No. 5 - SPC Report May 2004
The coordinated Cassini and Hubble observations were successfully conducted in January. Their main aim is to study how the Solar Wind controls Saturn aurora activity. Preliminary results were presented at the EGU meeting in Nice on 29 April.
Information on the Cassini-Huygens mission can be found on the ESA science website: http://saturn.esa.int/. The first images of Titan's surface obtained by Cassini with a resolution similar to that obtained by Hubble and by ground-based Adaptive Optics systems were released on Thursday 6 May.
Media/science communications activities are being prepared in coordination with NASA/JPL. The main upcoming events are:
- NASA Pre-arrival at Saturn Press Conference on 3 June in NASA/HQ
- Phoebe flyby (closed approach @ 2000 km) on 11 June
- Saturn Orbit Insertion on 1 July
- Titan untargeted flyby (closed approach @ 340 000 km) on 3 July
- First targeted Titan flyby (@ 1200 km altitude) on 26 October
- Second targeted Titan flyby (@ 2800 km altitude) on 13 December
- Probe separation on 25 December
- Probe entry on 14 January 2005
The International Conference organised on the occasion of the 375th Anniversary of Huygens Birthday was well attended. The e-proceedings are available at http://sci.esa.int/huygens/conference/.
Huygens Delta Flight Acceptance Review (Delta-FAR)
The Huygens Delta-FAR was successfully concluded at the meeting of the Review Board that took place on 13 February. The overall objectives of the review were the following:
- Validation of the new mission scenario designed to recover from the Huygens radio receiver design fault
- Re-validation of the entry and descent performances (with respect to the revised atmosphere model)
- Confirmation of the readiness of flight operations preparation for the revised Huygens Mission
The Board concluded that the objectives of the review have been met and that the Huygens Mission Team should proceed with the implementation of the mission as planned. However some discrepancies were found with the entry heat flux calculations made on the one hand by EADS/Alcatel and on the other hand by NASA/AMES in support of the review. The Huygens Mission Team has established an independent ESA-led team to re-assess all entry heat flux calculations and to reconcile the results. At the time of writing the work is still in progress. It is expected to be completed by end of May. One source of uncertainty is the level of CN produced in the shock layer, due to the presence of CH4 in Titan's Nitrogen atmosphere. CN is a strong radiator in the UV/Violet in the range 380-390 nm. In order to re-validate the heat-shield material performances under the expected heat-flux conditions during the Titan entry, two UV/Violet transparency tests were recommended by the Board on heat-shield tile samples.
The first test was performed in the ESTEC laboratories with a low intensity lamp. The initial data analysis indicates a good opacity of the material. The second test is being performed under the responsibility of NASA/AMES, which offered to include such a test in their planned series of tests of potential heat-shield material for future Titan missions. The NASA/AMES facility will allow irradiating the samples with heat flux compatible with the level expected during the mission. The test is planned for the end of June / early July. The results of the on-going heat-flux re-assessment and of the tests will be used to confirm whether the current baseline entry angle of -65(±3)º is well balanced in terms of overall residual risks inherent to an entry mission in Titan.