Skip to main content

Table 3 Scientific mission objectives and requirements of MMX

From: Martian moons exploration MMX: sample return mission to Phobos elucidating formation processes of habitable planets

Goal 1: Clarify the origins of the Martian moons and constrain processes for planetary formation and material transport in the region connecting the inner and outer Solar Systems

 Medium objective 1.1 Reveal whether Phobos originated as a captured asteroid or resulted from a giant impact

  MO1.1.1: Spectroscopically reveal the surface-layer distribution of the materials that make up Phobos with the spatial resolution required for the scientific evaluation of sampling points and geological structures, thereby constraining Phobos’ origin

SS

MR1.1.1: To grasp the distribution of the constituent materials of Phobos, material distributions of hydrous minerals and other related minerals should be obtained spectroscopically for main parts of the full body in correspondence with its topography (at horizontal spatial resolutions of 20 m or better) and in a radius of 50 m or more around the sampling point (at spatial resolutions of 1 m or better). Also, the mean global Si/Fe ratio, etc., of the moon should be determined to within an accuracy of 20%

  MO1.1.2: Identify the major components of constituent materials from samples collected on Phobos’ surface as Phobos indigenous materials that retain records of their formation, strongly constraining their origins from isotopic ratios, etc.

SS

MR1.1.2: To constrain the origins of Phobos, paying attention to the diversity and representativeness of Phobos’ surface, record the occurrence of and collect at least 10 g of particulate samples (Phobos samples), including samples 2 cm below the surface. Also, identify main sample components as moon-indigenous materials that were constituent materials at the time of formation, and measures their texture and mineral, elemental, and isotopic composition (oxygen, chromium, etc.) with sufficient accuracy to allow the specification of the moon’s origins

   MO1.1.3: Obtain information such as molecular release rates and mass distribution related to the presence of ice in Phobos, investigate the presence or absence of density contrasts on Phobos’ surface, and constrain Phobos’ origin independently of MO1.1.1 and MO1.1.2

S

MR1.1.3: To constrain the origin of Phobos from its internal structure, (1) measure the molecular release rate from internal ice at a detection limit of fewer than 1022 molecules/s, (2) investigate the presence or absence of inhomogeneity in the density structure due to localization of ice exceeding 10% of Phobos’ mass, and (3) investigate the presence or absence of density variation near the surface layer

 Medium objective 1.2a [If Phobos is determined to be a captured asteroid] Elucidate the composition and migration process of primitive materials supplied to the region of terrestrial planets and constrain the initial conditions of Martian surface evolution

  MO1.2a.1: By constraining the formation of primitive materials in the Solar System and primitive bodies in the vicinity of the snow line from a material science perspective, and by estimating the Phobos capture process, constrain the initial conditions for the processes of planetary migration, material transport and evolution of the Martian surface in the early Solar System

S

MR1.2a: To constrain the initial evolution of Solar System materials and volatile element supply, analyze texture, element and isotope composition, formation age, etc., of moon-indigenous materials in Phobos samples with the necessary accuracy and also extract information related to organic matter and hydrous minerals. Also, elucidate collision environments before and after moon capture from the age distribution of shock alteration in the collected sample and measurements of impact crater distributions on the moon surface

 Medium objective 1.2b [If Phobos is determined to originate from a giant impact] Elucidate giant impact and moon formation processes in the terrestrial planetary region and evaluate its influence on the early evolutionary process of Mars

  MO1.2b.1: For Phobos indigenous materials, identify primitive Martian components (Mars-originating components) ejected by a giant impact and components of the impactor body, clarify their features, estimate the scale and age of the impact, and constrain planetary migration, material transport, and planetary formation processes in the terrestrial planetary region

S

MR1.2b: To constrain the process of a giant impact, analyze the texture, elemental and isotopic composition, shock alteration age, etc., of moon-indigenous materials in the Phobos sample with sufficient accuracy, and estimate the peak temperature, timing of the collision, and the mixing ratio of components from primitive Mars and the impacting body. Also, restrict the mixing ratio of both components across the entire moon from measurements of the Si/Fe ratio, etc.

 Medium objective 1.3 Place new constraints on Deimos’ origin

   MO1.3.1: Elucidate the surface distribution of materials composing Deimos through spectroscopy with the spatial resolution necessary for grasping its geological structures and compare this with Phobos

S

MR1.3: To grasp the distribution of constituent materials of Deimos, from spectroscopic information, clarify the surface distribution of hydrous minerals and other related minerals corresponding to its topography at characteristic parts of the moon with a horizontal spatial resolution of 100 m or better

Goal 2 From the viewpoint of the Martian moons, clarify the driving mechanism of the transition of the Mars–moon system and add new knowledge to the evolution history of Mars

 Medium objective 2.1 Obtain a basic description of the elementary processes of surface evolution for moons in the circum-Martian environment

  MO2.1.1: Identify weathering and evolutionary processes (impact frequency, degree of gardening, and space weathering processes) in surface-layer regolith specific to the Martian moons as compared to asteroids

SS

MR2.1: To know the surface evolution processes of Martian moons, (1) observably constrain the circum-moons environment, (2) grasp Phobos’ geological features and surface structures (impact craters, boulders, thickness, and deposition state of the regolith layer) at horizontal spatial resolutions of 10 m or better, and (3) elucidate the state of space weathering and alteration in Phobos samples

 Medium objective 2.2 Add new findings and constraints on the history of changes in the Martian surface

  MO2.2.1: Search returned samples of the Phobos surface for materials ejected from Mars after the formation of Phobos and constrain the chemical state of the Martian surface layer and its transition if suitable samples are present

A

MR2.2.1: To constrain the chemical state and transition of the surface layer of Mars, search a Phobos sample of 10 g or more for materials (ejecta) from Mars from after moon formation, and, if appropriate samples are present, clarify features such as isotopic composition, formation age, and remanent magnetization

   MO2.2.2: Place constraints on the amount of atmospheric escape through the history of Mars from composition ratios and isotopic ratios in the current escaping atmosphere

A

MR2.2.2: To constrain the amount of atmospheric escape through the history of Mars, measure composition ratios and isotopic ratios of the main components of ions escaping from the current Martian atmosphere to an accuracy within 50%

 Medium objective 2.3 Constrain the mechanisms of material circulation in the Martian atmosphere affecting the transitions in the Martian climate

  MO2.3.1: Impose constraints on dust and water transport processes in the Martian atmosphere and between the atmosphere and the surface through observations of the temporal changes in dust storms and the global distributions of water vapor and clouds

A

MR2.3: To constrain transport processes for dust and water near the Martian surface, continuous observations of the mid-to-low-latitude distributions of dust storms, ice clouds, and water vapor in the Martian atmosphere are performed from high altitude equatorial orbit in different seasons to within 1-h time resolutions

  1. MO mission objectives, MR mission requirements, priority: SS = very high, S = high, A = valuable)