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Titan Fly-by - 3 November 2008

Titan Fly-by - 3 November 2008

6 November 2008

After more than three months since its previous visit, the Cassini spacecraft once again approached Saturn's largest moon for the mission's forty-seventh targeted encounter with Titan. The closest approach to Titan occurred on Sunday, 3 November, at 17:35:23 UT at an altitude of 1100 kilometres above the surface and at a speed of 6.3 kilometres per second. The latitude at closest approach was 3.5° S and the encounter occurred on orbit number 91.

This encounter was set up with two manoeuvres: an apoapsis manoeuvre on 17 October, and a Titan approach manoeuvre, that was scheduled for 29 October. T46 is the tenth in a series of outbound encounters and the second Titan encounter in Cassini's Equinox Mission. It occurs roughly three days after Saturn closest approach.

Science Highlights

  • Radio Science Subsystem (RSS)
    There are only five Radio Science atmospheric occultations in the entire extended mission; two of them occurred on this flyby. RSS observations on T46 included ionospheric/atmospheric occultations and bistatic surface scattering on both the ingress and egress sides. The T46 egress atmospheric occultation is the first to probe the mid northern-latitude of Titan (~34°). The ingress occultation probed mid-southern latitude (~40°). Combined with results from eight other latitudes probed during previous prime mission flybys, the occultations will shed more light on latitudinal variability of the electron density profile of the ionosphere, the temperature/pressure profile, the extinction profile, and the small scale-structure of the neutral atmosphere. Bistatic surface scattering was observed at low southern latitudes on the ingress side (25°-30°; ~90°-110° west longitude) and low northern latitude (25°-30° ; ~200°-220° west longitude) on the egress side. The incidence angle for both sides was close to the Brewster angle range for likely surface compositions. Same- and cross-polarized components of the mirror-like surface echo, if detectable, provide valuable information about the dielectric constant and physical state of the surface region probed.
  • Imaging Science Subsystem (ISS)
    ISS acquired a regional mosaic of Titan's leading hemisphere at mid-southern latitudes, including coverage of Hotei Arcus. The instrument also continued to monitor clouds.
  • Composite Infrared Spectrometer (CIRS)
    The CIRS scanned and integrated on Titan's northern limb, concentrating on far-IR wavelengths to map and identify condensates and aerosols in the winter stratosphere.
  • Ultraviolet Imaging Spectrograph (UVIS)
    UVIS obtained an image cube of Titan's atmosphere at EUV and FUV wavelengths by sweeping its slit across the disk. These cubes provide spectral and spatial information on nitrogen emissions, H emission and absorption, absorption by simple hydrocarbons, and the scattering properties of haze aerosols. This is one of many such cubes gathered over the course of the mission to provide latitude and seasonal coverage of Titan's middle atmosphere and stratosphere.
  • Dual Technique Magnetometer (MAG)
    T46 was a flank-in flyby with a minimum altitude of 1100 km. This geometry is adequate for studies of the draping of the external magnetic field around Titan on the nightside hemisphere. T46 took place in Saturn's near-noon sector (10.5 hours SLT), where Titan could be found in the magnetosheath if the solar wind pressure is high.
  • Magnetospheric Imaging Instrument (MIMI)
    The instrument studied energetic ion and electron energy input to Titan's atmosphere.
  • Radio and Plasma Wave Science (RPWS)
    RPWS measured thermal plasmas in Titan's ionosphere and surrounding environment, searched for lightning in Titan's atmosphere, and investigated the interaction of Titan with Saturn's magnetosphere. The RPWS objectives are to study the density and temperature of ionospheric electrons and to look for plasma waves that participate in the interaction of Saturn's magnetosphere with Titan. RPWS also looked for evidence of lightning from Titan's atmosphere.

Table of Events

18 October 2008

Time UTC Time wrt
T-46
Activity
20:21:00 -15d 21h Start of sequence S45 that contains Titan-46

29 October 2008

Time UTC Time wrt
T-46
Activity
10:37:00 -05d 07h OTM #169 prime.
Titan-46 targeting manoeuvre

30 October 2008

Time UTC Time wrt
T-46
Activity
10:37:00 -04d 07h OTM #169 backup

2 November 2008

Time UTC Time wrt
T-46
Activity
19:22:00 -22h 13m Start of the TOST segment
19:22:00 -22h 13m Turn cameras to Titan
20:02:00 -21h 33m New waypoint
20:02:00 -21h 33m Deadtime, 15 minutes 33 seconds long.
Used to accommodate changes in flyby time
20:17:33 -21h 18m Titan atmospheric observations-CIRS.
Obtain information on the thermal structure of Titan's stratosphere.

3 November 2008

Time UTC Time wrt
T-46
Activity
02:35:23 -15h 00m Titan atmospheric observations-CIRS.
Obtain information on CO, HCN, CH4
08:35:23 -09h 00m Titan surface observations-ISS. Global map
12:35:23 -05h 00m Titan surface observations-ISS. Regional map
14:05:23 -03h 30m Transition to thruster control
14:06:23 -03h 29m Titan atmospheric observations-CIRS.
Obtain information on surface & tropopause temperatures, and on tropospheric CH4
16:07:23 -01h 28m Turn cameras to new waypoint
16:09:23 -01h 26m New waypoint
16:09:23 -01h 26m Titan surface measurements-RSS.
Bistatic scattering measurements at three radio wavelengths to determine the physical properties of Titan's surface, including reflectivity, dielectric constant, and roughness
17:21:23 -00h 14m Titan atmospheric observations-RSS.
RSS ingress/egress occultation of Titan's atmosphere and ionosphere
17:35:23 +00h 00m Titan-46 Flyby Closest Approach Time. Altitude = 1613 km, speed = 6.3 kms-1, 49° phase at closest approach
17:54:23 +00h 19m Titan surface measurements-RSS.
Bistatic scattering measurments at three radio wavelengths to determine the physical properties of Titan's surface, including reflectivity, dielectric constant, and roughness
18:51:18 +01h 16m Turn cameras to new waypoint
19:04:23 +01h 29m New waypoint
19:04:23 +01h 29m Transition off of thruster control
18:08:16 +00h 33m Ascending ring plane crossing
19:26:23 +01h 51m Titan atmospheric observations-UVIS.
Several slow scans across Titan's visible hemisphere to form spectral images

4 November 2008

Time UTC Time wrt
T-46
Activity
02:35:23 +09h 00m Titan atmospheric observations-ISS. Photometry
03:35:23 +10h 00m Titan atmospheric observations-CIRS.
Obtain information on CO, HCN, CH4.
08:13:33 +14h 38m Titan surface observations-ISS.
Monitoring for surface/atmosphere changes. Attempt to see surface colour variations. Monitor limb hazes, 1-3 km/px
09:13:33 +15h 38m Deadtime, 14 minutes 26 seconds long.
Used to accommodate changes in flyby time
09:28:00 +15h 53m Turn to Earth-line
10:08:00 +16h 33m Playback of T46 data, Goldstone

Last Update: 1 September 2019
14-Apr-2021 14:31 UT

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