The increasing frequency of International Space Station (ISS) egress operations contaminates the spacecraft environment with propellant residues (such as anhydrous hydrazine) and their decomposition by-products, as well as coolants such as ammonia and Freon.  NH3 and N2H4 have a 24 hour Spacecraft Maximum Allowable Concentration (SMAC) of 7 ppm and 0.3 ppm, respectively.

TDA Research Inc. is developing a new adsorbent that can remove these contaminants to sub ppmv concentrations with high activity and capacity. The sorbent can be integrated as a thin layer into an existing cartridge used in the ISS first response crew mask; the new media will greatly extend the capability to protect against the NH3 and hydrazine for extended duration under high contaminant challenges, without undermining the ability of the cartridge to filter out other combustion by-products.

In Phase I, we successfully completed all proof-of-concept demonstrations at the bench-scale elevating the TRL to 3. The new adsorbent can provide over 1,400 minutes of protection when challenged with 50 ppmv NH3 and over 450 hrs with 1 ppmv anhydrous N2H4, even at a bed aspect ratio as low as 0.1 and at gas-solid contact times as low as 0.11 sec.  The NH3 and N2H4 capacity of the sorbent exceeds 1.8&#37; wt. and 1.4&#37; wt., respectively, with bed outlet concentrations maintained at less than 40 ppbv.

In Phase II, we will continue to optimize the sorbent formulations and scale-up the production.  We will design and fabricate full-scale experimental prototype cartridges at TDA to support demonstrations in an environmental chamber using a breathing apparatus.  Based on the results, we will design and fabricate high fidelity cartridges based on the flight qualified ISS Fire Recovery Respirator Cartridge and complete high fidelity demonstrations in an environmental chamber to fully demonstrate its capability (non-human testing at TRL 6). These will be provided to NASA for additional testing and demonstrations.