posted 05-02-2012 02:32 PM               

JUICE is Europe's next large science mission

Jupiter's icy moons are the focus of Europe's next large science mission, ESA announced today (May 2, 2012).

The JUpiter ICy moons Explorer — JUICE — was selected over two other candidates: NGO, the New Gravitational wave Observatory, to hunt for gravitational waves, and ATHENA, the Advanced Telescope for High-Energy Astrophysics.

Credit: ESA

Above: Artist's impression of JUICE

JUICE is the first Large-class mission chosen as part of ESA's Cosmic Vision 2015-2025 program.

It will be launched in 2022 from Europe's spaceport in Kourou, French Guiana, on an Ariane 5, arriving at Jupiter in 2030 to spend at least three years making detailed observations.

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?

The JUpiter ICy moons Explorer (JUICE) will continuously observe Jupiter's atmosphere and magnetosphere, and the interaction of the Galilean moons with the gas giant planet.

It 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.

"Jupiter is the archetype for the giant planets of the Solar System and for many giant planets being found around other stars," says Prof. Alvaro Giménez Cañete, ESA's Director of Science and Robotic Exploration.

"JUICE will give us better insight into how gas giants and their orbiting worlds form, and their potential for hosting life."

"The selection process has been challenging given the excellent quality of the three mission candidates, and I would like to thank the Space Science Advisory Committee for its hard work and for having carried out this very challenging process in a very rigorous way," says the Chair of ESA's Science Program Committee, Dr Richard Bonneville.

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 resulting Cosmic Vision 2015-2025 program identified four scientific aims. What are the conditions for life and planetary formation? How does the Solar System work? What are the fundamental laws of the Universe? How did the Universe begin and what is it made of?

In 2007, a 'Call for Missions' was issued around these aims and resulted in a number of L-class missions being considered.

"It was a difficult decision to choose one mission from three excellent candidates. All three would produce world-class science and put Europe at the forefront of space research," says Prof. Giménez Cañete.

"JUICE is a necessary step for the future exploration of our outer Solar System."

The high scientific value of both NGO and ATHENA was also recognized by the Science Program Committee in today's decision, and technology activities are planned to continue, enabling the missions to be considered as candidates for future launch opportunities. A second Call for Large Missions is expected in 2013.

posted 04-11-2023 06:42 PM               

JUICE rolled out to launch pad

On Tuesday (April 11), Arianespace rolled out the Ariane V rocket carrying ESA's Jupiter Icy Moons Explorer (JUICE) at Europe's Spaceport in French Guiana.

JUICE is scheduled to launch on Thursday (April 13) at 8:15 a.m. EDT (1215 GMT).

Photos: ESA/CNES/Arianespace/Optique vidéo du CSG/P.Baudon

posted 04-14-2023 07:45 AM               

European Space Agency launches JUICE probe to study Jupiter icy moons

An interplanetary probe is now on its way to "squeeze" out all it can about Jupiter and three of its large ocean-bearing moons.

The European Space Agency (ESA) launched its Jupiter Icy Moons Explorer, or JUICE, mission on Friday (April 14). The probe lifted off atop an Arianespace Ariane 5 ECA rocket from Europe's Spaceport in Kourou, French Guiana at 8:14 a.m. EDT (1214 GMT or 9:14 a.m. local time).

posted 04-28-2023 09:27 AM               

Work continues to deploy Juice RIME antenna

Juice's ice-penetrating RIME antenna has not yet been deployed as planned. During the first week of commissioning, an issue arose with the 16-metre-long Radar for Icy Moons Exploration (RIME) antenna, which is preventing it from being released from its mounting bracket.

Work continues to free the radar and teams at ESA's mission control centre in Darmstadt, Germany, along with partners in science and industry, have lots of ideas up their sleeves.

Above: Juice's longest antenna awaits deployment. (ESA)

Every day the RIME antenna shows more signs of movement, visible in images from the Juice Monitoring Camera on board the spacecraft with a partial view of the radar and its mount. Now partially extended but still stowed away, the radar is roughly a third of its full intended length.

The current leading hypothesis is that a tiny stuck pin has not yet made way for the antenna's release. In this case, it is thought that just a matter of millimetres could make the difference to set the rest of the radar free.

Various options are still available to nudge the important instrument out of its current position. The next steps to fully deploy the antenna include an engine burn to shake the spacecraft a little followed by a series of rotations that will turn Juice, warming up the mount and radar, which are currently in the cold shadows.

Juice is otherwise performing excellently after the successful deployment and operation of its mission-critical solar arrays and medium gain antenna, as well as its 10.6-m magnetometer boom.

With two months of planned commissioning remaining, there is plenty of time for teams to get to the bottom of the RIME deployment issue and continue work on the rest of the powerful suite of instruments on their way to investigate the outer Solar System.

Updates will be shared as new information becomes available.

The RIME instrument is an ice-penetrating radar designed to study the surface and subsurface structure of Jupiter's icy moons down to a depth of 9 km.

It is one of ten instruments on board ESA's Jupiter Icy Moons Explorer, Juice, set to investigate the emergence of habitable worlds around gas giants and the formation of our Solar System.

posted 05-12-2023 03:51 PM               

Juice's RIME antenna breaks free

More than three weeks after efforts began to deploy Juice's ice-penetrating Radar for Icy Moons Exploration (RIME) antenna, the 16-metre-long boom has finally escaped its mounting bracket.

During the first attempt to extend the folded-up antenna, only the first segments of each half were deployed. Flight controllers suspected that a tiny stuck pin jammed the other segments in place.

Above: The first stuck part of the RIME antenna deploys. (ESA)

Fortunately, the flight control teams at ESA's mission control centre in Darmstadt had lots of ideas up their sleeves.

To try to shift the pin, they shook Juice using its thrusters, then they warmed Juice with sunlight. Every day the RIME antenna was showing signs of movement, but no full release.

On 12 May RIME was finally jolted into life when the flight control team fired a mechanical device called a 'non-explosive actuator' (NEA), located in the jammed bracket. This delivered a shock that moved the pin by a matter of millimetres and allowed the antenna to unfold.

Above: The second stuck part of the RIME antenna deploys. (ESA)

But a final part of the antenna remained folded. Confirmation that the RIME antenna was successfully deployed came only when the flight control team fired another actuator in the bracket, causing RIME to fully stretch itself out after months spent folded up for launch.

Once ESA's Jupiter Icy Moons Explorer (Juice) arrives at Jupiter, it will use RIME to study the surface and subsurface structure of Jupiter's icy moons down to a depth of 9 km. RIME is one of ten instruments on board Juice set to investigate the emergence of habitable worlds around gas giants and the formation of our Solar System.

posted 08-21-2024 08:11 AM               

Juice rerouted to Venus in world's first lunar-Earth flyby

ESA's Jupiter Icy Moons Explorer (Juice) has successfully completed a world-first lunar-Earth flyby, using the gravity of Earth to send it Venus-bound, on a shortcut to Jupiter through the inner Solar System.

Above: During the second step of humankind's first-ever lunar-Earth flyby, ESA's Jupiter Icy Moons Explorer (Juice) captured this stunning view of Earth. The image covers the northern Pacific Ocean. The image was taken by Juice monitoring camera 1 (JMC1) just at 23:48 CEST on 20 August 2024, as Juice was heading towards its closest approach to Earth. (ESA/Juice/JMC)

The closest approach to the Moon was at 23:15 CEST (21:15 UTC) on 19 August, guiding Juice towards a closest approach to Earth just over 24 hours later at 23:56 CEST (21:56 UTC) on 20 August.

As Juice flew just 6840 km above Southeast Asia and the Pacific Ocean, it snapped a series of images with its onboard monitoring cameras, and collected scientific data with eight of its ten instruments.

"The gravity assist flyby was flawless, everything went without a hitch, and we were thrilled to see Juice coming back so close to Earth," says Ignacio Tanco, Spacecraft Operations Manager for the mission.

Above: ESA's Jupiter Icy Moons Explorer (Juice) captured this image covering the northern Pacific Ocean, with North America starting to appear on the right (east) side of Earth. The image was taken by Juice monitoring camera 1 (JMC1) just at 00:09 CEST on 21 August 2024. (ESA/Juice/JMC)

The purpose of the flyby was to reroute Juice's path through space, using the gravity of first the Moon and then Earth to change the spacecraft's speed and direction.

The flyby of the Moon increased Juice's speed by 0.9 km/s relative to the Sun, guiding Juice towards Earth. The flyby of Earth reduced Juice's speed by 4.8 km/s relative to the Sun, guiding Juice onto a new trajectory towards Venus. Overall, the lunar-Earth flyby deflected Juice by an angle of 100° compared to its pre-flyby path.

The inherently risky flyby required ultra-precise, real-time navigation, but is saving the mission around 100–150 kg of fuel. In the month before the flyby, spacecraft operators gave Juice slight nudges to put it on exactly the right approach trajectory. Then they tracked Juice 24/7 between 17–22 August.

Thanks to a flawless Ariane 5 launch back in April 2023, Juice has a little extra propellant in its tanks to get closer to Jupiter's moon Ganymede than originally planned. The success of the lunar-Earth flyby has safeguarded this bonus science.

"Thanks to very precise navigation by ESA's Flight Dynamics team, we managed to use only a tiny fraction of the propellant reserved for this flyby. This will add to the margins we keep for a rainy day, or to extend the science mission once we get to Jupiter," adds Ignacio.

A first taste of science in space

Whilst the main goal was to alter Juice's trajectory, the lunar-Earth flyby also provided an opportunity to test out Juice's scientific instruments in space, with all ten switched on during the Moon flyby, and eight switched on during the Earth flyby.

Above: ESA's Jupiter Icy Moons Explorer (Juice) mission captured this view of the Moon. The image was taken by Juice monitoring camera 1 (JMC1) at 23:25 CEST on 19 August 2024, soon after Juice made its closest approach to the Moon. (ESA/Juice/JMC)

We expect to publish images and spectra collected by some of Juice's instruments in the next weeks, as they are downlinked from the spacecraft and evaluated by the instrument scientists. This includes high-resolution images on the Moon and Earth from Juice's scientific camera, JANUS.

"The timing and location of this double flyby allows us to thoroughly study the behaviour of Juice's instruments," explains Claire Vallat, Juice Operations Scientist.

"It happens early enough in Juice's journey that we can use the data to prepare the instruments for arrival at Jupiter. And given how well we know the physical properties of Earth, the Moon, and the surrounding space environment, it's also the ideal location to understand how the instruments respond to a real target."

Above: ESA's Jupiter Icy Moons Explorer (Juice) captured this view of Earth and the Moon. The image was taken after the flyby was complete and Juice was moving away from the Earth-Moon system. The image was taken by Juice monitoring camera 1 (JMC1) just at 02:53 CEST on 21 August 2024. (ESA/Juice/JMC)

Next step: Venus

This lunar-Earth flyby actually reduced Juice's energy, redirecting it towards a meeting with Venus in August 2025. That Venus flyby will boost Juice back out towards Earth; the spacecraft will fly by our home planet again in September 2026 and January 2029, gaining two more boosts before arrival at Jupiter in July 2031.

posted 09-01-2025 05:37 PM               

Juice flys by Venus following anomaly resolution

Flyby success! ESA's Juice spacecraft passed Venus at 07:28 CEST on 31 August.

The European Space Agency's Jupiter Icy Moons Explorer (Juice) completed its gravity-assist flyby at Venus on 31 August, following the successful resolution of a spacecraft communication anomaly that temporarily severed contact with Earth.

The issue, which emerged during a routine ground station pass on 16 July, temporarily disrupted Juice's ability to transmit information about its health and status (telemetry).

Thanks to swift and coordinated action by the teams at ESA's European Space Operations Centre (ESOC) in Darmstadt, Germany, and Juice's manufacturer, Airbus, communication was restored in time for the planetary encounter.

Juice falls silent

The anomaly began when ESA's deep space antenna in Cebreros, Spain, failed to establish contact with Juice at the expected time of 04:50 CEST on 16 July. Initial checks ruled out ground station issues, prompting escalation to the Juice control team at ESOC. Attempts to reach the spacecraft via ESA's New Norcia station also failed, confirming that the problem was on board.

With no signal and no telemetry, engineers feared Juice might have entered survival mode – a last-resort configuration that is triggered by multiple onboard system failures. In such a state, the spacecraft spins slowly, sweeping its antenna across Earth once per hour. However, no such intermittent signal was detected.

"Losing contact with a spacecraft is one of the most serious scenarios we can face," said Angela Dietz, Juice Spacecraft Operations Manager. "With no telemetry, it is much more difficult to diagnose and resolve the root cause of an issue."

Attention turned to the communications subsystem. Engineers suspected either a misalignment of Juice's medium-gain antenna or a failure in the signal transmitter or amplifier.

Two recovery strategies were considered: waiting for the next automatic spacecraft reset in 14 days' time, or sending commands 'blind' into space in the direction that Juice should be and hoping that they are received by one of the backup low-gain antennas.

"Waiting was not an option," explained Angela. "We had to act fast. Waiting two weeks for the reset would have meant delaying important preparations for the Venus flyby."

20 hours of troubleshooting

Blind commanding was a challenge: Juice was around 200 million km from Earth and located on the other side of the Sun. It took each attempted rescue signal 11 minutes to reach the spacecraft, and the team then had to wait another 11 minutes to determine whether they had been successful.

Six attempts to steer the medium-gain antenna back towards Earth were unsuccessful. Recovery efforts continued overnight, lasting almost 20 hours and focusing on manually powering up Juice's onboard communication systems.

Eventually, a command succeeded in reaching Juice and triggering a response. The command activated the signal amplifier that boosts the strength of the signal that Juice sends towards Earth. Contact was re-established, and Juice was found to be in excellent condition. No systems had failed, and all telemetry was nominal.

The root cause was traced to a software timing bug. The software function that switches the signal amplifier on and off relies on an internal timer. This timer is constantly counting up and restarts from zero once every 16 months. If the function happens to be using the timer at the exact moment it restarts, the amplifier remains switched off, and Juice's signal is too weak to detect from Earth.

"It was a subtle bug, but one that we were prepared to investigate and resolve," said Angela. "We have identified a number of possible ways to ensure that this does not happen again, and we are now deciding which solution would be the best to implement."

All clear for the Venus flyby

Despite the high stakes and technical complexity, the recovery by ESA's mission operations team was achieved with minimal disruption.

"This was a textbook example of teamwork under pressure," said Angela. "Thanks to the team's calm and methodical approach, we were able to recover Juice without any lasting impact on the mission."

With the anomaly behind them, the Juice team returned their focus to preparations for the Venus flyby. Juice passed its closest point to Venus at 07:28 CEST on Sunday, 31 August as it completed the second of four planned gravity assists.

Designed for the cold, dark environment of Jupiter, Juice needed to adapt to the intense solar heat near Venus. To protect its sensitive components, the spacecraft used its main, high-gain antenna as a thermal shield. Due to thermal constraints, its remote sensing instruments could not be active during the flyby, and so no images of Venus were captured.

Juice's journey to Jupiter

To go directly to Jupiter, Juice would have needed to leave Earth with a velocity of 11 km/s. However, Juice is one of the heaviest interplanetary spacecraft ever launched, at almost 6000 kg. With such a massive payload, its Ariane 5 launcher provided an escape velocity of 2.5 km/s.

The spacecraft is using gravity-assist manoeuvres to pick up the rest of the required speed. Juice used the gravity of Venus this week to bend its orbit around the Sun and gain speed relative to Earth without using fuel.

The Venus flyby gave Juice a significant boost. When it next encounters Earth in September 2026, the spacecraft will have reached the required Jupiter transfer velocity of 11 km/s. However, Jupiter won't be in the right place to send Juice out towards it just yet.

Juice will use the Earth flyby in 2026 to further fine-tune its trajectory. After one more orbit around the Sun, the spacecraft will return to Earth for a final flyby in January 2029. This flyby will be used to send Juice on a transfer trajectory that intercepts Jupiter in July 2031.