Thermal Amine Scrubber – Renewed Operational Status & Planned Upgrades

The carbon dioxide (CO2) removal flight experiment known as 'Thermal Amine Scrubber' (TAS), developed collaboratively by Collins Aerospace and NASA/Johnson Space Center, has been operating on ISS since May 2019. Since our 2022 publication, TAS has accumulated additional run time but also experienced an operational fault that could not be resolved on-orbit, leading to return of the TAS Controller on SpX-26. The controller was refurbished and returned to ISS on SpX-29 where it was reinstalled and activated on 12/26/2023. TAS performance since reactivation has matched that of periods in 2021-2022, indicating negligible degradation with scrubbing capacity up to ~4 kg/day at 2 mmHg inlet ppCO2. In the interest of recovering oxygen from scrubbed CO2, evaluation of necessary changes to meet a new requirement of delivering a very pure CO2 product was investigated. This would be necessary to interface with Sabatier and assure no condensation occurs in the Sabatier compressor under anticipated operating conditions. Several approaches were analyzed and the most promising was tested. The testing revealed that the <1000 ppm requirement could not be met with current flight configuration hardware. Further lessons learned from ISS operation of TAS have been evaluated with consideration of scenarios from commercial and deep space markets to update the TAS design accordingly. Performance of TAS on ISS has provided insight into scaling of key components, including the CO2 canisters and system blower, to meet new mission requirements. Future TAS users are expected to have a range of crew sizes so we have evaluated an approach where modules can be added or removed based on crew size and redundancy requirements. We also anticipate updating the TAS system controller to incorporate space-rated components and utilize a standard architecture, consistent with other Collins designs, to achieve commonality benefits including ease of support and reductions in cost and lead-time.