The Europa Orbiter was a planned NASA

NASA

The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 mission to Jupiter

Jupiter

Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

's Moon Europa

Europa (moon)

Europa Slightly smaller than Earth's Moon, Europa is primarily made of silicate rock and probably has an iron core. It has a tenuous atmosphere composed primarily of oxygen. Its surface is composed of ice and is one of the smoothest in the Solar System. This surface is striated by cracks and...

, that was cancelled in 2002. Its main objectives included determining the presence or absence of a subsurface ocean and identifying candidate sites for future lander misions.

The results of the studies on the Europa Orbiter have been conducive to the Jupiter Europa Orbiter

Jupiter Europa Orbiter

As a part of the Europa Jupiter System Mission , the Jupiter Europa Orbiter is a proposed orbiter probe slated for lift-off in 2020 and planned for detailed studies of Jupiter's moons Europa and Io as well as the Jovian magnetosphere...

, NASA's contribution to the planned international Europa Jupiter System Mission

Europa Jupiter System Mission

The Europa Jupiter System Mission – 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...

 (EJSM) slated for launch in 2020.

The Europa Orbiter-concept should not be confused with the Jovian Europa Orbiter

Jovian Europa Orbiter

The Jovian Europa Orbiter was a feasibility study by the European Space Agency for a mission to Jupiter's moon Europa. JEO would be capable of collecting information about Europa by orbiting it, and would correspond with the Jovian Relay Spacecraft and the Jovian Minisat Explorer .The Jovian...

, a feasibility study conducted by the European Space Agency

European Space Agency

The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...

which was finally superseded by the EJSM, too.