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#Introduction  There is a growing appreciation of the importance of microbial communities found in diverse environments from the oceans, to soil, to the insides and outsides of plants and animals. Recently, there has been an expanding focus on the microbial ecology of the "built environment" - human constructed entities like buildings, cars, and trains - places where we spend a large fraction of our time . time.  One relatively unexplored, yet certainly important, unexplored  type of built environment is that found in space. As humans expand their reach into the solar system, with more and more plans for space travel, and with the possibility of the colonization of other planets and moons, 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 the surfaces of spacecraft were free of microbial contaminants in an effort to avoid inadvertent panspermia (seeding other planets with microbes from Earth) \cite{pierson2007microbial}. Work on human-occupied spacecraft such as Mir, Space Shuttle, Shuttles,  and Skylab focused more on microbes with possible human health effects. With the launch of the ISS, it was understood that this new built environment would be permanently 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. These early studies were unavoidably limited by their reliance on culturing to identify microbial species. Culture-independent approaches were eventually implemented, including some small-scale 16S rDNA PCR surveys \cite{14749908},\cite{Moissl_2007} and the Lab-On-a-Chip Application Development\cite{19845447} Portable Test System (LOCAD-PTS), which allows astronauts to test surfaces for lipopolysaccharide (LPS - a marker for gram Gram  negative bacteria). Originally launched in 2006, the capability of the LOCAD-PTS was expanded in 2009 to include an assay for fungi (beta-glucan, a fungal cell wall component) and gram Gram  positive bacteria (lipoteichoic acid, a gram positive component of the  cell wall component.) of Gram positive bacteria.)  Recently, the first large-scale, culture-independent 16S rDNA PCR survey was published using the Roche 454 platform, looking at dust on the ISS \cite{24695826}. We report here on a further effort to use involving  16S rDNA PCR and  sequencing, on using  the Illumina platform, to examine the microbial communities found on 15 surfaces inside the International Space Station. We have also compiled a collection of papers on space microbiology in an online resource to provide a more comprehensive historical perspective of this kind of work (see http://www.mendeley.com/groups/844031/microbiology-of-the-built-environment/papers/added/0/tag/space/).