# Analysis of Microbial Diversity and Evidence of Contamination at a Mars Analogue Habitat

## TL;DR

This study examines microbial contamination risks for Mars missions by analyzing a Mars simulation habitat and surrounding soil.

## Contribution

The paper provides evidence of backwards contamination of environmental microbes into the Mars Desert Research Station habitat.

## Key findings

- Interior surfaces were dominated by human-associated bacteria and fungi.
- Soil samples contained extremophiles but showed no evidence of contamination from the habitat.
- Three bacterial genera found in both soil and interior samples suggest backwards contamination.

## Abstract

We assessed the potential for a crewed mission to microbially‐contaminate the Martian surface by studying a terrestrial analogue facility, the Mars Desert Research Station. DNA sequencing of interior swab and exterior soil samples allowed characterisation of the microbiome present inside the habitation module and to seek evidence of escape into the desert surface outside the “airlock”. Microbial diversity of interior surfaces was dominated by Gram‐negative bacterial genera Acinetobacter, Pseudomonas, Escherichia and Shigella, with Penicillium and Aureobasidium most abundant amongst the fungal sequences—many members of which are human commensals. The soil microbiome sample was mostly characterised by Bacteroidota, Actinobacteriota and Pseudomonadota bacteria, with a number of extremophiles identified. The most abundant fungal genera were Alternaria, Neocamarosporium and Preussia. No archaeal sequences were isolated in either interior samples or soil. Principal Component Analysis of amplicon sequence variants shared between the soil sample and at least one indoor swab showed no evidence for contamination of the soil from the Hab microbiome. However, three bacterial genera—Paracoccus, Cesiribacter and Psychrobacter—identified in both soil and internal swabs are not commonly associated with humans and so represent evidence of backwards contamination of environmental microbes brought into the Hab during MDRS operations.

We assessed the potential of a crewed mission to Mars to microbially contaminate the surface by studying a terrestrial analogue facility, the Mars Desert Research Station. DNA sequencing of interior swabs and an external soil sample allowed us to characterise the microbiomes present. We did not detect contamination of the desert soil within our detection thresholds, but did find evidence of backwards contamination of environmental microbes into the MDRS.