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ItemSome Options for In Situ Geochemical and Geophysical Experiments in the Titan Environment by TandEM/TSSM(Georgia Institute of Technology, 2008-06-26) Ball, Andrew J.We present concepts for in situ instrumentation for Titan aerial platforms, probes, landers and penetrators, in the context of the TandEM mission proposal in ESA's Cosmic Vision programme and TSSM in NASA's New Frontiers program. These include 1) geochemical instrumentation for aerosol analysis, GCMS of surface materials, stable isotope analysis and trace gas detection, and 2) geophysical / meteorological instrumentation for studies of atmospheric science and energy balance. These concepts draw upon heritage and lessons learned from the Huygens Surface Science Package and Atmospheric Structure Instrument, the Beagle 2 Gas Analysis Package and the Ptolemy evolved gas analyser on the Philae comet lander.
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ItemExoMars Entry and Descent Science(Georgia Institute of Technology, 2008-06-26) Ball, Andrew J. ; Ferri, FrancescaThe entry, descent and landing of ExoMars offer a rare (once-per-mission) opportunity to perform in situ investigation of the martian environment over a wide altitude range. We present an initial assessment of the atmospheric science that can be performed using sensors of the Entry, Descent and Landing System (EDLS), over and above the expected engineering information. This is intended to help fulfill the concept of an Atmospheric Parameters Package (APP), as mentioned in the ExoMars draft Science Management Plan [ESA, 2005]. Mars' atmosphere is highly variable in time and space, due to phenomena including inertio-gravity waves, thermal tide effects, dust, solar wind conditions, and diurnal, seasonal and topographic effects. Atmospheric profile measurements, drawing on heritage from the Huygens Atmospheric Structure Instrument (HASI), which encountered Titan's atmosphere in 2005 [1], should allow us to address questions of the martian atmosphere's structure, dynamics and variability. By careful definition of EDLS measurements to yield science as well as a successful landing, we aim to obtain continuous atmospheric density, temperature and pressure profiles over the widest ever altitude range, with the highest sensitivity and spatial resolution. Extrapolation to the ExoMars case of the flight performance of the HASI entry accelerometry experiment is encouraging. Up to now, only three high vertical resolution and high accuracy vertical profiles of density, pressure and temperature of the martian atmosphere have been derived from in situ measurements performed by Viking 1 and 2 in day-time [2] and by Mars Pathfinder in night-time [3, 4]. Two more vertical profiles have been retrieved from the deceleration curves and aeroshell drag properties of the two Mars Exploration Rovers (MER) during atmospheric entry [5], but with a much lower accuracy. Such profiles are vital for testing of atmospheric models used in numerous studies of atmospheric variability, on a range of temporal and spatial scales, as well as for the practical issue of reaching the martian surface reliably [e.g. 6]. New data from different site, season and time period are essential to investigate the thermal balance of the surface and atmosphere of Mars, diurnal variations in the depth of the planetary boundary layer and the effects of these processes on the martian general circulation. A better understanding of the martian environment and meteorology is also essential for refining and constraining landing techniques at Mars and to evaluate the possible hazardous to machines and humans in view of future Martian explorations. As the ExoMars project definition proceeds, the entry, descent and landing sequence may offer further science opportunities. We would be interested in exploring these and welcome additional members to the consortium. References: [1] Fulchignoni, M. et al. (2005), Nature 438(7069), 785-791. [2] A. Seiff, D.B. Kirk, (1977) J. Geophys. Res 82,. 4364-4378,. [3] Schofield, T., et al. (1997) Science 278, 1752-1758 [4] Magalhães, J.A., J.T. Schofield, A. Seiff, (1999) J. Geophys. Res.104, 8943-8945. [5] Withers, P. and M. D. Smith (2006) Icarus 185, 133-142. [6] Montabone et al. (2006) Geophys.Res. Lett. 33, doi :10.1029/2006GL026565.
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ItemHistory of the Discovery of Lightning on Venus and Looking for its Origin(Georgia Institute of Technology, 2008-06-23) Ball, Andrew J. ; Ksanfomality, Leonid V.Studies of the atmosphere of Venus identified several minor gaseous components whose origin could involve electrical discharges, which produce high pressure and temperature in the discharge stroke. Measurements made by VENERA 11, 12, 13, 14 and PIONEER-VENUS (1978-83), as well as subsequent missions, indicated electrical activity of the atmosphere of Venus, and later of other planets. On 21 and 25 December 1978, VENERA 11, 12 detected a large number of electromagnetic pulses, from measurements by the Groza instrument during descent and on the surface of the planet. A few days later the same phenomena were detected by the OEFD instrument of the late Professor F. Scarf, on board the PIONEER-VENUS orbiter, which registered electromagnetic pulses. The periodicity of groups of pulses detected by Groza pointed to a distant source of the electromagnetic noise. The OEFD instrument registered pulses in low frequency whistler mode. No light flashes were found. Discharges inside Earth' clouds are well visible from outside. However a search for light flashes on the night side of Venus resulted in nothing. The hypothesis of possible volcanism as an origin of the lightning was proposed. A sudden enrichment of the atmosphere of the planet by SO2 was observed by the PV instruments and was tentatively connected with volcanic activity and electromagnetic noises. Later electromagnetic pulses coming from the atmosphere of Venus were observed by instruments of the GALILEO mission (Borucki et al., 1996). The lightning of Venus is unusual. We consider its possible similarity with high altitude discharges. Taiwanese researchers discovered recently huge lightning discharges, which rise as clusters from storm clouds to the upper layers of the atmosphere (up to 100 km). In contrast to normal lightning, these sparkling streams are propagated in rarefied air, occurring in huge clusters, having a height up to 80 km. Their duration was less than one second. It is very difficult to record these discharges. The researchers have also found that four of these streams radiated radiowaves of extremely low frequency.
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ItemMissions in Low T Environments: Architectures, Issues, Failures(Georgia Institute of Technology, 2008-06-21) Ball, Andrew J.
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ItemTitan Strawman Payload Options (including some from Titan Explorer and TandEM proposals)(Georgia Institute of Technology, 2008-06-21) Ball, Andrew J.