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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2007.02.004 Byline: A. Hagermann (a), P.D. Rosenberg (a), M.C. Towner (a), J.R.C. Garry (b), H. Svedhem (c), M.R. Leese (a), B. Hathi (a), R.D. Lorenz (a)(d), J.C. Zarnecki (a) Keywords: Titan; Atmospheres; composition Abstract: Aboard the Huygens probe, which descended through Titan's atmosphere in January 2005, was the Surface Science Package (SSP), a set of 9 sensors, including a speed-of-sound sensor. We present the first detailed description of the SSP speed of sound measurements and report constraints on the methane content in Titan's lower atmosphere based on these measurements. After a careful calibration and subsequent Bayesian analysis, our measurements yield a most likely methane fraction in Titan's lower atmosphere of approximately 2% at 10 km, increasing to 3.5% at lower altitudes, based on a binary composition. Our data show that any large scale variation of methane within the lower 11 km of Titan's atmosphere is unlikely. Within experimental and theoretical uncertainties, our results are compatible with earlier estimates obtained from the GCMS experiment [Niemann, H.B., Atreya, S.K., Bauer, S.J., Carignan, G.R., Demick, J.E., Frost, R.L., Gautier, D., Haberman, J.A., Harpold, D.N., Hunten, D.M., Israel, G., Lunine, J.I., Kasprzak, W.T., Owen, T.C., Paulkovich, M., Raulin, F., Raaen, E., Way, S.H., 2005. Nature 438 (7069), 779-784]. Author Affiliation: (a) Planetary and Space Sciences Research Institute, The Open University, Walton Hall, Milton Keynes, MK7 GAA, United Kingdom (b) Astrobiology Group, Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands (c) ESA/ESTEC, Research and Scientific Support Department, Postbus 299, 2200 AG Noordwijk, The Netherlands (d) Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA Article History: Received 22 September 2006; Revised 7 February 2007

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2006.07.013 Byline: M.C. Towner (a), J.R.C. Garry (b), R.D. Lorenz (e), A. Hagermann (a), B. Hathi (a), H. Svedhem (c), B.C. Clark (d), M.R. Leese (a), J.C. Zarnecki (a) Keywords: Titan; Geological processes Abstract: We present the results from the first sonar to be deployed outside of Earth, and the first active acoustic instrument on Titan, onboard the Huygens probe, and the implications of its data for the geomorphology and characteristics of the Huygens landing site. Signals were recorded from 90 m downwards until impact, with a maximum sensor footprint diameter at the ground of 39.2 m. Probe impact speed was measured to be 4.67 mas.sup.-1. Derivation of terrain topography in a transect beneath the probe may indicate a ridge-trough terrain with an amplitude of about 1 m and a wavelength of about 10 m, although a flat surface is also consistent with the results. Modelling of the returned signal indicates that the surface acoustic properties at the landing site must be specular in nature, which may have two possible (not incompatible) causes -- the surface may consist of sorted interlocking grains, smooth on the centimetre scale, which would imply either fluvial sorting or the infill of small particles interstitial to the larger particles (similar to a terrestrial playa). Alternatively, specularity may indicate the presence of methane as an interstitial liquid or as very small pools. Due to mission constraints, tens of metres around the landing site were not well-imaged by Huygens' cameras except for the narrow azimuth observed after impact (the camera did not look straight down, and was not in imaging mode during the last few hundred metres of descent). Thus the data presented are among the few direct observations of the landing site surroundings. Author Affiliation: (a) Planetary and Space Sciences Research Institute, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK (b) Astrobiology Group, Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands (c) ESA/ESTEC, Research and Scientific Support Department, Postbus 299, 2200 AG Noordwijk, The Netherlands (d) Lockheed Martin Astronautics, PO Box 179, Denver, CO 80201, USA (e) University of Arizona, Lunar and Planetary Laboratory, Tucson, AZ 85721, USA Article History: Received 5 May 2006; Revised 26 July 2006

Author(s): M. Fulchignoni [1, 2]; F. Ferri (corresponding author) [3]; F. Angrilli [3]; A. J. Ball [4]; A. Bar-Nun [5]; M. A. Barucci [1]; C. Bettanini [3]; G. Bianchini [3]; [...]

We present a method for inferring the relative molar abundance of constituents of a liquid mixture, in this case methane, ethane, nitrogen and argon, from a measurement of a set of physical properties of the mixture. This problem is of interest in the context of theHuygensSurface Science Package, SSP, equipped to measure several physical properties of a liquid in case of a liquid landing on Saturn's moon Titan. While previous models emphasized the possibility ofverifyinga certain model proposed by atmospheric composition and equations of state, we use an inverse approach to the problem, i.e. we will infer the liquid composition strictly from our measurements of density, refractive index, permittivity, thermal conductivity and speed of sound. Other a priori information can later be used to improve (or reject) the model obtained from these measurements. [ABSTRACT FROM AUTHOR]

NOMAD is a spectrometer suite on board the ESA/Roscosmos ExoMars Trace Gas Orbiter, which launched in March 2016. NOMAD consists of two infrared channels and one ultraviolet and visible channel, allowing the instrument to perform observations quasi-constantly, by taking nadir measurements at the day- and night-side, and during solar occultations. Here, in part 2 of a linked study, we describe the design, manufacturing, and testing of the ultraviolet and visible spectrometer channel called UVIS. We focus upon the optical design and working principle where two telescopes are coupled to a single grating spectrometer using a selector mechanism.

The surface of Saturn's largest satellite--Titan--is largely obscured by an optically thick atmospheric haze, and so its nature has been the subject of considerable speculation and discussion. The Huygens probe entered Titan's atmosphere on 14 January 2005 and descended to the surface using a parachute system. Here we report measurements made just above and on the surface of Titan by the Huygens Surface Science Package. Acoustic sounding over the last 90 m above the surface reveals a relatively smooth, but not completely flat, surface surrounding the landing site. Penetrometry and accelerometry measurements during the probe impact event reveal that the surface was neither hard (like solid ice) nor very compressible (like a blanket of fluffy aerosol); rather, the Huygens probe landed on a relatively soft solid surface whose properties are analogous to wet clay, lightly packed snow and wet or dry sand. The probe settled gradually by a few millimetres after landing.

A 60-year-old man presented with features of superior vena cava (SVC) obstruction. On evaluation, he was diagnosed as having angioimmunoblastic lymphadenopathy with dysproteinemia (AILD). SVC obstruction due to AILD, to our knowledge, has not been described.