A thick icy shell spans the surface of Europa, one of Jupiter’s moons. Beneath it lies a vast ocean — twice the volume of our planet’s — that teems with the possibility of life. This body of salt water lends potential clues to inform NASA scientists studying life beyond Earth.
NASA’s Jet Propulsion Laboratory (JPL) launched the Europa Clipper mission in 2024 — one of many projects that aim to tackle the fundamental question of whether we are alone in the universe. But how does an icy moon hundreds of millions of miles away help in answering it?
In an earth and planetary sciences seminar last month, JPL’s director Laurie Leshin shared video montages and context for projects like the one sent to Europa. She said that the answer to the origin of life remains elusive given the messy nature of the Earth’s archaeological record — wind, weather and water have disorganized ancient evidence that contains the first billion years of solar system history. Thus, scientists have had to turn elsewhere for answers, and Europa has shown evidence of possessing a massive sub-surface salty ocean, exciting the planetary community.
Ocean worlds in solar systems like our own are “the best places today that we might actually find evidence of extant living things,” Leshin said, generating nods from the audience of Stanford faculty and staff in a Geology Corner classroom.
The Europa Clipper will perform 50 flybys of the moon while in orbit around Jupiter, gathering data on its composition, geology and surface interactions that will provide information about potential habitability.
“As someone deeply passionate about space exploration, I’m always astonished by the complexity behind these large-scale missions,” said Vittorio Colicci, a first-year earth and planetary science Ph.D. student. “[Leshin] described spacecraft as ‘modern cathedrals,’ which I think perfectly captures the hard work and vision that brings them to life.”
Laura Schaefer, a planetary sciences professor who attended the seminar, believes that missions dedicated to studying Earth and sending technology beyond our orbit are not mutually exclusive endeavors.
“It’s like shower thoughts. You are working on one thing, and you discover something totally different,” Schaefer said. “There’s a lot of ways in which exploring other planets is beneficial to us.”
In the past, studying Mars’ atmosphere as a dusty giant has helped scientists understand how dirt and debris affect climate patterns on Earth. Similarly, Venus exemplifies the conditions of the runaway greenhouse effect, in which the accumulation of greenhouse gasses in the atmosphere continuously traps heat. While Earth’s atmospheric carbon dioxide (CO2) concentrations differ vastly from those that caused the runaway effect on Venus, studying its chemical makeup has helped researchers understand what Earth’s threshold of CO2 emissions might be.
Even if the Europa mission does not identify life, scientists remain open to unexpected discoveries. Anton Ermakov, an assistant professor and planetary scientist, is involved in JPL’s Juno spacecraft studying Jupiter. He said that while scientists base missions on an expected hypothesis, the actual data often challenge the very nature of the questions they ask.
“If we discover life forms on different planets, I would not be surprised if they were so different from what the Earth life forms,” Ermakov said. “That would lead to a complete transformation of our understanding of biology and evolution.”
Results from the spacecraft are fast approaching. April 11 marked five years until the mission reaches Jupiter’s orbit.
For a moon that lies 390 million miles away, “It’s practically tomorrow that we will be out at Jupiter and seeing what’s going on with Europa,” Leshin said.