Juice represents Europe's inaugural mission to the Jupiter system. To reach its distant objective, the spacecraft will perform several gravity assists, also known as flybys, swingbys, or slingshots.

These maneuvers leverage the gravity of large celestial bodies like planets or moons to alter the spacecraft's speed and trajectory, conserving fuel and allowing for a greater payload of scientific instruments to explore remote worlds.

Juice's initial gravity assist is notably complex, involving two consecutive flybys. The lunar-Earth flyby will bring Juice within 700 km of the Moon's surface at 23:16 CEST on August 19 and then 6807 km from Earth's surface nearly exactly 24 hours later at 23:57 CEST on August 20.

The Moon's gravity will slightly bend Juice's trajectory, enhancing the effectiveness of the subsequent, larger gravity assist at Earth. This dual flyby demands exceptionally precise navigation and timing, as minor deviations could misdirect Juice.

"For a typical gravity assist, spacecraft operations have to be highly precise," says Angela Dietz, Juice Spacecraft Operations Engineer. "For a double flyby, they must be pinpoint."

Mission Control on High Alert
ESA's ESOC operations center has mobilized teams across the organization for Juice's lunar-Earth flyby.

Currently, the Juice team is conducting a series of trajectory correction maneuvers to fine-tune the spacecraft's path as it nears the Earth-Moon system, ensuring it arrives at the correct angle and speed.

During this critical phase, the deep space antennas in ESA's Estrack network will maintain a nearly constant communication link with Juice.

Real-time telemetry data will allow the flight control and flight dynamics teams to closely monitor Juice's position, speed, and trajectory, enabling rapid responses to any anomalies or deviations.

During the Earth flyby, Juice will pass within the altitude of satellites in geostationary and medium-Earth orbits. ESA's Space Debris Office will scan Juice's trajectory to ensure a safe passage free from other satellites or space debris.

After the lunar-Earth flyby, as Juice departs from Earth for the second time, the teams will evaluate its new trajectory and perform any necessary minor correction maneuvers.

"A lunar-Earth flyby has never been attempted before," says Angela Dietz. "There are risks, but all of Juice's onboard systems have been rigorously tested, and we are well prepared." She added, "Due to the low altitudes, large velocity changes and strict navigation requirements involved, the flight control team needs to be ready to react at a moment's notice."

This week, a training campaign is underway to develop and rehearse recovery procedures to quickly get the spacecraft back on track in case of any anomalies.

During a recent 'dry run' of the payload operations scheduled for the double flyby, the flight control team commanded Juice to operate its various cameras and scientific instruments exactly as it will during the actual flybys, ensuring all systems function as expected.

Juice's instruments, designed to study a planet and its moons, will have a unique opportunity to test and calibrate on similar objects during the lunar-Earth flyby, preparing them for their scientific activities at Jupiter.

In many ways, the successful execution of this first lunar-Earth flyby will advance Juice's mission to uncover the mysteries of Jupiter and its icy moons.

Related Links
Jupiter Icy Moons Explorer
Space Tourism, Space Transport and Space Exploration News