[Reading Science] Searching Every Corner of the Jupiter System to Find Extraterrestrial Life

European Space Agency to Launch JUICE Probe on 13th
Exploring Three Moons: Ganymede, Europa, and Callisto
Focused Investigation on Ocean Composition and Potential for Life

The full-scale exploration of Jupiter and its surrounding moons by humanity is about to begin.

The European Space Agency (ESA) plans to launch the Jupiter moon explorer spacecraft 'JUICE (Jupiter Icy Moons Explorer)' using an Ariane 5 launch vehicle from the Guiana Space Centre in Kourou, French Guiana, after 8:15 a.m. Eastern Time on the 13th. This spacecraft will travel for a remarkable eight years and arrive at the Jupiter system, 715 million km away from Earth, in 2031. It will visit the moons Europa and Callisto, then orbit Ganymede, the largest moon, conducting exploration for about two years. This marks the first time humanity has sent a probe to a moon of a planet other than Earth.

Notably, the journey to the Jupiter system will take as long as eight years. This is much longer than previous missions that visited Jupiter, such as NASA's Pioneer 10 (640 days), Pioneer 11 (606 days), and Galileo (6 years). Currently, the distance between Earth and Jupiter is relatively large, and ESA plans to take a complex flight path that does not go directly to Jupiter but instead orbits the Sun, using the gravity of the Moon, Earth, and Venus to enter Jupiter's orbit.

An artist's rendering of the Jupiter moon probe 'JUICE' to be launched by the European Space Agency (ESA) on the 13th (local time). Photo by ESA website

The most important mission is to investigate whether actual oceans exist beneath the frozen surfaces of the three moons Callisto, Ganymede, and Europa. Observations from previous spacecraft, space telescopes, and ground observatories have suggested that these three moons may have oceans beneath their thick icy surfaces that could support life. Although they contain abundant water, their surfaces are expected to be covered with thick ice due to the low temperatures caused by their distance from the Sun. In particular, the Hubble Space Telescope has found evidence of geysers ejecting water into space through cracks in the ice on Europa, similar to Saturn's moon Enceladus. The existence of such geysers suggests that these moons have internal heat sources and environments that could potentially support life, according to scientists.

However, scientists currently estimate that the JUICE spacecraft will not find extraterrestrial life or direct evidence of it. Since it will not carry a lander, it will only measure physical properties such as the depth of possible oceans and chemical compositions from orbit hundreds of miles above the moons.

In this regard, NASA plans to launch the Europa lander mission 'Europa Clipper' next year. Europa Clipper is expected to find traces of life (biomarkers) in the ocean beneath the ice through ice drilling exploration. It is scheduled to launch next year and arrive at Europa around 2030, about one year earlier than the JUICE spacecraft.

Ariane 5 launch vehicle scheduled to be launched on the 13th (local time) carrying the Jupiter moon explorer Juice spacecraft of the European Space Agency (ESA). Photo by ESA website

The JUICE spacecraft will collect detailed information about the oceans of Jupiter's moons using 10 scientific instruments. For example, it will measure the chemical composition and magnetic field of the ocean on Ganymede, whose ice thickness is expected to be up to 150 km. Ganymede is a massive moon roughly the size of Mercury, and previous observations have suggested that its magnetic field is weak, implying that the ocean may have low levels of nutrients such as salt. JUICE will verify this hypothesis using its magnetometer.

An ESA official explained, "The JUICE spacecraft will lay the foundation for future missions to search for signs of life on Jupiter's moons. Just as we do not fully understand life existing in extreme environments like Earth's deep oceans, we do not know what traces of extraterrestrial life might look like. It will take the efforts of many scientists to understand what JUICE discovers and its significance."

This is the first time humanity has conducted such detailed exploration of Jupiter's moons. NASA's Galileo spacecraft, which operated from 1995 to 2003, and the Juno spacecraft, which replaced it in 2016, focused solely on Jupiter itself. Although missions such as Pioneer 10 and 11, Voyager 1 and 2 launched in the 1970s, the Saturn explorer Cassini, and the Pluto explorer New Horizons have visited the Jupiter system, they only passed through without detailed study.