ESA's Juice completes world's first lunar-Earth flyby

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

The flyby, which took place on Monday and Tuesday, 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, according to ESA.

The flyby of the Moon increased Juice's speed by 0.9 km/s relative to the Sun, guiding Juice toward 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 degrees compared to its pre-flyby path.

Jupiter is on average 800 million km away from Earth. Without an enormous rocket, sending Juice straight to the giant planet would require an impossible 60,000 kg of onboard propellant. And then Juice would need to be carrying an enormous additional amount of propellant to slow itself down enough to go into orbit around Jupiter once it arrives.

Launched on an Ariane 5 from Europe's Spaceport in Kourou in April 2023, Juice has an eight-year cruise with flybys of Earth and Venus to slingshot it to Jupiter. The spacecraft will make detailed observations of gas giant Jupiter and its three large ocean-bearing moons-Ganymede, Callisto and Europa-to discover more about these destinations as potential habitats for past or present life.