Human Research Program Architecture
To the extent that research can address human health and performance risks, the Human Research Program (HRP) provides essential countermeasures and technologies in order to enable human space exploration. The HRP utilizes the Integrated Research Plan (IRP), a compilation of individual risk research plans and multi-disciplinary research plans (MDRP), to address these risks which are assigned to specific Elements within the program.

The IRP was baselined as HRP-47065, Human Research Program Integrated Research Plan, in 2008 and is revised as required. In 2010, the technical content of the IRP (formerly Appendix A) transitioned to a web-based format contained in the Human Research Roadmap (HRR). The introduction and overview of each risk in the IRP continues to be maintained in the document

The IRP describes the approach, and research and technology development (R&TD) activities intended to mitigate the risks of human space exploration. The risks-gaps-tasks-deliverables detail in the IRP is required to ensure completeness in addressing the risks. The forecasted research schedule to mitigate risks is then captured in a strategy chart called the Risk Approach Plan (found at the "Risk Approach Plan" link on each risk page). This chart includes a Path to Risk Reduction (PRR) bar to depict an overall timeline and significant risk milestones, along with research logic descriptions and flow chart to show the research strategy being used to potentially improve the risk ratings (transitioning from red to yellow to green).

The HRP utilizes various research platforms to conduct research. Ground research occurs in laboratories and analogs that mimic a portion of the spaceflight environment. In addition, the International Space Station (ISS) is used to conduct research requiring the unique environment of space and serves as an analog for long-duration planetary missions. Spaceflight data primarily identify and/or quantify physiological and behavioral changes to the human system under microgravity conditions and can validate potential countermeasures. The use of the ISS platform is critical to obtaining the required knowledge to build products to support longer and more challenging missions.

The HRP IRP content captured in the HRR is organized according to the following management architecture:


In the HRR, the user will be able to download and view risk Evidence Reports; review the IRP's risk, gap, task and deliverable information; and understand the cross-integration of gaps across multiple risks, and tasks across multiple gaps.

Reviews of the evidence compiled by HRP Elements and discipline scientists are found in the HRP risk Evidence Reports. Individual risk reports are written for risks for which HRP has active or completed research in support of the integrated evidence base that HSRB develops for this subset of HSRB risks. These reports make important data accessible and available for periodic review, and also provide the basis for identifying gaps and tasks in the IRP. As research work progresses, new evidence, along with various deliverables, are generated and contribute to the body of evidence that informs the progress of risk reduction.

Human system risks include physiological and performance effects from the hazards of spaceflight, such as altered gravity, radiation, isolation and confinement, distance from Earth, and hostile and closed environments, as well as unique challenges in medical support, human factors, and behavioral health support. HRP contributes to the overall risk mitigation of a subset of the HSRB risks and concerns that have high value risk mitigation targets that can be supported by research. These Risks and Concerns are assigned to the appropriate Element within the HRP to support the development of research plans. In the past, the HRP documented some risks at a more-detailed level than the HSRB. These sub-risks were documented as standalone risks in the HRR. As part of the 2020 IRP revision (revision L), the risks included in the HRR as part of HRP's portfolio now align with how this subset of risks is bookkept at the HSRB. Information explaining the transition from the past sub-risks to the current combined risks is provided for traceability on the affected risk pages in the HRR.

The HSRB assesses human system risks against four Design Reference Missions (DRM) categories: low Earth orbit, lunar orbit, lunar orbit + surface, and Mars for both in-mission and long-term health impacts (and flight recertification status impacts as applicable). These DRM categories are not directly mapped to programs and are scoped to allow the flexibility to provide risk characterization and assessments that will be applicable to a range of human space exploration missions, including those yet to be defined.

For each DRM and impact category, a Risk has a set of risk posture information approved as the HSRB. This includes a likelihood and consequence (LxC) score (with associated drivers and assumptions), a risk disposition (and rationale), a risk color (based on where the LxC scores land in the 5x5 risk matrix), and levels of evidence ratings (that support the LxC scores). The LxC scale definitions and risk matrix are shown below. In certain cases where there is not sufficient evidence to support an LxC assessment, the item is labeled a concern, rather than a risk, and HRP may choose to conduct research that could build the evidence base.

Source: Human System Risk Management Plan, Revision A (October 2020) – JSC 66705


These LxC ratings are tracked in the iPRR as an indication of progress of research work towards risk mitigation. They serve as one of several inputs to determine the research priority of each risk, helping HRP Management make decisions and allocate resources. The HSRB also designates Risk Dispositions with the LxC scores to indicate the HSRB's assessment of the adequacy of mitigation efforts (e.g., Requires Mitigation, Accepted). The LxC ratings and Risk Dispositions are used as a tool to communicate to Agency management the seriousness of a risk to crew health and performance and the Office of the Chief Health and Medical Officer (OCHMO) position on future actions for the risk.

The HSRB maintains a risk record system for approved risk summary reports and supporting evidence for all the risks (including those not assigned to HRP) in its portfolio. This set of information is used by the HSRB to track and monitor the status of the risks, and to inform its decisions. The HRP utilizes the HSRB as a forum to communicate updates to risks resulting from HRP research and technology development activities.


For each risk, the responsible HRP Element identifies gaps in knowledge about characterizing the risk and ability to mitigate the risk. Gaps represent the critical unknowns that need to be addressed to mitigate a risk and therefore serve to focus the areas of research work to address risk reduction milestones. In some cases a gap may map to more than one risk. During FY20 the HRP Elements completed a strategic re-planning exercise to perform an in-depth evaluation of their research plans for many of the HRP Risks in the HRR. The new strategies required significant gap updates for many of the HRP Risks. The 2020 IRP revision (revision L) includes these new gap structures. Traceability information to show the transition from the old gaps to the current gaps is given on the affected gap pages in the HRR.


A task may partially or completely close a gap by better characterizing a risk or developing mitigation capabilities to reduce the risk to an acceptable level. In some cases, a task can address multiple gaps across multiple risks. Tasks are solicited through NASA Research Announcements (NRA), the Small Business Innovation Research (SBIR) program, NASA Request for Proposals, etc. In certain unique cases, the HRP may conduct research tasks in-house if there is insufficient time for the research solicitation or it is highly constrained research (e.g., involves aspects of on-going mission operations).



Each task, or progression of tasks, is designed to ultimately culminate in deliverables or products. Several organizations are the typical external customers for the HRP deliverables: OCHMO, HSRB, Health and Medical Technical Authority (HMTA), System Capability Leadership Team (SCLT), Crew Health & Safety (CHS), and Human Health and Performance Directorate (HHPD) System Manager.


Common deliverables include recommended standards (e.g., Permissible Exposure Limits), requirements (e.g., flight rules), risk characterization, countermeasures, clinical practice guidelines, and technologies. Specifications for some deliverables may be agreed upon with customers of the HRP products through the use of Customer-Supplier Agreements (CSAs). After deliverables are provided, the R&TD results are assessed for applicable updates to the evidence base as it impacts risks, gaps and tasks in order to achieve risk reduction goals as laid out in the PRR.

Two repositories contain human spaceflight data evidence:

  • Life Science Data Archive (LSDA) - contains research data from NASA-funded experiments.
  • Lifetime Surveillance of Astronaut Health (LSAH) - contains electronic health records (medical data) of all astronauts, including mission data. For the LSAH, astronaut medical data are collected per requirements in the Medical Requirements Integration Documents (MRID).

Both datasets are available from the Life Sciences Data Repositories and contain searchable, public data. In addition, a User’s Guide includes a description of data types (e.g., pooled, de-identified and identifiable data), data locations (by MRID category), the process for obtaining data (via the data request form), and a summary of applicable laws and regulations. The LSDA and LSAH repositories are continually updated with data resulting from HRP research as well as spaceflight missions and are available for use, as applicable.