ESA Science & Technology - Titan Flyby - 25 March 2008

This encounter is set up with two manoeuvres: an apoapsis manoeuvre on 17 March and a Titan approach manoeuvre on 22 March. T42 is the seventh in a series of outbound encounters that will last until the end of the prime mission, and it occurs less than two days after Saturn closest approach. This is the last in a series of seven Titan southern hemisphere encounters.

Science Highlights

• Ion and Neutral Mass Spectrometer (INMS)
  This will be the second time in the entire mission when INMS has used its open source neutral beaming mode to see reactive neutrals and understand wall effects, where detected particles end up sticking to the source. The instrument is unable to measure both ions and neutrals at the same time. Part of the Magnetosphere and Plasma Science Titan campaign, this observation will help sort out compositional changes of minor species during ingress vs. egress.
• Visible and Infrared Mapping Spectrometer (VIMS)
  VIMS rides along on the INMS closest approach observations using the noodle mode, where VIMS captures a long noodle-shaped swatch of Titan's surface. The noodle mode was first tried in the T20 flyby: the noodle observation, using a RADAR swath for context, showed correlation between interdune terrain and types of ices. If this particular observation is successful, VIMS scientists expect to exploit it more during the extended mission. Pointing is especially tricky for this mode. VIMS is not expected to capture the Huygens landing site, but will get medium resolution imaging of adjacent unknown territory. VIMS non-noodle prime observations during T42 include a mosaic at 5 kilometres per pixel of unknown territory at the northern rim of the dark units and cloud tracking.
• Imaging Science Subsystem (ISS)
  Similar to the T41 encounter, ISS captures regional mapping and full-disk mosaics covering Adiri and East Belet, giving one of the best views of the high northern latitudes and filling in coverage. The team is looking forward to seeing a high resolution image of a complex boundary in that northern region. The instrument may be able to see all the way up to the pole due to scattering by the atmosphere. In addition, the Narrow Angle Camera monitors for surface/atmosphere changes, attempts to see surface colour variations, and monitors limb hazes. As the geometries of the T41 through T44 flybys are very similar, it will be possible to monitor how the clouds change in this region every few weeks.
• Composite Infrared Spectrometer (CIRS)
  CIRS continues to extend spatial and temporal coverage of Titan, from low-spectral resolution disk maps to high spectral resolution nadir and limb integrations. Getting good time resolution is very important in the search for seasonal changes in the stratosphere, especially the expected break-up of the northern polar vortex in northern spring.
• Radio and Plasma Wave Science (RPWS)
  As Titan is out "in front" of Saturn, the T41 through T44 flybys put the spacecraft in an ideal location to have another opportunity to see Titan outside of Saturn's magnetosphere, in shocked solar wind ahead of the magnetosheath as happened on T32. It is interesting to duplicating the flyby geometry to look for shorter time-scale phenomena in Titan's plasma environment, so this series of four flybys, especially T41 through T43, will offer that opportunity.

Table of Events

22 March 2008

23 March 2008

24 March 2008

25 March 2008

26 March 2008

Titan Ground Trace

Image courtesy NASA/JPL/Space Science Institute

The above image shows the ground trace of the Titan-42 flyby on a mosaic of Titan's surface, for a period of 32 hours around closest approach (going from ~30° to ~243° longitude). 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 T42 (Cassini at 1000 km altitude).