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#Introduction  There is a growing appreciation of the importance of communities of microbes found in diverse environments from the oceans, to soil, to the insides and outsides of various plants and animals. Recently Recently,  there has been an expanding focus on the microbial ecology of the "built environment" -those  human constructed entities like buildings, cars, ships ships,  and planes - places where we spend a large fraction of our time. One somewhat unexplored - unexplored,  yet certainly important - important,  type of built environment is that found in space. As humans expand their reach into the solar system - system,  with more and more plans for space travel, and possible with the possibility of the  colonization of other planets and moons,we believe  it is of critical importance to understand the microbial ecology of the built environments being utilized for such endeavors. Interest in the microbial occupants of spacecraft long precedes the launch of the International Space Station (ISS) \cite{11883448}\cite{5173646}. Early work primarily focused on ensuring that spacecraft were free of microbial contaminants in an effort to avoid inadvertent panspermia (seeding other planets with microbes from Earth). Work on occupied spacecraft such as Mir, Space Shuttle, and Skylab focused more on microbes with possible human health implications. With the launch of the ISS, it was clear that this new built environment would be permenantly housing microbes as well as humans. Calls were made for a better understanding of microbial ecology and human-microbe interactions during extended stays in space \cite{pierson2007microbial} \cite{14994179} \cite{14569419}. Efforts were made to establish a baseline microbial census. For example, Novikova et al \cite{16364606} obtained more than 500 samples from the air, potable water, and surfaces of the ISS, over the course of 6 years.