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Oxygen Delivery System (O2_Delivery_Sys)
Principal Investigator
Research Area:
Operational and clinical research
Species Studied
Scientific Name: Species: N/A

Future space missions will take astronauts beyond Earth’s orbit. The spacecraft that will be used for these missions is currently envisioned to have an internal atmosphere that is at a reduced pressure and elevated oxygen percentage, which assists with extra-vehicular activities. These exploration missions may be long in duration such as 36 months, which requires that medical support be available for the crew. This medical support will include advanced life support equipment, which includes patient ventilation with oxygen.

There are two US oxygen delivery systems currently used onboard the International Space Station (ISS) - the Respiratory Support Pack (RSP) and the Portable Breathing Apparatus (PBA). The RSP uses the ISS 120 psi oxygen lines and delivers pure oxygen up to 12 L/min. The RSP is for medical O2 usage. The PBA consists of a non-refillable portable oxygen bottle that provides 15 minutes of oxygen and also includes a 30 foot hose to attach to the ISS oxygen lines for long term oxygen supply. The PBAs are distributed throughout the ISS, and a few are available in each module or node. Both the PBAs and the RSP can obtain their oxygen supply from high pressure tanks located on the ISS. The PBAs also attached to the ISS oxygen line for use during the pre-Extravehicular Activity (EVA) pre-breathe protocol (a method of decreasing the body’s nitrogen load and the risk of decompression sickness). The PBAs are also used for emergency oxygen usage. An alternative to the US oxygen mask is the Russian isolating gas mask that can be used during fire or atmospheric contamination events. It provides 70 minutes of oxygen, but has been reported to be bulky, hot, and uncomfortable to wear for long periods of time. The main challenge with the current systems is that when using either the RSP or PBAs, the cabin oxygen concentration is elevated which increases the fire hazard. Modeling results have shown that when a patient is receiving oxygen, the oxygen concentration aboard the ISS rises very slowly secondary to the large volume and good mixing due to ventilation. In a much smaller spacecraft, the oxygen concentration increases much more rapidly and the risk of fire increases accordingly. Even in the ISS well-mixed scenario there is a pocket of elevated oxygen around the astronaut’s head and chest area that creates a high risk situation. If an ignition source is introduced into this area, the resulting fire can rapidly spread through the oxygen-saturated clothing and hair as well as to other astronauts who may be treating the patient. For exploration atmospheres, the ambient atmosphere may be at elevated oxygen and reduced pressure as the norm, increasing the flammability of materials in general.

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Ebner AD, Mehrotra A, and Ritter JA. Graphical unit block approach for complex PSA cycle scheduling of parallel interacting trains of columns and tanks. Adsorption. 2015. April; 21(3):229-24. [DOI]

Technology assessment

Data Information
Data Availability
Archive is complete. Data sets are not publicly available but can be requested.
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Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Ground 05/01/2009 In Progress

Human Research Program (HRP) Human Research Roadmap (HRR) Information
Crew health and performance is critical to successful human exploration beyond low Earth orbit. The Human Research Program (HRP) investigates and mitigates the highest risks to human health and performance, providing essential countermeasures and technologies for human space exploration. Risks include physiological and performance effects from hazards such as radiation, altered gravity, and hostile environments, as well as unique challenges in medical support, human factors, and behavioral health support. The HRP utilizes an Integrated Research Plan (IRP) to identify the approach and research activities planned to address these risks, which are assigned to specific Elements within the program. The Human Research Roadmap is the web-based tool for communicating the IRP content.

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Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Eric R. Gallagher
Institutional Support
National Aeronautics and Space Administration (NASA)
Proposal Date
Proposal Source
Directed Research