Juice journey flybys

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While the launch of JUICE will certainly be an exciting and critical event in the mission timeline, what occurs after the launch is, perhaps, some of the most important events of the mission. Following the launch, JUICE will spend eight years traveling through the inner solar system, performing four gravity assists to raise its aphelion (the farthest point from the Sun in its orbit) to Jupiter’s orbital plane. What’s more, when at Jupiter itself, JUICE will perform several flybys of three Jovian icy moons — Ganymede, Callisto, and Europa — to uncover the secrets of these potentially habitable celestial bodies.

With JUICE’s launch and the start of the spacecraft’s eight-year coast phase quickly approaching, NASASpaceflight sat down with Cyril Cavel, JUICE project manager of Airbus Defence and Space, to learn more about the upcoming mission, its eight-year coast phase, and the science it will gather when at Jupiter.

JUICE’s Trajectory

When JUICE launches from French Guiana in April, it will be equipped with some of the latest and greatest planetary science instrumentation to investigate the characteristics of Ganymede, Callisto, and Europa. However, before it can use any of these instruments, the spacecraft has to fly out to Jupiter, doing so through the use of four flybys.

The first of these four flybys will see JUICE perform a first-of-its-kind flyby of the Earth-Moon system called a Lunar-Earth Gravity Assist (LEGA). The maneuver will take place in August 2024 and will have JUICE fly past both the Moon and Earth, utilizing the gravity of both celestial bodies in a single flyby maneuver. If successful, the LEGA flyby will save JUICE a significant amount of propellant, potentially providing mission teams with more opportunities for flybys at Jupiter or a mission extension.


Juice’s journey to Jupiter.

The second flyby, planned for August 2025, will see JUICE fly past Venus, utilizing the planet’s gravity to increase its aphelion height. The final two flybys, planned for September 2026 and January 2029, will be of Earth, with the fourth flyby increasing the spacecraft’s aphelion height to the orbital plane of Jupiter and placing the spacecraft on a trajectory to intercept the planet’s immense gravity well.

The four flybys are often referred to as “gravity assists.” During each flyby, JUICE will harness the gravity of either the Earth-Moon system, Venus, or Earth itself to increase its velocity around the Sun. When the spacecraft’s orbital velocity is increased, the height of its orbit is also increased. By performing multiple gravity assists rather than one, single burn that would place the spacecraft on a direct trajectory to the Jovian system, mission teams can reduce the amount of propellant on the spacecraft, reducing spacecraft mass and costs.

What’s more, following the fourth and final gravity assist flyby of Earth, JUICE could potentially perform a flyby of an asteroid while traveling out to Jupiter. If mission teams choose to perform the flyby of the asteroid, named 223 Rosa, the flyby will serve as a dress rehearsal for the spacecraft’s first flyby of Ganymede following its arrival at the Jovian system in July 2031.

“[The flyby of 223 Rosa] can effectively be used as a dress rehearsal for the very first flyby of Ganymede, which will take place just before Jupiter orbit insertion,” Cavel said. “We perform our first Ganymede flyby before performing the orbital insertion maneuver at Jupiter in order to do an initial reduction of the spacecraft’s energy and to reduce the amplitude of the maneuver that we have to do when arriving at Jupiter. And so a flyby of an asteroid on the way to Jupiter could be used as a rehearsal of this first Ganymede flyby that we do when arriving in the Jovian system,” Cavel said.

The decision to fly past the asteroid will be important for JUICE teams. However, as Cavel explained, they have plenty of time to assess their options and make the final decision to fly past the asteroid.

“The opportunities that flight dynamics and mission analysis at ESA have found for a flyby of an asteroid are typically after the last Earth gravity assist, so on the final trajectory arc to Jupiter. JUICE will be on that trajectory at least five to six years after launch. So there is some time to think about that, meaning the decision would need to be made in the first few years after launch. Then the trajectory would be fine-tuned at the expense of a few meters per second of additional delta-v, which we can accommodate, in order to really target these asteroids on the way to Jupiter.”

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Mission milestones. ESA.

 

Updated/maj. 16-04-2023

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