Planetary Aerobiomes in Dust- and Aerosol-Dominated Extraterrestrial Environments

The search for extraterrestrial life has traditionally focused on environments where liquid H2O is stable over long timescales, such as subsurface aquifers, hydrothermal systems, or ice-rich deposits. However, many planetary bodies are characterized by active cycles of particulate transport involving either mineral dust or atmospheric aerosols. In planetary science, these are commonly distinguished as refractory particles (non-volatile mineral dust) and volatile or mixed aerosol particles, including condensates such as ices, organics, or acidic droplets. Here, we propose the concept of planetary aerobiomes, defined as distributed particle-associated microbial persistence and dispersal systems in extraterrestrial environments. In this framework, refractory mineral particles may act as mobile particle-associated microenvironments that could support microbial survival and dispersal, while in some cases also providing partial physical shielding from environmental stressors. Drawing on observations from terrestrial dust-associated microbiomes and mineral–microbe interactions, particle-associated systems may represent previously overlooked ecological substrates in planetary environments. Rather than replacing models centred on environments with persistent liquid H2O, this perspective expands them by considering particle-associated microenvironments as transient but potentially relevant biosignature-preservation niches in arid, dust-dominated worlds such as Mars, as well as in aerosol-rich environments including Titan, Venus, and icy moons. We further discuss the implications for life-detection strategies, highlighting atmospheric particles as potential reservoirs of biosignatures, and consider their relevance for applied microbiology, including in situ resource utilization (ISRU) and bioregenerative life-support systems (BLSS). Beyond astrobiological implications, understanding microbial persistence within particle-associated extreme environments may provide useful models for applied microbiology, including stress-resilient microbial engineering, biomining, contamination control, and bioregenerative technologies for space exploration.