In April 2023, the European Space Agency (ESA) launched its largest interplanetary space probe to date: the Jupiter Icy Moons Explorer (JUICE). Scheduled to arrive at Jupiter in July 2031, JUICE will conduct a four-year investigation of the planet and its Galilean moons, concluding with an orbital phase and final impact on Ganymede. This paper summarizes the mission drivers and key system and subsystems design. Instrument accommodation, verification strategy, launch and commissioning activities, and the principal performance characteristics of the spacecraft and payload are also outlined.

The JUpiter ICy moons Explorer (JUICE) is an ESA-led L-class mission of the ESA’s Cosmic Vision 2015-25 Programme. JUICE is aimed at a thorough investigation of the Jupiter system in all its complexity with emphasis on Galilean satellites, and in particular the potential habitability of the two icy moons, Ganymede and Europa. A large international community of scientists eagerly await the data of the JUICE spacecraft and of its on-board instruments. The mission must be orchestrated flawlessly to ensure that the mission fulfills its expectations, while balancing risks and cost. This is the task of the ESA Ground Segment. We present in this paper the organisation, development and tasks carried out by the Ground Segment of the JUICE mission, from the translation of the scientific questions into a science operation plan that can be executed by the spacecraft and its instruments, to the chain of data acquisition, processing, delivery to the public and archiving for the generations to come. We focus this paper specifically on a description the ESA component of the Ground Segment, while empathising the crucial collaboration with the instrument teams.

The JUICE mission has been launched by an Ariane 5 launcher on April 14, 2023 and is now on its way to reach Jupiter and its icy moons in 2031. The focus of JUICE is to characterise the conditions that may have led to the emergence of habitable environments among the Jovian icy satellites, with special emphasis on the internally active ocean-bearing worlds, Ganymede and Europa. Following a Jupiter Touring phase of 4 years, JUICE will become the first orbiter of a moon that is not our own, entering Ganymede orbit in 2034.The spacecraft passed its commissioning review successfully on July 19, 2023, following the Near Earth Commissioning Phase (NECP), and, despite a few hickups, the ESA and multi-national instruments teams are now operating our interplanetary ship successfully. The preparation of the first combined flyby of the Earth and the Moon in the history of space exploration (August 2024) is on-going. The first planning training exercise was completed by the Science Ground Segment, complementing the preparation of the strategic science planning of the Jupiter Tour.

The JUICE mission has been launched by an Ariane 5 launcher on April 14, 2023 and is now on its way to reach Jupiter and its icy moons in 2031. The focus of JUICE is to characterise the conditions that may have led to the emergence of habitable environments among the Jovian icy satellites, with special emphasis on the internally active ocean-bearing worlds, Ganymede and Europa. Following a Jupiter Touring phase of 4 years, JUICE will become the first orbiter of a moon that is not our own, entering Ganymede orbit in 2034.The spacecraft passed its commissioning review successfully on July 19, 2023, following the Near Earth Commissioning Phase (NECP), and, despite a few hickups, the ESA and multi-national instruments teams are now operating our interplanetary ship successfully. We report on the interplanetary cruise so far, and in particular on the first-ever Moon-Earth double gravity assist manouver performed on August 19-20.

JUICE - JUpiter ICy moons Explorer - is the first large mission in the ESA Cosmic Vision 2015-2025 programme. The mission was selected in May 2012, and is now (May 2021) in the final stages of its integration and testing campaigns. Following its arrival at Jupiter in July 2031, JUICE will spend 4.2 years making detailed observations of Jupiter and three of the Galilean moons, Ganymede, Callisto and Europa. We present here the plan of activities to be carried out during the interplanetary cruise phase.1. Trajectory during the cruise phaseThe mission will be launched from Kourou with an Ariane 5. The baseline launch window is between 26 August – 15 September 2022, with a backup launch slot in August 2023. The interplanetary transfer sequence relies on gravity assist manoeuvres with Venus, Earth and the Moon. The Jupiter orbit insertion will be performed in July 2031. The cruise phase officially starts after the end of the near-Earth commissioning (launch + 3 months) and ends six months before the Jupiter orbit insertion, when the nominal science mission begins.The list of planetary gravity assists is given in Table 1: Date Planet Pericenter altitude [km] 01/09/2023 02/09/2023 Moon Earth 300 180,000 23/08/2024 Earth 13,400 31/08/2025 Venus 5,100 29/09/2026 Earth 8,600 18/01/2029 Earth 4,600 2. Spacecraft and mission constraints during the cruise phaseThe main limitations during the cruise phase are:Priority of operations in support of navigation and spacecraft safety, especially in the preparation of gravity assist manoeuvres, in particular the world premiere of Lunar-Earth gravity assist The thermal design of the spacecraft which imposes, for heliocentric distances lower than 1.34 AU, restricted pointing capabilities and limitations in the number of instruments that can operate simultaneously. Quiet Cruise baseline: Reduced number of ground contacts (one ground station pass per week except for planetary flybys). Operational constraint to minimize the use of the mass memory during Cruise to preserve unit lifetime, limiting the possibility to operate the instruments and store their data. Budgetary restrictions that result in small operation teams during this phase. The baseline operations of the instruments are two one-week checkouts per year. It is expected that at least some of the observations will take place during the planetary flybys, with different possibilities still under study. The requests for operating the payload beyond this baseline will be carefully analyzed and agreed on a best-effort basis. The next section gives example of possible observations.3. Potential scientific investigations to be performed during the cruise phaseInstrument operations during the cruise phase are always useful: they allow calibrating instruments in known environments (e.g. solar wind, Earth’s magnetosphere), checking possible interferences between instruments, they provide scientific results (sometimes not expected and outstanding, resulting in high standard publications) and attract public attention. During the long cruise phase of the JUICE mission, a number of scientific opportunities have been identified, beyond the obvious case of the planetary flybys. They include: solar wind campaigns, neutral atoms imaging in the heliosphere, measurement of Jovian escaping relativistic electrons, measurements of interplanetary dust, test of the general relativity around solar conjunctions, observation of the cosmological radio background, and an asteroid flyby (to be further studied).4. JUICE teams activities during the cruise phaseThe JUICE teams (mission operation center, science operations center, instrument teams, science working team, working groups, project scientist and mission manager) will be busy with numerous activities. A non-exhaustive list is given below:Spacecraft navigation and operations in the inner solar system, including planetary flybys and payload checkouts; Decision about an asteroid flyby (shortly after launch); Analysis of the cruise data, instrument calibration, scientific analysis, publication and archive; Refinement and agreement (three years before Jupiter orbit insertion) on the trajectory within the Jupiter system; Preparation of the science planning of the nominal mission and of the science analysis of the future data; Studying and preparing the coordination with ground-based and space observatories; Publication of a special issue with mission, instruments and science articles; Recruitment of guest investigators and of potentially additional interdisciplinary scientists; Continue the fruitful collaboration with the NASA Clipper teams. Conclusions The JUICE cruise phase, despite its long duration (9 years), will be busy with many activities, with the goal of being fully ready to start the scientific observations from early 2031 onwards. FiguresFigure 1: Evolution of distances (in AU) between the Sun, the Earth, Jupiter and JUICE as a function of time. Figure 2: Overall cruise projected in the ecliptic frame Figure 3: Lunar-Earth flyby in 2023Figure 4: Illustration of the 300 km lunar flyby in 2023. The lunar and Earth disks are dark due the Sun position.

The JUpiter ICy Moons Explorer (JUICE) is a European Space Agency mission that will fly by and observe the Galilean satellites Europa, Ganymede and Callisto, characterize the Jovian system in a lengthy Jupiter-orbit phase, and ultimately orbit Ganymede for in-depth studies of habitability, evolution and the local environment [1].

(1) ESA / ESTEC, Noordwijk ZH, Netherlands (dmitri.titov@esa.int, +31-71-565-37-70), (2) Swedish Institute for Space Physics, Sweden, (3) University of Trento, Italy, (4) Imperial College, London, UK, (5) University of Oxford, UK, (6) Southwest Research Institute, San Antonio, TX, USA, (7) University of Nantes, France, (8) JIVE, The Netherlands, (9) Delft University of Technology, The Netherlands, (10) Max Planck Institute for Solar System Research, Goettingen, Germany, (11) Institute of Planetary Research, DLR, Berlin, Germany, (12) Sapienza Universita di Roma, Italy, (13) IAS, Orsay, France, (14) Universita Parthenope Napoli, Italy, (15) IAPS, Roma, Italy, (16) IRF-Uppsala, Sweden

This presentation will give a status of the JUICE mission in the end of the definition phase, its science scenario, and the observation strategies that are foreseen with a strong emphasis on the complemen-tarity of the suite of instruments. To summarize, the instrument suite on-board JUICE will allow the inte-gration of datasets into a comprehensive multisensor / multitemporal / multiresolution view maximizing the scientific return of the data. This will be demonstrated using six examples that are briefly described in this abstract.

Past exploration of Jupiter's diverse satellite system has forever changed our understanding of the unique environments to be found around gas giants, both in our solar system and beyond. The detailed investigation of three of Jupiter's Galilean satellites (Ganymede, Europa, and Callisto), which are believed to harbour subsurface water oceans, is central to elucidating the conditions for habitability of icy worlds in planetary systems in general. The study of the Jupiter system and the possible existence of habitable environments offer the best opportunity for understanding the origins and formation of the gas giants and their satellite systems. The JUpiter ICy moons Explorer (JUICE) mission, selected by ESA in May 2012 to be the first large mission within the Cosmic Vision Program 2015–2025, will perform detailed investigations of Jupiter and its system in all their inter-relations and complexity with particular emphasis on Ganymede as a planetary body and potential habitat. The investigations of the neighbouring moons, Europa and Callisto, will complete a comparative picture of the Galilean moons and their potential habitability. Here we describe the scientific motivation for this exciting new European-led exploration of the Jupiter system in the context of our current knowledge and future aspirations for exploration, and the paradigm it will bring in the study of giant (exo) planets in general.

In this paper, we provide a detailed review of Ganymede's characteristics that are germane to any consideration of its planetary protection requirements. Ganymede is the largest moon in our solar system and is the subject of one of the main science objectives of the JUICE mission to the jovian system. We explore the probability of the occurrence of potentially habitable zones within Ganymede at present, including those both within the deep liquid ocean and those in shallow liquid reservoirs. We consider the possible exchange processes between the surface and any putative habitats to set some constraints on the planetary protection approach for this moon. As a conclusion, the "remote" versus "significant" chance of contamination will be discussed, according to our current understanding of this giant icy moon. Based on the different estimates we investigate here, it appears extremely unlikely that material would be exchanged downward through the upper icy layer of Ganymede and, thus, bring material into the ocean over timescales consistent with the survival of microorganisms.

The discovery of four large moons orbiting around Jupiter by Galileo Galilei four hundred years ago spurred the Copernican Revolution and forever changed our view of the Solar System and universe. Today, Jupiter is seen as the archetype for giant planets in our Solar System as well as for the numerous giant planets known to orbit other stars. In many respects, and in all their complexities, Jupiter and its diverse satellites form a mini-Solar System. By investigating this system, and thereby unravelling the history of its evolution, from initial formation of the planet to the development of its satellite system, we will gain a general understanding of how gas giant planets and their satellite systems form and evolve and of how our Solar System works.

A primary motivation for in situ probe and balloon missions in the solar system is to progressively constrain models of its origin and evolution. Specifically, understanding the origin and evolution of multiple planetary atmospheres within our solar system would provide a basis for comparative studies that lead to a better understanding of the origin and evolution of our own solar system as well as extra-solar planetary systems. Hereafter, the authors discuss in situ exploration science drivers, mission architectures, and technologies associated with probes at Venus, the giant planets and Titan.

The Jovian radiation environment experienced by spacecraft such as the proposed Jupiter Ganymede Orbiter (JGO) is intense and characterized by a harder electron spectrum than typical of the terrestrial radiation belts. The DICTAT code is a 1-d analytical tool that is widely used for the assessment of electron-induced internal charging effects in terrestrial orbit. This code has been modified to extend the validity of the code to higher electron energies. In addition, the current deposition algorithm has been made material-specific, so that high atomic number materials used as shielding can be modelled. These changes are to enable the more energetic Jovian environment to be simulated and to allow the effects of Tantalum shielding to be modelled. Tantalum is expected to be widely used to control radiation levels on the JGO spacecraft. Simulations using the modified code indicate that the Jovian environment is more severe in terms of internal charging than the terrestrial geostationary environment and that shielding mass can be saved by using Tantalum instead of Aluminium.