GALA

Laser altimeter system focused on geodetic and geophysical investigations of Jupiter icy satellites.

The icy moons of Jupiter -- Europa, Ganymede, and Callisto -- are believed to contain global subsurface water oceans underneath their icy crusts. Each of these oceans would contain more water than all Earth's oceans combined. The possibility is intriguing that these large liquid water oceans represent "habitable" environments. Investigation of the latter is one of the main motivations for the Jupiter Icy Moons Explorer (JUICE).

The Ganymede Laser Altimeter (GALA) as part of the JUICE payload is one of the instruments focusing on aspects related to the presence and characterizations of subsurface water oceans. With respect to evolution of the Galilean Moons, the JUICE mission aims at an exploration of the morphology and surface geology of Ganymede, Europa and Callisto, a determination of their interior structures from a combination of shape, topography and gravitational field data, the exploration of their surface chemistry and physical properties, and at their formation and evolution especially with respect to subsurface water oceans. To this end, precise geodetic measurements to determine the figures of the moons and their topography are mandatory.

GALA is a powerful instrument in achieving these goals. The topography is needed to account for the effects of topographic heights on the gravity field and to account for near surface mass distribution anomalies above the reference figure; to support geological studies, e.g. to identify and characterize tectonic and cryo-volcanic regions on the icy moons.