On Friday, 14 April, the European Space Agency successfully launched JUICE to study Jupiter’s frozen moons. Jupiter Icy Moons Explorer will investigate three of Jupiter’s biggest moons, Europa, Ganymede and Callisto, to determine whether they are potentially habitable. This question has been stirring debate among astronomers ever since the Galileo spacecraft discovered evidence of subsurface water on these moons in the 1990s.

JUICE was launched by Ariane 5 at 8:14am ET from Europe’s Spaceport, French Guiana. Weather conditions had delayed the launch from April 13th to today.

It separated from the rocket soon after launch, and made contact with Earth by 9:04AM. The spacecraft then unfurled its 27-meter wide solar arrays. The spacecraft now begins its eight-year trip to Jupiter.

The mission’s goal is to determine if Jupiter’s Moons are habitable

Launching the spacecraft within just one second was necessary to accommodate its complex trajectory . In August 2024, the spacecraft will start its orbit around Earth. It will then make a flyby over Earth and the Moon. It will be the very first time a spacecraft performs a maneuver known as a Lunar Earth gravity assist (LEGA), in which it will fly first past the Moon, and then pass Earth just one day and half later. The spacecraft will get a boost from this maneuver, but the launch time must be exact.

Alessandro Atzei, ESA’s payload system engineer, explained this in a briefing before launch.

It will then continue to circle the inner solar systems, flybying Venus in 2025. Then it will return out into Earth’s orbit and make two more flybys 2026-2029. It will then be able power out towards Jupiter, arriving in the Jupiter system by 2031.

It will be the very first time a spacecraft performs a maneuver known as a Lunar Earth gravity assist

The spacecraft needs to have enough fuel to perform maneuvers on Jupiter. This trip is designed to save as much fuel possible. JUICE will fly by Europa, Ganymede and Callisto 35 times in total once it reaches Jupiter.

The spacecraft is so far away from the Sun at this point that the huge solar panels will only produce a few hundred Watts, enough to power a microwave. The instruments must be designed so that they can operate with very little power and also deal with the harsh radiation of Jupiter.

There are 10 instruments aboard, including remote sensing tools like a camera or spectrograph to observe targets far away and in situ instruments such as a magnetometer, radio and plasma wave instruments for measuring the immediate surroundings of the spacecraft. The Planetary Radio Interferometry and Doppler Experiment (PRIDE) will test if it is possible to use Earth-based radio telescopes to determine the precise location of the spacecraft.

The probe will reach Jupiter in 2031

These instruments will be utilized to investigate Jupiter’s satellites with special focus on Ganymede. Ganymede has a unique feature in that it’s the largest satellite in the solar-system and is the only one known to have its own magnetic field. This magnetic field is surrounded by the powerful magnetic field from Jupiter. The two fields interact to produce strong auroras all around the moon. Ganymede has a surface that is both smooth and older, with pockmarks. This can help scientists to understand how Jupiter’s system evolved.

Ganymede is also thought to contain a liquid ocean under a thick crust of ice. Galileo’s mission found that Jupiter’s magnetic fields were perturbed near Europa, suggesting a subsurface water ocean. Hubble detected plumes of water breaking through the surface. And ground-based telescopes detected water vapor in Europa’s atmosphere.

These moons are the most likely to have habitable environments in the solar system, due to the fact that they all require liquid water. The JUICE probe will not directly search for signs of life, but instead will be looking for biosignatures like the presence of essential elements such as carbon and oxygen.

Scientists need to consider the Jupiter system in its entirety when assessing whether or not these environments are truly habitable. In the briefing, JUICE scientist Olivier Witasse said that to understand the question of habitability, we must explore the Jupiter system as a whole. This means studying Jupiter’s atmosphere, weather, magnetic field and its volcanic moon Io. We also need to know how these bodies are interconnected. Jupiter is a miniature solar system.

To understand the question of habitability, we must explore Jupiter’s system globally.

This system will help us to learn more about our solar system and investigate if these distant worlds may host life. In a press release, Carole Mundell said, “Today we sent a suite a ground-breaking scientific instruments on a voyage to Jupiter’s Moons, which will give us a close-up look that was unimaginable for previous generations.”

The ESA Juice data will allow scientists to explore and discover the mysteries of Jupiter’s system, the nature and habitability on other planets and answer unasked questions.


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