The Grain Impact Analyser and Dust Accumulator (GIADA) Experiment for the Rosetta Mission: Design, Performances and First Results

The 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. The International GIADA Consortium (I, E, UK, F, D, USA).     

Characterization of Cosmic Materials in the Laboratory

One of the main objectives of modern astrophysics is the characterisation of properties and evolution of materials present in space. Production, processing and analysis of cosmic dust analogues in the laboratory represents a powerful tool to interpret astronomical observations and to contribute to the solution of puzzling problems which are so far unsolved. In the present paper we summarize recent results obtained in our laboratory on carbon-based and silicate materials able to simulate various types of cosmic grains. The laboratory data are applied to discuss the nature of spectral features observed in the interstellar medium and in comets. This revised version was published online in June 2006 with corrections to the Cover Date.     

The MAGO experiment for dust environment monitoring on the Martian surface

Among the main directions identified for future Martian exploration, the study of the properties of dust dispersed in the atmosphere, its cycle and the impact on climate are considered of primary relevance. Dust storms, dust devils and the dust “cycle” have been identified and studied by past remote and in situ experiments, but little quantitative information is available on these processes, so far. The airborne dust contributes to the determination of the dynamic and thermodynamic evolution of the atmosphere, including the large-scale circulation processes and its impact on the climate of Mars. Moreover, aeolian erosion, redistribution of dust on the surface and weathering processes are mostly known only qualitatively. In order to improve our knowledge of the airborne dust evolution and other atmospheric processes, it is mandatory to measure the amount, mass-size distribution and dynamical properties of solid particles in the Martian atmosphere as a function of time. In this context, there is clearly a need for the implementation of experiments dedicated to study directly atmospheric dust. The Martian atmospheric grain observer (MAGO) experiment is aimed at providing direct quantitative measurements of mass and size distributions of dust particles, a goal that has never been fully achieved so far. The instrument design combines three types of sensors to monitor in situ the dust mass flux (micro balance system, MBS) and single grain properties (grain detection system, GDS + impact sensor, IS). Technical solutions and science capabilities are discussed in this paper.     

In Situ Collection of Refractory Dust in the Upper Stratosphere: The DUSTER Facility

DUSTER (Dust from the Upper Stratosphere Tracking Experiment and Retrieval) is an instrument designed to collect nanometer to micrometer scale solid aerosol particles in the upper stratosphere on board balloons. With three DUSTER flights we have demonstrated that: (1) the instrument’s performance was within the design parameters of environmental specifications (?80 ^°C; 3–10?mbar); (2) inertial impact collection of aerosols ～500?nm to 24 microns on holey-carbon thin films mounted on Transmission Electron Microscope mesh grids was achieved; (3) the design of an active collector exposed to the air flux and an identical collector “blank”, not exposed to the air flux, to monitor possible contamination permits unambiguous identification of collected particles; (4) save storage of collected samples and subsequent retrieval in the laboratory was achieved with no measurable contamination; (5)?reduced sample manipulation allowed the chemical and structural characterization of collected dust particles by Field-emission scanning electron microscopy and energy dispersive X-Ray analyses, and infrared and Raman micro-spectroscopy. The main and most ambitious goal is the collection and characterization of solid aerosol particles smaller than 3 microns of solar system debris that are currently not sampled on a routine basis by other instruments in the upper stratosphere. DUSTER will provide a record of the amount of solid aerosols, their size, shapes and chemical properties in the upper stratosphere, including particles less than 3 microns in size. The DUSTER program identified 25 particles as collected during the 2008 flight with sizes in the range of 0.4 to 24 microns.