Threshold Geological Criteria

  1. Presence of subaqueous sediments or hydrothermal sediments (equal 1st priority),
    hydrothermally altered rocks or low-T fluid-altered rocks (equal 2nd priority)
  2. Presence of minerals indicative of aqueous phases (e.g., phyllosilicates, carbonates, sulfates, etc.) in outcrop
  3. Noachian/Early Hesperian age based on stratigraphic relations and/or crater counts
  4. Access to unaltered igneous rocks as float
  5. Not a Special Region

Potential Qualifying Geological Criteria:

  1. Morphological evidence for standing bodies of water and/or fluvial activity (deltaic deposits, shorelines, etc.).
  2. Assemblages of secondary minerals of any age.
  3. Presence of former water ice, glacial activity or its deposits.
  4. Igneous rocks of Noachian age, of known stratigraphic relation, better if including exhumed megabreccia.
  5. Volcanic unit of Hesperian or Amazonian age well-defined by crater counts and well-identified by morphology and/or mineralogy.
  6. Probability of samples of opportunity (ejecta breccia, mantle xenoliths, etc.).
  7. Potential for resources for future human mission.


Landing Site Workshop: John Grant (, Matthew Golombek (