  Enceladus, an icy moon of Saturn, possesses an internal water ocean and jets
expelling ocean material into space. Cassini investigations indicated that the
subsurface ocean could be a habitable environment having a complex interaction
with the rocky core. Further investigation of the composition of the plume
formed by the jets is necessary to fully understand the ocean, its potential
habitability, and what it tells us about Enceladus' origin. Moonraker has been
proposed as an ESA M-class mission designed to orbit Saturn and perform
multiple flybys of Enceladus, focusing on traversals of the plume. The proposed
Moonraker mission consists of an ESA-provided platform, with strong heritage
from JUICE and Mars Sample Return, and carrying a suite of instruments
dedicated to plume and surface analysis. The nominal Moonraker mission has a
duration of 13.5 years. It includes a 23-flyby segment with 189 days allocated
for the science phase, and can be expanded with additional segments if
resources allow. The mission concept consists in investigating: i) the
habitability conditions of present-day Enceladus and its internal ocean, ii)
the mechanisms at play for the communication between the internal ocean and the
surface of the South Polar Terrain, and iii) the formation conditions of the
moon. Moonraker, thanks to state-of-the-art instruments representing a
significant improvement over Cassini's payload, would quantify the abundance of
key species in the plume, isotopic ratios, and physical parameters of the plume
and the surface. Such a mission would pave the way for a possible future landed
mission.
