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Titan Fly-by - 5 December 2008

Titan Fly-by - 5 December 2008

10 December 2008

Sixteen days after its previous flyby, the Cassini spacecraft once again approached Saturn's largest moon for the mission's forty-ninth targeted encounter with Titan. The closest approach to Titan occured on Friday 5 December at 14:25:45 UTC, at an altitude of 960 kilometres above the surface and at a speed of 6.3 kilometres per second. The latitude at closest approach was 10.3°S and the encounter occured on orbit number 95.

This encounter was set up with two manoeuvres: an apoapsis manoeuvre on 27 November, and a Titan approach manoeuvre, scheduled for 1 December. T48 was the twelfth in a series of outbound encounters and the fourth Titan encounter in Cassini's Equinox mission. It occured just over three days after Saturn closest approach.

T-48 was a unique flyby (along with T-47) with low phase and high resolution imaging opportunities for the imaging instruments.

Science Highlights

  • Ion and Neutral Mass Spectrometer (INMS)
    T48 is the only dayside pass near Titan's equator in the Prime Mission or the Equinox Mission. This INMS prime observation will measure non-reactive neutrals while simultaneously observing the dayside ionosphere. This fly-by also gives INMS coverage of the boundary between the outer flank and wake magnetospheric interaction regions. Outbound, INMS will collect measurements from closest approach to the ionospheric peak and into the transition from thermal to co-rotating particles
  • Cassini Radar (RADAR)
    T48 represents the end of a series of fly-bys that observe territory that may be cryovolcanic. RADAR has the opportunity to look at part of Tui Regio inbound, prior to turning to INMS's preferred attitude. VIMS observations suggest that this region may resemble Hotei Arcus, with an anomalous composition and possible cryolava flow morphologies. Near closest approach, RADAR will observe the dark dunefields of Shangri-La while riding along on the INMS observation. HiSAR in south midlatitudes will look at a possible impact structure feature seen in ISS data.
  • Composite Infrared Spectrometer (CIRS)
    CIRS conducts far-IR limb composition measurements, and maps vertical distributions of CO, CH4, H2O and others. In addition, CIRS continues its campaign of mapping the planet in the mid and far-infrared to obtain the spatial and temporal variation of temperature and more abundant hydrocarbon and nitrile molecules, which provide information on seasonal changes in weather, climate and chemistry that may be occurring.
  • Imaging Science Subsystem (ISS)
    ISS returns to getting much higher resolution observations of the leading hemisphere with a mosaic along a portion of Hotei Arcus. The instrument will also collect global and regional mosaics of Titan's leading hemisphere, including a view of Hotei Arcus in its entirety, as well as southern Xanadu and the western reaches of Tsegihi.
  • Visual and Infrared Mapping Spectrometer (VIMS)
    VIMS will conduct global mapping.
  • Magnetospheric Imaging Instrument (MIMI)
    T48 is part of the Titan MAPS Campaign, investigating micro-scale and near aspects of the Titan interaction by making observations during about one hour period around an encounter. With the spacecraft -Y pointed toward Titan, when within 30 minutes of the targeted fly-by, optimize secondary axis for corotation flow as close to the spacecraft -X, +/- Z plane as possible with the other constraints on pointing. Also, measure the Titan exosphere/magnetosphere interaction by imaging in ENA with INCA (when the Sun is not in the INCA FOV).
  • Ultraviolet Imaging Spectrograph (UVIS)
    UVIS will have its FUV Occultation slit boresite on the star Epsilon CMa as Titan occults the star. Over the course of the nominal mission and extended mission UVIS stellar occultations will sample about 12 latitudes and this sampling will help constrain photochemistry, dynamics and aerosol microphysical processes in the upper stratosphere and mesosphere.
  • Dual Technique Magnetometer (MAG)
    T48 is very similar to T47, with a minimum altitude of 1000 km. Therefore, it will be possible to look for temporal effects in response to changes in the upstream conditions (i.e. the fly-by occurring at a different SKR phase). T48 also takes place in Saturn's near-noon sector (10.5 hours Saturn local time), where Titan could be found in the magnetosheath if the solar wind pressure is high.

Table of Events

26 November 2008

Time UTC Time wrt
T-48
Activity
17:55:00 -08d 20h Start of sequence S46 that contains Titan-48

1 December 2008

Time UTC Time wrt
T-48
Activity
14:56:00 -03d 23h OTM #175 prime. Titan-48 targeting manoeuvre

2 December 2008

Time UTC Time wrt
T-48
Activity
14:56:00 -02d 23h OTM #175 backup

4 December 2008

Time UTC Time wrt
T-48
Activity
17:26:00 -20h 59m Start of the TOST segment
17:26:00 -20h 59m Turn cameras to Titan
18:06:00 -20h 19m New waypoint
18:06:00 -20h 19m Deadtime, 15 minutes and 33 seconds long. Used to accommodate changes in fly-by time
18:21:33 -20h 04m Titan surface observations-VIMS. Global map

5 December 2008

Time UTC Time wrt
T-48
Activity
01:25:45 -13h 00m Titan atmospheric observations-CIRS. Obtain information on CO, HCN, CH4. Integrate on disk at airmass 1.5-2.0
05:25:45 -09h 00m Titan surface observations-ISS. NAC global map
09:25:45 -05h 00m Titan surface observations-ISS. NAC regional map
11:25:45 -03h 00m Titan atmospheric observations-CIRS. Vertical sounding of stratospheric compounds on Titan, including H2O. Integrations at 2 locations on the limb displaced vertically
12:25:45 -02h 00m Titan surface observations-ISS. NAC regional map
13:13:45 -01h 12m Transition to thruster control
13:14:45 -01h 11m Titan surface observations-ISS. NAC regional map during transition to thruster control
13:35:45 -00h 50m Titan RADAR/INMS observations. Inbound HiSAR
13:55:45 -00h 30m Titan RADAR/INMS observations. Inbound altimetry
14:07:45 -00h 18m Titan RADAR/INMS observations. Inbound SAR for Tui Regio
14:20:45 -00h 05m Titan RADAR/INMS observations. RADAR ride-along SAR with INMS
14:25:45 +00h 00m Titan-48 fly-by Closest Approach Time. Altitude = 960 km, speed = 6.3 kms-1, 25° phase at closest approach
14:47:45 +00h 22m Transition off of thruster control
14:56:57 +00h 31m Ascending ring plane crossing
15:08:49 +00h 43m Titan atmospheric observations-UVIS. Titan occults Eps CMa
15:20:45 +00h 55m Titan atmospheric observations-CIRS. Vertical sounding of stratospheric compounds on Titan, including H2O. Integrations at 2 locations on the limb displaced vertically
16:40:45 +02h 15m Titan atmospheric observations-UVIS. EUV-FUV imaging of Titan. Several slow scans across Titan's visible hemisphere to form spectral images
18:19:47 +03h 54m Apoapse
23:25:45 +09h 00m Titan surface observations-VIMS. Global map

6 December 2008

Time UTC Time wrt
T-48
Activity
03:25:45 +13h 00m Titan surface observations-ISS. Nightside monitoring for surface/atmosphere changes; attempt to see surface color variations; monitor limb hazes
04:25:45 +14h 00m Titan atmospheric observations-CIRS. Obtain information on the thermal structure of Titan's stratosphere.
07:32:33 +17h 07m Deadtime,14 minutes and 27 seconds long. Used to accommodate changes in fly-by time
07:47:00 +17h 22m Turn to Earth-line
08:27:00 +18h 02m Playback of T48 data. Goldstone 704m

Last Update: 1 September 2019
21-Apr-2021 14:53 UT

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