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Answer: Europa, Jupiter's fourth largest moon, very likely has a saltwater ocean under its ice that may hold more than twice the water of all Earth's oceans. NASA's Europa Clipper, launched October 14, 2024, is the first mission built to study whether that ocean could support life.

The moon

Europa is the sixth-closest moon to Jupiter. Six robotic spacecraft have explored it, and Hubble observes it regularly. Its icy surface hides the ocean beneath.

Why it matters

NASA calls Europa one of the best places to look for environments where life could exist beyond Earth. The ingredients for life may be present there.

Europa Clipper

• A solar-powered robotic spacecraft.
• Main goal: determine whether places below the surface could support life.
• It will study the ice shell, the ocean and the moon's composition with repeated flybys.

Caveat

Habitable conditions are not the same as life; Clipper is not designed to detect life directly.

Claims

• id: C1 claim: There is strong evidence that Europa has a saltwater ocean. source: S1 evidence: "There is strong evidence Jupiter's moon Europa has a saltwater ocean"
• id: C2 claim: Europa is the fourth largest of Jupiter's moons. source: S1 evidence: "Europa is the fourth largest of Jupiter’s moons."
• id: C3 claim: Europa Clipper launched Oct. 14, 2024. source: S2 evidence: "Europa Clipper launched Oct. 14, 2024, on a journey to explore Europa"
• id: C4 claim: Clipper's main goal is whether places below the surface could support life. source: S2 evidence: "determine whether there are places below the surface of Jupiter’s icy moon, Europa, that could"

Sources

• [S1] Europa. NASA. https://science.nasa.gov/jupiter/moons/europa/ . License: US government work, public domain. Accessed 2026-11-04.
• [S2] Europa Clipper. NASA. https://science.nasa.gov/mission/europa-clipper/ . License: US government work, public domain. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_3erws9n7,
  author = {{iinventedlight}},
  title = {{Europa and Europa Clipper: Jupiter's ocean moon}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/europa-moon/},
  note = {Permanent ID iil:note:3erws9n7. License: CC-BY-4.0.},
}

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