Space enthusiasts and observers have a rare chance to witness the European Space Agency’s (ESA) JUICE spacecraft as it makes a historic Earth-Moon flyby next week.
This remarkable maneuver will help the spacecraft pick up the speed it needs to continue its eight-year journey to Jupiter, where it will study the planet’s icy moons, including Ganymede, which is believed to harbor a subsurface ocean.
A Daring Double Flyby: First of Its Kind
The Jupiter Icy Moons Explorer (JUICE), launched in April 2023, is set to execute the first-ever dual Earth-Moon flyby. This complicated maneuver will involve using both the Moon’s and Earth’s gravity to slingshot the spacecraft deeper into space. This flyby marks a “double-world first,” as it is the first time a spacecraft will use a twin flyby to adjust its trajectory towards Jupiter.
According to ESA, the mission has been meticulously planned over the last 20 years and is a feat of precision engineering.
The spacecraft will pass within 700 kilometers of the Moon’s surface on August 19th, followed by a close pass within 6,807 kilometers of Earth on August 20th.
The daring feat is likened to “passing through a very narrow corridor, very, very quickly,” as JUICE navigates its way through space using gravity for course correction.
"The margin for error is minimal," said Ignacio Tanco, Spacecraft Operations Manager for JUICE. "Even a small mistake could send the spacecraft off course."
Gravity Assist: Essential for Deep Space Travel
The gravity assist maneuver allows JUICE to gain the energy required to continue its journey toward Jupiter without needing vast amounts of onboard propellant. “Without this technique, JUICE would have required an impossible 60,000 kg of propellant,” explained Nicolas Altobelli, JUICE Mission Manager.
The spacecraft’s trajectory will bend through space during the flyby, effectively “braking” it and redirecting it toward Venus for another gravity assist in 2025.
After the Venus flyby, JUICE will return for two more Earth flybys, one in 2026 and another in 2029, which will give it the final push needed to reach Jupiter by 2031.
Observing JUICE's Flyby
Observers in well-placed regions will have a rare opportunity to catch a glimpse of JUICE as it passes near Earth and the Moon. If skies are clear, skywatchers in Australia and southeast Asia will have the best chance of spotting the spacecraft as it approaches Earth in the pre-dawn sky on August 20th.
Though harder to see, other regions such as Europe and North America will also be able to view JUICE from farther out in space. Astronomers recommend using tracking maps from sources like Heavens-Above and ephemerides from JPL Horizons to pinpoint JUICE’s precise position in the sky.
JUICE is an impressive 27 meters across from solar panel to solar panel, and if you’re lucky, you may catch a specular glint of sunlight reflecting off the spacecraft’s panels as it passes Earth, potentially making it visible to the naked eye.
Testing Instruments En Route to Jupiter
As JUICE makes its way through this crucial flyby, ESA’s mission controllers will use the opportunity to test several of the spacecraft’s scientific instruments. One instrument, in particular, the Radar for Icy Moon Exploration (RIME), will undergo important testing during the lunar flyby. RIME has been experiencing interference from other spacecraft instruments, and mission controllers will use this pass to troubleshoot the issue.
During its closest pass by the Moon, RIME will have a limited eight-minute window to conduct vital observations of the lunar surface. ESA hopes that this brief window will provide enough data to develop an algorithm that will help mitigate the noise issue, ensuring that RIME is fully operational when JUICE reaches Jupiter’s moons.
JUICE’s Mission: Unveiling the Mysteries of Jupiter's Icy Moons
JUICE's primary mission is to explore Jupiter's icy moons, including Europa, Callisto, and Ganymede. These moons are of particular interest to scientists because of their potential to harbor subsurface oceans beneath their icy crusts. Ganymede, the largest moon in the solar system, is of particular interest due to its magnetic field and potential habitability.
Once JUICE arrives at Jupiter in 2031, it will begin its long-term study of these moons, searching for signs of water, ice, and possible life. The spacecraft’s suite of 10 scientific instruments, including RIME, will help map the surface and study the interior of these mysterious worlds.