The Radiation Environment of Ceres and Implications for Surface Sampling

Area of Science:

• Planetary Science
• Astrobiology
• Geophysics

Background:

• Ceres, a dwarf planet in the asteroid belt, is water-rich with evidence of subsurface liquid brine.
• Its surface lacks a substantial atmosphere and global magnetic field, exposing it to space radiation.
• This makes Ceres a candidate ocean world with potential for present-day activity.

Purpose of the Study:

• To evaluate the effects of charged particle radiation on near-surface materials on Ceres.
• To determine timescales for radiation-induced modification of organics and endogenic material.
• To assess the sterilization timescale for potential subsurface life on Ceres.

Main Methods:

• Analysis of charged particle radiation effects on materials within the top 10-20 cm of Ceres' surface.
• Modeling of radiation-induced modification and destruction of organics.
• Calculation of sterilization timescales for putative organisms.

Main Results:

• Radiation-induced modification and destruction of organics and endogenic material occur on timescales of approximately 100 million to 1 billion years.
• Sterilization of potential life within near-surface materials occurs on timescales less than 500,000 years.
• A significant difference exists between timescales for material processing and biological sterilization.

Conclusions:

• Future missions to Ceres should target regions with specific geologic ages to balance sample integrity and contamination risks.
• Geologic ages between 500,000 years and 100 million years may offer the best opportunities for sampling pristine yet unsterilized material.
• Understanding radiation effects is crucial for planning astrobiological investigations on airless bodies like Ceres.