Search Results

The proliferation and growth of microorganisms in the Internal Active Thermal Control System (IATCS) aboard the International Space Station (ISS) has been of significant concern since 2001. Initial testing and assessments of biocides to determine bacterial disinfection capability, material compatibility, stability (rate of oxidative degradation and identification of degradation products), solubility, application methodology, impact on coolant toxicity hazard level, and impact on environmental control and life support systems identified a prioritized list of acceptable biocidal agents including glutaraldehyde, ortho-phthalaldehyde (OPA), and methyl isothiazolone. Glutaraldehyde at greater than 25 ppm was eliminated due to NASA concerns with safety and toxicity and methyl isothiazolone was eliminated from further consideration due to ineffectiveness against biofilms and toxicity at higher concentrations.

The ISS (International Space Station) ITCS (Internal Thermal Control System) includes two internal coolant loops that utilize an aqueous based coolant for heat transfer. A silver salt biocide had previously been utilized as an additive in the coolant formulation to control the growth and proliferation of microorganisms within the coolant loops. Ground-based and in-flight testing demonstrated that the silver salt was rapidly depleted, and did not act as an effective long-term biocide. Efforts to select an optimal alternate biocide for the ITCS coolant application have been underway and are now in the final stages. An extensive evaluation of biocides was conducted to down-select to several candidates for test trials and was reported on previously.

The International Space Station (ISS) IATCS (Internal Active Thermal Control System) includes two internal coolant loops that use an aqueous based coolant for heat transfer. A silver salt biocide was used initially as an additive in the coolant formulation to control the growth and proliferation of microorganisms in the coolant loops. Ground-based and in-flight testing has demonstrated that the silver salt is rapidly depleted and not effective as a long-term biocide. Efforts are now underway to select an alternate biocide for the IATCS coolant loop with greatly improved performance. An extensive evaluation of biocides was conducted to select several candidates for test trials.