HP-SSA-DTWG-6-TRAJECTORY

Data Set Overview This data set contains the revised trajectory data (DTWG#5) of the Huygens probe in the atmosphere of Titan and is decribed in KAZEMINEJAD2011. The DOCUMENT directory contains the files that provide documentation and supplementary information to assist in understanding and using the data products. Especially, the EAICD document describes the data set. Seven data products are archived in the DATA directory. Browse files in the BROWSE directory are JPG files providing quicklook view of trajectory data. Input files that were needed to compute the trajectory can be found in the EXTRAS directory. Warnings It should be pointed out that the reconstruction of descent trajectory of the Huygens probe is not coherent with the altitude profile retrieved from the Huygens radar altimeter. Different approaches/methods for descent trajectory reconstruction resulted in altitude and velocity profiles that show discrepancy, not consistent with uncertainty range r^ant to models and measurements. Significant effort was put in the investigation of the possible error sources using the two radar flight spares. These investigations also encompassed extensive laboratory tests at ESA/ESTEC with several weeks of vacuum exposure with intermediate measurements at ambient temperature (20 deg C) and two radiation exposures (1.14 krad and 1.35 krad Si). Preliminary tests results clearly show that the altitude counter oscillators show an increased output in vacuum which is relaxed again in ambient conditions. Based on these laboratory measurements a correction factor could be derived which allowed to significantly reduce the originally observed residuals. For further details on the RAU investigations contact Roland Trautner at ESA/ESTEC/RSSD ([e-mail]). Software The data are stored as ASCII files and do not need any specific software. An update of the DTWG software (now v5.1) was truncated!, Please see actual data [truncated!, Please see actual data for full text]