Characterisation of the Microbial Community in Spacecraft Assembly Facilities

Kurzfassung

The characterization of the microbial load of spacecraft and the spacecraft assembly facilities is of growing interest to the space industry with the prospect of sample return missions to Mars in the near future. The planetary protection policy of COSPAR, where the total amount of microbes on the surface of a spacecraft may not exceed 3 x 105 spores for life detecting missions to Mars, has to be followed by all space agencies. In order to stay under that limit, guidelines of how to analyze the microbial load as well as new cleaning and sterilization techniques have to be developed. The first step is to characterize the microbial communities on spacecraft and in spacecraft assembly facilities. The second step is to find ways to keep the spacecraft sterile so that the forward contamination of other bodies in the Solar System as well as the backward contamination of Earth by extraterrestrial life can be prevented. The characterization of the microbial communities in spacecraft assembly facilities was carried out at ESTEC in the Netherlands where the Automated Transfer Vehicle (ATV) was assembled. Culture-based and molecular methods were used to characterize the microbial load in the clean room and on the spacecraft itself. The methods included purification of cultures, DNA isolation, polymerase chain reaction (PCR), 16S rDNA analysis, and antibiotic resistance tests. The distribution of the cultivable microbes in the clean room was determined. The isolated microbes showed different phenotypes from spore-forming to fungi-like bacteria and different resistance to various antibiotics. A final 16S rDNA genetic characterization to determine the exact species could not be performed in time. This study intends to improve the understanding of the microbial diversity and the survival capabilities of microorganisms found in spacecraft assembly facilities. This project is done by a PhD student at DLR and this report summarizes a 12 week internship period and covers therefore only a small part of the whole project.