SPC Report November 2005
The engineering analysis of the probe performance has been divided in two phases. The phase-1 engineering data analysis is essentially based on the evaluation of the limited engineering data set. Part of the phase-1 documentation prepared by the industrial consortium, led by Alcatel, has been finalized and accepted by ESA's Huygens Mission Team. The remainder of the phase-1 documentation is expected to be completed by end of October.
An extended analysis (phase 2) is planned that will rely on the combined and coordinated evaluation of both the engineering and the science data sets which will provide information about the atmosphere conditions. This phase 2 analysis will be performed under GSP funding with one of the main objectives to fully exploit the unique Huygens data set and to document thoroughly lessons learned from Huygens that would be applicable to future planetary probe missions.
The analysis of the Huygens data set is progressing well. A major effort is being made in coordinating the data analysis and interpretation among the Huygens teams. Several synergy studies using both probe and orbiter data have also been initiated. Two specific aspects of the Huygens data set are receiving special attention, as they need to be fully resolved to progress further the interpretation of the data:
- i) the probe descent trajectory reconstruction and
ii) the probe rest attitude on the surface
A coordinated Huygens data analysis workshop, that will involve all Huygens science teams, the Huygens VLBI team and the Huygens engineering team, will take place in Meudon on 10-13 January 2006, with the objectives to address all science issues that need to be tackled by several instruments and/or in an interdisciplinary approach to be solved.
The coordinated set of Huygens publications in Nature is expected to appear in November. Here is a brief summary of the main finding so far. Huygens revealed an extraordinary world, resembling Earth in many respects, especially in meteorology, geomorphology, and fluvial activity. The images show strong evidence for erosion due to liquid flows, possibly methane, on Titan. The probe trajectory carried it across a boundary between a bright, icy, rugged terrain and a darker flat area. Huygens landed in the dark area. The measured pressure and temperature profiles below 150 km are close to those expected on the basis of Voyager observations. The measured surface temperature and pressure at the landing site were ~93.7 K and ~1470 mbar respectively. At the landing site, the surface is relatively flat and solid. Reflectance spectra show that it is mostly composed of dirty water-ice. Water-ice pebbles up to a few cm in diameter were scattered near the landing site. Impact measurements found the surface here to be unconsolidated, with the consistency of loose wet sand.
Plans are in place for the Cassini Orbiter radar to acquire a SAR image of the Huygens landing site area with a resolution of the order of 1 km during the 8th targeted Titan flyby on 28 October 2005.