Europa Jupiter System Mission – Laplace

The Europa Jupiter System Mission – Laplace (EJSM/Laplace) was a proposed joint NASA/ESA unmanned space mission slated to launch around 2020 for the in-depth exploration of Jupiter's moons with a focus on Europa, Ganymede and Jupiter's magnetosphere. The mission would comprise at least two independent elements, NASA's Jupiter Europa Orbiter (JEO) and ESA's Jupiter Ganymede Orbiter (JGO), to perform coordinated studies of the Jovian system.

The Japan Aerospace Exploration Agency (JAXA) and the Russian Federal Space Agency (Roscosmos) had expressed their interest in contributing to EJSM/Laplace, although no deals had been finalized. JEO was estimated to cost $4.7 billion, while ESA would spend $1.0 billion (€710 million) on JGO.

In April 2011, ESA stated that it seemed unlikely that a joint US–European mission will happen in the early 2020s given NASA's budget, so ESA continued with its initiative, called the Jupiter Icy Moon Explorer (JUICE) that will be based on the JGO design. Selection of JUICE for the L1 launch slot of ESA's Cosmic Vision science programme was announced on 2 May 2012.