324,609 research outputs found
GIADA - Grain Impact Analyser and Dust Accumulator - on board the ESA/Rosetta space mission
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 plunged in the dust environment
of the coma of comet 67P/Churyumov–Gerasimenko and since August 2014 till end of September 2016 is exploring the dust flux evolution and grain dynamic properties with position and time. GIADA is giving unique measurements on key parameters that no
ground-based observation or fly-by space missions are able to obtain. GIADA is measuring
mass/size of individual dust particles larger than about 60 μm in diameter together, their momenta, in the range 6.5 ×
10^−10 ÷ 4.0 × 10^−6 kg m s^−1, and velocities up to about 30 m s^−1. For micron/submicron particles
the cumulative mass is being measured with a 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. GIADA is behaving as expected according to the design
specifications
Dynamics of non-spherical dust in the coma of 67P/Churyumov- Gerasimenko constrained by GIADA and ROSINA data
No full textAmong the comet 67P/Churyumov-Gerasimenko (67P/C-G) in situ measurements, the closest that have ever been performed at a comet nucleus, are also those of speed, mass, and cross-section of cometary grains performed by the Grain Impact Analyser and Dust Accumulator (GIADA) instrument. To interpret GIADA data, we performed dust dynamical numerical simulations with both spherical and non-spherical (spheroids) shapes. This allowed us to analyse how the grain non-sphericity affects the data interpretation. We find that some measured dust speeds are unlikely reproducible when a spherical shape is considered. We considered two GIADA observational periods, 2015 February 19-27 and 2015 March 13-28. Gas parameters calibrated with the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) measurements have been used to retrieve the gas conditions to set up the dust particle motion. The dust grains are assumed to be out of the near nucleus coma, i.e. where the gas velocity is radial and constant, therefore they are either aligned or have random but constant orientation with respect to the gas drag. We reproduced the GIADA dust speeds, using spheres and two different spheroidal shapes. We find that the particle shapes that reproduce best the GIADA dust speeds are consistent with the particle shape constrained by the GIADA data. We obtain different terminal velocities for spherical and non-spherical particles of the same mass. The shape, which reproduces the GIADA data, is oblate rather than prolate spheroid. We obtain rotational frequencies of the spheroidal particles that best fit the GIADA measurements in these periods
Green Innovation Actions Digital Assessment – GIADA
No full textLa piattaforme GIADA (Green Innovation Actions Digital Assessment) è un sistema
informatizzato web-based di raccolta dati e di valutazione di impatto delle politiche e
delle strategie di green economy. Tale strumento è stato sviluppato quale supporto
all’esigenza di allinearsi agli orientamenti dell’Unione Europea per quanto concerne
l’applicazione dei concetti di Smart Regulation [1] e per un miglioramento continuo
dell’attività di pianificazione strategica, di semplificazione normativa ed
amministrativa al fine di incrementare la qualità della regolazione. GIADA, applicato
in modo sperimentale ad un bando ministeriale rivolto al settore dell’energia
sostenibile, permette di conseguire diverse finalità: archiviazione digitale e
standardizzata dei dati progettuali; monitoraggio delle iniziative; applicazione di un
framework multi-livello di valutazione d’impatto di iniziative afferenti a diversi livelli di
programmazione [2][3].The platform GIADA (Green Innovation Actions Digital Assessment web-based) is a
web-basedn informatic system for data collection and for the impact evaluation of green
economy policies and strategies. This tool has been developed to support the need to
align with the guidelines of the European Union with regard to the application of the
Smart Regulation concepts [1] and for the improvement of the strategic planning
activities, for the regulatory and administrative simplification and forin order to
increase the quality of regulation. GIADA, experimentally applied to a specific
ministerial tender regarding the sustainable energy allows to achieve several
objectives: standardized and digital archiving and projects data; monitoring the
initiatives progress; application of a multi-level framework for the impact assessment of
initiatives relating various programming levels [2][3]
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)
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
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
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&
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
The grain detection system for the GIADA instrument: design and expected performances
No full textThe Grain Detection System (GDS) is part of the instrument GIADA (Grain Impact Analyser and Dust Accumulator), included in the scientific payload of the ESA Rosetta mission towards comet 46P/Wirtanen. GIADA is aimed at analysing the grain dynamic properties and the dust flux evolution in the cometary environment. The GDS is devoted to the detection of single grains entering the instrument, to measure their velocity and to obtain information about their morphology and possibly composition. In this paper we describe the design of the GDS instrument and give some predictions on GDS performances at the comet. In particular, the simulation shows that the GDS will be able to count a total of 4.7 × 105 particle ``events'' during all the GIADA operating phase and so satisfy scientific requirements for a statistically reliable analysis of cometary grains
67P/Churyumov–Gerasimenko’s dust activity from pre- to post-perihelion as detected by Rosetta/GIADA
No full textWe characterized the 67P/Churyumov–Gerasimenko’s dust activity, by analysing individual dust particle velocity and momentum measurements of Grain Impact Analyser and Dust Accumulator (GIADA), the dust detector onboard the ESA/Rosetta spacecraft, collecting dust from tens to hundreds of kilometres from the nucleus. Specifically, we developed a procedure to trace back the motion of dust particles down to the nucleus, identifying the surface’s region ejecting each dust particle. This procedure has been developed and validated for the first part of the mission by Longobardo et al. and was extended to the entire GIADA data set in this work. The results based on this technique allowed us to investigate the link between the dust porosity (fluffy/compact) and the morphology of the ejecting surface (rough/smooth). We found that fluffy and compact particles, despite the lack of correlation in their coma spatial distribution (at large nucleocentric distances) induced by their different velocities, have common ejection regions. In particular, the correlation between the distributions of fluffy and compact particles is maintained up to an altitude of about 10 km. Fluffy particles are more abundant in rough terrains. This could be the result of past cometary activity that resurfaced the smooth terrains and/or of the comet formation process that stored the fluffy particles inside the voids between the pebbles. The variation of fluffy particle concentration between rough and smooth terrains agrees with predictions of comet formation models. Finally, no correlation between dust distribution on the nucleus and surface thermal properties was found
- …
