Add a new subrule to the rule “Local Maneuvring”, called “Orbital Dockyards”:-

An Orbital Dockyard is a type of Structure. If a Shuttle’s Orbit contains an Orbital Dockyard, that Shuttle may spend 1 tonne of any Substance to replace one of their own XDICEY Thrusters with an ADICEB Thruster, where “A” and “B” are positive integers whose sum is equal to “X” plus “Y”.

After “and a maximum value of at most 12.” in rule “Local Maneuvring”, add:-

A DICEX Thruster may also be considered to be a 1DICEX Thruster.

Select a random Orbit on Ganymede that contains no Structures, and a random Orbit on Europa that contains no Structures, and add an Orbital Dockyard to each of those Orbits.