The European Space Agency has launched the Jupiter Icy Moons Explorer (JUICE) on an eight-year voyage to the moons of Jupiter. Starting in July 2031, JUICE will explore Jupiter, the largest planet in the solar system, and its three ocean-bearing moons, Europa, Callisto and Ganymede. In December 2034, JUICE will orbit Ganymede to give that moon a closer look. Ganymede is of particular interest as it is the only moon in the solar system known to have a magnetic field. The mission will end a year later when it expends its propellent and crash-lands onto Ganymede.
JUICE joins several spacecraft that have explored Jupiter and its moons. NASA’s Pioneer 10 and Voyager 1 and 2 flew by the Jovian system in the 1970s. Ulysses flew by Jupiter in 1992 on its way to exploring the north and south poles of the Sun. Galileo explored Jupiter and its moons between 1995 and 2004. New Horizon flew by Jupiter on its way to Pluto in 2007. Currently, Juno is in a polar orbit around Jupiter
Europa Clipper will launch in October 2024 on a Falcon Heavy. It will enter orbit around Jupiter in 2030 and will conduct numerous close flybys of the moon Europa. A probe called Europa Lander would land on that icy moon. It has been proposed but not yet authorized.
The holy grail of space science has been the discovery of life that has evolved on other worlds. The search for such life has concentrated on Mars, a world that billions of years ago had an Earth-like environment. Scientists believe that microbes might still lurk somewhere on or just below the Martian surface. Despite some tantalizing indications, thus far no robotic probe sent to Mars has discovered alien life.
Recently, scientists have wondered if the subsurface oceans of some of the moons of the outer planets are better candidates for life. Europa, Callisto and Ganymede orbiting Jupiter and Enceladus orbiting Saturn have warm, sub-surface oceans. If one adds certain chemicals, life might well have evolved under the icy crust of one or more of these moons. The lifeforms could conceivably be more complex than single-cell organisms.
The discovery of even indirect indications of life beneath the icy crusts of the Jovian ocean moons would be an epic event in the history of science. It would prove that life did not just evolve and take root on Earth, one planet in one solar system in one galaxy in the universe. It would also mean that life can evolve in one of the most unusual environments imaginable.
The ESA has launched several high-profile space probes before, ROSETTA landed on the comet Philae, a bizarre double-lobed object 510 million kilometers from Earth. BepiColombo, a joint mission with the Japanese Aerospace Exploration Agency (JAXA) is currently enroute to Mercury.
JUICE will be the most complex planetary mission the ESA has ever undertaken. The probe will have to complete three gravity-assist maneuvers — one by Earth, one by Mars, and one by Venus — just to get to the Jovian system. JUICE will closely examine three moons and the planet Jupiter with a suite of instruments over a four-year mission. At the end of the JUICE mission, scientists will have a better understanding of the characteristics of Jupiter’s ocean moons.
If JUICE successfully completes its mission, it could presage the European Union’s rise as an independent space power. The world has changed since the space race between the United States and the Soviet Union of the 1960s. Russia has all but collapsed as a space-faring nation. China has risen as a rival in space. NASA has adroitly created an international Artemis Alliance to support its return to the moon program, including many of the counties comprising the ESA.
The EU probably won’t develop an independent crewed space capacity. The Europeans will find it easier to partner with NASA to send its astronauts to the moon and hire rides on the SpaceX Crew Dragon for orbital missions than to spend uncounted euros to build its own spacecraft.
However, JUICE will show that the ESA can conduct independent planetary science missions. Considering how much trouble the Europeans are having with ExoMars, a series of missions to Mars scheduled to climax with landing the Rosalind Franklin rover, a success at Jupiter would be a good development.
Mark R. Whittington is the author of space exploration studies “Why is It So Hard to Go Back to the Moon?” as well as “The Moon, Mars and Beyond,” and “Why is America Going Back to the Moon?” He blogs at Curmudgeons Corner.