Titan Flyby - December 2005
25 December 2005
After a nearly 2 month hiatus, Cassini returns to Titan for its ninth targeted encounter. The closest approach to Titan occurs on Monday, 26 December (DOY 360), at 18:59 UT at an altitude of 10 409 kilometres above the surface and at a speed of 5.6 kilometres per second. The latitude at closest approach is 0° (equator) and the encounter occurs on orbit number 19.This encounter was initially to be set up with two manoeuvres: an apoapsis manoeuvre on 11 December, and an approach manoeuvre on 23 December. However, the apoapsis manoeuvre is so small that it has been cancelled. This outbound encounter occurs about 2 days after Saturn closest approach.
Science Activities
- Imaging Science Subsystem (ISS)
ISS will acquire a mosaic of Titan's albedo features Aztlan and Quivira, Bazaruto and Elba Faculae (the former surrounds the 80 kilometre-diameter crater), and Omacatl Macula, at a low phase angle of approximately 25 degrees and pixel resolution scales of approximately 700 to 450 metres. This ISS observation will also overlap eastern portions of the TA and T03 RADAR swaths. - Composite Infrared Spectrometer (CIRS)
Obtain information on trace constituents in Titan's stratosphere. An integration of the limb will obtain information on CO, HCN, and CH4. - Ultraviolet Imaging Spectrograph (UVIS)
Will use the UVIS HDAC (Hydrogen-Deuterium Absorption Cell) to conduct key measurements of the Titan atmosphere as well. Measurements of the D/H ratio in the Titan atmosphere will yield clues to the formation and history of Titan and the Saturnian system. - Visual and Infrared Mapping Spectrometer (VIMS)
Will also obtain a medium resolution regional map using the same observing strategy as the previous Titan flyby. - Magnetosphere And Plasma Science (MAPS)
Moreover, this Titan flyby will also present an excellent diametric wake crossing at 5.04 Titan Radii downstream for all of the MAPS instruments, as it will ultimately be ideal for comparisons to the Voyager-1 Titan flyby data set. Cassini's tail encounter will possess similar observing geometry as the tail encounter of Voyager-1 in November 1980. Especially with the increased capability of Cassini, the MAPS instruments will finally be able to compare the Cassini and Voyager data sets to further study Titan's atmospheric loss and the structure of Titan's plasma wake. But more importantly, this flyby will represent the only tail crossing at an intermediate distance in the planned Cassini Titan Tour, which will be highly valuable for the study of the formation of Titan's magnetotail as a function of distance.
Table of Events
17 December 2005
| Time UTC | Time wrt Titan-9 |
Event |
| 14:21:00 | - 9d 05h | Start of Sequence S08 which contains Titan-9 |
23 December 2005
| Time UTC | Time wrt Titan-9 |
Event |
| 06:25:00 | - 3d 13h | OTM #46 Prime, Titan-9 minus 3 day targeting manoeuvre |
24 December 2005
| Time UTC | Time wrt Titan-9 |
Event |
| 04:40:00 | - 2d 14h | OTM #46 Backup |
26 December 2005
| Time UTC | Time wrt Titan-9 |
Event |
| 06:59:00 | - 12h 00m | Start of the TOST Segment |
| 06:59:00 | - 12h 00m | Turn cameras to Titan |
| 07:34:30 | - 11h 25m | Deadtime, 15 minutes; used to accommodate change in flyby time |
| 07:49:30 | - 11h 10m | Titan limb observations; examine trace constituents in Titan's stratosphere |
| 12:59:30 | - 06h 00m | Titan atmospheric observations; examine wind/cloud motions and capture a low-phase global map |
| 14:59:30 | - 04h 00m | Titan surface observations; examine Titan's secular point |
| 18:59:30 | + 00h 00m | Titan-9 Flyby Closets Approach; altitude=1577 km, speed=5.95 kms-1, low phase inbound, 98.4° phase at closest approach, high phase outbound |
| 21:29:30 | + 02h 30m | Titan surface observations; several slow scans across Titan's visible hemisphere to form spectral images |
27 December 2005
| Time UTC | Time wrt Titan-9 |
Event |
| 03:53:30 | + 08h 54m | Deadtime, 15 minutes; used to accommodate change in flyby time |
| 04:04:00 | + 09h 05m | Turn to Earth line |
| 04:34:00 | + 09h 35m | Begin playback of T9 data; Goldstone 70m |
| 13:34:00 | + 18h 35m | End playback of T9 data |
30 December 2005
| Time UTC | Time wrt Titan-9 |
Event |
| 23:00:08 | + 3d 04h | Descending Ring Plane Crossing |
5 January 2006
| Time UTC | Time wrt Titan-9 |
Event |
| 14:08:54 | + 9d 19h |
Saturn Apoapse; Period=23.4d, inclination=0.4°, r=48.3 RSaturn, phase=94° |
Observation Results
Cassini Instrument: Imaging Science Subsystem(ISS)
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Date: 13 February 2006 Credit: NASA/JPL/Space Science Institute Image Notes: Wide-angle camera image in violet light showing structure of Titan's atmosphere: detached high haze layer and additional structure in the far north. |
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Date: 13 February 2006 Credit: NASA/JPL/Space Science Institute Image Notes: Colour composite, contrast-enhanced wide-angle camera view, showing structure in the atmosphere in the far north that is also visible in violet light (above). |
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Date: 29 December 2006 Credit: NASA/JPL/Space Science Institute Image Notes: Colour composite of narrow-angle camera images, showing Saturn's south pole through the hazy atmosphere of Titan. |
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