87,853 research outputs found
GIADA: The Grain Impact Analyser and Dust Accumulator for the Rosetta space mission
No full textThe ESA ROSETTA mission will perform a rendezvous with comet 67P/Churyumov-Gerasimenko and will follow and study it from about 3.25 AU to perihelion at 1.34 AU and, during the foreseen extended mission, up to 2 AU post-perihelion, in order to observe for the first time the onset of activity of a comet and to follow its evolution. The GIADA (Grain Impact Analyser and Dust Accumulator) instrument, on board the ROSETTA orbiter, is aimed to analyse physical and dynamical properties of individual particles ejected by the nucleus and to monitor the dust flux and spatial distribution as a function of time. To achieve these scientific goals, GIADA is composed of different modules: an optical detection system, to monitor the light scattered by single particles entering the instrument, an impact sensor, to detect the momentum carried by the particles, and five micro-balances, to measure the dust flux from different directions. In this work we will describe the technical characteristics and the scientific performances of the flight model of the instrument. The preliminary results of GIADA calibration demonstrate that the instrument is perfectly compatible with design specifications and is suitable to achieve unprecedented scientific results about cometary dust physics
Chairman della "S14 Seismic Design Optimization" in sostituzione del Prof. T. Trombetti alla 14th World Conference on Earthquake Engineering, October 12-17, 2008, Beijing, China
No full textChairman della "S14 Seismic Design Optimization" (Oct.14 Tuesday, 13:30-15:20) in sostituzione del Prof. T. Trombetti alla 14th World Conference on Earthquake Engineering, October 12-17, 2008, Beijing, China
Session S14 Seismic Design Optimization
Co-Chairmen: Silvestri S., Gasparini G.
in substitution of
Salajegheh, E.; Trombetti, T.
Meeting Room No.111
S14-038 Stiffness-Strength-Ductility-Design for C
Braces
rescent Shaped Trombetti, Tomaso Trombetti, Tomaso; Silvestri, Stefano;
Gasparini, Giada
S14-012 Passive Control System of a Steel Truss
Bridge
Girder Cable-Stayed Wang, Kehai Wang, Ke
S14-018 Cost Modeling of Foundations of Reinfo
Buildings Designed for Seismic Effects
rced Concrete Thiruvengadam,
Vellaichamy
Thiruvengadam, Vellaichamy; Wason, J.C.;
Praseeda, K.I.
S14-021 Cost-Effectiveness of Tuned Mass Damper and Base Isolation Hong, Han Ping Lee, C.S.; Goda, Katsuichiro; Hong, Han
Ping
S14-040 Risk-Based Multi-Hazard Optimization o
Structures Using Evolutiounary Algorith
f Passsively Damped
ms
Dogruel, Seda Dogruel, Seda; Dargush, Gary F.
S14-050 Risk Based Minimum Life-Cycle Cost D
Structures
esign of Aseismic Lu, Dagang Lu, Dagang; Wang, Guangyuan
S14-053 Sensitivity Analysis of SDOF Structure P
Damage Ratio Coefficient
arameters on Hadzima-Nyarko,
Marijana
Hadzima-Nyarko, Marijana; Nyarko,
Emmanuel; Moric, Draga
Multi-instrument analysis of 67P/Churyumov-Gerasimenko coma particles: COPS-GIADA data fusion
No full textThe European Space Agency's Rosetta mission to comet
67P/Churyumov-Gerasimenko has offered scientists the opportunity to study a
comet in unprecedented detail. Four instruments of the Rosetta orbiter, namely,
the Micro-Imaging Dust Analysis System (MIDAS), the Grain Impact Analyzer and
Dust Accumulator (GIADA), the COmetary Secondary Ion Mass Analyser (COSIMA),
and the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) have
provided information on cometary dust particles. Cross-instrument comparisons
are crucial to characterize cometary dust particles beyond the capabilities of
individual sensors, as they are sensitive to different dust components. We
present the first comparison between detections of the ROSINA COmet Pressure
Sensor (COPS) and GIADA. These two instruments are complementary as the former
is sensitive solely to volatiles of icy particles, while the latter measured
the dust particle as a whole, including refractories and condensed
(semi)volatiles. Our goal is to correlate the particles detected by COPS and
GIADA and to assess whether they belong to a common group. We statistically
analyzed the in situ data of COPS and GIADA by calculating Pearson correlation
coefficients. Among the several types of particles detected by GIADA, we find
that COPS particles are significantly correlated solely with GIADA fluffy
agglomerates (Pearson correlation coefficient of 0.55 and p-value of ). This suggests that fluffy particles are composed of both
refractories and volatiles. COPS volatile volumes, which may be represented by
equivalent spheres with a diameter in the range between 0.06 m and 0.8
m, are similar to the sizes of the fractal particle's subunits identified
by MIDAS (i.e., 0.05-0.18 m).Comment: 6 pages, 3 figures, accepted for publication in A&
The GIADA experiment for ROSETTA mission to comet 46P/Wirtanen: Design and performances
No full textRosetta is one of the most ambitious missions planned by ESA for the beginning of the next millennium. It will explore from very close a comet nucleus along its trajectory up to perihelion. In the instrument complex forming the scientific payload, the GIADA (Grain Impact Analyser and Dust Accumulator) experiment is devoted to study the cometary dust flux evolution and grain dynamic properties. To achieve the required performances and the expected scientific return, GIADA has been designed as a multi-sensor instrument. It is able to detect grain passage by laser light scattering measurement, particle momentum through piezoelectric transducers and mass flux by means of quartz crystal microbalances. In this paper we describe the technical solutions and performances which have been reached on the development models of GIADA. (C) 1999 COSPAR. Published by Elsevier Science Ltd
GIADA - Grain Impact Analyzer and Dust Accumulator - Onboard Rosetta spacecraft: Extended calibrations
No full textDespite a long tradition of dust instruments flown on-board space mission, the largest number of these can be considered unique as they used different detection techniques. GIADA (Grain Impact Analyzer and Dust Accumulator), is one of the dust instruments on-board the Rosetta spacecraft and is devoted to measure the dust dynamical parameters in the coma of comet 67P/Churyumov-Gerasimenko. It couples two different techniques to measure the mass and speed of individual dust particles. We report here the results of an extended calibration activity carried-out, during the hibernation phase of the Rosetta mission, on the GIADA Proto Flight Model (PFM) operative in a clean room in our laboratory. The main aims of an additional calibration campaign are:to verify the algorithms and procedures for data calibration developed before Rosetta launch;to improve the comprehension of GIADA response after the increased knowledge on cometary dust, e.g. the composition of dust particles after Stardust mission.These calibration improvements implied a final step, which consisted in defining transfer functions to correlate the new calibration curves obtained for the GIADA PFM to those to be used for GIADA onboard the Rosetta spacecraft. The extended calibration activity allowed us to analyze GIADA data acquired in the 67P/C-G coma permitting to infer additional information on cometary dust particles, e.g. density and tensile strength
Multi-instrument analysis of 67P/Churyumov-Gerasimenko coma particles: COPS-GIADA data fusion
No full textContext. The European Space Agency ' s Rosetta mission to comet 67P/Churyumov-Gerasimenko has offered scientists the opportunity to study a comet in unprecedented detail. Four instruments of the Rosetta orbiter, namely, the Micro-Imaging Dust Analysis System (MIDAS), the Grain Impact Analyzer and Dust Accumulator (GIADA), the COmetary Secondary Ion Mass Analyser (COSIMA), and the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) have provided information on cometary dust particles. Cross-instrument comparisons are crucial to characterize cometary dust particles beyond the capabilities of individual sensors, as they are sensitive to different dust components.Aims. We present the first comparison between detections of the ROSINA COmet Pressure Sensor (COPS) and GIADA. These two instruments are complementary as the former is sensitive solely to volatiles of icy particles, while the latter measured the dust particle as a whole, including refractories and condensed (semi)volatiles. Our goal is to correlate the particles detected by COPS and GIADA and to assess whether they belong to a common group.Methods. We statistically analyzed the in situ data of COPS and GIADA by calculating Pearson correlation coefficients.Results. Among the several types of particles detected by GIADA, we find that COPS particles are significantly correlated solely with GIADA fluffy agglomerates (Pearson correlation coefficient of 0.55 and p-value of 4.6 x 10(-3)). This suggests that fluffy particles are composed of both refractories and volatiles. COPS volatile volumes, which may be represented by equivalent spheres with a diameter in the range between 0.06 mu m and 0.8 mu m, are similar to the sizes of the fractal particle ' s subunits identified by MIDAS (i.e., 0.05-0.18 mu m)
The Grain Impact Analyser and Dust Accumulator (GIADA) experiment for the Rosetta mission: design, performances and first results
No full textThe Grain Impact Analyser and Dust Accumulator (GIADA) onboard the ROSETTA mission to comet 67P/Churyumov Gerasimenko is devoted to study the cometary dust environment. Thanks to the rendezvous configuration of the mission, GIADA will be plunged in the dust environment of the coma and will be able to explore dust flux evolution and grain dynamic properties with position and time. This will represent a unique opportunity to perform measurements on key parameters that no ground-based observation or fly-by mission is able to obtain and that no tail or coma model elaborated so far has been able to properly simulate. The coma and nucleus properties shall be, then, clarified with consequent improvement of models describing inner and outer coma evolution, but also of models about nucleus emission during different phases of its evolution. GIADA shall be capable to measure mass/size of single particles larger than about 15 μm together with momentum in the range 6.5 × 10-10 ÷ 4.0 × 10-4 kg m s-1 for velocities up to about 300 m s-1. For micron/submicron particles the cumulative mass shall be detected with sensitivity 10-10 g. These performances are suitable to provide a statistically relevant set of data about dust physical and dynamic properties in the dust environment expected for the target comet 67P/Churyumov Gerasimenko. Pre-flight measurements and post-launch checkouts demonstrate that GIADA is behaving as expected according to the design specifications
GIADA performance during Rosetta mission scientific operations at comet 67P
No full textThe Grain Impact Analyser and Dust Accumulator (GIADA) instrument onboard Rosetta studied the dust environment of comet 67P/Churyumov–Gerasimenko from 3.7 au inbound, through perihelion, to 3.8 au outbound, measuring the dust flow and the dynamic properties of individual particles. GIADA is composed of three subsystems: 1) Grain Detection System (GDS); 2) Impact Sensor (IS); and 3) Micro-Balances System (MBS). Monitoring the subsystems’ performance during operations is an important element for the correct calibration of scientific measurements. In this paper, we analyse the GIADA inflight calibration data obtained by internal calibration devices for the three subsystems during the period from 1 August 2014 to 31 October 2015. The calibration data testify a nominal behaviour of the instrument during these fifteen months of mission; the only exception is a minor loss of sensitivity for one of the two GDS receivers, attributed to dust contamination
GIADA - Grain Impact Analyzer and Dust Accumulator - Onboard Rosetta spacecraft: Extended calibrations
No full textDespite a long tradition of dust instruments flown on-board space mission, the largest number of these can be considered unique as they used different detection techniques. GIADA (Grain Impact Analyzer and Dust Accumulator), is one of the dust instruments on-board the Rosetta spacecraft and is devoted to measure the dust dynamical parameters in the coma of comet 67P/Churyumov-Gerasimenko. It couples two different techniques to measure the mass and speed of individual dust particles. We report here the results of an extended calibration activity carried-out, during the hibernation phase of the Rosetta mission, on the GIADA Proto Flight Model (PFM) operative in a clean room in our laboratory. The main aims of an additional calibration campaign are:to verify the algorithms and procedures for data calibration developed before Rosetta launch;to improve the comprehension of GIADA response after the increased knowledge on cometary dust, e.g. the composition of dust particles after Stardust mission.These calibration improvements implied a final step, which consisted in defining transfer functions to correlate the new calibration curves obtained for the GIADA PFM to those to be used for GIADA onboard the Rosetta spacecraft. The extended calibration activity allowed us to analyze GIADA data acquired in the 67P/C-G coma permitting to infer additional information on cometary dust particles, e.g. density and tensile strength. © 2016 IAA. Published by Elsevier Ltd. All rights reserved.GIADA was built by a consortium led by the Universit'a degli Studi di Napoli Parthenope and INAF – Osservatorio Astronomico di Capodimonte, in collaboration with the Instituto de Astrofisica de Andalucia, Selex-ES, FI, and SENER. GIADA is presently managed and operated by Istituto di Astrofisica e Planetologia Spaziali-INAF, Italy. GIADA was funded and managed by the Agenzia Spaziale Italiana, with the support of the Spanish Ministry of Education and Science Ministerio de Educacion y Ciencias (MEC). GIADA was developed from a Principal Investigator proposal from the University of Kent; science and technology contributions were provided by CISAS, Italy; Laboratoire d‘Astrophysique Spatiale, France, and institutions from the UK, Italy, France, Germany, and the USA. Science support was provided by NASA through the U.S. Rosetta Project managed by the Jet Propulsion Laboratory/ California Institute of Technology. We would like to thank A. Coradini for her contribution as a GIADA Co-Investigator. GIADA calibrated data will be available through ESA's Planetary Science Archive (PSA) Web site (www.rssd.esa.int/index.php?~project=PSA&page=index). All data presented here are available on request before archival in the PSA. This research was supported by the Italian Space Agency (ASI) within the ASI-INAF agreements I/032/05/0 and I/024/12/0
Giada: its Status after the Rosetta Cruise Phase and On-Ground Activity in Support of the Encounter with Comet 67P/CHURYUMOV-GERASIMENKO
No full textInternational audienceGIADA (Grain Impact Analyser and Dust Accumulator) on-board the Rosetta mission to comet 67P/Churyumov-Gerasimenko was designed to study the physical and dynamical properties of dust particles ejected by the comet during the encounter. In this paper we report the results of the analysis of data collected by GIADA during the past seven years of the cruise phase. During this period the GIADA detection subsystems were switched on for periodic in-flight payload checkouts to monitor their state-of-health including potential changes in its performance that could affect its data collection. Only slight variations in sensitivity and dynamical range were identified that will not affect the GIADA measurement capability during the Rosetta comet encounter and rendezvous phase. The GIADA microbalance system detected the presence of low-volatility material over a period of about 169 days when the GIADA cover remained partially opened. It is highly probable that this material originated from the spacecraft itself, as a spacecraft's outgassing was observed by the ROSINA mass spectrometer (on-board Rosetta) during the cruise phase. The identification of the low-volatility mass deposited on the microbalances as self-contamination will allow us to evaluate the mass rate background to be subtracted from the GIADA science data. These results obtained from GIADA cruise data analysis coupled with laboratory calibration data obtained from measurements using the GIADA spare model for selected cometary dust analogs will be the basis for the interpretation of the GIADA scientific data
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