03 Dec 2007

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

2 December 2007

3 December 2007

4 December 2007

5 December 2007

6 December 2007

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.