Variability of the plasma environment around Jupiter's icy moons
Lead Research Organisation:
Imperial College London
Department Name: Physics
Abstract
Why? The icy moons, Ganymede, Callisto, and Europa, are surrounded by a thin gas envelop which can be ionized. The composition of the induced plasma is a signature of the moon's surface composition and its density is linked to the neutral atmospheric source. The presence of this conductive layer plays a key role in the interaction of the moon with Jupiter's magnetosphere with moon's particularities (e.g., intrinsic magnetic field at Ganymede). This project is in support to ESA Jupiter Icy Moon Explorer (JUICE).
The PhD project will focus on modeling the plasma environment around Jupiter's icy moons and study its variability. Voyager, Galileo and Earth-based observations will be used for constraining the gas sources. Some goals to be addressed include:
- How does Ganymede's intrinsic magnetic field influence the plasma environment?
- How variable in time and in space is the moon's conductivity? - How different is the conductivity at each moon? How does it influence the detection of the subsurface ocean?
The PhD project will focus on modeling the plasma environment around Jupiter's icy moons and study its variability. Voyager, Galileo and Earth-based observations will be used for constraining the gas sources. Some goals to be addressed include:
- How does Ganymede's intrinsic magnetic field influence the plasma environment?
- How variable in time and in space is the moon's conductivity? - How different is the conductivity at each moon? How does it influence the detection of the subsurface ocean?
Publications
Carnielli G
(2020)
Simulations of ion sputtering at Ganymede
in Icarus
Carnielli G
(2019)
First 3D test particle model of Ganymede's ionosphere
in Icarus
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| ST/N504336/1 | 01/10/2015 | 31/03/2021 | |||
| 1708329 | Studentship | ST/N504336/1 | 01/10/2015 | 31/03/2019 | Gianluca CARNIELLI |
| Description | Ganymede is one of the Galilean moons orbiting Jupiter. Besides being the largest moon in the Solar System (and larger than Mercury), it is also the only one known to generate internally a dipole magnetic field that is strong enough to create a region of closed magnetic field lines at low latitudes. Therefore, Ganymede generates effectively its own magnetosphere embedded inside that of Jupiter: a unique environment within the Solar System. Moreover, there is observational evidence that the Galilean moons (except for Io) bear a subsurface ocean, which makes them potential habitats for extraterrestrial life. Currently, our knowledge of Ganymede builds primarily upon from relatively recent remote-sensing observations and a limited set of in situ measurements acquired during flybys of the NASA spacecraft 'Galileo' between 1996 and 2000. Our understanding of this moon is far from complete. In fact, very little is known regarding its geological history, subsurface ocean, neutral atmosphere, ionosphere and interaction between the moon's and planet's magnetic fields. For this reason, the European Space Agency has selected a mission, called JUpiter ICy moon Explorer (JUICE), that will perform detailed measurements of this moon by orbiting it. In preparation for the upcoming JUICE mission, I have developed a model aimed at advancing our understanding of the neutral and plasma environments around Ganymede, with a focus on the ionosphere. The model is based on 3-D test particle simulations of ion species present in the moon's magnetosphere, including ions from Jupiter's magnetosphere and Ganymede's ionosphere, and energetic neutrals formed from the interaction between the neutral atmosphere and ionosphere. In particular, these constitute the first 3-D simulations of Ganymede's ionospheric ions. The model generates a 3-D mapping of the plasma moments around the moon, including number density, bulk velocity, thermal and average kinetic energy for all species. It records individual test particle trajectories, and it generates a surface mapping of the average impact energy, and impact and sputtering rates. The simulated ionosphere agrees well with Galileo in situ data in terms of the energy spectrogram, but differs from it concerning the electron number density along the spacecraft trajectory. Such a discrepancy is resolved by adapting the input exospheric configuration used in the model, suggesting that our current picture of Ganymede's exosphere is incorrect. According to the simulations, the exospheric column density should be at least one order of magnitude higher compared to previous estimates. Furthermore, the model finds that ionospheric ions provide a major contribution to the surface sputtering, which is a new finding that needs to be addressed in our theory of the moon's exosphere. Hence, this source needs to be taken into account in exospheric models. The results from this model will be used as a tool in preparation for the JUICE mission and the model itself will serve as a useful tool for the interpretation of data acquired by the payload instruments on board the spacecraft. |
| Exploitation Route | The findings from the ionospheric model developed will be used by the science teams (in particular, the science teams of the magntometer, the UV spectrometer, and the radio wave plasma instrument) of the ESA JUICE mission to plan measurement campaigns and to interpret in situ data measured by the spacecraft payload instruments. |
| Sectors | Aerospace, Defence and Marine |
| URL | https://spiral.imperial.ac.uk/handle/10044/1/78695 |
| Description | I have presented my work at several outreach events throughout my research project, inspiring future scientists and non-experts on the mysteries and fascinating aspects of space. In addition, the findings from this project will be used by the European Space Agency to help planning the measurement campaign of the JUICE spacecraft at the time it will fly by or orbit Ganymede, Jupiter's largest moon. |
| Sector | Aerospace, Defence and Marine,Education |
| Impact Types | Cultural |
| Description | EPSC 2018 Bursary |
| Amount | € 450 (EUR) |
| Organisation | Europlanet |
| Sector | Charity/Non Profit |
| Country | France |
| Start | 09/2018 |
| End | 09/2018 |
| Description | Financial assistance to attend EGU 2018 conference |
| Amount | € 290 (EUR) |
| Organisation | European Geosciences Union |
| Sector | Charity/Non Profit |
| Country | Germany |
| Start | 04/2018 |
| End | 04/2018 |
| Description | Collaboration on the development of a test particle model |
| Organisation | Sorbonne University |
| Country | France |
| Sector | Academic/University |
| PI Contribution | I developed the ionospheric model. I am also looking at how the results of the ionospheric model can be used to improve the exospheric and hybrid models on which it relies, in order to improve the models self-consistently. |
| Collaborator Contribution | They helped in the development of the ionospheric model through discussions. We also discussed the results of the models together. |
| Impact | Oral presentations at: EPSC 2017, 1st IUGG symposium in Berlin (2017), 1st British Planetary Science Congress in Glasgow (2017). Poster presentations at: EGU 2017, EGU 2018. Paper submitted to Icarus (under revision) |
| Start Year | 2015 |
| Description | Outreach |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | Regional |
| Primary Audience | Public/other audiences |
| Results and Impact | The outreach event was part of the "Imperial Fringe Festival" on Space Science. Lots of people attended and were amazed by the work we do. Another even took place at the Science museum, in conjunction with the return of Tim Peake from the ISS. The focus theme for that even was Rosetta, and people enjoyed it a lot. |
| Year(s) Of Engagement Activity | 2015,2016 |