Overview of the coordinated ground-based observations of Titan during the Huygens mission

Coordinated ground-based observations of Titan were performed around or during the Huygens atmospheric probe mission at Titan on 14 January 2005, connecting the momentary in situ observations by the probe with the synoptic coverage provided by continuing ground-based programs. These observations consisted of three different categories: (1) radio telescope tracking of the Huygens signal at 2040 MHz, (2) observations of the atmosphere and surface of Titan, and (3) attempts to observe radiation emitted during the Huygens Probe entry into Titan's atmosphere. The Probe radio signal was successfully acquired by a network of terrestrial telescopes, recovering a vertical profile of wind speed in Titan's atmosphere from 140 km altitude down to the surface. Ground-based observations brought new information on atmosphere and surface properties of the largest Satumian moon. No positive detection of phenomena associated with the Probe entry was reported. This paper reviews all these measurements and highlights the achieved results. The ground-based observations, both radio and optical, are of fundamental imnortance for the interpretatinn of results from the Huygens mission

The Huygens Doppler Wind Experiment : a Titan Zonal Wind Retrieval Algorithm

The Cassini/Huygens mission to Saturn, a joint venture of NASA and ESA, was launched on 15 October 1997 from Kennedy Space Center, Cape Canevaral, Florida (USA) and will reach its destination in July 2004. The Huygens Probe is dedicated to descent through the atmosphere of Saturn's largest moon Titan by parachute. The scientific data gathered during the descent will be broadcasted to the Cassini orbiter for temporary storage and later transmitted to Earth using Cassini's powerful High Gain Antenna. The Doppler Wind Experiment (DWE), one of the six experiments carried out during the Huygens descent through Titan's atmosphere, utilizes the Doppler effect on the radio link between Huygens and Cassini to measure the radial velocity of Huygens with respect to Cassini. Its primary goal is the determination of the altitude dependence of Titan's zonal (east-west) winds along the descent track, thereby providing in situ verification (``ground truth'') of remote Cassini observations. The most problematic DWE issue is an accurate extraction of all Doppler components other than that due to the zonal wind. This thesis shows the development of the algorithm necessary for retrieval of the zonal wind speed from the frequency measurement and gives an estimation of the accuracy to which this can be performed

The Huygens scientific data archive: Technical overview

The Cassini/Huygens mission was launched in October 1997, and during the third orbit around Saturn, the Huygens probe was released on course to enter Titan's atmosphere. During the descent, six science instruments provided in situ and remote sensing measurements of Titan's atmosphere and surface. Doppler tracking was performed with two Earth-based radio telescopes, and a Very Long Base Interferometry (VLBI) experiment was carried out. Data acquisition began around 1500 km altitude and continued throughout the 2 h and 30 min descent and for 1 h and 12 min after landing. This unique set of data is available in the ESA Planetary Science Archive (PSA) and mirror imaged in the NASA Planetary Data System (PDS). This paper presents an overview of the process the Huygens Data Archiving Working Group followed to develop and ingest the data set. A description of the data sets is also given

Overview of the coordinated ground-based observations of Titan during the Huygens mission

[1] Coordinated ground-based observations of Titan were performed around or during the Huygens atmospheric probe mission at Titan on 14 January 2005, connecting the momentary in situ observations by the probe with the synoptic coverage provided by continuing ground-based programs. These observations consisted of three different categories: (1) radio telescope tracking of the Huygens signal at 2040 MHz, (2) observations of the atmosphere and surface of Titan, and (3) attempts to observe radiation emitted during the Huygens Probe entry into Titan’s atmosphere. The Probe radio signal was successfully acquired by a network of terrestrial telescopes, recovering a vertical profile of wind speed in Titan’s atmosphere from 140 km altitude down to the surface. Ground-based observations brought new information on atmosphere and surface properties of the largest Saturnian moon. No positive detection of phenomena associated with the Probe entry was reported. This paper reviews all these measurements and highlights the achieved results. The ground-based observations, both radio and optical, ar