Exploring the Bimodal Solar System via Sample Return from the Main Asteroid Belt: The Case for Revisiting Ceres

Area of Science:

• Planetary Science
• Cosmochemistry
• Solar System Evolution

Background:

• The main asteroid belt's structure is key to understanding early Solar System evolution and giant planet migration.
• Isotopic studies reveal two distinct compositional groups: carbonaceous chondrite (CC) from the outer Solar System and non-carbonaceous (NC) from the inner Solar System.
• A compositional gap exists between CC and NC materials, with the asteroid belt containing a mix of both.

Purpose of the Study:

• To assess the scientific rationale and technological feasibility of sample return missions from main-belt asteroids.
• To test planet migration models and the bimodal Solar System concept through isotopic and geochemical analysis of returned samples.
• To identify the optimal target for a main-belt sample return mission to maximize insights into Solar System variation.

Main Methods:

• Review of existing data on asteroid composition and Solar System formation models, including the Grand Tack model.
• Analysis of isotopic variation diagrams to understand the separation between CC and NC material.
• Evaluation of potential sample return mission scenarios, including projectile impact and direct sampling.
• Assessment of dwarf planet Ceres as a prime target based on its composition and accessibility.

Main Results:

• Sample return from main-belt asteroids is technologically feasible, though costly, with significant scientific rewards.
• Asteroid belt material represents a mixture of inner and outer Solar System components, providing a unique laboratory for studying Solar System history.
• A sample return mission to the asteroid belt can test the bimodal Solar System paradigm, even without targeting both CC and NC groups.
• Dwarf planet Ceres is identified as the most compelling target for a sample return mission due to its unique composition and potential to represent displaced trans-Neptunian objects.

Conclusions:

• Sample return missions to main-belt asteroids are essential for understanding Solar System formation and evolution.
• A dedicated sample return mission to Ceres offers unparalleled potential to explore early Solar System variation and test formation models.
• Ceres represents a unique compositional end-member, likely distinct from any meteorite samples currently available, making it a high-priority target for scientific investigation.