183 research outputs found
Thermal analysis and testing of a spaceborne passive cooler
No full textThis thesis describes the thermal design and thermal testing of the development model radiative cooler for the Composite Infra-Red Spectrometer (CIRS) due for launch on the Cassini spacecraft in 1997. The radiative cooler is used to cool the instrument's Focal Plane Assembly (FPA) to approximately 80K. The FPA holds two arrays of HgCdTe detectors for the mid infra-red spectrometer of the instrument which covers the wavelength range 7μm to 17μm. The FPA is mounted from the optics on a titanium alloy tripod and is cooled conductively by the radiator via a flexible link and a cold finger. A range of thermal models of the system have been developed ranging from a simple, analytical model to a finite difference numerical model. A calorimeter was designed to perform heat leak measurements on samples of Multi- Layer Insulation (MLI) blankets to determine the number and type of shields required for the MLI blanket covering the back of the cooler radiator. A test facility incorporating a vacuum system, a space simulator target, and a simulator for the CIRS instrument was designed and constructed for testing the assembled cooler. Various configurations of the Development Model (DM) CIRS cooler were tested as components became available and the results obtained compared to the thermal model predictions. It was found that the cooler will attain a temperature of 80K in operation, but with less excess cooling power than predicted by the thermal models
Acoustic anemometry on the surface of Mars
No full textThere is a need for wind sensors with high accuracy and measurement frequency for deployment on the surface of Mars. The wind data obtained to date have been adversely affected by thermal contamination and calibration issues. Improved data would not only help to constrain and validate theoretical models, but also increase safety and longevity of lander operations. The mechanical and thermal wind sensing techniques used on previous missions, whilst sufficient for basic meteorology, are wholly inadequate for measuring fundamental phenomena such as dust and volatile transport. Two promising technologies, optical and acoustic anemometry, could permit precise and high-frequency measurement of three-dimensional wind speeds on the Martian surface. Ultrasonic acoustic anemometry, which relies on time-of-flight measurements, was ultimately chosen for its lower processing requirements and ability to measure the speed of sound; and therefore temperature. Capacitive transducers were selected for their low impedance and high sensitivity, to maximise signal transmission through the rarefied Martian atmosphere. These transducers, which consist of a metallised polymer film oscillating on top of a contoured metal backplane, were evaluated for their suitability as anemometers on the Martian surface. A theoretical framework was assembled to model transducer performance and determine which factors are the most important in determining received signal amplitude. A pair of transducers were designed and manufactured to allow for testing of a wide range of parameters including thickness of the oscillating membrane and diameter. Tests were carried out on the assembled transducers to investigate the dependence on these parameters, and their behaviour was generally found to fit the assembled theoretical framework well. Transducer performance was highly dependent on roughness depth of the backplanes, as expected. The frequency response of the transducers was dominated by the backplane roughness at atmospheric pressure but by film thickness at low pressures. Cross-correlation of the sent and received signals was confirmed as the most reliable signal detection method at low signal amplitudes. The transducers were tested under simulated Martian conditions (a low-pressure carbon dioxide atmosphere with airborne dust), and found to be capable of accurately and reliably measuring the incident wind speed. The cumulative deposition of airborne dust noticeably reduced received signal amplitude, but further testing is required to determine the effect of significant amounts of dust on transducer performance. The impact of the transducer heads impeding the incident fluid flow was found to be very significant in wind tunnel testing. Preliminary computational models were found to accurately predict these effects, but a more comprehensive modelling campaign and experimental validation would be required to ensure accurate instrument calibration
CONSTITUTIONALSM - REFORM ON DATA PROTECTION LAW AND HUMAN RIGHTS
No full textThe purpose of this paper is to address one of the most Fundamental Freedom and Human Rights the protection of privacy, particularly under the provisions of the European Convention on Human Rights as interpreted by the Strasbourg institutions and by national courts. Article 8 of the Convention provides in its first paragraph that everyone has the right to respect for his private and family life, his home and his correspondence. This paper is focused to one of the central issues of the problem of “human rights and scientific and technological developments” i.e., the protection of the privacy. This paper is intended to achieve to explain the legal measures and the state efforts to regulate and to protect the privacy. It tries to interpret the Directive 95/46/EC of the European Parliament and of the Council and to present the major reasons for the movement towards comprehensive privacy and data protection laws.This paper seeks to arrive at conclusions that the problem is continuing even with the adoption of legal and other protections measurements, violations of privacy remain a concern. In many countries, laws have not kept up with the technology, leaving significant gaps in protections. In other countries, law enforcement and intelligence agencies have been given significant exemptions. Finally, in the absence of adequate oversight and enforcement, the mere presence of a law may not provide adequate protection.human rights, privacy, data protection, threat, technological developments.
Measurement of wind on the surface of Mars
No full textThe Martian atmosphere is of great scientific interest, both because of its similarity to Earth’s atmosphere, and because of its relevance to exploration of Mars. Although satellite instruments have provided a wealth of atmospheric data, they have provided little information about the atmospheric boundary layer. Conditions in the lowest few metres of the Martian atmosphere are perhaps the most directly interesting to humans, as this is the portion of our own atmosphere with which we have the most contact. In this thesis is described the design, calibration and operations planning for a new wind sensor for use on Mars. This sensor is lighter and smaller than previous Mars wind sensors. At the time of writing, the wind sensor is on its way to Mars as part of the science payload of Beagle 2, a small exobiology lander due to arrive in December 2003. The Beagle 2 wind sensor (B2WS) is a hot-film anemometer. Three platinum films are equally spaced around the surface of a vertical cylinder. A known current is dissipated in each film, heating the film 40-80°C above the ambient gas temperature. The film temperature is obtained by measuring its resistance. An effective heat transfer coefficient is then calculated for each film. A novel scheme has been developed which allows calculation of a wind vector from the differences between these heat transfer coefficients, rather than from their average. This makes the measured wind vector less prone to common-mode errors such as uncertainties in air temperature or sky temperature. The sensor was calibrated in a low density wind tunnel, optimised to provide stable winds of air or carbon dioxide at Martian pressures (5 – 10 mbar) and speeds (0.5 – 30 m/s). The flow field in the test section was calculated using analytical and finite element modelling techniques, and validated experimentally using a pitot probe. This facility’s stability and accuracy represent a significant improvement over previous calibration facilities. An analytical model of heat flow in the sensor has been developed in order to permit correction for conditions which may be encountered on Mars, but were not tested for in the wind tunnel. The wind sensor’s performance in a real Martian atmosphere is simulated using wind and temperature data from a previous Mars lander. The position of the wind sensor position at the end of Beagle 2's motorised arm allows several new possibilities for wind measurement on Mars that were unavailable in previous missions. The height of the wind and air temperature sensors can be adjusted to any height between 20 and 95 cm above the ground. The temperature sensor can be scanned horizontally and vertically above the lander to study convective updrafts above the heated lander. Planned operations sequences on Mars are discussed
Variability of CO concentrations in the Venus troposphere from Venus Express/VIRTIS using a Band Ratio Technique
No full textA fast method is presented for deriving the tropospheric CO concentrations in the Venus atmosphere from near-infrared spectra using the night side 2.3 μm window. This is validated using the spectral fitting techniques of Tsang et al. [Tsang, C.C.C., Irwin, P.G.J., Taylor, F.W., Wilson, C.F., Drossart, P., Piccioni, G., de Kok, R., Lee, C., Calcutt, S.B., and the Venus Express/VIRTIS Team, 2008a. Tropospheric carbon monoxide concentrations and variability on Venus with Venus Express/VIRTIS-M observations. J. Geophys. Res. 113, doi: 10.1029/2008JE003089. E00B08] to show that monitoring CO in the deep atmosphere can be done quickly using large numbers of observations, with minimal effect from cloud and temperature variations. The new method is applied to produce some 1450 zonal mean CO profiles using data from the first eighteen months of operation from the Visible and Infrared Thermal Imaging Spectrometer infrared mapping subsystem (VIRTIS-M-IR) on Venus Express. These results show many significant long- and short-term variations from the mean equator-to-pole increasing trend previously found from earlier Earth- and space-based observations, including a possible North-South dichotomy, with interesting implications for the dynamics and chemistry of the lower atmosphere of Venus. © 2009 Elsevier Inc. All rights reserved
Characterising Saturn's vertical temperature structure from Cassini/CIRS
No full textThermal infrared spectra of Saturn from 10-1400 cm-1 at 15 cm-1 spectral resolution and a spatial resolution of 1°-2° latitude have been obtained by the Cassini Composite Infrared Spectrometer [Flasar, F.M., and 44 colleagues, 2004. Space Sci. Rev. 115, 169-297]. Many thousands of spectra, acquired over eighteen-months of observations, are analysed using an optimal estimation retrieval code [Irwin, P.G.J., Parrish, P., Fouchet, T., Calcutt, S.B., Taylor, F.W., Simon-Miller, A.A., Nixon, C.A., 2004. Icarus 172, 37-49] to retrieve the temperature structure and para-hydrogen distribution over Saturn's northern (winter) and southern (summer) hemispheres. The vertical temperature structure is analysed in detail to study seasonal asymmetries in the tropopause height (65-90 mbar), the location of the radiative-convective boundary (350-500 mbar), and the variation with latitude of a temperature knee (between 150 and 300 mbar) which was first observed in inversions of Voyager/IRIS spectra [Hanel, R., and 15 colleagues, 1981. Science 212, 192-200; Hanel, R., Conrath, B., Flasar, F.M., Kunde, V., Maguire, W., Pearl, J.C., Pirraglia, J., Samuelson, R., Cruikshank, D.P., Gautier, D., Gierasch, P.J., Horn, L., Ponnamperuma, C., 1982. Science 215, 544-548]. Uncertainties due to both the modelling of spectral absorptions (collision-induced absorption coefficients, tropospheric hazes, helium abundance) and the nature of our retrieval algorithm are quantified. Temperatures in the stratosphere near 1 mbar show a 25-30 K temperature difference between the north pole and south pole. This asymmetry becomes less pronounced with depth as the radiative time constant for the atmospheric response increases at deeper pressure levels. Hemispherically-symmetric small-scale temperature structures associated with zonal winds are superimposed onto the temperature asymmetry for pressures greater than 100 mbar. The para-hydrogen fraction in the 100-400 mbar range is greater than equilibrium predictions for the southern hemisphere and parts of the northern hemisphere, and less than equilibrium predictions polewards of 40° N. The temperature knee between 150-300 mbar is larger in the summer hemisphere than in the winter, smaller and higher at the equator, deeper and larger in the equatorial belts and small at the poles. Solar heating on tropospheric haze is proposed as a possible mechanism for this effect; the increased efficiency of ortho- to para-hydrogen conversion in the southern hemisphere is consistent with the presence of larger aerosols in the summer hemisphere, which we demonstrate to be qualitatively consistent with previous studies of Saturn's tropospheric aerosol distribution. © 2007 Elsevier Inc. All rights reserved
A Cheery Soul: (Union Theatre , 1963)
No full textWorld PremiereUnion Theatre Repertory Company, 1963Patrick White's classic comedy of manners is set in his favourite fictional suburb of Sarsaparilla at the end of the 1950s. It is a satirical look at the mores of a so-called Christian society. Decribed by White as being about "the destructive power of good."Venue: Union Theatre , Parkville, VICCredits: Elspeth Ballantyne (Actor), Jane Bertelson (Actor), Dorothy Bradley (Actor), Christine Calcutt (Actor), Moira Carleton (Actor), Jane Casson (Actor), Heather Charles (Actor), Simon Chilvers (Actor), Sydney Conabere (Actor), Wyn Cunningham (Actor), Henry Drazak (Actor), Paul Eddey (Actor), Paul Float (Actor), Eric Hoek (Actor), Louise Homfrey (Actor), Helene Jacoby (Actor), Brian James (Actor), Marie Locantro (Actor), Cherie Martini (Actor), Renee Martini (Actor), Gerda Nicolson (Actor), Nita Pannell (Actor), Bettina Smeaton (Actor), Doreen Warburton (Actor), Dawn Wright (Actor), Desmond Digby (Costume Designer), John Sumner (Director), Michael Boudrie (Electrician), Patrick White (Playwright), Richard Prins (Set and/or Property Maker), Desmond Digby (Set Designer), Silver Harris (Stage Manager
THE DEEP ATMOSPHERE OF VENUS
No full textVenus as a planet resembles the Earth, but has a much hotter and denser atmosphere due to an extreme case of the greenhouse effect, caused by compositional differences and tile thick cloud cover. Studies of the lower atmosphere are inhibited by the cloud opacity, which makes remote measurements at most frequencies short. of the radio range quite difficult. Progress in understanding of the com position and thermal structure below the clouds has been made by the Pioneer and Venera entry probes of the 1970s, and more recently with results from the Galileo fly-by in 1990. The latter exploited the newly discovered near-infrared 'windows' to achieve measurements of carbon monoxide and water vapour abundances in the deep atmosphere, and provided the first detailed view of the global cloud structure. The morphology and spatial variations seen in the main mass of clouds are remarkable, and suggest a powerful and diverse meteorology dominated by convection. Carbon monoxide is significantly more abundant at high northern latitudes than at low latitudes in either hemisphere
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