Hypobaric Hypoxia Characterization Studies

Purpose of this RFI:

The information obtained will be used by NASA for planning and acquisition strategy development. NASA will use the information obtained through this RFI on a non-attribution basis. Providing data and information that is limited or restricted for use by NASA for that purpose would be of very little value and such restricted/limited data/information is not solicited. No information or questions received will be posted to any website or public access location. NASA may respond to the individual responses.

The Government does not intend to grant an award on the basis of this RFI or to otherwise pay for the information solicited. Later participation in the interdisciplinary team is not guaranteed, nor is compensation for any later participation. As stipulated in Federal Acquisition Regulation (FAR) 15.201(e), responses to this notice are not considered offers, shall not be used as a proposal, and cannot be accepted by the Government to form a binding contract. Inputs shall be compliant with all legal and regulatory requirements concerning limitations on export-controlled items. To the full extent that it is protected pursuant to the Freedom of Information Act and other laws and regulations, information identified by a respondent as "Proprietary or Confidential" will be kept confidential.

Description:
The NASA Human Research Program (HRP) is requesting information on capabilities and recommendations for implementation of multiple-day hypobaric chamber studies to characterize the physiological, performance, and cognitive risks of a hypobaric, mild hypoxic atmosphere (equivalent to 4,000 – 12,000 ft) that might be used during future space exploration missions.

Appropriate responses to this RFI should address:

1. Recommendations for candidate facilities with capabilities, expertise, and staffing to perform continuous 24-hour habitation for at least 7 and up to 30 consecutive days in a hypoxic environment using hypobaric chamber(s). At a minimum, facilities will be requested to perform tests at a lower atmospheric pressure atmosphere (between 14.7 and 7.6 psia) and with specified ambient gas mixtures (e.g., air with 21% O2 only, or reduced oxygen concentrations at 15-21% O2). If applicable, facilities also may be requested to test in hypobaric conditions with enriched O2 (up to 34% O2). Facilities ideally should be able to accommodate at least 6 persons per chamber test, including supply of in-chamber diet, sanitary facilities, and support to implement a standardized suite of measures designed to characterize the effects of mild hypoxia on mission-relevant physiological, performance, and cognitive outcomes in healthy volunteers.  Facilities also should have capabilities to recruit, screen, and provide in-chamber medical support of the test subjects.  Facilities should have the capability to access an “astronaut-like” population of study participants with target physiological characteristics of age 30-60 yrs, 50% male-female split, V02max >27.5 ml/min/kg and in overall good health (equivalent to passing a medical flight physical examination).  Facilities would ideally have an airlock to allow for removal of a subject or personnel from the chamber while other subjects remain in testing.
2. Recommendations for standardized measures and analyses of physiological, performance, and cognitive outcomes and a relative prioritization of each measure to characterize safe execution of a “space exploration-like mission” that requires physical work, critical thinking and decision-making, and individual and team task performance in a hypobaric hypoxic environment.  These might include indices of hypoxic stress, altitude sickness, sleep quality, exercise performance, cognitive performance, visual acuity, team cohesion and performance, and other measures.  Test and assessment modalities must be able to be performed in the enclosed hypobaric environment, and protocols should provide meaningful results in a time-efficient manner for testing of multiple subjects in a single day. Consideration also should be given to frequency of the measures required before the hypobaric hypoxic exposure to establish a baseline, during the exposure to characterize the potential for impairment, its onset, and if there is resolution through acclimation, and after the exposure to assess time course of readaptation to a normoxic normobaric environment.  These will be considered for approaches to surveil, reduce risk of, and/or treat potential hypoxia-related conditions during future space exploration missions. Standardization of measures across (international) facilities also should be considered to enable comparisons between studies.

Background:
NASA is prioritizing efforts to mitigate the risk of decompression sickness (DCS) during surface extravehicular activity (EVA) in upcoming missions to the Moon. During EVA, the pressure of the spacesuit is typically low to enhance mobility and allow astronauts to safely and efficiently perform exploration activities. The transition from a higher atmospheric pressure habitat to a lower pressure in the spacesuit can cause DCS when inert gas (typically nitrogen) stored in tissue comes out of solution and forms bubbles that can cause symptoms ranging from mild pain to serious pulmonary or neurological deficits.1 To reduce the risk of DCS during surface EVA, astronauts will live in a surface habitat with reduced atmospheric pressure and nitrogen content (by increasing oxygen concentration) relative to Earth. Equilibration to this Lunar habitat “Exploration Atmosphere” will reduce decompression stress during EVA, and thus the need for lengthy and complex denitrogenation protocols (i.e. oxygen prebreathe) as currently seen in EVA operations on the ISS.2,3

The design of an appropriate Exploration Atmosphere must balance risks for DCS, material flammability at high oxygen concentrations, and hypoxia. While a reduced atmospheric pressure can help minimize DCS risk, it increases the risk of hypobaric hypoxia on human health and performance, which may significantly impact mission success.4,5 A better understanding of the risk of hypoxia in operationally-relevant atmospheres with and without enriched oxygen will enable NASA to make informed decisions on Exploration Atmosphere design to enable safe and flexible operations during exploration missions.

NASA plans to perform a series of hypobaric chamber tests to characterize the risk of hypobaric hypoxia on human health and performance and to engage other facilities to support an increased tempo of data collection and enhance mission-relevant modeling capabilities. These tests will inform requirements for future vehicles, habitats, suits, and mission planning.

References:

1.            Garbino A, Norcross JR. NASA Evidence Report: Risk of Reduced Crew Health and Performance Due to Decompression Sickness and Hypoxia. Houston, TX: National Aeronautics and Space Administration, Lyndon B. Johnson Space Center; 2023 Oct.  https://humanresearchroadmap.nasa.gov/Evidence/other/Evidence%20Report%20Hypoxia%20and%20DCS_FINAL_1-8-2024.pdf

2.            Lange KE, Perka AT, Duffield BE, Jeng FF. Bounding the Spacecraft Atmosphere Design Space for Future Exploration Missions (NASA/CR—2005–213689). Houston, TX: National Aeronautics and Space Administration, Lyndon B. Johnson Space Center; 2005 June. Report No.: NASA/CR—2005–213689.

3.            NASA Exploration Atmospheres Working Group. Recommendations for Exploration Spacecraft Internal Atmospheres: The Final Report of the NASA Exploration Atmospheres Working Group. Houston, TX: National Aeronautics and Space Administration, Lyndon B. Johnson Space Center; 2010 Oct. Report No.: NASA/TP-2010-216134.

4.            Norcross J, Norsk P, Law J, Arias D, Conkin J, Perchonok M, et al. Effects of the 8 psia / 32% O2 Atmosphere on the Human in the Spaceflight Environment (NASA/TM-2013-217377). 2013 June. Report No.: NASA/TM-2013-217377.

5.            Conkin J, Wessel JH. Critique of the Equivalent Air Altitude Model. Aviat Space Environ Med. 2008 Oct 1;79(10):975–82.

Additional Resources:

• Decompression Sickness (DCS) Risk Mitigation Technical Brief (OCHMO-TB-037 Rev C)

https://www.nasa.gov/wp-content/uploads/2023/12/ochmo-tb-037-decompression-sickness.pdf

The Human Research Program:

The Human Research Program investigates and mitigates the highest risks to astronaut health and performance in exploration missions. The goal of the HRP is to provide human health and performance countermeasures, knowledge, technologies, and tools to enable safe, reliable, and productive human space exploration, and to ensure safe and productive human spaceflight. The scope of these goals includes both the successful completion of exploration missions and the preservation of astronaut health over the life of the astronaut.

HRP has developed an Integrated Research Plan (IRP) to describe the requirements and notional approach to understanding and reducing the risks to human health and performance. The IRP describes the Program’s research activities that are intended to address the needs of human space exploration and serve HRP customers. The IRP illustrates the HRP’s research plan through the timescale of exploration missions of extended duration.

The Human Research Roadmap (HRR - https://humanresearchroadmap.nasa.gov) is a web-based version of the IRP that allows users to search HRP risks, gaps, and tasks.