Search Publications

Hydrogen cyanide polymers, comets and the origin of life

Matthews, Clifford N.; Minard, Robert D.

Hydrogen cyanide polymers - heterogeneous solids ranging in colour from yellow to orange to brown to black - could be major components of the dark matter observed on many bodies of the outer solar system including asteroids, moons, planets and, especially, comets. The presence on cometary nuclei of frozen volatiles such as methane, ammonia and wat…

The two Titan stellar occultations of 14 November 2003

Glass, I. S.; Jones, T.; Colas, F. +49 more

We report the observation of two stellar occultations by Titan on 14 November 2003, using stations in the Indian Ocean, southern Africa, Spain, and northern and southern Americas. These occultations probed altitudes between ~550 and 250 km (~1 to 250 µbar) in Titan's upper stratosphere. The light curves reveal a sharp inversion layer near 51…

Electric properties and related physical characteristics of the atmosphere and surface of Titan

Lara, L. M.; Rodrigo, R.; López-Moreno, J. J. +17 more

The permittivity, waves and altimetry (PWA) instrument was designed for the investigation of the electric properties and other related physical characteristics of the atmosphere of Titan, from an altitude around 140 km down to the surface. PWA carried sensors to measure the atmospheric conductivity, and record electromagnetic and acoustic waves up…

Winds on Titan from ground-based tracking of the Huygens probe

Plettemeier, D.; Bird, M. K.; Asmar, S. W. +14 more

Large radio telescopes on Earth tracked the radio signal transmitted by the Huygens probe during its mission at Titan. Frequency measurements were conducted as a part of the Huygens Doppler Wind Experiment (DWE) in order to derive the velocity of the probe in the direction to Earth. The DWE instrumentation on board Huygens consisted of an ultrasta…

Titan's planetary boundary layer structure at the Huygens landing site

Colombatti, Giacomo; Tokano, Tetsuya; Ferri, Francesca +2 more

Huygens Atmospheric Structure Instrument (HASI) for the first time performed an in situ measurement of the thermal structure in Titan's atmosphere with a vertical resolution sufficient to analyze the planetary boundary layer (PBL). The vertical potential temperature profile reveals the presence of a weakly convective PBL, with a surface layer thic…

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

de Pater, Imke; Sicardy, Bruno; Buratti, Bonnie J. +50 more

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 t…

Characterization of zonal winds in the stratosphere of Titan with UVES: 2. Observations coordinated with the Huygens Probe entry

Livengood, T.; Kostiuk, T.; Witasse, O. +8 more

The Huygens Probe has successfully entered Titan's atmosphere and landed on its surface on 14 January 2005. With the aim of characterizing the zonal wind flow in Titan's stratosphere close to the time of entry, coordinated observations were carried out at the Very Large Telescope on the nights of 7, 12, 14, and 15 January. As in our previous inves…

Vertical pressure profile of Titan—observations of the PPI/HASI instrument

Harri, Ari-Matti; Mäkinen, Teemu; Siili, Tero +2 more

The Huygens entry probe descended through the atmosphere of Titan and provided an excellent set of observations of the atmosphere and the surface of Titan. During the 150-min descent the Huygens Atmospheric Structure Instrument (HASI) observed a comprehensive set of variables, including pressure, temperature, density and atmospheric electricity. T…

Stratospheric global winds on Titan at the time of Huygens descent

Sonnabend, G.; Kostiuk, T.; Witasse, O. +9 more

Measurements of stratospheric zonal winds on Titan were made in preparation for and during the time of the descent of the Huygens Probe into Titan's atmosphere on 14 January 2005. Fully resolved emission lines from ethane near 11.7 µm were measured on the east, center, and west positions on Titan using the NASA/GSFC Heterodyne Instrument for…

Astrochemistry: Complex organic matter in Titan's aerosols?

Biemann, K.