Gas Emissions in the Inner Coma of Comet 67P as seen by ROSETTA/OSIRIS Monica Lazzarin, Fiorangela La Forgia

Rosetta has been one of the most fruitful spacecraft mission directed to a comet. It obtained a wealth of data and results that changed completely our understanding of comets. It was the first mission to not just fly-by a comet but stay around it for more than two years, following its orbital evolution around the Sun and witnessing the onset of its activity as it approached perihelion and afterwards.

However, a huge amount of data are still to be analyzed and investigated. OSIRIS high-resolution camera onboard Rosetta was equipped with a series of filters especially designed to measure the gaseous emissions and spatial distribution in the coma of comet 67P/Churyumov-Gerasimenko.

The interpretation of these data requires a deep understanding of the dust coma brightness and colors, and the mechanisms responsible for the gaseous emissions such as resonance fluorescence.

Our team is deeply involved in Rosetta mission and OSIRIS instrument since it was partially built in Padova. We are expert on OSIRIS data reduction and analysis.

The PhD student will be involved in the reduction and interpretation of OSIRIS/WAC gas filters images. He/She will have to apply fluorescence and coma models in order to derive gas column densities, abundances and production rates. Seasonal and diurnal variation effects will be investigated and comparison with data from other instruments onboard Rosetta will be considered.

This study will help deepen our knowledge of the cometary gas activity evolution but also it will be essential to study the dust/gas interaction in the inner coma, their decoupling and the dust-to-gas ratio, one of the most important parameters connected to the comets formation models. For this work the PhD student will also interact with other members of the Rosetta team, of the OSIRIS instrument, but also of other instruments such as VIRTIS.

Characterization of Dynamically New Comets in favour of Comet Interceptor ESA mission  

Monica Lazzarin, Fiorangela La Forgia, Elisa Frattin

The recently selected ESA mission Comet Interceptor (Snodgrass & Jones 2019) to be launched in 2029 will encounter a Dynamically New Comet (DNC) at its first approach to the Sun, a truly pristine comet that never entered in the inner Solar System before.

Comet Interceptor will wait on a rest orbit around the Sun-Earth Lagrangian point L2 waiting for its target to be discovered. The candidate target will be possibly discovered and selected, on the basis of orbital constraints from the mission, when it will be at about 8-10 AU from the Sun in its inboud orbit.

Comet Interceptor will leave its rest orbit to be directed to the intercept point to the comet when it will cross the ecliptic plane, i.e. around perihelion.

Dynamically New Comets are the most primordial and well preserved objects in the Solar System, they formed very early when the protoplanetary disk was still evolving into planets  and being so small and cold bodies they retain much information on the pristine Solar System.

A few DNCs have been observed in detail so far, primarily at their closest approach to the Sun. Therefore a complete characterization of their properties and activity levels is still to be performed and it is extremely important in view of the challenge that Comet Interceptor mission will take in encountering such a mysterious object.

Our team is widely involved in ground-based observations of DNCs in the visible and near-IR wavelength range in support to Comet Interceptor mission as we are also part of the mission Science Team.

The PhD student will be involved in ground-based observations including preparation of the proposals for observing at TNG (Telescopio Nazionale Galileo, Canary Island), VLT (Very Large Telescope, ESO, Chile) and other major facilities, planning of the observations, data reduction and analysis.

He/she will be involved in the interpretation of the data in terms of activity, gas coma abundances, production rates using combined fluorescence and coma models, as part of the characterization of DNCs that would be used both for the target selection and for the development of models for gas activity predictions for Comet Interceptor mission.

He/She will interect with the whole team involved in Comet Interceptor and will have the possibility to spend also part of the PhD in insitutions involved in the project.

Spectroscopic Investigation of Near Earth Objects connected with the EU project "NEOROCKS"

Monica Lazzarin, Elisa Frattin, Fiorangela La Forgia

This PhD thesis is connected with the ongoing European project named NEOROCKS, for a spectroscopic Investigation of Near Earth Objects (NEOs), in particular Potentially Hazardous Asteroids. NEOs  represent  one  of the  most peculiar  populations  of  Solar System small bodies.  Their origin and their link with the other minor bodies of the Solar System are still a matter of debate. Moreover they represent a real threat for our planet. The  population appears  heterogeneous  in all  the aspects of its physical  properties and they are also very interesting mineralogical sources and only 5% of NEO with known orbits are taxonomically classified. During the PhD, proposals to telescopes such as TNG or NTT, VLT and also Asiago will be prepared and submitted to spectroscopically observe NEOs in the visible and near infrared region. The PhD student will perform observations at the telescopes. In the meanwhile more than 150 spectra are already available for reduction and analysis from TNG adn NTT telescopes. Some of the objectives are:

•       Investigate in  detail  the  surface  composition  of the  objects and  make  a correspondence between taxonomic type and surface mineralogy

•       Search  for  meteorite  parent  bodies  among  NEOs.

•       Investigate the space weathering effects on S-type, C-type and D-type asteroids.

•       Investigate NEOs with peculiar  dynamical properties (e.g. Tisserand invariant<3)   in   order   to   contribute   to   the identification  of possible  NEO  of cometary  origin.

The PhD student will collaborate with the other members of the european Consortium (from Spain, France,  UK, ...).

Modeling and analysis of Mars and Mercury surfaces

G.Cremonese (INAF), A.Lucchetti (INAF)

On March 2016, the European Space Agency (ESA) in collaboration with Russian federal space agency (Roscosmos) launched the Exomars Trace Gas Orbiter (TGO) having on board the stereo visible imaging system CaSSIS (Colour and Stereo Surface Imaging System). Our team has been involved in the realization of the instrument and in the scientific analysis, which includes observations planning, Digital Terrain Models (DTM) generation and target selection.

In addition, our team has the responsibility of the SIMBIO-SYS instrument (Spectrometers and Imagers fro MPO BepiColombo integrated observatory system) on board the upcoming ESA/JAXA BepiColombo mission, which will be launched in October 2018 toward the innermost planet Mercury. SIMBIO-SYS will provide high resolution and stereo visible images and Vis-NIR spectra of the entire surface of the planet.

In this framework, the PhD student will conduct analysis of the surfaces of Mars and Mercury using data coming from ExoMars TGO, which will be operative around Mars at the beginning of 2018, and from NASA/MESSENGER mission in preparation to the upcoming BepiColombo mission. Specifically, the candidate will be able to investigate different surface processes and conduct geomorphological analysis of a wide variety of landforms characterizing the planets’ surface. He/She will be included in a team that is already carrying on surface analysis according to specific subjects, as impact processes, search for water traces, hollows, volcanic activity and so on.

3D analysis of planetary surfaces

Gabriele Cremonese (INAF), Alice Lucchetti (INAF), Cristina Re (INAF)

In the last decades the space missions of any space agencies toward planets or minor bodies have on board a stereo camera or an imaging system in order to 3D reconstruct the surface of the studied body. After the first experience in acquiring 3D images of the Moon and Mars, the planetary scientists have realized the plenty of more information they may get on the studied body.

However, the elaboration and the analysis of stereo images, in order to generate a Digital Terrain Model, is very complex starting from the design of the imaging system and requirements to the satellite in terms of resources and operations.

Our team is involved in the design and realization of a new concept of stereo camera, which also includes a new method of stereo acquisition for the  ESA BepiColombo and ExoMars missions. In addition, our team is working on developing an advanced concept of stereo camera including the hyperspectral information.

The PhD student will be involved in the analysis of stereo images of Mars acquired by the CaSSIS imager on board the ExoMars TGO mission, he/she will contribute in the development of new software and tools to analyze stereo data and in the design of new stereo cameras.

Volatiles in comets

Monica Lazzarin , Fiorangela La Forgia

The Solar System formed from a primordial molecular cloud in physical conditions that are still subject of great debate. The most primordial objects of the Solar System are comets, which formed very early at very low temperatures and slowly accumulated ices for a long time. Comets retain thus great amounts of primordial volatiles and supervolatiles such as water, carbon monoxide, and oxygen that conceal crucial physical parameters such as the temperature formation and the relative composition of the primordial molecular cloud. The PhD project focuses on the spectral analysis of the volatiles released by comets. Data available from Rosetta mission (comet 67P/Churyumov-Gerasimenko), other space missions such as Deep Impact (comet 1P/Tempel1 and 103P/Hartley 2) and ground-based data (from Asiagoand other observing proposal to be submitted) will be used for the purpose. Combined fluorescence and coma models for various molecules at a wide range of wavelengths together with the modelling of numerous chemical reactions acting in extreme conditions are necessary to interpret the data and build a complete scenario of how volatiles behave in comets.

This PhD project will be performed in collaboration also with Dr. Dennis Bodewits of the University of Maryland-USA that could act as external supervisor.

High resolution spectroscopy of bright comets         

Gabriele Cremonese (INAF), Pamela Cambianica (INAF)

High resolution spectroscopy of comets allows to get important insights on the origin of the object and on the physical and chemical processes working in the coma and in the nucleus.

In the 2020 we obtained very good data of the bright comet C/2020 F3 NEOWISE using the TNG telescope and the HARPSN spectrograph. The spectra obtained in 3 different nights are a real mine for the comet analysis and in general for the cometary objects. Starting from the catalog of all the emission lines present in the visible spectral range it is possible to work on different topics as follows:

• To make a model to calculate the isotopic ratios of Carbon and Nitrogen,
• To derive the production rate of several molecules, as the spectra are absolute calibrated
• To compare the observation of some molecules with other comets, including the N2+ that is rarely observed in other objects
• To search for identifying several unknown emissions

The PhD student will work on the deep analysis of the data and on preparing the theoretical models, then he/she support the observations and analysis of other bright comets.

This work will be within the project of analysis of cometary dust and gas coma within the team including M.Fulle (INAF-Trieste) and Maria Teresa Capria (INAF-IAPS).