The Human Health and Performance Risks for Space Exploration Missions book,
a collection of many of the evidence reports, is available in an electronic .pdf
format! Download a copy by clicking this
EVIDENCE BOOK OVERVIEW
I. BACKGROUND AND DOCUMENTS
The HRP, within the NASA Human Exploration and Operations Mission Directorate (HEOMD),
is a research and technology development (R&TD) program that addresses NASA's needs for
human health and performance risk mitigation capabilities in support of space exploration
missions. These exploration undertakings include missions to Near Earth Asteroid (NEA),
including the Moon, and Mars. Although all of these mission types involve some of the same
human health and performance challenges, each also includes specific challenges that depend
on the nature of the mission and the mission development schedule. HRP R&TD are focused on
the highest-priority risks to crew health and safety, with the goal of ensuring mission success
nd maintaining long-term crew health.
The development of HRP content has been formulated around the management
architecture of “Evidence to Risk to Gap to Task to Deliverables”. In
other words, evidence indicates that a risk exists to the human system, and
gaps in our knowledge about the risk or how to mitigate it indicate what tasks
need to be carried out in order to produce the deliverables needed to fill
these gaps. Three core documents thus describe the HRP:
Program Requirements Document (PRD),
Integrated Research Plan (IRP).
These documents are updated regularly and provide relevant information that
can be used to manage the program.
The HRP PRD defines, documents, and allocates the high-level requirements to each of
the HRP Program Elements: Behavioral Health and Performance, Exploration Medical
Capability, Human Health Countermeasures, ISS Medical Projects (as an implementing
Element, no risks assigned), Space Human Factors and Habitability, and Space Radiation.
These requirements are derived to satisfy the exploration mission requirements of the
HEOMD and the Office of the Chief Health and Medical Officer (OCHMO) and are essentially
the set of spaceflight human health and performance risks and standards of acceptability
for these risks upon which the HRP is focused [NASA Standard (STD) 3001, Space Flight
Human System Standard - Volume 1: Crew Health, and Volume 2, Human Factors, Habitability,
and Environmental Health, available on the
Standards and Technical Assistance Resource Tool (START)].
In addition, NASA/SP-2010-3407,
Human Integration Design Handbook (HIDH)
as a compendium of human space flight history, lessons learned, and design information
for a wide variety of disciplines to serve as a companion document to NASA-STD-3001,
Volume 2, Human Factors, Habitability, and Environmental Health.
The Evidence Book provides a record of the state of knowledge from research and
operations for each risk currently in the PRD. The book consists of an evidence-based
report or collection of citations for each individual risk. Each report is essentially
a brief review article, written for a scientifically-educated, non-specialist reader.
The IRP documents what implementation activities are necessary to fill the knowledge
and mitigation gaps associated with each risk listed in the PRD and supported by the
Evidence Book. It also details when those activities will be accomplished, where they
will be accomplished (for example, the International Space Station or a ground analog),
who will accomplish them (investigators within a specific project or organization within
the HRP), and what is being produced (risk uncertainty reduction, candidate health or
performance standard, countermeasure strategy, etc.). The Human Research Roadmap is
the web-based tool for communicating the IRP content.
The Bioastronautics Roadmap (BR) documents the health and performance risks and
areas of concerns of a wide cross-section of the professional space life sciences community,
but it does not have the level of detail necessary to prioritize risks across physiological
disciplines or to compare strategies for how to manage a given risk across mission
operational architectures. In order to identify missing risk details, organize the diverse
risk information needed and facilitate mission-focused analysis and communication of risks,
the NASA Human Health and Performance Directorate (HHPD) developed the Risk Mitigation Analysis Tool
(RMAT). It provides a method to consolidate information such as identified risk and evidence
base; the standard level of acceptable risk; likelihood and consequence of risk; current and
proposed mitigation capabilities for risk; and potential costs and benefits of mitigation
capabilities for risk. Further, all of the information in the RMAT is provided in the context
of specific mission architectures, which vary in duration, degree of autonomy (due to
distance from Earth), onboard capabilities, etc. In total, this tool permits analysis of
risks in a manner based on evidence and provides a platform for comparison within and between
The HRP 2008 PRD risk list, which has no cross-risk prioritization, was generated from an
extensive discipline-by-discipline Program Review of risks held in 2006. This review began
with the BR risk list, continued with an extensive assessment of medical observations and
research findings, and finally led to the identification of a slightly narrowed and more
operationally-focused series of risks and risk factors. During this review, teams of
discipline experts analyzed the current evidence for each risk and presented their
assessments to HRP management. Each HRP element then evaluated the available information
from the discipline teams and determined whether the risks were relatively high priority
and operationally relevant. For many risks, the data to generate information regarding the
likelihood and consequences of a risk were not yet available. Although probabilistic risk
methodology was currently being used to provide this information, most of these analyses
had not yet been completed; therefore cross-risk prioritization is not yet possible. However,
the HRP expects to have this capability in the near future. As more mission experience and
space and ground-based evidence become available, new risks may be identified and added to
the PRD, while other risks and contributing factors may be taken off the PRD requirements
list. The HRP shall thus periodically review the available evidence and revise the lists
of risks and contributing factors in the PRD as appropriate.
III. EVIDENCE BOOK
A. Evolution of the Evidence Book
The original Evidence Book, the 2008 Evidence Book, is a collection of evidence reports
created from the information presented verbally and discussed within the NASA HRP in 2006.
In April of 2008, the 2008 Evidence Book was reviewed by the members of the Committee on
NASA's Research on Human Health Risks, established by the Institute of Medicine (IOM).
The resulting thorough Review of NASA's Human Research
Program Evidence Books: A Letter
Report (2008) provided guidance for both the revision of the current Risk Reports and for
the development of future versions. It is publicly available via the
National Academies Press
As per the recommendations of the IOM Review, risk report information was made publicly
available. The method was either to publish the content of selected reports in multiple
specialized journals or to publish a subset of the reports in a collection, forming a NASA
Special Publication entitled the HRP Evidence Book 2008.
The reports revised for presentation
in the HRP Evidence Book 2008 incorporate the
recommendations from the IOM Review as much as
possible. The specialized journal publications containing the evidence report information
were revised and reviewed as per the specifications of the particular journals in which
they are to be published.
Since this original publication, the HRP elements continue to update each evidence report
given results from ongoing research and technology development tasks. The Human Research
Roadmap contains the most up-to-date evidence reports in the above table..
B. Spaceflight and Ground-Based Evidence
Each risk report contains a narrative discussion of the risk and its supporting evidence.
Every declarative statement concerning the risk is supported by a description of the evidence.
All cited publicly-available references are listed at the end of the report. In addition,
data that are significant or pivotal are summarized in text, tables, and charts in sufficient
detail to allow the reader to critique and draw conclusions. The authors also indicate whether
the data are from human, animal, or tissue, cellular, or molecular studies. The reports discuss
evidence from both spaceflight (including biomedical research, Medical Requirements Integration
Document [MRID] data, and operational performance or clinical observations) and ground (including
space analog research and non-space analog biomedical or clinical research). When providing
evidence from ground-based studies, authors discuss why these results are likely to be
applicable in the space environment, offering any available validation information for the use
of these ground-based systems.
C. Categories of Evidence
To help characterize the kind of evidence provided in the reports, authors were encouraged to
label evidence according to the "NASA Categories of Evidence." These categories indicate whether
data are from two possible types of controlled experiments, are observational, or are expert
opinion. As shown below, the NASA categories are compared to a more familiar version of a scale
for levels of evidence. The use of a coordinated data categorization system is new to many NASA
life scientists, but authors were encouraged to use such a system to help clarify the type of
evidence presented and thus provide some additional information about the strength of interpretations
derived from those data. They were not required to use the categorization system hierarchically.
|Broad "Experimental" Design Type
||Silagy & Haines Levels of Evidence* (for comparison only)
||NASA Categories of Evidence
||Ia. Meta-analysis of randomized trials
||I. At least one randomized, controlled trial
|Ib. At least one randomized trial
|IIa. At least one controlled study without randomization
||II. At least one controlled study without randomization,
including cohort, case-control, or subject operating as own control
|IIb. At least one other type quasi-experimental study
||III. Non-experimental descriptive studies, e.g. comparative correlation, or case studies
||III. Non-experimental observations or comparative, correlation, and case or case-series studies
||IV. Expert committee reports or opinions or clinical experiences of respected authorities
||IV. Expert committee reports or opinions of respected authorities based on clinical experiences
bench research, or "first principles"
*Source: Silagy C, Haines A. Evidence Based Practice in Primary Care, 2nd ed., London: BMJ Books, 2001.
D. Computer-Based Simulation Information
Mathematical modeling and computer simulation provide another type of information distinct from experimental
evidence, observation, and expert opinion that can support decision making, including the identification of
risks. In the evidence reports, authors presented the results of simulations, the types of models used, and
the reasoning that supports the acceptance of the modeling and simulation results as valid and appropriate
in the situation of interest. Appropriate references to papers or reports describing the types of verification
to which models were subjected and the validation methods used were also provided.
E. Risk in Context of Exploration Mission Operational Scenarios
The HRP uses a research rating as a tool to communicate to Agency management the seriousness of a risk to crew
health and performance when applied to the mission architecture and/or mission characteristics defined for each
DRM. The research ratings serve as one of several inputs to determine the priority of each human risk, helping
HRP Management make program decisions and allocate program resources.
Each research rating is derived by comparing the current state of knowledge about a risk, whether existing standards
are defined and met, and the degree to which research will improve the current risk posture with respect to crew
health and performance during long duration missions. Each human risk has one of four research ratings identified
for each of the four DRMs, driven by its applicability to the DRM mission architecture and/or mission characteristics.
HRP uses the following four DRMs to bound its exploration mission assumptions: (1) 12-month mission on ISS (ISS-12);
(2) Lunar (Outpost) mission; (3) NEA mission; and (4) Mars mission [Appendix B of this document for further definition
and assumptions for each DRM]. The four possible research ratings are: Controlled, Acceptable, Unacceptable, and
Insufficient Data. These ratings are described below.
Rating: Controlled (C) - Green
A risk is deemed to have a research rating of Controlled if based on available evidence, the projected mission
architecture (with assumptions on DRM-specific vehicle design and operations constraints) meet existing standards
for maintaining crew health and performance and countermeasures exist to control the risk. Continued research or
technology development will improve capabilities, provide additional trade space to support meeting crew health
standards or ensure that vital Agency core competencies are accessible.
The scientific, operational and clinical evidence for the risk and current available mitigations and
countermeasure capabilities demonstrate that the Agency can meet the existing standards for maintaining crew
health and performance during all phases of the mission. Research has provided at least one solution capability
to address the risk. Additional research or technology development could further reduce risk by enhancing
understanding and offering different options to increase engineering and operational efficiencies, make the best
use of unique assets such as ISS in optimizing risk posture, and maintain vital Agency core competencies.
Rating: Acceptable (A) - Yellow
A risk is deemed to have a research rating of Acceptable if based on available evidence, the projected mission
architecture (with assumptions on DRM-specific vehicle design and operations constraints) likely provides the
capability to meet existing standards for maintaining crew health and performance but the risk is not fully
controlled. The remaining level of uncertainty would likely lead the Agency to accept a higher than expected
level of risk to crew health and performance during some phases of the mission. Continued research or technology
development is expected to improve capabilities or substantiate crew health standards.
The scientific, operational and clinical evidence for the risk and current available mitigation and countermeasure
capabilities demonstrate that the Agency can likely meet existing standards for maintaining crew health and
performance during some, but not all phases of the mission. Additional research or technology development may
further improve the risk research rating to achieve a Controlled rating.
Rating: Unacceptable (U) - Red
A risk is deemed to have a research rating of Unacceptable if based on available evidence, the projected mission
architecture (with assumptions on DRM-specific vehicle design and operations constraints) will not provide the
capabilities required to meet existing standards for maintaining crew health and performance during all phases
of the mission. Therefore, research is required to acquire necessary information and develop necessary capabilities
and countermeasures to arrive at an acceptable risk posture.
The scientific, operational and clinical evidence for the risk and current available mitigations and countermeasure
capabilities do not adequately demonstrate the capability of the Agency to meet existing standards to protect
and/or maintain crew health and performance during all phases of the mission. The inadequacy and uncertainty in the
risk mitigation capabilities and countermeasures will require additional data and/or mitigation strategies to be
developed through the research performed by the HRP.
Rating: Insufficient Data (I) - Gray
A risk is deemed to have a research rating of Insufficient Data if there is not enough available evidence to assess
whether the projected mission architecture (with assumptions on DRM-specific vehicle design and operations
constraints) can meet existing standards for crew health and performance or if such standards need to be developed.
Research is required to further understand and define the risk to the point that its research rating can be
determined by HRP to controlled, acceptable or unacceptable. This rating is primarily for new risks before a research
rating can be determined.
The scientific, operational and clinical evidence for the risk and current mitigation and countermeasures
capabilities are inadequate to allow the assessment of the ability of the mission architecture and/or mission
characteristics to support crew health and performance standards. Additional research is expected to support
determination of a new research rating.
The research rating of a risk alone is not sufficient to determine its priority within the HRP research portfolio.
Priority is dependent on other factors such as limited availability of certain necessary resources (as the ISS,
ground analogs, etc.), program funding, exceptionally long lead times (e.g., needed to improve understanding and
mitigation of radiation risks), or the amount of risk reduction that can be obtained with a specific set of
resources. The level of activity (or budget) and timing of research investments reflect the final prioritization
of the risks.
Implementation of the HRP Research Rating and applicability to the HRP owned risks are contained in the
Human Research Program Requirements Document (HRP-47052)