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, 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 is investigating the possibility of proceeding with a European-led mission. The ESA-led mission is called the Jupiter Icy Moon Explorer (JUICE) and 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 May 2, 2012.

Pierre-Simon, marquis de Laplace (/ləˈplɑːs/; 23 March 1749 – 5 March 1827) was a French mathematician and astronomer whose work was pivotal to the development of mathematical astronomy and statistics. He summarized and extended the work of his predecessors in his five volume Mécanique Céleste (Celestial Mechanics) (1799–1825). This work translated the geometric study of classical mechanics to one based on calculus, opening up a broader range of problems. In statistics, the so-called Bayesian interpretation of probability was mainly developed by Laplace.

Laplace formulated Laplace's equation, and pioneered the Laplace transform which appears in many branches of mathematical physics, a field that he took a leading role in forming. The Laplacian differential operator, widely used in mathematics, is also named after him. He restated and developed the nebular hypothesis of the origin of the solar system and was one of the first scientists to postulate the existence of black holes and the notion of gravitational collapse.