Silver and its compounds are of significant appeal for long-duration space missions, as they are capable of destroying or inhibiting the growth of microorganisms including bacteria, viruses, algae, molds and yeast, while exhibiting low toxicity to humans. The general pharmacological properties of silver are based upon the affinity of silver ion for biologically important moieties such as sulfhydryl, amino, imidazole, carboxyl and phosphate groups, and these multiple mechanisms are primarily responsible for its antimicrobial activity. Silver can impact a cell through multiple biochemical pathways, making it difficult for a cell to develop resistance to it, and it can be precisely and efficiently delivered using controlled-release technology.
An engineering approach is detailed that optimizes the epidemiological features of silver compounds in conjunction with the chemical and mechanical features desirable for long-duration space missions. Phase I builds upon three distinct engineering approaches to produce flow-through silver biocide delivery devices based on controlled-release designs that have multiple decades of success in process industrial applications. Phase II will consist of design optimization and extensive parametric testing to support on-site NASA tests and long-duration flight requirements. Phase II will also investigate a regenerate approach to maintaining device activity over multi-year operational lifetimes. The long-term results and benefits to the manned space program are high antimicrobial effectiveness, low toxicity, simple integration and operation into advanced life support systems, maximum operational life, and superior mass/volume efficiency compared to any other possible approach.
This technology is expected to be baselined for all future advanced space missions including Lunar and Mars bases, and vehicles required for transport to those destinations. The option to retro-fit International Space Station with silver-based biocide delivery units is possible.
The proposed technology has extensive commercial potential in the $3.2B global water treatment market for biocides and includes applications in aquaculture, ultrapure water, industrial process water, emergency and outdoor markets The low manufacturing cost of the proposed device will result in significant market potential for this NASA-sponsored technology.