Science Traceability Matrix (STM)

L4 – the mission to Enceladus has three main scientific themes derived from the Expert Committee report:

(A) Habitability and surface–interior interactions.

(B) Enceladus interaction with the external environment and the Saturnian system.

(C) Prebiotic chemistry and biosignature detection.

Based on these themes the L4 independent science expert committee, in collaboration with the L4 Payload Working Group, has developed a first version of a Science Traceability Matrix (STM), deriving scientific questions for each theme and a set of scientific objectives for each question.

This STM guides the mission study and especially the assessment of strawman payload complements. The L4 community is invited to use this as guidance to advance their own instrument ideas in preparation for the next phase of the L4 development and the L4 community workshop at ESTEC in December.

An excel version of the STM is available here.

  • A1.1: Define the moon's interior structure including the properties of the core
  • A1.2: Determine the structure and dynamics of the ice shell
  • A1.3: Define the depth, dimensions and dynamics of aqueous reservoirs (e.g., global ocean, brine pockets)
  • A1.4: Characterise the potential hydrothermal exchange between the liquid environment and the rocky layer
  • A1.5: Define the thermal state and heat budget of the interior (Potential sources of planetary energy may include, e.g., tides, geochemical processes, and isotopic decay)
  • A1.6: Define the evolution of the orbit of Enceladus over geological periods
  • A2.1: Characterise the chemical composition
  • A2.2: Characterise physical–chemical parameters (e.g. salinity, redox, pH, temperature)
  • A2.3: Characterise the available sources of energy to support life (hydrothermal activity and chemical imbalance)
  • A2.4: Assess the long-term stability and evolution of the liquid ocean
  • A3.1: Characterise the geological features and processes (constrain stress history, deformation evolution and resurfacing mapping and characterising geological features, e.g. craters, boulders, fractures, ridges, fine particle deposits, landslides)
  • A3.2: Identify surface distribution of ices, salts, organics, and silicates to trace internal vs. external material sources. Detect cryovolcanic features and relate them to subsurface ocean chemistry.
  • A3.3: Charactarise in detail the physical properties and morphology of the South Polar Terrain, including the tiger stripes (e.g. venting activity, connecting fracture system).
  • A3.4: Characterise plume deposition and deposits
  • A4.1: Characterise plume vents (including subsurface structure)
  • A4.2: Characterise the energy balance driving plume activities (tidal vs internal heat, seismic activity)
  • B1.1: Characterise how the dust and gas environment interacts with the surface
  • B1.2: Characterise effects of micrometeorite bombardment
  • B1.3: Characterise how the electromagnetic environment, charged particles, and radiation interact with surface materials
  • B2.1: Characterise plume morphology, structure, and temporal variability
  • B2.2: Characterise gaseous and particle components of plumes
  • B2.3: Define how plume material interacts with the Saturnian system (e.g. E-ring, torus)
  • B3.1: Constrain the interior of other Saturnian moons
  • B3.2: Identify and characterise the liquid environments (if any) of other Saturnian moons (e.g. Mimas)
  • B3.3: Characterise the geological history and evolution of other Saturnian moons
  • B3.4: Characterise the surface composition of other Saturnian moons
  • B3.5: Constrain the orbital evolution of other Saturnian moons.
  • B3.6: Characterise the dust distribution and composition in the Saturnian system
  • B3.7: Characterise Saturn's magnetosphere and its interaction with other Saturnian moons
  • C1.1: Determine the inventory of organic molecules, and characterise their abundance and distribution
  • C1.2: Determine the processes at the origin of organic molecules (e.g. methanogenesis/serpentinization)
  • C1.3: Determine the inventory of inorganics related to organic chemistry, and characterise their abundance and distribution
  • C1.4: Determine the molecular complexity of organics, and characterize its diversity and distribution
  • C2.1: Determine and characterise the inventory of potential chemical biosignatures (e.g. from monomers to polymers)
  • C2.2: Search for any other detectable non-chemical biosignatures
  • C2.3: Determine metabolic pathways, if biosignatures are present
  • C2.4: Determine local influences on the preservation state of biosignatures