It appears that life does indeed exist on Earth.

The European Space Agency’s Jupiter Icy Moons Explorer (Juice) pre-mission test has confirmed that its instruments are ready to explore Jupiter’s icy moons. During a flyby of Earth last month, the spacecraft successfully found that its instruments could detect elements critical for life, using our Pale Blue Dot for its practice run.

A trial run for finding signs of life

Juice, launched in 2023, will travel to Jupiter over eight years. Upon arrival, it will spend another three years researching its largest moons. The mission’s main goal is to determine whether the moons’ environments and elemental compositions are similar to those on Earth, including the possibility of supporting biological activity.

To get warmed up, Juice used a model of Earth’s atmosphere to test its instruments, searching for the elements carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur—all essential for life and collectively called CHNOPS.

“We are obviously not surprised by these results…it would have been extremely concerning to find out that Earth was not habitable!” said ESA Juice project scientist Olivier Witasse. “But they indicate that MAJIS (Moons and Jupiter Imaging Spectrometer) and SWI (Submillimetre Wave Instrument) will work very successfully at Jupiter, where they will help us investigate whether the icy moons could be potential habitats for past or present life.”

Scientists are confident that Juice is ready for its next mission after identifying life-supporting elements in an atmosphere known to contain them.

SWI was designed to “listen” for the molecular signatures of gases in atmospheres, and this test verified that it can successfully carry out its main task of locating these same elements in the atmospheres of Jupiter’s moons. As Juice looks for indications that these moons may have conditions similar to Earth’s, especially within their hidden oceans, the ability to detect CHNOPS will be crucial.

By measuring other vital molecules in the Earth’s atmosphere, like oxygen and ozone, MAJIS was able to provide additional data. The instrument also produced in-depth temperature maps of the planet’s surface, providing information that the spacecraft will need to start researching the icy terrain of Jupiter’s moons. Scientists can determine whether liquid water could exist beneath the moons’ surfaces thanks to the thermal data.

This early experimental triumph raises hopes for potential discoveries once the spacecraft reaches its destination by demonstrating that it is prepared for the difficulties. Juice will begin a three-year investigation of Europa, Ganymede, and Callisto when it arrives at Jupiter in December 2031.

Scientists are particularly interested in Europa because of the possibility that its subterranean ocean is in direct contact with the moon’s rocky core. This could produce a setting akin to the deep-sea hydrothermal vents on Earth, where life exists despite the lack of sunlight. Juice’s research on Europa may be able to shed light on whether comparable mechanisms operate beneath the ice, providing evidence as to whether life is possible under these harsh circumstances.

Juice’s mission also includes a trip to Ganymede, the largest moon in the solar system. Its magnetic field alone makes it a fascinating subject for study, as it implies that there might be liquid layers beneath its surface. Callisto, a moon whose surface hasn’t extensively changed in billions of years, might hold some secrets about the early phases of solar system formation.