Xanadu (of which I am a co-author, though Jason B. has done all the work except for ISS mosaicking and encouragement). I am a bit confused about their targeting. The beginning of their swath had covered Guabonito, a circular bright feature in eastern Shangri-la, but they may have moved the swath further north. Chuck Wood seemed to think they are now covering Santorini Facula and Veles, two additional eastern Shangri-la bright rings, that may be impact craters filled in with sediment. So hopefully they will get those features so we can pin down what those features are.

Moving on to ISS, we have a high-pixel scale (0.2-0.7 km/pixel) mosaic over Shiwanni Virgae in northern Tsegihi, central Aztlan and Quivira, and eastern Fensal. Not quite sure what we will get out of that data, but it could be useful in constraining the small facula population in central Aztlan and to provide a look at the bright diffuse deposit (landslide? alluvial fan?) northwest of Elba Facula.

[Guest_AlexBlackwell_*]

That's what the VIMS highlight always says.

It's only slightly less vague but here is another description of the VIMS T13 HIGHRESNA001_PRIME observation centered on 7 degrees latitude and 30 degrees longitude, at a distance of 28,000 km:

"Identification of geologic features including volcanoes, eolian features, and craters, and their correlation with composition. Search for shadows."

Better? Same? Worse?

[volcanopele]

It's only slightly less vague but here is another description of the VIMS T13 HIGHRESNA001_PRIME observation centered on 7 degrees latitude and 30 degrees longitude, at a distance of 28,000 km:

"Identification of geologic features including volcanoes, eolian features, and craters, and their correlation with composition. Search for shadows."

Better? Same? Worse?

Don't know how large their footprint is in this area. That would be in central Fensal, a fairly bland area of dark material with a few small (10-25 km) faculae, but nothing major. Depending on how large their footprint is, they may get the northern and southern boundaries of Fensal which contain some interestingly shaped albedo contrasts.

[Guest_AlexBlackwell_*]

Don't know how large their footprint is in this area.

I would post this info but... Well, you know how the VIMS folks are

[belleraphon1]

I can try to fill in some of the gaps in the info for ISS and RADAR. There will be a long E-W SAR swath through central Xanadu. Xanadu's geology continues to be a puzzle, though we maybe making some headway, if you believe Barnes et al.'s cryovolcanism model for western Tui Regio in SW Xanadu (of which I am a co-author, though Jason B. has done all the work except for ISS mosaicking and encouragement). I am a bit confused about their targeting. The beginning of their swath had covered Guabonito, a circular bright feature in eastern Shangri-la, but they may have moved the swath further north. Chuck Wood seemed to think they are now covering Santorini Facula and Veles, two additional eastern Shangri-la bright rings, that may be impact craters filled in with sediment. So hopefully they will get those features so we can pin down what those features are.

Moving on to ISS, we have a high-pixel scale (0.2-0.7 km/pixel) mosaic over Shiwanni Virgae in northern Tsegihi, central Aztlan and Quivira, and eastern Fensal. Not quite sure what we will get out of that data, but it could be useful in constraining the small facula population in central Aztlan and to provide a look at the bright diffuse deposit (landslide? alluvial fan?) northwest of Elba Facula.

Personally I was hoping they would point the RADAR further south and target Tui and Hotei. I can understand the desire to pin down some of the features that have the better ISS coverage, but I would think the 5-micron anomalies would be even more desirable targets.

Are there other opportunities in the prime mission for RADAR to cover these areas?

Sad and confused Craig

[volcanopele]

They won't be able to cover Tui or Hotei, but they swath is a little farther south than I thought and is still in the location that covers Shikoku Facula and Guabonito.

[Guest_BruceMoomaw_*]

That's what the VIMS highlight always says. Rare data releases, and the ones that do come out are always huge discoveries. Is that an ESA-run instrument?

VIMS, if I remember correctly, DID depend upon Italy for a lot of its financing -- its initial inclusion on the instrument payload was provisional, and took a while to finalize.

[Decepticon]

A off topic question.

When does Cassini view this area, if ever?

[alan]

After February of 2007.

[Matt]

I heard the SAR imaging will be at low latitudes during T13......but does anybody know exactly where?

[Guest_AlexBlackwell_*]

I heard the SAR imaging will be at low latitudes during T13......but does anybody know exactly where?

RADAR on T13 covers the central brightest areas of Xanadu, which, from what I understand, is important since these regions won't be covered again until late in the primary mission (T43 and T44). There is also outbound altimetry on T13, scatterometry (south of Shangri-La), and new radiometry coverage complementary to TA-T8.

[Matt]

Excellent thanks for the info Alex. Central Xanadu will be really interesting.

Im starting to favour a cryovolcanic origin for the brightness of Xanadu Regio.....or a combination of cryovolcanism and rain cleansing.

I suppose if Xanadu Regio has been a hotspot for volcanism and outgassing in the past, could that have also lead to heavy bursts of methane rain associated with the outgassing?