SPC Report April 2005
The engineering analysis is carried out in parallel by the industrial consortium led by Alcatel Space and the Project Scientist team. The following aspects are addressed: software performance, entry detection, thermal behaviour, power budget, parachute performances, spin and attitude profiles, radar altimeter calibration, and link budget. An anomaly has been discovered in the spin direction. Approximately 10 minutes after the start of the descent, the probe stopped spinning and began to spin in the other direction. This affected mainly the camera operations. The explanation for this behaviour is under study.
In addition, the reconstruction of the trajectory is being performed under the umbrella of the Descent Trajectory Working Group and is progressing well. The final product is expected end of June. JPL delivered the final trajectory of Cassini and Huygens from the Ta flyby (26 October 2004) until the interface point (1270 km above Titan, 14 January 2005).
All experiment teams are working extremely hard to analyse the data quickly and have already provided many scientific results that were presented and discussed at a number meetings and conferences, including:
- Atmosphere structure (temperature, density and pressure profiles) from the surface up to 1500 km. The atmosphere was found highly structured during the whole entry phase and turbulent in the lower stratosphere and in the upper troposphere.
- First detection of the cosmic-ray ionised layer at round 60 km altitude- The methane concentration increased in the last 20 km of the descent and reached 5% near the surface. The evaporation of methane after touch-down indicates that the surface at the landing site was soaked in methane.
- 120 ms-1 wind at high altitude, but winds are in general lower than expected. A peculiar layer was detected in the altitude range between 80 and 60 km where the wind decreased to a very low value. Meteorologists are working on finding an explanation for this unexpected finding.
The VLBI data analysis is progressing well. The mass production of the correlation is done. Post-processing analysis is ongoing. The final results on the Huygens position should be available in June/July.
Data analysis of the ground-based measurements of Titan around or during the Huygens descent is also ongoing. Outstanding observations by the VLT, showing high contrast, were reported in a press release issued by ESO end of February. Those data are complementary to the information gathered by Huygens.
The synergy between the Cassini and Huygens PI teams is a key element to fully interpreting the data sets from both spacecraft. Therefore it was decided that the Huygens Science Working Team will continue and will serve as a forum for discussing Titan science. It would therefore be important that the PI teams continue to receive funding until 2009.
The project scientist team is coordinating the first joint publication of the Huygens results in Nature. This special edition shall include one article per team and one overview article written under the leadership of the Project Scientist. The Huygens mission overview and results were presented at a number of conferences to the wide scientific community and the general public. The ESA web site published stories on the wind measurement and on visible and infrared spectra.