Mission Type: Orbiter

The proposed Europa Jupiter System Mission (EJSM) would consist of two separate vehicles, one provided by NASA and the other by ESA, which would each launch separately.

Both the NASA-built Jupiter Europa Orbiter (JEO), and the ESA-built Jupiter Ganymede Orbiter (JGO) would be powered by chemical propulsion. Venus and Earth gravity assists would speed each spacecraft onward for arrival at Jupiter only 6 years later.

JEO would carry 11 instruments and JGO would carry 10 instruments to study dynamic phenomena such as Io's volcanoes and Jupiter's atmosphere. In addition, the orbiters would map Jupiter's massive magnetosphere and study how it interacts with its moons. The orbiters would also map any liquid water oceans, which are believed to exist beneath the ice shells of Europa and Ganymede.

Also planned is NASA's Jupiter Polar Orbiter (Juno), which will arrive at the Jupiter system in 2016.

EJSM has two major goals with supporting science objectives:

Goal: Determine Whether the Jupiter System Harbors Habitable Worlds. The fundamental theme for EJSM can be further focused into science objectives relating to habitability (focusing on Europa and Ganymede). The main science objectives supporting this goal are:

• Characterize sub-surface oceans
• Characterize the ice shells and any subsurface water
• Characterize the deep internal structure for Ganymede and the intrinsic magnetic field
• Compare the exospheres, plasma environments, and magnetospheric interactions.
• Determine global surface compositions and chemistry
• Understand the formation of surface features, including sites of recent or current activity, and identify and characterize candidate sites for future in situ exploration.

Goal: Characterize the Processes Within the Jupiter System. The Jupiter system includes a broad diversity of objects, including Jupiter itself, 55 currently known outer irregular satellites, the Jovian ring system, four small inner satellites, and the four large Galilean Satellites: Io, Europa, Ganymede, and Callisto. The main science objectives supporting this goal are:

• Understand the Jovian satellite system, especially as context for Europa and Ganymede.
• Evaluate the structure and dynamics of the Jovian atmosphere.
• Characterize processes the Jovian magnetodisk/magnetosphere.
• Determine the interactions occurring in the Jovian system.
• Constrain the origin of the Jupiter system.

Biochemistry on Europa: Scientists think it very likely that oceans exist beneath Europa's icy crust. If so, life could exist within the liquid water. On Earth, extremophiles (life forms that can survive in extreme variations in temperature and other conditions) have been found living near volcanic vents at the bottom of the ocean. These Earth extremophiles have shown scientists that sunlight is not a requirement for biochemistry, just water warm enough to be liquid, combined with other minerals and food sources.

The Europa Jupiter System Mission (EJSM) would help to answer key questions about the moon: how thick is the ice? As the ice shifts, does liquid water come to the surface where it may be studied by future probes? If biochemistry (life) exists on Europa, EJSM would help to map out sites for future probes and landers to sample frozen microscopic Europa life.