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Titan Flyby - 5 December 2007

Titan Flyby - 5 December 2007

3 December 2007

Sixteen days after Cassini's Titan-37 flyby, the spacecraft revisits Titan for its thirty-ninth targeted encounter: T38. The closest approach to Titan occurs on Wednesday, 5 December, at 00:06:50 UT at an altitude of 1300 kilometres and at a speed of 6.3 kilometres per second. The latitude at closest approach is 79° S and the encounter occurs on orbit number 53.

This encounter is set up with two manoeuvres: an apoapsis manoeuvre on 26 November, and a Titan approach manoeuvre on 2 December. T38 is the third in a series of outbound encounters that will last until the end of the prime mission, and occurs less than two days after Saturn closest approach. This is also the third in a series of seven Titan southern hemisphere encounters.

Science Activities

  • Visible and Infrared Mapping Spectrometer (VIMS)
    VIMS will carry out high-resolution surface coverage of the Ontario lake area at closest approach. This will be a good opportunity to characterize the environment of the lake at optical wavelengths. This North-South flyby will also allow for seeing the Huygens landing site at 5 to 10 kilometre resolution. More opportunities in the extended mission will allow assessment of Titan's spin rate, which seems to be different from synchronous with its orbit around Saturn. Imaging will start at Adiri and then continue southward to Lacus Ontario. The instrument will also conduct medium resolution mapping of Titan's southern hemisphere, and search for atmospheric and surface changes relative to images taken early in the mission.
  • Imaging Science Subsystem (ISS)
    ISS will conduct a high-resolution regional mapping just after closest approach. There may be an opportunity for stereo imaging in conjunction with images from an earlier flyby. The instrument will ride along with VIMS observations of Lacus Ontario and the landing site. As Cassini recedes, ISS will make a regional-scale mapping of the equatorial bright-dark boundary around 7-10° N, 213° W. and a full-disk, colour mosaic.
  • Composite Infrared Spectrometer (CIRS)
    CIRS will obtain information on surface and tropopause temperatures, and on tropospheric CH4. Other observations include vertical sounding of stratospheric compounds on Titan via a rare far-infrared limb scan, including H2O and vertical aerosol sounding of Titan's stratosphere.
  • Ultraviolet Imaging Spectrograph (UVIS)
    UVIS will make several slow scans across Titan's visible hemisphere to form spectral images. The objective is to obtain spectral images of Titan in the EUV and FUV to map the aurora and dayglow, to map hydrocarbon absorption, and to measure scattering and absorption by aerosols in the stratosphere. The UVIS slit will be scanned across Titan's disk to build up an image at many wavelengths.
  • Dual Technique Magnetometer (MAG)
    MAG will examine the transition area from the southern lobe to the outer flank region of its induced magnetosphere.
  • Radio and Plasma Wave Science (RPWS)
    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.

Table of Events

31 October 2007

Time UTC Time wrt
Titan-38
Activity
18:40:00 -34d 05h Start of sequence S35 which contains Titan-38

2 December 2007

Time UTC Time wrt
Titan-38
Activity
07:44:00 -02d 16h OTM #136 prime. Titan-38 targeting manoeuvre

3 December 2007

Time UTC Time wrt
Titan-38
Activity
06:41:51 -01d 17h Descending ring plane crossing
07:39:52 -01d 16h Saturn periapse, R = 2.5 RS, lat = -6°, phase = 155°
09:10:00 -01d 15h OTM #136 backup

4 December 2007

Time UTC Time wrt
Titan-38
Activity
09:14:00 -14h 52m Start of the TOST segment
09:14:00 -14h 52m Turn cameras to Titan
09:44:00 -14h22m Deadtime, 15 minutes and 50 seconds long. Used to accommodate changes in flyby time
09:59:50 -14h 07m Titan atmospheric observations - CIRS. Obtain information on CO, HCN, CH4. Integrate on disk at airmass 1.5-2.0
14:06:50 -10h 00m Titan atmospheric observations - ISS. WAC Photometry
15:06:50 -09h 00m Titan atmospheric observations - UVIS. Spectral scans across Titan's visible hemisphere
18:36:50 -05h 30m Titan atmospheric observations - CIRS. Obtain information on surface & tropopause temperatures, and on tropospheric CH4.
21:36:50 -02h 30m Titan atmospheric observations - CIRS. Vertical sounding of stratospheric compounds on Titan, including H2O
22:51:50 -01h 15m Titan atmospheric observations - CIRS. Vertical aerosol sounding of Titan's stratosphere.
23:16:50 -00h 50m Titan atmospheric observations - CIRS. Vertical temperature sounding of Titan's tropopause & stratosphere
23:51:50 -00h 15m Titan surface observations - VIMS. High resolution mapping

5 December 2007

Time UTC Time wrt
Titan-38
Activity
00:06:50 +00h 00m Titan-38 Flyby Closest Approach Time.
70° phase at closest approach. Altitude = 1300 km, speed = 6.3 kms-1
02:17:32 +02h 11m Ascending ring plane crossing
02:06:50 +02h 00m Titan surface observations - ISS. Regional Map
04:06:50 +04h 00m Titan atmospheric observations - CIRS. Obtain information on surface & tropopause temperatures, and on tropospheric CH4
05:06:50 +05h 00m Titan surface observations - ISS. Global Map
08:06:50 +08h 00m Titan surface observations - VIMS. Regional Map
09:06:50 +09h 00m Titan atmospheric observations - CIRS. Obtain information on CO, HCN, CH4. Integrate on disk at airmass 1.5-2.0
11:06:50 +11h 00m Monitoring of surface and atmosphere - ISS. Monitoring for surface/atmosphere changes; attempt to see surface colour variations; monitor limb hazes
13:06:50 +13h 00m Titan surface observations - VIMS. Regional Map
14:06:50 +14h 00m Titan atmospheric observations - CIRS. Obtain information on the thermal structure of Titan's stratosphere
23:43:50 +23h 37m Deadtime, 15 minutes and 10 seconds long. Used to accommodate changes in flyby time
23:59:00 +23h 53m Turn to Earth-line

6 December 2007

Time UTC Time wrt
Titan-38
Activity
00:29:00 +01d 00h Playback of T38 data, Madrid 70M

Titan Ground Trace

Image courtesy NASA/JPL/Space Science Institute

The above image shows the ground trace of the Titan-38 flyby on a mosaic of Titan's surface, for a period of 32 hours around closest approach. The colour of the trace indicates Cassini's altitude above the surface. Blue: > 100 000 km, green: < 100 000 km, light blue: < 50 000, yellow: < 10 000 km, orange: < 5000 km, red: < 2000 km. The point of closest approach is marked T38 (Cassini at 1300 km altitude). Cassini approaches Titan over the equatorial region at 16 hours before closest approach (centre right in this image), and then continues to pass over Titan's southern hemisphere.

Last Update: 1 September 2019
21-Apr-2021 10:14 UT

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