JUICE (Jupiter Icy Moons Explorer)
JUICE is the first large-class mission in ESA's Cosmic Vision 2015-2025 program. Planned for launch in 2022 and arrival at Jupiter in 2029, it will spend at least three years making detailed observations of the giant gaseous planet Jupiter and three of its largest moons, Ganymede, Callisto and Europa. 1) 2)
Science objectives: The focus of JUICE is to characterize the conditions that may have led to the emergence of habitable environments among the Jovian icy satellites, with special emphasis on the three ocean-bearing worlds, Ganymede, Europa, and Callisto. Ganymede is identified for detailed investigation since it provides a natural laboratory for analysis of the nature, evolution and potential habitability of icy worlds in general, but also because of the role it plays within the system of Galilean satellites, and its unique magnetic and plasma interactions with the surrounding Jovian environment. JUICE will determine the characteristics of liquid-water oceans below the icy surfaces of the moons. This will lead to an understanding of the possible sources and cycling of chemical and thermal energy, allow an investigation of the evolution and chemical composition of the surfaces and of the subsurface oceans, and enable an evaluation of the processes that have affected the satellites and their environments through time. The study of the diversity of the satellite system will be enhanced with additional information gathered remotely on Io and the smaller moons. The mission will also characterize the diversity of processes in the Jupiter system that may be required in order to provide a stable environment at the icy moons on geologic time scales, including gravitational coupling between the Galilean satellites and their long term tidal influence on the system as a whole. JUICE will carry out extensive new studies of Jupiter’s atmosphere, magnetosphere and their interaction with the satellites to further enhance our understanding of the evolution and dynamics of the Jovian system. 3) 4) 5)
In 2012, ESA selected the JUICE mission over two other candidates: NGO (New Gravitational wave Observatory), to hunt for gravitational waves, and ATHENA (Advanced Telescope for High-Energy Astrophysics). 6)
Jupiter’s diverse Galilean moons – volcanic Io, icy Europa and rock-ice Ganymede and Callisto – make the Jovian system a miniature Solar System in its own right. With Europa, Ganymede and Callisto all thought to host internal oceans, the mission will study the moons as potential habitats for life, addressing two key themes of Cosmic Vision: what are the conditions for planet formation and the emergence of life, and how does the Solar System work? JUICE will continuously observe Jupiter’s atmosphere and magnetosphere, and the interaction of the Galilean moons with the gas giant planet.
JUICE will visit Callisto, the most heavily cratered object in the Solar System, and will twice fly by Europa. JUICE will make the first measurements of the thickness of Europa’s icy crust and will identify candidate sites for future in situ exploration.
The spacecraft will finally enter orbit around Ganymede in 2032, where it will study the icy surface and internal structure of the moon, including its subsurface ocean. Ganymede is the only moon in the Solar System known to generate its own magnetic field, and JUICE will observe the unique magnetic and plasma interactions with Jupiter’s magnetosphere in detail.
Today’s announcement is the culmination of a process started in 2004 when ESA consulted the wider scientific community to set Europe’s goals for space exploration in the coming decade.
The planned journey of JUICE
• May 12, 2020: Jupiter’s moon Europa is a fascinating world. On its surface, the moon appears to be scratched and scored with reddish-brown scars, which rake across the surface in a crisscrossing pattern. These ‘scars’ are etched into a layer of water ice, which is thought to be at least several kilometers thick and covering a vast – and potentially habitable – subsurface ocean. 7)
Figure 1: The scars seen in this view of the moon (Europa) from the archives of NASA’s Galileo mission – based on images taken by the spacecraft in the 1990s – are a series of long cracks in its icy surface, thought to arise as Jupiter tugs at Europa and breaks the ice apart. The colors visible across the moon’s surface are representative of the surface composition and size of the ice grains: reddish-brown areas, for instance, contain high proportions of non-ice substances, while blue-white areas are relatively pure (image credit: NASA/JPL-Caltech/SETI Institute)
Scientists are keen to explore beneath Europa’s thick blanket of ice, and they can do so indirectly by hunting for evidence of activity emanating from below. A new study, led by ESA research fellow Hans Huybrighs and published in Geophysical Research Letters, did exactly this. Building on previous magnetic field studies by Galileo, the simulation-based study aimed to understand why fewer than expected fast-moving protons – which are subatomic particles with a positive charge – were recorded in the vicinity of the moon during one of the flybys of the moon performed by the Galileo probe in the year 2000. 8)
Researchers initially put this down to Europa obscuring the detector and preventing these usually abundant charged particles from being measured. However, Hans and colleagues found that some of this proton depletion was due to a plume of water vapor shooting out into space. This plume disrupted Europa’s thin, tenuous atmosphere and perturbed the magnetic fields in the region, altering the behavior and prevalence of nearby energetic protons.
Scientists have suspected the existence of plumes at Europa already since the times of the Galileo mission, however indirect evidence for their existence has only been found in the last decade. Excitingly, if such plumes are indeed present, breaking through the moon’s icy shell, they would offer a possible way to access and characterize the contents of its subsurface ocean, which would otherwise be hugely challenging to explore.
These prospects are of great interests to ESA’s upcoming Juice mission, planned for launch in 2022 to investigate Jupiter and its icy moons. Juice will carry the equipment needed to directly sample particles within the moon’s water vapor plumes and also to detect them remotely, aiming to reveal the secrets of its vast, mysterious ocean.
Scheduled to arrive in the Jupiter system in 2029, the mission will study the potential habitability and the underground oceans of three of the giant planet’s moons – Ganymede, Callisto and Europa. As this new study demonstrates, tracing the energetic charged and neutral particles in Europa’s vicinity offers huge promise in efforts to probe the moon’s atmosphere and wider cosmic environment – and this is precisely what Juice plans to do.
Olivier Witasse, ESA’s Juice project scientist, is also a co-author on the study, along with a number of ESA research fellows, including former Science Directorate fellows Lina Hadid and Olivier Lomax, Mika Holmberg, a research fellow in the Technology, Engineering and Quality Directorate.
The new study is based on data collected by Galileo during a flyby of Europa in 2000. The image comprises data acquired by the Galileo Solid-State Imaging (SSI) experiment on the spacecraft's first and fourteenth orbits through the Jupiter system, in 1995 and 1998, respectively, and was recently re-processed in 2014. The image scale is 1.6 km/pixel, and the north pole of the moon is to the right.
Main requirements of the spacecraft design (Ref. 2)
Radiation mitigation: The radiation environment is dominated by the bound electrons in the Jupiter magnetosphere. Their fluence is dominating over the solar proton contribution by several orders of magnitude. The electron spectrum also has a high energy component, which extends to higher energies than exposed to in geo-stationary. At low energies of the electron spectrum, the expected total mission fluence is actually lower than a typical exposure for 10–15 year geostationary mission. Such electrons are predominantly absorbed at the surface, and therefore heritage is available of materials withstanding such doses. For the surfaces of the spacecraft, standard mitigation strategies for geostationary applications will be used, such as coating with conductive layers.
For the considerations of shielding the benefit of units shielding each other has been considered and evaluated with detailed radiation transport simulations. The required radiation tolerance was set at 50 krad at the outside of each unit.
Power: The other main mission drivers are related to the large distance from the Sun, and the requirements that the mission generate power by solar cells. The worst case solar intensity is 46 W/m2. Together with detailed analysis of all critical mission phases, the requirements on the power generation were obtained resulting in a solar array area of close to100 m2. This solar array size can only be obtained when eclipses in the final phases of the mission around Ganymede were excluded. Furthermore, when in Ganymede’s orbit, the normal incidence of the sunlight onto the solar arrays will be maintained through one-axis solar array drive mechanisms combined with a rotation of the spacecraft around the nadir axis. It is however foreseen that this yaw steering could be paused for a limited period of time, e.g. in support of high resolution imaging.
Thermal: The entire spacecraft will be optimized for operations in the cold environment at Jupiter and will be covered by MLI (Multi-Layer Insulation). The albedo heating from the Jupiter moons is negligible. During the Venus gravity assist, the high gain antenna will be used as sun-shield, so as to avoid forcing the spacecraft design to also accommodate for this hot case in full. Passive thermal control will be achieved with radiators; only electrical heating will be provided.
Propulsion: The orbit insertions at Jupiter and Ganymede, the reductions of the altitude of the orbit around Ganymede, and the large number of gravity assists and flyby maneuvers (>25) lead to a high Δv requirement, and consequently to a high wet/dry mass ratio (about 2.6:1). The spacecraft architecture will therefore need to include large volume of propellant tanks.
Communications: The large distance to Earth results in a signal round trip time of up to 1h 46 minutes requiring careful pre-planning and autonomous execution of operations by the spacecraft. Additionally, a high gain antenna is required for data downlink. The data downlink system is sized for an average daily data volume of at least 1.4 Gbit, assuming maximum telecommunication pass of 8 h/day.
AOCS (Attitude and Orbit Control Subsystem): The AOCS is driven by the need for maintaining nadir pointing of the spacecraft during flybys for observations with the scientific instruments. In addition the spacecraft has a large angular inertia mainly due to the large area of the solar panels. The remaining deployable appendices (sub-surface radar antenna and magnetometer boom) add constraints on the pointing stability.
The attitude will be provided through the use of momentum wheels, supported by a propulsion system for off-loading. Off-loading will be scheduled outside science observation windows.
Avionics: The avionics subsystem provides for sufficient command storage to enable the required autonomy of operations. A storage for several days of science data will be included to provide sufficient flexibility such that the spacecraft can be pointed according to the needs of the science instrumentation, and buffer the data for downlink later.
Mechanisms: Mechanisms include the solar panels, the solar array drive mechanisms, the sub-surface radar boom, the magnetometer boom and the RPWI antennae. The appendices will be accommodated such that their deployment can be performed independently, and that they do not infringe the field-of-view of the optical and particle instruments, including stray light avoidance cones.
Launcher: The baseline launcher is Ariane 5 ECA from Kourou.
The mission will include a limited number of flybys of Callisto, Ganymede and Europa, and will then finally go into orbit around Ganymede and will be disposed on Ganymede’s surface. The highest Planetary Protection Category targets are Europa and Ganymede.
Europa is a Planetary Protection Category III target (“chemical evolution and/or origin of life interest or for which scientific opinion provides a significant chance of contamination which could jeopardize a future biological experiment”). The mission therefore either needs to demonstrate that the likelihood of collision with Europa is <10–4, or undergo active bioburden reduction to meet the requirement that the probability of inadvertent contamination of the Europa ocean is <10–4. The first option was taken as the baseline for proceeding. The risk of collision with Europa is limited to the period up to the Europa flybys. After this period the spacecraft has a perijove higher than Europa’s orbit and a lower apocenter, such that collisions are sufficiently unlikely within the timeframe of concern (several 100 years). A dedicated study was performed analyzing the likelihoods of impact, in case of spacecraft failures after each maneuver. Depending on the time and location of the maneuver, this ranges from below 5% to 40% (only for the case of the Europa flyby) for the duration during which it was estimated that the spacecraft would be sterilized by radiation (200 years). Consequently an allocation for the reliability of the spacecraft against total loss was allocated including a margin of at least a factor of two. A preliminary bottom-up assessment of spacecraft’s subsystem reliabilities taking into considerations the lifetime and the exposure to the environment indicated that the overall allocated spacecraft reliability can be met. As for short term failures, i.e. loss of spacecraft control during approach for the Europa flyby, a re-targeting strategy will be performed: the spacecraft trajectory will be implemented such that Europa always remains outside the 3σ uncertainty, and small correction maneuvers be performed during the approach (step-in procedure).
Ganymede is a Planetary Protection Category II target (“significant interest relative to the process of chemical evolution and the origin of life, but only a remote chance that contamination by spacecraft could compromise future investigations”). For Ganymede the bio-burden brought to it shall be controlled and limited such that the likelihood of one active organism reaching the Ganymede subsurface ocean shall be <10–4. For the calculation of the likelihood of bringing a surviving organism to the Ganymede subsurface ocean, the recommendations in [D-3] are followed, and it is largely reduced by the assumption of the low probability of the burial mechanism (10–4) and by the low likelihood of landing in an active region (2 x 10–3). Further factors, such as the estimated cruise survival fraction (10–1), sterilization through radiation (10–1), and probability of survival during transport on the surface (10–2), bring the total likelihood to 2 x 10–11. Assuming a typical bioburden at launch around 106 based on the assumption of equipment exposure to a standard clean room environment, the requirement of 10–4 would be met by a factor of 5.
Consequently, apportionment and monitoring of the bioburden will be required during the mission implementation, by break down and allocation of allowed budgets to each hardware supplier, including payload. Monitoring will be achieved through essays taken at regular intervals.
Furthermore, collateral probability of contamination of alternative critical bodies, such as Mars by any part of the flight segment, including any part of the launch vehicle within 50 years shall be smaller than 10–2. Some launch opportunities consider Mars gravity assists, and it will be demonstrated for these that neither the spacecraft nor any part of the launcher will impact Mars within this timescale. Early assessment confirmed this assumption.
Ground segment and operations
The JUICE mission will be planned and operated by ESA. The ground segment will consist of the Mission Operation Center (MOC) and the Science Operation Center (SOC). The JUICE Science Ground Segment (SGS) is made of the SOC and of the PI instrument teams and will be implemented according to the guidelines described in the Science Management Plan.
The S/C will be operated by an off-line monitoring and control approach. A pre-scheduled timeline (planned sequences of operations, defining S/C or instrument activities) will be uploaded by the MOC at regular intervals and stored on-board. During the nominal science operations, the ground station contact will happen daily, and will be used to upload new S/C and instrument commands, as well as to retrieve the scientific data together with the housekeeping data (for the S/C and instruments). No routine science operations are foreseen in the mission baseline scenario during the cruise phase.
The JUICE SGS is responsible for performing the science operations related to the implementation of the high-level science activities designed by the SWT (Science Working Plan).
Science operations encompass two main groups of activities, called hereafter the Uplink or Downlink side of Science Operations.
The Uplink activities are related to the generation of an instrument operations timeline to be uplinked to the Spacecraft. The SOC and the PI teams will consolidate and validate the science operations requests from individual instrument teams into an instrument operation timeline delivered to the MOC before being uplinked onboard the spacecraft.
In case of non-routine operations (reference measurements during the Earth and Venus flybys during the cruise phase) the SOC will assist the instrument teams in generating Pointing Timeline Request (PTR) files and delivering the instrument commanding directly to the MOC.
Figure 2: Top-level overview of the JUICE operations planning activities. Schematic timeline, workflow and interfaces of the different science planning levels, from the top level science activity plan to the uplink of instrument commands. The blue, semi-transparent box indicates all science planning related to SGS activities (PI teams and SOC).
The nominal science operation planning will be divided in three steps. The first step is the Long Term Planning (LTP) covering 6 months of mission, addressing in more details the top-level planning with a refined knowledge of the S/C resources and constraints. The next step is the MTP (Medium Term Planning) performed on a monthly basis. The main goal of the MTP phase is the finalization of the integration of the observations pointings as well as the validation of the associated instrument modes against the latest knowledge of S/C available resources, constraints and flight rules. The output of this phase is a frozen PTR (Pointing Timeline Request) file. The last step is the STP (Short Term Planning), performed on a monthly basis, whose main goal is the finalization of the instrument commanding.
Downlink activities encompass all data handling and archiving tasks, from retrieval of instrument telemetry and auxiliary data from the DDS (Data Disposition System) under MOC responsibility and all subsequent processing to higher data levels, as well as quick look checks of the performed observations. Data archiving is performed at different levels of the data processing chain.
The SOC will process the telemetry data and distribute the resulting raw data to the instrument teams and to the archive. The raw data processing (telemetry into uncalibrated science data) is centralized at the SOC. Raw data product will be made available to the instrument teams about 4 hours after the telemetry packets are available on the DDS. Immediately after the data becomes available in the DDS, SOC retrieves, verifies and processes all spacecraft and instrument related telemetry (house-keeping and science data) obtained from the DDS. Telemetry integrity (science packets) will be checked by SOC. In addition, SOC retrieves any auxiliary data needed for science data processing, in particular the data from Flight dynamics: reconstructed spacecraft trajectory and attitude.
The instrument teams have the responsibility to generate their calibrated data and distribute them to the archive and follow the general requirements for science data archive format (PDS4). All calibration products (software, procedures and calibration files) must be delivered by the PI teams to the SOC and archived as PDS4 products. The SOC works closely with the instrument teams to facilitate the generation of these products in PDS compliant formats, thereby minimizing the additional effort required for this activity.
Airbus is developing and building JUICE (JUpiter ICy moons Explorer) spacecraft for the European Space Agency, which will study Jupiter and its icy moons. In July 2015, the company was selected by ESA (European Space Agency) as prime contractor for the design, development, production, and testing of a new spacecraft named ‘JUICE’. As prime contractor, Airbus will employ 150 people and lead a consortium of more than 60 companies during the course of the project. 9)
In May 2022, JUICE will begin a 7.6 year cruise to Jupiter to spend three and a half years in the Jovian system. Its main mission will be to explore the huge planet’s three largest icy moons in the hope of determining whether life is possible on these dwarf planets. What if extra-terrestrial life does exist? For centuries, this question – which both fascinates and frightens mankind – has remained unanswered. But by the year 2030, answers to the questions: how do planets form? how does life emerge? how does the solar system work? may well have been found.
It will take JUICE seven and a half years to travel the almost 600 million kilometers to the gas giant. Once the spacecraft enters Jupiter’s gravitational field, the first two and a half years of its three-and-a-half-year mission will be spent making about 30 observation overflights of the three moons, observing examining gravity and magnetic interactions, amongst other things. The last year will be spent in orbit around Ganymede to observe this moon in much greater detail.
The challenges are enormous. JUICE must deal with very low and very high temperatures as it will circle Earth, Mars and Venus for gravity assist maneuvers to build up enough speed to reach Jupiter’s orbit. Jupiter’s cold environment also makes it hard to collect energy. "The goal is to investigate whether there are liquid oceans under these icy crusts which might harbor organic components or even life" says Vincent Poinsignon, JUICE project manager.
Figure 3: In July 2019, Airbus has completed the first step in the construction of the inner structure of ESA's JUICE satellite. The inner structure or SSTS (Structure, Shielding and Thermal control Subsystem), built at the Madrid-Barajas site of Airbus, is carbon fibre and is composed of the central load carrying cylinder, shear panels, two equipment protecting Vaults, the TCS (Thermal Control System) which includes a heat pipes network and multilayer insulation, and secondary elements such as 13 additive manufacturing brackets. This key element weighs 580 kg and will support the satellite’s weight of 5,300 kg (of which about 3,000kg is chemical propellant). Jupiter’s distance from the Sun will make it challenging to generate energy. For this reason the spacecraft is equipped with solar arrays with a total surface of 85 m2, the largest ever built for any interplanetary spacecraft (image credit: Airbus DS) 10)
The JUICE spacecraft is a 3-axis stabilized platform that will accommodate 10 instruments. The power subsystem consists in a solar array with two wings of five panels each for a total surface of 97 m2 providing ~820 W at Jupiter (end of life conditions), and a Li-ion battery. 11)
A 2.5 m diameter High Gain Antenna, using X- and Ka- bands, will ensure telemetry/telecommand links for routine operations, safe-mode, and radio science related investigations. At least, 1.4 Gbits of scientific data will be downloaded every day.
Figure 4: Artist's impression of JUICE (image credit: Spacecraft: ESA/ATG medialab; Jupiter: NASA/ESA/J. Nichols; Ganymede: NASA/JPL; Io: NASA/JPL/University of Arizona; Callisto and Europa: NASA/JPL/DLR) 12)
The propulsion system is a bi-propellant main engine plus a set of 10 thrusters. The two main mission maneuvers are the Jupiter and Ganymede orbit insertions. Two vaults will provide to some electronics a shielding against the harsh Jupiter radiation environment, as well as adequate thermal conditions.
The spacecraft includes deployable appendices such as a 10.6 m boom supporting J-MAG (JUICE Magnetometer) and RPWI (Radio and Plasma Wave Instrument) sensors, a 16 m radar antenna, and a steerable medium gain antenna used for communication and radio-science investigations.
PVA (Photovoltaic Assembly) for JUICE: The PVA design, development and verification (DD&V) foresee a thorough development, design verification and qualification activities along with associated test samples. 13)
The development of the JUICE PVA is progressing. A number of issues have been identified and recovery / alternative plans put in place to identify solutions. A robust baseline design is under final consolidation and will be available by the third quarter of 2018 allowing the release of all qualification campaigns.
• October 16, 2020: All ten solar panels for ESA’s Jupiter Icy Moons Explorer, JUICE, have arrived at Airbus Defence and Space in The Netherlands ready to be turned into the spacecraft’s two solar wings. The solar panels are a key element of the mission, providing the necessary power to run the spacecraft and operate the science instruments. 14)
- En route to Jupiter, JUICE will make several gravity assist flybys at Earth, Venus and Mars before heading to the outer Solar System, meaning that the solar panels have to withstand a large temperature range from +110ºC to -230ºC. At Jupiter, there will be times when the spacecraft is temporarily eclipsed by the giant planet and the moons, depriving it from any sunlight, leading to a rapid cool down of the solar arrays. In addition, the spacecraft will be subjected to a harsh radiation environment. Extensive testing is carried out to ensure the spacecraft and its solar arrays can survive these tough conditions.
- The next step for the solar panels is to turn them into wings and to test the deployment mechanisms. Further checks will also be made to verify that the spacecraft and its instruments can receive all of the power generated by the solar array even under the most challenging conditions.
- JUICE is scheduled to launch in 2022, arriving in the Jovian system in 2029. It will investigate Jupiter and three of its planet-sized moons – Ganymede, Europa and Callisto – which are thought to have oceans of liquid water beneath their icy crusts. This makes them extremely interesting to study to better understand the habitability potential of ocean worlds – in our own Solar System and in exoplanet systems beyond.
Figure 5: JUICE solar panels ready to turn into wings. Each panel measures about 2.5 m x 3.5 m, and with five on each side of the spacecraft, total an area of about 85 m2. They have to be folded up to fit inside the launcher, and after launch, will deploy in a distinctive cross-like formation (image credit: Airbus Defence and Space Netherlands)
• September 21, 2020: Engineers at NASA's Jet Propulsion Laboratory met a significant milestone recently by delivering key elements of an ice-penetrating radar instrument for an ESA (European Space Agency) mission to explore Jupiter and its three large icy moons. 15)
- Part of the RIME (Radar for Icy Moon Exploration) instrument, the transmitter sends out radio waves, which can penetrate surfaces of icy moons and help scientists "see" underneath. A collaboration between JPL and the Italian Space Agency (ASI), RIME is one of the JUICE instruments.
- Despite COVID-19-related hurdles, crucial NASA instrument components for the European-led JUICE spacecraft have been delivered. Engineers at NASA/JPL met a significant milestone recently by delivering key elements of an ice-penetrating radar instrument, RIME (Radar for Icy Moons Exploration), for an ESA mission to explore Jupiter and its three large icy moons.
- While following the laboratory's stringent COVID-19 Safe-at-Work precautions, JPL teams managed to build and ship the receiver, transmitter, and electronics necessary to complete the radar instrument for the JUICE mission.
- RIME is key to exploring those moons. It sends out radio waves that can penetrate the surface up to 10 km and collects data on how the waves bounce back. Some of the waves penetrate the crust and reflect off subsurface features - and the watery interiors - enabling scientists to "see" underneath.
- In the case of Europa, which is believed to have a global ocean beneath its crust, the radar data will help gauge the thickness of the ice. NASA's Europa Clipper mission, set to launch in the mid-2020s, will arrive around the same time as JUICE and collect complementary science as it performs multiple flybys of Europa.
- A collaboration between NASA/JPL in Pasadena and the Italian Space Agency (ASI), JUICE's RIME is led by Principal Investigator Lorenzo Bruzzone of the University of Trento in Italy. JPL's responsibility was to make and deliver the transmitter and receiver - the pieces that send out and pull in radio signals - as well as the electronics that help those pieces communicate with RIME's antenna. Now that the components have been delivered to ASI in Rome, the next steps are to test and integrate them before assembling the instrument.
- "I'm really impressed that the engineers working on this project were able to pull this off," said JPL's Jeffrey Plaut, co-principal investigator of RIME. "We are so proud of them, because it was incredibly challenging. We had a commitment to our partners overseas, and we met that - which is very gratifying."
Figure 6: NASA's Jet Propulsion Laboratory built and shipped the receiver, transmitter, and electronics necessary to complete the radar instrument for JUICE (Jupiter Icy Moons Explorer), the ESA mission to explore Jupiter and its three large icy moons. In this JPL photo of April 27, 2020, the transmitter undergoes random vibration testing to ensure the instrument can survive the shaking that comes with launch (image credit: NASA/JPL-Caltech)
• June 26, 2020: Despite certain operational difficulties caused by the COVID-19 pandemic, the assembly and integration of the flight model for ESA's JUICE (JUpiter ICy moons Explorer) spacecraft has continued with few delays during the first six months of the year. 16)
• April 23, 2020: ESA's upcoming JUICE spacecraft arrives at the satellite integration center of the project’s prime contractor Airbus in Friedrichshafen, Germany, in April 2020, to undergo final integration. 17)
- Expected to set out for its seven-year cruise to Jupiter in 2022, JUICE will carry 10 scientific instruments for detailed inspection of the largest planet of the Solar System and its moons, including Ganymede, Europa and Callisto, which are believed to host oceans of water. During its planned three-year mission, the spacecraft is expected to answer the question whether the oceans of the icy moons host any forms of life.
- A result of cooperation of more than 80 companies from all over Europe, JUICE was built and assembled in Airbus’ facilities in Madrid. The spacecraft was then fitted with a propulsion system at ArianeGroup’s site in Lampoldshausen, Germany, to form the spacecraft body, and transported to Friedrichshafen inside a special secured container on board of an oversized transporter.
Figure 7: The 5.2-ton spacecraft will be fitted with remaining components such as power electronics, an on-board computer, communication systems and navigation sensors, before continuing its journey to ESTEC (ESA Space Technology and Research Center) in the Netherlands for testing (image credit: Airbus)
• February 25, 2020: The first instrument to fly on ESA’s JUICE ( Jupiter Icy Moon Explorer) has been delivered for integration onto the spacecraft this month. The UVS (Ultraviolet Spectrograph), pictured in this photo while being prepared before shipping, was designed and built by Southwest Research Institute in San Antonio, TX, US. 18)
- Juice is the first large-class mission in ESA's Cosmic Vision 2015–2025 program. With launch scheduled in 2022, it will arrive at Jupiter in 2029 to perform detailed observations of the giant planet and three of its largest moons: Ganymede, Callisto and Europa.
- The mission, which is being developed by Airbus Defence and Space as prime contractor, comprises 10 state-of-the-art instruments to investigate the Jupiter system plus one experiment that uses the spacecraft telecommunication system jointly with ground-based radio observations (Very Long Baseline Interferometry). The 10 instruments will perform in situ measurements of Jupiter's atmosphere and plasma environment as well as remote observations of the surface and interior of the three icy moons.
- As part of Juice’s comprehensive suite of instruments, UVS will get close-up views of Europa, Ganymede and Callisto, which are all thought to host underground oceans beneath their icy surfaces. By recording the ultraviolet light emitted, transmitted and reflected by the moons, the instrument will reveal the composition of their surfaces and atmospheres, and enable investigations of how these icy bodies interact with Jupiter and its giant magnetosphere.
- UVS will cover the wavelength range between 55 and 210 nm with spectral resolution better than 0.6 nm. It will achieve a spatial resolution of 0.5 km at Ganymede and up to 250 km at Jupiter.
- The instrument is now at the premises of Airbus Defence & Space GmbH in Friedrichshafen, Germany, where it will be integrated on the spacecraft. The other nine instruments are being integrated and tested by the respective instrument teams and will be delivered for integration over the course of 2020.
- The UVS instrument represents NASA’s contribution to the mission. The instrument team, led by scientists at Southwest Research Institute, includes additional scientists from University of Colorado Boulder and SETI institute in the US, as well as University of Leicester and Imperial College London (UK), University of Liège (Belgium) and Laboratoire Atmosphères, Milieux, Observations Spatiales (France). NASA’s New Frontiers Program at Marshall Space Flight Center (MSFC) oversees the UVS contribution to ESA.
Figure 8: Photo of the UVS instrument (image credit: SwRI)
• November 19, 2019: For the solar array of ESA's JUICE mission to Jupiter, Airborne delivered the last 4 out of 10 XL substrate panels to Airbus Defence and Space Netherlands. As timing is critical for the interplanetary spacecraft to be put on the right trajectory enabling gravity-assist flybys after its launch in 2022, the delivery of the XL panels is crucial in order for the solar array to be readied according to schedule. Given extreme distance from the Sun, the JUICE spacecraft asked for an exceptionally large solar array in order to generate sufficient power. 19)
- As market leader in the manufacturing of solar array substrate panels in Europe, Airborne was selected by Airbus Defence and Space Netherlands to develop and manufacture the XL substrate panels for JUICE's solar array. With a total surface area of 85 m2 the satellite will be equipped with the largest solar array ever flown on an interplanetary mission.
- Airborne's specific expertise was required to produce the substrate panels for the solar panels with a surface area of almost 9 m2 per panel - the largest units manufactured by Airborne to date. To enable production Airborne modified the manufacturing equipment, including extending the maximum inside diameter of the autoclave from 2.6 to 2.9 meters. Combined with a length of 13 meters, the extended autoclave enables Airborne to produce more XL size panels for aerospace customers.
- JUICE's solar array is built with the new ARA (Advanced Rigid Array) Mk4 technology, which has been developed and qualified by Airbus Defence and Space Netherlands in close cooperation with Airborne. Airbus' ARA Mk4 technology allows for 20 percent cost reduction and increases the robustness of the solar array by expanding the temperature range and adding stiffness. As the satellite will be exposed to extreme conditions during the full length of the mission, the panels need to withstand temperatures as low as -240º Celsius, as well as space radiation.
- The extreme temperatures to which the satellite will be exposed near Jupiter made additional qualification necessary on the panel design and its interfaces. Airborne manufactured 160 qualification test samples and two full-size panels which were delivered in January 2017. After an intensive testing campaign by Airbus Defence and Space Netherland, Airborne manufactured a total of 10 substrate panels. The last 4 panels were completed in October 2019 - on time for the next step in the manufacturing process of JUICE's solar array.
- Arno van Mourik, CEO of Airborne says: "JUICE is a great example of what we can do in terms of state-of-the-art substrate panel technology for solar arrays of extremely demanding space missions. Building on this position we are determined to move forward in the domain of affordable space panels for new space. Combining our knowledge on high end substrates with our capabilities in the domain of industrialization of composites will allow us to provide the new space market with high performance, yet radically affordable solutions in high volumes."
- After its launch in 2022 and a journey that will last seven and a half years, the JUICE (JUpiter ICy moons Explorer) satellite of the European Space Agency will spend three and a half years making detailed observations of the giant gaseous planet Jupiter and three of its largest moons. ESA selected Airbus as prime contractor for the design, development, production, and testing of spacecraft JUICE.
• November 4, 2019: In a decade’s time, an exciting new visitor will enter the Jovian system: ESA’s JUICE (Jupiter Icy Moons Explorer) mission. As its name suggests, the mission will explore Jupiter and three of its largest moons – Ganymede, Callisto and Europa – to investigate the giant planet’s cosmic family and gas giant planets in general. 20)
- JUICE is planned for launch in 2022, and its instruments are currently being perfected and calibrated so they are ready to start work once in space. This image shows one of the many elements involved in this calibration process: a miniature gold-plated metallic model of JUICE used to test the spacecraft’s antennas.
Figure 9: This model of JUICE was built by the Technical University of Dresden, Germany, and the tests were performed by the Austrian Academy of Sciences’ Space Research Institute in Graz, Austria, as part of a project financed by the Austrian Research Promotion Agency (FFG). The lead scientist for the calibration effort was Georg Fischer of the Space Research Institute, also using computer simulations performed by Mykhaylo Panchenko (image credit: G. Fischer/IWF Graz)
- JUICE will carry multiple antennas to detect radio waves in the Jupiter system. These antennas will measure the characteristics of the incoming waves, including the direction in which they are moving and their degree of polarization, and then use this information to trace the waves back to their sources. In order to do this, the antennas must work well regardless of their orientation to any incoming waves – and so scientists must figure out and correct for the antennas’ so-called ‘directional dependence’.
- This shiny model was used to perform a set of tests on JUICE’s Radio and Plasma Wave Instrument (RPWI) last year. It was submerged in a tank filled with water; an even electric field was then applied to the tank, and the model was moved and rotated with respect to this field. The results revealed how the antennas will receive radio waves that stream in from different directions and orientations with respect to the spacecraft, and will enable the instrument to be calibrated to be as effective as possible in its measurements of Jupiter and its moons.
- Similar tests, which are technically referred to as rheometry, were conducted in the past for spacecraft including the NASA/ESA/ASI Cassini-Huygens mission to Saturn (which operated at Saturn between 2004 and 2017), NASA’s Juno spacecraft (currently in orbit around Jupiter), and ESA’s Solar Orbiter (scheduled for launch in early 2020 to investigate the Sun up close).
- The test performed for Juice posed a few additional hurdles – the model’s antennas were especially small and needed to be fixed accurately onto the model’s boom, which required scientists to create a special device to adjust not only the antennas, but also the boom itself.
- The model was produced at a 1:40 scale, making each antenna 62.5 mm long from tip to tip; scaled up, the antennas will be 2.5 m long on JUICE. The main spacecraft parts modelled here include the body of the probe itself, its solar panels, and its antennas and booms. The model has an overall ‘wingspan’ of 75 cm across its solar panels. The photo also shows a spacecraft stand, which extends out of the bottom of the frame. The gold coating ensured that the model had excellent electric conducting properties, and reacted minimally with the surrounding water and air during the measurements.
- Meanwhile, the assembly of the JUICE flight model has started in September, with the delivery of the spacecraft's primary structure, followed by integration of the propulsion system.
• October 23, 2019: The assembly of the flight model of ESA's JUICE spacecraft began in September, with the delivery of the spacecraft's primary structure, followed by integration of the propulsion system that will enable the mission to reach and study Jupiter and its moons. 21)
- The primary structure of the spacecraft features a central tube – the main load bearing element – with vertical shear panels located radially around the tube, and horizontal floor panels. This will be completed later with the optical bench and external closing panels that will form the outer walls and will be added when all the internal equipment has been integrated.
- The structure is part of the SSTS ( Structure, Shielding and Thermal Subsystem), built under the responsibility of Airbus Defence & Space in Madrid, Spain, with participation by RUAG Space Switzerland and RUAG Space Austria.
- One of the features of the JUICE SSTS is that the some of the vertical panels and parts of the closing walls of the structure are lined with a thin layer of lead, which provides shielding to protect the spacecraft's electronic systems from damage by the severe radiation environment at Jupiter.
- One of the features of the JUICE SSTS is that the some of the vertical panels and parts of the closing walls of the structure are lined with a thin layer of lead, which provides shielding to protect the spacecraft's electronic systems from damage by the severe radiation environment at Jupiter.
- Over the coming months, five companies will be working almost simultaneously on the SSTS in order to ensure that JUICE can proceed to the assembly and integration phase that will take place in Airbus facilities in Friedrichshafen, Germany, so that it will be completed and ready for launch in 2022.
- One of the main tasks at Lampoldshausen will be to integrate the propulsion system. This includes two identical propellant tanks that have been newly developed for EuroStar Neo, ESA's new generation of platforms for geostationary telecommunications satellites. JUICE will be the first space mission to actually utilize them.
- The first titanium tank, capable of holding 1600 liters of oxidant (mixed oxides of nitrogen, or MON), was carefully lowered inside the spacecraft's central cylinder on 7 September. The second tank, which will contain monomethyl hydrazine (MMH) fuel, is scheduled for installation at the end of October.
- "JUICE will need to carry more than 3000 kg of propellant in these tanks," said Daniel Escolar, ESA's Mechanical, Thermal & Propulsion System Engineer for the mission. ”Such a large load will be essential for JUICE to arrive in orbit around Jupiter and complete its scientific tour with multiple flybys of the Galilean moons, before eventually becoming the first spacecraft ever to enter orbit around Ganymede."
Figure 10: The unpacking of the primary spacecraft structure of ESA's JUICE mission in the airlock at the Arianegroup facility in Lampoldshausen, Germany on 5 September 2019. The delivery marked the beginning of the flight model assembly, with the integration of the propulsion system that will enable the mission to reach and study Jupiter and its moons (image credit: Airbus and ArianeGroup)
- The integration of the spacecraft's propulsion system will, however, involve much more than installing two propellant tanks. Eventually, three fairly small tanks, each filled with helium pressurant, will be affixed around the exterior of the central cylinder, together with all the necessary plumbing. Some 130 meters of titanium piping will also have to be installed and welded in the SSTS.
- Other hardware to be added during installation of the propulsion system will include pressure regulators, valves, filters and thrusters. In addition to its single 400-newton main engine that will be used for the larger orbital maneuvers, JUICE will carry eight 22-newton thrusters for smaller maneuvers and as a backup system, along with twelve 10-newton thrusters for attitude control.
- Meanwhile, engineers are busy carrying out other essential tasks that can only be completed whilst the external panels are not fitted, enabling easy access to the spacecraft's interior. These include placing single layer insulation around the central cylinder, adding thermocouples to measure temperatures, and attaching support fixtures for the harness that will eventually be required to carry around 10 km of electrical cable.
- According to the current schedule, the JUICE flight model will be moved to Friedrichshafen around March next year for integration and testing of its electrical systems.
- In the meantime, development of the JUICE scientific payload is continuing, and the magnetometer boom for the flight model has recently been delivered to ESA/ESTEC (Space Research and Technology Center) in Noordwijk, the Netherlands, for three weeks of vibration and deployment tests.
• August 28, 2019: The test facility at CERN, the European Organization for Nuclear Research, was used to simulate the high-radiation environment surrounding Jupiter to prepare for ESA’s JUICE mission to the largest planet in our Solar System. 22)
- All candidate hardware to be flown in space first needs to be tested against radiation: space is riddled with charged particles from the Sun and further out in the cosmos. An agreement with CERN gives access to the most intense beam radiation beams available – short of travelling into orbit.
- Initial testing of candidate components for ESA’s JUpiter ICy moons Explorer, JUICE, took place last year using CERN’s VESPER (Very energetic Electron facility for Space Planetary Exploration missions in harsh Radiative environments) facility.
- VESPER’s high energy electron beamline simulated conditions within Jupiter’s massive magnetic field, which has a million times greater volume than Earth’s own magnetosphere, trapping highly energetic charged particles within it to form intense radiation belts.
- Due to launch in 2022, JUICE needs to endure this harsh radiation environment in order to explore Callisto, Europa and Ganymede – moons of Jupiter theorized to hide liquid water oceans beneath their icy surfaces. JUICE is being built by Airbus for ESA, with construction of its spacecraft flight model due to begin next month.
- Last month ESA and CERN signed a new implementing protocol, building upon their existing cooperation ties.
- Signed by Franco Ongaro, ESA’s Director of Technology, Engineering and Quality, and Eckhard Elsen, CERN Director for Research and Computing, this new agreement identifies seven specific high-priority projects: high-energy electron tests; high-penetration heavy-ion tests; assessment of commercial off-the-shelf components and modules; in-orbit technology demonstration; ‘radiation-hard’ and ‘radiation-tolerant’ components and modules; radiation detectors monitors; and dosimeters and simulation tools for radiation effects.
- “The radiation environment that CERN is working with within its tunnels and experimental areas is very close to what we have in space,” explains Véronique Ferlet-Cavrois, Head of ESA’s Power Systems, EMC & Space Environment Division.
- “The underlying physics of the interaction between particles and components is the same, so it makes sense to share knowledge of components, design rules and simulation tools. Plus access to CERN facilities allows us to simulate the kind of high-energy electrons and cosmic rays found in space. At the same time we are collaborating on flying CERN-developed components for testing in space.”
- Petteri Nieminen, heading ESA’s Space Environments and Effects section adds: “Along with JUICE, CERN heavy-energy radiation testing will also be useful for our proposed Ice Giants mission to Neptune and Uranus. The spacecraft may have to be pass through Jupiter’s vast magnetic field on the way to these outer planets, and both worlds have radiation belts of their own.
- “And the ability to simulate cosmic rays benefits a huge number of missions, especially those venturing beyond Earth orbit, including Athena and LISA as well as JUICE. It is also a huge interest for human spaceflight and exploration to study radiobiology effects of heavy ion cosmic rays on astronaut DNA. Not to mention that radiation simulations developed in collaboration with CERN help set space environment specifications for all ESA missions.”
Figure 11: Technology image of the week: this CERN test facility was used to recreate the highly radioactive environment surrounding Jupiter for ESA’s JUICE mission (image credit: CERN)
• August 22, 2019: As part of preparations for the launch of ESA’s Jupiter Icy Moons Explorer, its navigation camera has been given a unique test: imaging its destination from Earth. 23)
Figure 12: Annotated image of Jupiter system captured in JUICE NavCam test from Earth (image credit: Airbus DS)
- The NavCam has been specifically designed to be resistant to the harsh radiations environment around Jupiter and to acquire images of the planet, moon and background stars. Importantly, NavCam measurements will allow the spacecraft to be in the optimal trajectory and to consume as little fuel as possible during the grand tour of Jupiter, and to improve the pointing accuracy during these fast and close rendezvous approaches. The close encounters will bring the spacecraft between about 200 and 400 km to the moons.
- In June, a team of engineers took to the roof of the Airbus Defence and Space site in Toulouse to test the NavCam engineering model in real sky conditions. The purpose was to validate hardware and software interfaces, and to prepare the image processing and onboard navigation software that will be used in-flight to acquire images.
- In addition to observing Earth’s Moon and other objects, the instrument was pointed towards an obvious target in the night sky: Jupiter. The camera used the ‘Imaging mode’ and ‘Stars Centroiding Mode’ to test parameter settings which in turn will be used to fine-tune the image processing software at attitude control and navigation levels.
- “Unsurprisingly, some 640 million km away, the moons of Jupiter are seen only as a mere pixel or two, and Jupiter itself appears saturated in the long exposure images needed to capture both the moons and background stars, but these images are useful to fine-tune our image processing software that will run autonomously onboard the spacecraft,” says Gregory Jonniaux, Vision-Based Navigation expert at Airbus Defence and Space. “It felt particularly meaningful to conduct our tests already on our destination!”
- During the flybys themselves it will be possible to see surface features on these very different moons. In a separate test, the NavCam was optically fed with simulated views of the moons to process more realistic images of what can be expected once in the Jupiter system.
Figure 13: Simulated NavCam views of the Jupiter moons. Impressions of how the Jupiter Icy Moons Explorer will see moons Europa (left), Ganymede (middle) and Callisto (right) with its Navigation Camera (NavCam). To generate these images, the NavCam was fed simulated views – based on existing images of the moons – to process realistic views of what can be expected once in the Jupiter system (image credit: Airbus DS)
- Meanwhile the test navigation camera will be further improved with a full flight representative performance optics assembly by the end of the year, and will subsequently be used to support onboard software tests of the complete JUICE spacecraft. After launch, the test camera will be used at ESA’s operations center to support the mission operations throughout its mission.
• June 17, 2019: JUICE, will ride into space on an Ariane launch vehicle, Arianespace and ESA confirmed today at the International Paris Air Show. 24)
- JUICE is the first large-class mission in ESA's Cosmic Vision 2015–2025 program. Its mission is devoted to complete a unique tour of the Jupiter system.
- JUICE will spend at least three years making detailed observations of the giant gaseous planet Jupiter and in-depth studies of three of its largest moons and potentially ocean-bearing satellites, Ganymede, Europa and Callisto.
- The launch period for JUICE will start in mid-2022 aboard an Ariane 5 or an Ariane 64 launch vehicle – depending on the final launch slot from from Europe’s Spaceport in French Guiana, South America.
• April 3, 2019: ESA's JUpiter ICy moons Explorer, JUICE, has been given the green light for full development after its CDR (Critical Design Review) was successfully concluded on 4 March. This major milestone marks the beginning of the qualification and production phase, taking this flagship mission one key step closer to starting its long journey to Jupiter in 2022. 25)
• March 20, 2019: A test version of the 10.5 m long magnetometer boom built for ESA’s mission to Jupiter, developed by SENER in Spain, seen being tested at ESA’s Test Center in the Netherlands, its mass borne by balloons. 26)
- The flight model will be mounted on the JUICE (Jupiter Icy Moons Explorer) spacecraft, due to launch in 2022, arriving at Jupiter in 2029. The mission will spend at least three years making detailed observations of the giant gaseous planet Jupiter and three of its largest moons: Ganymede, Callisto and Europa.
- The Juice spacecraft will carry the most powerful remote sensing, geophysical, and in situ payload complement ever flown to the outer Solar System. Its payload consists of 10 state-of-the-art instruments.
- This includes a magnetometer instrument that the boom will project clear of the main body of the spacecraft, allowing it to make measurements clear of any magnetic interference. Its goal is to measure Jupiter’s magnetic field, its interaction with the internal magnetic field of Ganymede, and to study subsurface oceans of the icy moons.
- The deployment of this qualification model boom has been performed before and after simulated launch vibration on the Test Center shaker tables to ensure it will deploy correctly in space. Since the boom will deploy in weightlessness, three helium balloons were used to help bear its weight in terrestrial gravity.
Figure 14: A test version of the 10.5 m long magnetometer boom built for ESA’s mission to Jupiter, developed by SENER in Spain, seen being tested at ESA’s Test Center in the Netherlands, its weight borne by balloons (image credit: ESA–G. Porter, CC BY-SA 3.0 IGO)
• December 11, 2018: The JUICE engineering model spacecraft test readiness review was completed successfully on 2 October, and the first engineering model instruments are now being delivered and tested. 27)
Figure 15: The engineering model of ESA's JUICE at the facilities of prime contractor Airbus Defence and Space in Toulouse, France. The central cylinder of the spacecraft is well visible in this view, along with the electrical harness (image credit: Airbus DS)
- A major step in the development of ESA's upcoming JUICE mission to the Jupiter system is the start of integration and testing of the spacecraft engineering model at the facilities of prime contractor Airbus Defence and Space in Toulouse, France.
- Following the JUICE flight model spacecraft test readiness review, in October 2019, the engineering model will be used to test procedures and study functional issues that may arise during the development testing of the flight model. The engineering model will also be used, on ground, in support of the actual spacecraft operations after launch.
• November 12, 2018: JUICE is ESA's future mission to explore the most massive planet in Solar System and its large moons Ganymede, Europa and Callisto. Planned for launch in June 2022, it will embark on a seven-year cruise that will make use of several flybys – of Earth, Venus, Earth, Mars, and Earth again – before leaving the inner Solar System en route to Jupiter. 28)
- All three moons are thought to have oceans of liquid water beneath their icy crusts, and the Radar for Icy Moons Exploration (RIME) instrument on Juice will be used to probe their subsurface structure. Emitted by a 16-m long antenna, the radar signals will penetrate the icy surfaces of Jupiter’s moons down to a depth of 9 km.
- RIME will be the first instrument of its kind capable of performing direct subsurface measurements of worlds in the outer Solar System, and it should provide key clues on the potential for such bodies to harbor habitable environments.
- Once in space, the instrument’s performance will be influenced by several factors, including the radiation pattern of the antenna. To evaluate these effects, a series of tests were carried out at ESA’s Hertz facility in September, using a 1:18 scale model of the RIME antenna – shrunk to a length of about 80 cm and mounted on a simplified, scaled-down model of the spacecraft.
Figure 16: A miniaturized model of the Juice spacecraft during electromagnetic tests at ESA's technical heart in the Netherlands (image credit: ESA–M. Cowan)
• June 7, 2018: One of the major challenges facing ESA's JUICE (JUpiter Icy Moon Explorer) will be the extreme temperatures that the spacecraft and its suite of instruments will have to endure. 29)
In order to ensure that the orbiter survives the voyage to Jupiter and the cold, hostile environment of the Solar System's largest planet, the spacecraft will have to pass a series of challenging tests during its lengthy development process. The first of these – known as a TDM (Thermal Development Model) test – was recently completed.
The objective of the test, which took place between 5 and 10 May at ESA/ESTEC in The Netherlands, was to verify that the spacecraft's thermal control system could protect the spacecraft from extreme temperatures during its complex mission.
After launch, JUICE will embark on an 88-month cruise that will make use of several flybys – of Earth, Venus, Earth, Mars, and again Earth – before leaving the inner Solar System on its way to Jupiter.
En route, the spacecraft will have to endure the effects of solar heating, particularly during the flyby of Venus. Eventually, it will have to operate in an extremely cold environment where some of its external surfaces will experience temperatures below -200º Celsius after arrival at Jupiter, with even colder conditions during solar eclipses, when the spacecraft will be in the planet's shadow.
The JUICE thermal control system is designed to minimize the impact of the external environment on the spacecraft through the use of high efficiency MLI (Multi-Layer Insulation). The material that is used to blanket the spacecraft's exterior is known as StaMet coated black kapton 160XC.
The MLI will moderate the external temperature during the spacecraft's closest approach to the Sun. It must also limit heat leakage in the cold Jupiter environment in order to minimize demand for power from the spacecraft's heaters, especially when its instruments are operating during the science and communication phases.
The power demand will be a crucial factor during operations given the limited power generated by the spacecraft's solar panels at Jupiter's distance from the Sun, where the amount of incoming solar energy is 25 times lower than on Earth.
Efficient passive thermal insulation also minimizes hardware mass – always a major concern for spacecraft designers – by reducing the need for radiators and heaters.
Thermal verification test: The thermal verification test was required to check the passive heat loss properties of the spacecraft in both cold and hot environments. It used a full scale model, the TDM, which comprised a simplified version of the JUICE flight model structure.
The spacecraft's central cylinder was replaced by a basic hexagonal structure and the HGA (High Gain Antenna) was simulated by a simple, white-painted aluminum disc with the same diameter as the HGA flight model. This was relevant for the test, because the HGA will be used as an umbrella shielding the structure when the spacecraft will be at its closest to the Sun.
Figure 17: The JUICE TDM inside the Large Space Simulator (image credit: ESA–M. Cowan)
There were no other protruding instruments or appendages on the TDM, but heat dissipation from the platform and internal instruments was simulated by adding test heaters.
The TDM itself, wrapped in MLI, was placed in the LSS (Large Space Simulator) at ESA/ESTEC (European Space Research & Technology Centre) in Noordwijk, the Netherlands. Operated by European Test Services, the LSS is the largest space simulation facility in Europe, enabling a wide variety of tests to be performed on spacecraft.
Engineers began pumping the air out of the 9.4-m diameter chamber on 5 May, in order to create a vacuum comparable to the airless environment of deep space. This vacuum was maintained throughout the test.
Figure 18: The JUICE TDM inside the Large Space Simulator, before (left) and after (right) closing the 5 m diameter side door (image credit: ESA–M. Cowan)
• April 14, 2017: NASA’s partnership in a future ESA (European Space Agency) mission to Jupiter and its moons has cleared a key milestone, moving from preliminary instrument design to implementation phase. 30)
- Designed to investigate the emergence of habitable worlds around gas giants, JUICE is scheduled to launch in five years, arriving at Jupiter in October 2029. JUICE will spend almost four years studying Jupiter’s giant magnetosphere, turbulent atmosphere, and its icy Galilean moons—Callisto, Ganymede and Europa.
- The April 6 milestone, known as Key Decision Point C (KDP-C), is the agency-level approval for the project to enter building phase. It also provides a baseline for the mission’s schedule and budget. NASA’s total cost for the project is $114.4 million. The next milestone for the NASA contributions will be the Critical Design Review (CDR), which will take place in about one year. The CDR for the overall ESA JUICE mission is planned in spring 2019.
- JUICE is a large-class mission—the first in ESA’s Cosmic Vision 2015-2025 program carrying a suite of 10 science instruments. NASA will provide the UVS (Ultraviolet Spectrograph), and also will provide subsystems and components for two additional instruments: the PEP (Particle Environment Package) and the RIME (Radar for Icy Moon Exploration) experiment.
- The UVS was selected to observe the dynamics and atmospheric chemistry of the Jovian system, including its icy satellites and volcanic moon Io. With the planet Jupiter itself, the instrument team hopes to learn more about the vertical structure of its stratosphere and determine the relationship between changing magnetospheric conditions to observed auroral structures. The instrument is provided by the Southwest Research Institute (SwRI), at a cost of $41.2 million.
- The PEP is a suite of six sensors led by the Swedish Institute of Space Physics (IRF), capable of providing a 3-D map of the plasma system that surrounds Jupiter. One of the six sensors, known as PEP-Hi, is provided by the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, and is comprised of two separate components known as JoEE and JENI. While JoEE is focused primarily on studying the magnetosphere of Ganymede, JENI observations will reveal the structure and dynamics of the donut-shaped cloud of gas and plasma that surrounds Europa. The total cost of the NASA contribution to the PEP instrument package is $42.4 million.
- The Radar for Icy Moon Exploration (RIME) experiment, an ice penetrating radar, which is a key instrument for achieving groundbreaking science on the geology, is led by the Italian Space Agency (ASI). NASA’s Jet Propulsion Laboratory (JPL), in Pasadena, California, is providing key subsystems to the instrument, which is designed to penetrate the surface of Jupiter's icy moons to learn more about their subsurface structure. The instrument will focus on Callisto, Ganymede, and Europa, to determine the formation mechanisms and interior processes that occur to produce bodies of subsurface water. On Europa, the instrument also will search for thin areas of ice and locations with the most geological activity, such as plumes. The total cost of the NASA contribution is $30.8 million.
• March 15, 2017: Demanding electric, magnetic and power requirements, harsh radiation, and strict planetary protection rules are some of the critical issues that had to be tackled in order to move ESA's JUICE (Jupiter Icy Moons Explorer) from the drawing board and into construction. The PDR (Preliminary Design Review) is completed. 31)
• December 9, 2015: The mission was selected in May 2012 as the first Large-class mission within ESA's Cosmic Vision 2015–25 program, and is planned for launch in 2022 to arrive at the giant planet in 2030. 32)
- For three and a half years, JUICE will sweep around Jupiter, exploring its turbulent atmosphere, enormous magnetosphere and tenuous set of dark rings, as well as studying the icy moons Ganymede, Europa and Callisto. It will eventually go into orbit around Ganymede, a first in Solar System exploration.
- All three of these planet-sized satellites are thought to have oceans of liquid water beneath their icy crusts and should provide clues on the potential for such moons to offer habitable environments.
- Airbus Defence & Space SAS in France was announced as the prime contractor in July when ESA approved the €350 million contract.
- The contract covers the design, development, integration, test, launch campaign and in-space commissioning of the spacecraft. The Ariane 5 launch is not included and will be procured later from Arianespace.
- The 10 state-of-the-art instruments were approved by ESA in February 2013 and are being developed by teams spanning 16 European countries, the USA and Japan, under national funding.
- The spacecraft will be assembled at Airbus Defence and Space GmbH in Friedrichshafen, Germany.
• In July 2015, Airbus DS was selected by ESA (European Space Agency) as prime contractor for the design, development, production, and testing of a new spacecraft named ‘JUICE’. As its name implies (Jupiter Icy Moons Explorer), the mission will be to explore the Jovian system, focusing on three of Jupiter’s huge Galilean moons: Europa, Ganymede and Callisto, which are as large as dwarf planets and covered by an icy crust (Ref. 9).
Launch: In May 2022, Ariane 5 will lift Juice into space from Europe’s Spaceport in Kourou. A series of gravity-assist flybys at Earth (3), Venus (1) and Mars (1) will set the spacecraft on course for its October 2029 rendezvous in the Jovian system. 33) 34)
Figure 19: This animation depicts the journey to Jupiter and the highlights from its foreseen tour of the giant planet and its large ocean-bearing moons (video credit: ESA)
- The satellite will have a mass at liftoff of approximately six tons and will be placed in an Earth escape orbit in a direction to Jupiter starting a journey of 600 million kilometers. After a 7.5-year cruise, which includes gravitational assists from Earth, Venus and Mars, the spacecraft will enter orbit around the giant planet in October 2029.
- "JUICE is the first 'large-class' mission in our Cosmic Vision program and of prime importance for investigating the habitability potential of ocean-worlds beyond our own," said Günther Hasinger, ESA's Director of Science. "We're delighted to confirm it will have a flying start with an Ariane launch vehicle, setting it on course to fulfil its scientific goals in the Jupiter system."
- Stéphane Israël, Chief Executive Officer of Arianespace, added: "Arianespace is honored to be awarded this new scientific mission from ESA, which will advance our understanding of the Universe. Less than a year after the launch of BepiColombo to Mercury, we have won the launch contract for the JUICE mission to Jupiter's moons, further confirmation of Arianespace's ability to ensure Europe's independent access to space for all types of missions. We are once again marshaling all of our strengths and capabilities to support Europe's spaceborne ventures, with a launch services offering based on Ariane 5 and Ariane 6 so we can deliver the availability and flexibility needed by ESA for its latest emblematic mission."
Sensor complement (3GM, Gala, JANUS, J-MAG, MAJIS, PEP, PRIDE, RIME, RPWI, SWI, UVS)
The payload consists of 10 state-of-the-art instruments plus one experiment that uses the spacecraft telecommunication system with ground-based instruments. This payload is capable of addressing all of the mission's science goals, from in situ measurements of Jupiter's atmosphere and plasma environment, to remote observations of the surface and interior of the three icy moons, Ganymede, Europa and Callisto.
Figure 20: Overview of JUICE instruments (image credit: ESA/ATG medialab)
3GM (Gravity & Geophysics of Jupiter and Galilean Moons)
The instrument is a radio package comprising the KaT (Ka-Transponder), USO (ultrastable oscillator) and HAA (High Accuracy Accelerometer). The experiment will study the gravity field at Ganymede, the extent of the internal oceans on the icy moons, and the structure of the neutral atmosphere and ionosphere of Jupiter (0.1 - 800 mbar) and its moons.
PI: L. Iess, Università di Roma "La Sapienza", Italy. Lead funding agency: ASI.
GALA (GAnymede Laser Altimeter)
GALA will study the tidal deformation of Ganymede and the topography of the surfaces of the icy moons. GALA will have a 20 m spot size and 0.1 m vertical resolution at 200 km.
PI: H. Hussmann, DLR, Institut für Planetenforschung, Germany. Lead funding agency: DLR.
JANUS (optical camera system)
JANUS will study global, regional and local features and processes on the moon, as well as map the clouds of Jupiter. It will have 13 filters, a FOV of 1.3º, and spatial a resolution up to 2.4 m on Ganymede and about 10 km at Jupiter.
PI: P. Palumbo, Università degli Studi di Napoli "Parthenope", Italy. Lead funding agency: ASI.
J-MAG (JUICE Magnetometer)
J-MAG is equipped with sensors to characterize the Jovian magnetic field and its interaction with that of Ganymede, and to study the subsurface oceans of the icy moons. The instrument will use fluxgates (inbound and outbound) sensors mounted on a boom.
PI: M. Dougherty, Imperial College London, United Kingdom. Lead funding agency: UKSA, United Kingdom.
MAJIS (Moons and Jupiter Imaging Spectrometer)
MAJIS will observe cloud features and atmospheric constituents on Jupiter, and will characterize ices and minerals on the icy moon surfaces. MAJIS will cover the visible and infrared wavelengths from 0.4 to 5.7 µm, with spectral resolution of 3-7 nm. The spatial resolution will be up to 25 m on Ganymede and about 100 km on Jupiter.
PI: Y. Langevin, Institut d'Astrophysique Spatiale, France. Lead funding agency: CNES.
PEP (Particle Environment Package)
PEP comprises a package of sensors to characterize the plasma environment of the Jovian system. PEP will measure density and fluxes of positive and negative ions, electrons, exospheric neutral gas, thermal plasma and energetic neutral atoms in the energy range from <0.001 eV to >1 MeV with full angular coverage. The composition of the moons' exospheres will be measured with a resolving power of more than 1000.
PI: S. Barabash, Swedish Institute of Space Physics (Institutet för rymdfysik, IRF), Kiruna, Sweden. Lead funding agency: SNSB, Sweden.
PRIDE (Planetary Radio Interferometer & Doppler Experiment)
PRIDE will use the standard telecommunication system of the spacecraft, together with radio telescopes on Earth, VLBIs (Very Long Baseline Interferometry systems), to perform precise measurements of the spacecraft position and velocity to investigate the gravity fields of Jupiter and the icy moons.
PI: L. Gurvits, Joint Institute for VLBI in Europe, The Netherlands. Lead funding agency: NWO (Dutch Research Council) and NSO (Netherlands Space Office), The Netherlands.
RIME (Radar for Icy Moons Exploration)
RIME is an ice-penetrating radar to study the subsurface structure of the icy moons down to a depth of around nine kilometers with vertical resolution of up to 30 m in ice. RIME will work at a central frequency of 9 MHz (1 and 3 MHz bandwidth) and will use a 16 m antenna.
PI: L. Bruzzone, Università degli Studi di Trento, Italy. Lead funding agency: ASI.
The transmitter of RIME, developed and built by NASA/JPL, is shown in Figure 6.
RPWI (Radio and Plasma Wave Investigation)
The instrument will characterize the radio emission and plasma environment of Jupiter and its icy moons using a suite of sensors and probes.
RPWI will be based on four experiments, GANDALF, MIME, FRODO, and JENRAGE. It will use a set of sensors, including two Langmuir probes to measure DC electric field vectors up to a frequency of 1.6 MHz and to characterize thermal plasma and medium- and high-frequency receivers, and antennas to measure electric and magnetic fields in radio emission in the frequency range 80 kHz- 45 MHz.
PI: J.-E. Wahlund, Swedish Institute of Space Physics (Institutet för rymdfysik, IRF), Uppsala, Sweden. Lead funding agency: SNSB, Sweden.
Figure 21: The RPWI will measure electric and magnetic fields to identify and map the oceans beneath the frozen ice cover of the moon Ganymede (image credit: IRF) 36)
SWI (Sub-millimeter Wave Instrument)
The objective of SWI is to investigate the temperature structure, composition and dynamics of Jupiter’s atmosphere, and the exospheres and surfaces of the icy moons. SWI is a heterodyne spectrometer using a 30 cm antenna and working in two spectral ranges 1080-1275 GHz and 530-601 GHz with spectral resolving power of ~107.
PI: P. Hartogh, Max-Planck-Institut für Sonnensystemforschung, Germany. Lead funding agency: DLR, Germany.
UVS (UV imaging Spectrograph)
The aim of UVS is to characterize the composition and dynamics of the exospheres of the icy moons, to study the Jovian aurorae, and to investigate the composition and structure of the planet’s upper atmosphere. The instrument will perform both nadir observations and solar and stellar occultation sounding.
UVS will cover the wavelength range 55-210 nm with a spectral resolution of <0.6 nm. The spatial resolution will reach 0.5 km at Ganymede and up to 250 km at Jupiter.
PI: R. Gladstone, SwRI (Southwest Research Institute), USA. Lead funding agency: NASA.
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The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (email@example.com).