Alessandra Rotundi

The laboratory analyses of cosmic dust analogues have a critical role in the understanding of cosmic dust condensation processes. The morphological, structural and chemical characterisation of these analogues are critical for comparisons with astronomical observations data and models. Carbon-rich dust samples are prepared by arc discharge in Ar and H2 atmosphere at pre-selected proportions. To identify their internal textures we used High Resolution Electron Microscopy and chemical analyses was done by HPLC and mass spectrometer. Carbon soot grains, crystallographically amorphous, consist of individual Single-Wall Spheres (SWS - diameters: 0.7 nm to 10nm) forming close-packed arrangements. These spheres are also observed in short and straight, or long and curved, liner arrangement called proto-fringes with a thickness corresponding to the diameters of the SWS. SWS resemble structures in synthetic C60 crystals, including C50, possibly C32, and larger elongated fullerenes. The fringe ...

The Grain Impact Analyzer and Dust Accumulator (GIADA) instrument on board ESA’s Rosetta mission is constraining the origin of the dust particles detected within the coma of comet 67 P/Churyumov–Gerasimenko (67P). The collected particles belong to two families: (i) compact particles (ranging in size from 0.03 to 1mm), witnessing the presence of materials that underwent processing within the solar nebula and (ii) fluffy aggregates (ranging in size from 0.2 to 2.5 mm) of sub-micron grains that may be a record of a primitive component, probably linked to interstellar dust. The dynamics of the fluffy aggregates constrain their equivalent bulk density to <1 kg m−3. These aggregates are charged, fragmented, and decelerated by the spacecraft negative potential and enter GIADA in showers of fragments at speeds <1m s−1. The density of such optically thick aggregates is consistent with the low bulk density of the nucleus. The mass contribution of the fluffy aggregates to the refractory ...

HRTEM and microRaman spectroscopy can detect minute amounts of C60 fullerene in cometary IDPs and carbonaceous chondrites prior to destruction by interactions with the atmosphere. STARDUST samples must be protected to avoid fullerene deterioration.

... Campins, H., and Rayan, EV: 1989, 'The identification of crystalline olivine in cometary silicates', Astrophys ... Mennella, V., Colangeli, L., Cecchi Pestellini, C., Palomba, E., Palumbo, P., Rotundi, A., and Bus-soletti, E.: 1996b, 'The role of hydrogen in small amorphous carbon grains ...

Imaging of comet 46P/Wirtanen was performed in the standard VRI filters on 10 and 11 November 1996 with the 1.0 m telescope of the South African Astronomical Observatory (SAAO). After proper processing and calibration, the images have been used to derive information about the isophote distribution, magnitude and colour indices. We observed a coma extending to at most ∼5×103 km.

ABSTRACT The study of cosmic dust and its evolution from molecular clouds, through protoplanetary disks to planets, is one of the outstanding challenges of contemporary astronomy. Interplanetary Dust Particles (IDPs) represent the fossil pre-solar dust that provides a unique access to the materials and processes occurred during Solar System formation and evolution. IDPs collected in the stratosphere have been widely analysed. Despite the information acquired, the links between IDPs, asteroids, comets, interstellar and circumstellar dust are not yet fully understood. The characterisation performed in our laboratory on IDPs, both stratospheric and collected in space, is aimed to understand their history, from formation to collection. To this aim, we implemented a micro-manipulation work station for the complete automatised, non contaminant and safe handling of micro-samples. Combined analyses are necessary in order to acquire the most comprehensive set of information on each sample. The non destructive analyses performed so far are: micro-infrared spectroscopy, Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray (EDX) analysis. Results from our IDPs research program are reported.

The Cosmic Physics Laboratory (CPL) work is focused to study materials present in various space environments (comets, asteroids, planets, interstellar medium). The study is performed on dusty materials which are selected among natural rocks and minerals that, properly treated and/or processed, are able to simulate extraterrestrial materials. An accurate characterisation of each kind of sample is performed by means of

In preparation for the Stardust sample analyses, we performed combined micro-IR/micro-Raman measurements on five Interplanetary Dust Particles (IDPs) that were characterized by Field Emission Scanning Electron Microscope analyses. We demonstrate the synergy between these techniques to detect Fe-oxides and the degree of ordering in amorphous carbons, and IR-based classification of these IDPs collected in the lower stratosphere. We present IR

Spectroscopic observations performed by the ISO satellite of cometary and circumstellar dust have provided the evidence that crystalline silicates are among their major constituents. The presence in various astronomical environments of crystalline grains raises problems on the formation processes. Once amorphous dust is formed, thermal annealing can change the internal structure, supplying enough energy to the atoms to overcome the energy barrier to reach more ordered configurations. In this work we present laboratory results on amorphous-crystalline transitions of olivine and pyroxene samples by thermal annealing at 800 and 1000 C for various time lags. Monitoring of the process is performed by infrared spectroscopy. The results show that the analysed samples present high activation energy preventing crystallization at low temperature.

Meteorites and interplanetary dust particles (IDP's) are extraterrestrial samples available for investigation in the laboratory. This inventory will be soon enriched by solid fragments directly coming from plantary bodies, thanks to sample return space missions such as Stardust (Brownlee et al., 2000) and Muses-C (Fujiwara et al., 1999). One of the most important requirements for the analysis of these materials is the application of nondestructive methods. A quite complete overview of the analytical techniques, used in experiments on nanosamples, is given by Zolensky et al. (2000). In the present work we will show the potential of infrared micro-spectroscopy (IMS), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) analysis for the characterisation of extraterrestrial samples and the identification of possible bio-signatures.

... The FESEM and TEM data show that the smallest soot grain was 7 nm in diameter.77. Rotundi, A., Rietmeijer, FJM, Colangeli, L., Mennella, V., Palumbo, P. and Bussoletti, E ... Taylor, R., Parsons, JP, Avent, AG, Rannard, SP, Dennis, TJ, Hare, JP, Kroto, HW and Walton, DRM 1991 ...

The Grain Impact Analyzer and Dust Accumulator - GIADA - is one of the payloads on-board Rosetta Orbiter. Its three detection sub-systems are able to measure the speed, the momentum, the mass, the optical cross section of single cometary grains and the dust flux ejected by the periodic comet 67P Churyumov-Gerasimenko. During the Hibernation phase of the Rosetta mission, we have performed a dedicated extended calibration activity on the GIADA Proto Flight Model (accommodated in a clean room in our laboratory) involving two of three sub-systems constituting GIADA, i.e. the Grain Detection System (GDS) and the Impact Sensor (IS). Our aim is to carry out a new set of response curves for these two subsystems and to correlate them with the calibration curves obtained in 2002 for the GIADA payload onboard the Rosetta spacecraft, in order to improve the interpretation of the forthcoming scientific data. For the extended calibration we have dropped or shot into GIADA PFM a statistically rele...

Introduction. We report the latest improvements of the model of aspherical dust grain dynamics [1] in the cometary atmosphere of 67P/Churyumov- Gerasimenko(67P/C-G). The model is aimed to support the scien- tific objectives of GIADA (Grain Impact Analyzer and Dust Accumulator) in-situ experiment [2] on board of the ESA ROSETTA spacecraft. The instrument will measure individual dust grain mass, number density and velocity in the immediate vicinity of the cometary nucleus. In this report we discuss the distinctions in the dy- namics of the aspherical dust in comparison with the spherical approximation developed in the currently used 3D+t spherical dust models [3,4]. Model. We assume that dust grains are homogeneous, isothermal polygonal convex bodies (close to ellipsoid of revolution with different aspect ratios of axes). The grains are moving under influence of three forces: aero- dynamic , gravitational and torque. The gas distribution (density, velocity, temperature) in the coma is...

In this work we investigated the ability of four extremophilic bacteria from Archaea and Bacteria domains to resist to space environment by exposing them to extreme conditions of temperature, UV radiation, desiccation coupled to low pressure generated in a Mars' conditions simulator. All the investigated extremophilic strains (namely Sulfolobus solfataricus, Haloterrigena hispanica, Thermotoga neapolitana and Geobacillus thermantarcticus) showed a good resistance to the simulation of the temperature variation in the space; on the other hand irradiation with UV at 254 nm affected only slightly the growth of H. hispanica, G. thermantarcticus and S. solfataricus; finally exposition to Mars simulated condition showed that H. hispanica and G. thermantarcticus were resistant to desiccation and low pressure.

This self-contained instrument was designed to collect nanometer to micrometer scale solid and condensed-liquid aerosol particles in the upper stratosphere at about 40 km that operates in a stand-alone autonomous mode when carried aloft during long-duration stratospheric balloon flights. During its maiden flight as part of an Italian Space Agency campaign, DUSTER [0.4x0.4x0.3 m3 and weighing 30 kg] was launched

ABSTRACT In order to prepare the interpretation of the GIADA in-situ data of Comet 67P/ Churyumov-Gerasimenko a model of dust dynamics is indispensable. The currently used 3D+t model assumes sphericity of the grains. We report the first steps in developing of the model of aspherical dust grain dynamics in the cometary atmosphere. On this stage we study the grain motion in aerodynamic force free region. The grains are convex polygonal bodies. In addition, a new approach for resolving the inverse problem is discussed, namely, based on GIADA observations, we could determine the probable location of the particles emission on the nucleus.