INVESTIGATING ICY MOONS

The Search for Hidden Oceans-and Extra-Terrestrial Life

- Rachel Kehoe

On April 14, 2023, a sleek rocket took off from Europe's Spaceport in French Guiana, in northeast South America. It blasted beyond Earth's atmosphere, soaring into the darkness of space. Onboard was a brand new space probe called the Jupiter Icy Moons Explorer, or Juice for short. Juice has an exciting trip ahead. It will travel through our solar system, with its sights set on reaching the planet Jupiter by July 2031. This probe will be so far from Earth-hundreds of millions of miles away—that it needs a 2.5-meter (8.2-foot) antenna to send information to us back home. It is also equipped with large solar panels to provide power. Once near Jupiter, Juice will embark on a planned four-year mission to study the planet and its mysterious icy moons: Ganymede, Callisto, and Europa.

Galileo Galilei (1564-1642) first spotted these moons along with Io (which isn't icy) in 1610. It seemed as if they were all too far from the Sun to have life. Space probes such as Galileo (1989-2003) and Cassini (1997-2017), however, have sparked fresh interest in the possibility of alien life on water-rich worlds. Galileo hinted at the existence of hidden oceans on Europa, Ganymede, and Callisto, and Cassini caught Saturn's moon Enceladus shooting water plumes into space.

Water Could Mean Life

Why is water such a big deal? "Scientists have spent decades looking for life in space, and they start by finding places with water," says Olivier Witasse. He is the project scientist for European Space Agency's Juice mission.