ESA Science & Technology - Enceladus Fly-by - 9 October 2008

The plume passage will allow in situ measurements by fields-and-particles instruments such as the Ion and Neutral Mass Spectrometer and the Cosmic Dust Analyzer, to gain an understanding of plume and surface composition.

This encounter will be set up with a manoeuvre on October 6. The Enceladus flyby occurs on the day of orbit number 88 periapse, on the inbound leg of the orbit.

Science Activities

• Imaging Science Subsystem (ISS)
  Coverage of the south polar region during the EN-88 fly-by will be used to investigate plume temporal variability.
• Composite Infrared Spectrometer (CIRS)
  CIRS will make observations of the south polar temperatures during solar eclipse to determine the heat capacity and textural properties of the regolith. These maps will complement data obtained in the previous fly-by. During EN-88, while in sunlight, CIRS will focus on plume source III on Damascus Sulcus, and during eclipse will concentrate on Damascus and Baghdad sulci (tiger stripes), fill in gaps in spatial coverage, and look for time variability.
• Visual and Infrared Mapping Spectrometer (VIMS)
  VIMS will perform compositional mapping and will look for confirmation of weak spectral features such as those due to organics, CO₂, ammonia, and other compounds. VIMS will search for hotspots with temperatures >140K.
• Ultraviolet Imaging Spectrograph (UVIS)
  UVIS will obtain spectral images of Enceladus in the EUV (500-1100 Å) and FUV (1100-1900 Å) to map the surface composition, including water ice abundances and grain sizes, and will search for volatiles in the vicinity of Enceladus.
• Magnetospheric and Plasma Science (MAPS)
  MAPS instruments will examine the particle environment at ~25 km from the surface during the fly-by. The fields-and-particles instruments will determine the nature of the material coming form the surface and its relationship to the E ring, and distinguish between two potential populations of particles: plume particles and sputtered particles from elsewhere on the surface (impactor ejecta). Optimal pointing during this fly-by coupled with the trajectory relative to the plume source should provide the highest signal and best INMS composition results to date. CDA measurements will determine the composition of surface ejecta and plume particles. The close fly-by distance will allow the magnetometer to determine whether Enceladus generates an induced magnetic field from a subsurface ocean. The magnetometer will also determine the composition of plume material from measurement of ion cyclotron waves in the magnetic field measurements. RPWS will study whether there is evidence for local ionization (other than charge exchange) in the plumes, the flux and size distribution of dust from the geysers, and the interaction between Enceladus and its magnetospheric environment. CAPS will study the ionosphere of Enceladus.
• Cassini Radar (RADAR)
  During the inbound leg of the EN-88 fly-by, RADAR will make scatterometry measurements to determine cm-scale roughness and radiometry measurements to understand the energy balance.

Table of events

13 September 2008

6 October 2008

7 October 2008

8 October 2008

9 October 2008

10 October 2008

Observation Results

Cassini Instrument: Imaging Science Subsystem (ISS) 

Date: 15 December 2008  Credit: NASA/JPL/Space Science Institute Image Notes: False-colour mosaic centred at ~65°S, 284°W, created from 28 NAC images that were each derived from data in several bands (between 338-930nm).