Review of NASA's Space Flight Health Standards: Letter Report (2007)

At the request of the National Aeronautics and Space Administration, the Institute of Medicine (IOM) recently established the Committee to Review NASA’s Space Flight Health Standards. The committee’s charge was to examine the process by which NASA establishes space flight health standards for human performance, including assessments of the validity and integrity of the current process and considerations related to ensuring worker safety, integrating stakeholder input, and assuring transparency of the process.

The committee appreciated the opportunity to be briefed on the standards-setting process by you and many other senior NASA staff members and to engage in discussions regarding various aspects of the process. The committee also benefited from briefings and discussions with staff members from the Occupational Safety and Health Administration (OSHA), the Environmental Protection Agency (EPA), the U.S. Air Force, the U.S. Navy, and the U.S. Antarctic Program (Appendix C). The committee’s findings are provided as a letter report as this effort addresses a focused task that builds on several recent IOM and National Research Council (NRC) reports (IOM, 2001a,b, 2004, 2006; NRC, 1994b, 1998, 2000) and examines an issue that requires prompt attention as part of its evolution.

As outlined in the 2006 NASA Strategic Plan (NASA, 2006b), NASA is moving toward the goal of a return to lunar landings in the next 15 years and further plans for potential human flights to Mars. Given the amount of planning and effort needed to design the exploration architecture and carry out these goals, it is imperative that the best currently available evidence on preventing and mitigating health risks be incorporated into the design and mission plans from the earliest stage possible. Through the delineation of human space flight health standards, NASA is taking the steps that will foster mission success, mitigate in-flight health risks to the extent currently feasible, and outline a research agenda that will more fully foster crew health and mission success on increasingly longer-duration space flights to more distant destinations. The standards-setting process is currently designed to address acceptable levels of risk for three categories of in-flight health concerns:

• fitness-for-duty standards for maintaining the physiological and behavioral parameters necessary to perform required duties;

• space permissible exposure limits (e.g., radiation exposure standards); and

• permissible outcome limits for the changes in health outcomes that are potentially impacted or resulting from prolonged space flight and habitation at low gravity (e.g., bone loss, aerobic capacity).

The agency’s standard-setting process has resulted in an initial set of space flight health standards (NASA, 2006a).

The committee began its assessment of the standards-setting process by specifying the principles that the members deem to be the hallmarks of an exemplary deliberative process:

• evidence-based: Policy decisions are based on the best available evidence and can stand up to scientific scrutiny.

• open and transparent: All interested and affected parties have opportunities for meaningful participation, including opportunities to review and comment on draft or proposed health standards.

• well documented: A written record that includes all proceedings, communications, and documents that are a part of the decision-making process is created and preserved. Linkages between evidence and the decisions that are based on that evidence are explicit, along with quantification of uncertainty when the evidence is not definitive.

• well informed: Decision makers make their policy choices on the basis of all available input. Policy decisions are rationally related to the facts on record and explained, including responses to any written comments from reviewers.

• dynamic: There are mechanisms for updating, revising, adding, or deleting standards as evidence and circumstances evolve over time. Updating is done both in response to new relevant findings and as part of calendar-based review cycles.

The committee’s overall assessment is that the initial space flight health standards (NASA, 2006a) represent a diligent and well-reasoned effort. The approach uses an occupational health model recommended in Safe Passage (IOM, 2001a) and provides an analytical framework for enhancing the safety of human space flight. NASA staff are thinking proactively about a range of potential health risks, some of which might result from exposures that are unique to space (e.g., galactic cosmic radiation, lunar dust) and others that are somewhat similar to exposures and experiences faced in similar environments (e.g., nonionizing radiation, confined spaces, prolonged isolation). The committee throughout this report notes opportunities for improvement to the standards setting process and makes recommendations for strengthening the process.

The initial space flight health standards—along with the more detailed program and project-level requirements—set the operational criteria for protecting human health for crew members while in flight. Refining those criteria and relating them to the type and duration of each mission is an inherent strength of the iterative and ongoing nature of the standards-setting process. This tiered approach allows NASA to address hazards common to all missions while also taking into account the challenges and issues relevant to longer duration, more distant, and more complex missions. Updates to the knowledge base are used to refine the standards.

NASA’s recently constituted independent technical authorities in three areas (health and medical, engineering, and safety and mission assurance) are significant assets in overcoming barriers to communication and effective decision-making that can occur in a large, complex, and geographically dispersed organization such as NASA. Their active participation in the ongoing process can be expected to contribute to enhanced human health and safety during space flight.

As recommended by the report of the Columbia Accident Investigation Board (CAIB, 2003) and outlined in the recent IOM report on the bioastronautics roadmap (IOM, 2006), these three independent technical authorities report directly to the NASA administrator and are independent of program funding and project management. With responsibilities for oversight of standards and technical requirements, these independent technical authorities provide the checks and balances that are needed to ensure that the mis-

sion’s operational, safety, and health objectives are met. Such a structure provides a clearly defined mechanism for integrating space flight health standards into engineering, safety, and operations.

Key to this process is the provision of a mechanism for resolving issues of concern through discussion and decision making by the technical authorities and the NASA administrator. This structure and empowerment of the chief health and medical officer as a technical authority should ensure that health and medical issues are an integral part of mission planning throughout the operational course of every NASA project that involves human space flight.

As a part of the process of developing the initial new standards, NASA staff collected the existing standards and procedures from various parts of the complex NASA organization and collated and refined them into a single updated document. Having a single point of reference enhances communication and information transfer to key individuals and programs throughout the organization and decreases future administrative burdens.

The remainder of this report delineates the committee’s findings and gives recommendations related to these issues for next steps that NASA staff should consider in their quest to foster mission success and maintain the health and well-being of space crew members. The committee notes that there are opportunities for improvement, especially in the following areas: enhanced input to the standards setting process; strengthened review of the evidence; increased research and validation to support standards development; clearly defined mechanisms for appeals, updates and the development of new standards; and use of an integrated systems approach to explore potential relationships among individual standards. Each topic will begin with an assessment of the issues and will be followed by the committee’s key findings that lead to a recommendation.

In the current process, the request for a new or revised space flight health standard can come from multiple offices within NASA. The requests are handled through the Office of the Chief Health and Medical Officer (OCHMO), and a decision is made regarding the need to assemble a standards development team. The team is composed of experts in various fields from NASA staff and can be supplemented with outside experts. After the standard is drafted, it is reviewed by experts, including representatives from the Astronaut Office and the Aerospace Medicine Board. Input from these reviews is considered in the final revisions made by the OCHMO. The standards documentation becomes a part of the permanent record in the Office of the Chief Engineer.

As stated above, opportunities for revision and improvement are an inherent part of a high-quality standards-setting process. Although NASA received external input on the initial set of standards, the committee believes that the process could be further enhanced by input from a wider circle of developers and reviewers, with additional input beginning early on in the standards development process. The size and composition of the eight standards development teams that developed the initial set of standards ranged from 2 to 16 individuals, with one team having no external scientists and other teams having as many as 4 scientists who were not NASA contractors or staff members. Increased input early in the proc-

ess is particularly beneficial because the initial part of the process is more dynamic and fluid with opportunity for additional input and exploration of the available evidence.

A more robust, independent, and active review process will further improve the quality of the decision making. Multiple opportunities for input from the Astronaut Office are particularly important throughout the development of the standards, beginning with inclusion on the standards development team. Acceptance of the resulting standards by the stakeholders will be enhanced if they are fully engaged in the review process from the outset.

As noted throughout this report, the committee believes that relevant data exist on research efforts and experiences that have some comparability to space flight and that could be used to more fully inform the standards-setting processes. These data come from analog environments such as the isolated conditions of saturation diving, submarine service, space capsule simulation, or extended polar expeditions and from analog models such as extended human bed rest, animal hind limb suspension protocols, or other research efforts. The data from these and other relevant studies will provide valuable insights that further inform the standards-setting process.

From the selection of the standards development team and continuing through the standards development and review process, increased involvement by external experts could expand the breadth of expertise, add new perspectives, and enhance knowledge of the relevant scientific literature. In particular, it would be valuable to involve national and international experts in analog environments, experts from the Air Force and other military services that address flight health issues, prior astronauts, and experts in specific relevant areas of study (e.g., behavioral health, risk assessment, and risk characterization) from other federal agencies, nonprofit organizations, and academia. In continuing to build on collaborations with other federal agencies, the process would benefit from additional input from other federal agencies (including OSHA and EPA) that set similar exposure limits or health standards.

Efforts to improve group decision-making should also be explored. Iterative knowledge-intensive methods, such as modified Delphi, and techniques such as “prospective hindsight” can help experts to overcome confirmation biases and encourage them to fully use available knowledge to envision potential future failures. These methods can also help to mitigate some of the most common limitations of group decision processes, such as a tendency to prematurely agree on conclusions and recommendations without sufficiently exploring alternatives (Plous, 1993; Russo and Schoemaker, 1989; see also IOM, 2006).

NASA has to respond to multiple internal and external constituencies, and part of the challenge will be to obtain additional input without making the process too lengthy or unwieldy. In terms of strategic positioning, the committee believes that NASA’s standard-setting approach should lie somewhere between that of the very open, often lengthy processes that are used to protect the general public from work or environmental health hazards (e.g., OSHA, EPA), and the more agile processes that are used by organizations (such as the military) for mission-oriented decisions that face great urgency and that do not ordinarily have a direct impact upon public health.

The processes for eliciting public and private sector comments by OSHA, EPA, and other public health-related agencies are outlined in the rule-making process set forth by the Administrative Procedure Act (5 U.S. Code Subchapter II) and other federal statutes, such as the Clean Air Act (Public Laws 88-206, 91-604, 101-549), the Occupational Safety and Health Act (Public Law 91-596), and the Small Business Regulatory Enforcement Fairness Act (Public Law 104-121). The Office of Management and Budget oversees the regulatory actions of the various agencies and may add additional requirements. The standards-setting processes used by OSHA and EPA provide multiple opportunities for comment from a wide variety of potential stakeholders. This assures broad awareness and communication with the public, but frequently results in a lengthy process that would not provide the rapid updates that are needed as new evidence (either from research or experience) emerges to protect the astronaut community and foster mission success. Although extensive procedures are not appropriate for NASA’s standards-setting process, what can be gained from them is the value given to an open and transparent process that involves relevant stakeholders at the outset and at many points in the development and revision of standards.

A highly restrictive or closed process would be inappropriate for NASA because it could jeopardize the public image of the agency and congressional support for its goals and initiatives and it could erode

the confidence of the astronaut community. NASA has responsibilities to current and future astronauts, the public, taxpayers, and policy makers that favor being as transparent and open to input as possible, yet the NASA process must also be timely to support mission design and engineering, as well as accepting of the reality that some individual risk is an inherent part of space flight.

The committee strongly supports the recommendations of the Safe Passage report that urges NASA to “give increased priority to understanding, mitigating, and communicating to the public the health risks of long-duration missions beyond Earth orbit” (IOM, 2001a, p. 6). Furthermore, with the goal of ensuring transparency, it is important for NASA to make the space flight health standards publicly accessible, through Internet sites and other mechanisms, and incorporate this information into the space flight information and communication of risk that is widely disseminated.

The occupational risks faced by astronauts, especially space explorers, are far greater than those faced by most workers. Space crew members are well informed about the risks they face, are involved in efforts to mitigate that risk, and should be fully engaged in the occupational health decisions regarding all aspects of their missions. The challenge in developing space flight health standards is to determine an acceptable level of risk that provides maximum feasible protection of crew health and safety without jeopardizing mission success or “overengineering” either the technical or medical solutions that mitigate these risks. This challenge becomes more daunting as missions become more complex, involving new vehicles, longer durations, greater distances from Earth, and novel environments. Collectively, these factors result in greater exposure to existing and new space flight hazards. The effects of new and longer duration exposures will drive a research agenda much broader than today’s.

A thorough literature review is the starting point of any standards-setting process and should encompass the relevant literature, including data on analog environments and models. To enrich the quality of the review process, the standards documentation needs to include details regarding the extent of the literature review, as well as the details of the analysis that led to the selection of a certain standard. In the initial space flight health standards (NASA, 2006a), it is not clear from the bibliographies to what extent data from analog environments and models have been used. Standards documentation should also clearly detail the quality and rigor of the available evidence, with an emphasis on the methodological strengths and weaknesses. As discussed in the recent report by the Institute of Medicine (IOM, 2006, pp. 60–62),

the quality of the evidence needs to be thoroughly and explicitly reviewed. The Guide to Clinical Preventive Services (DHHS, 1996, 2000) provides an example of an in-depth process with rigorous methodology for identifying and describing the quality of the evidence and basing conclusions on that evidence review. The documentation of the analytical literature review should include the identification of significant gaps in the research literature, and pooling data from the literature through standard statistical methods should be undertaken in order to provide more precise estimates. The standards could be considered as a hypertext-type document in which there are layers of information behind the standards that provide the information on which the standards are based.

Written documentation is critical for all steps of a standards-setting process to improve transparency, to ensure that the process is flexible and responsive to new data, and to specify all of the assumptions that were used in setting the standards so those assumptions will be appropriately considered in relation to any subsequent changes of the standards. The availability of an in-depth well-referenced rationale for each standard also improves the ease by which future revisions can be made.

The committee believes it is important that the documentation for each standard include a detailed list of the uncertainties associated with that risk assessment, as well as suggestions for specific research that is needed to address those uncertainties. Work should be done with the appropriate technical advisers and major project managers to highlight the engineering and human factors tradeoffs involved in these knowledge gaps, as well as the desirability of increasing the overall understanding of human limitations and strengths in the human space flight programs. Focused research in these areas should be a high priority.

The presentations to our committee by EPA and OSHA staff members highlighted the thorough risk assessments that underlie standards-setting and rule making at those federal agencies. As outlined in previous reports of the National Research Council (1983, 1994a), the steps in risk assessment—hazard identification, dose-response assessment, exposure assessment, and risk characterization—require extensive data if they are to result in a meaningful quantitative risk profile.

Risk assessment is also the underpinning of the NASA standards. As more data become available through subsequent space flight missions and other relevant research, increasingly sophisticated risk assessment methodologies will offer the potential to refine the NASA standards.

The EPA’s IRIS (Integrated Risk Information System) database illustrates how a continually evolving database can be used to collect and store risk assessment data, including updates and refinements to the database. The process used by EPA to develop IRIS assessments has many steps that are similar to the standards-setting process outlined by NASA. EPA’s process for developing IRIS assessments consists of: (1) an annual Federal Register announcement of the upcoming IRIS agenda and a call for scientific information from the public on the specific chemical substances to be reviewed, (2) literature search, (3) development of health assessments and draft IRIS summaries, (4) peer consultation, (5) agency review, (6) external peer review, (7) management approval and preparation of final IRIS summaries and supporting documents, and (8) entry of summaries and supporting documents into the IRIS database (EPA, 2006). As discussed above, an open process that features a robust peer review by many stakeholders is critical.

In implementing the standards and considering issues for each specific exploration architecture and mission duration, NASA staff developed a Risk Management Analysis Tool (RMAT). For each exposure or event, the RMAT provides, where feasible, an estimate of the probability of an adverse outcome and the uncertainty factor that is relevant to the specific mission architecture and estimated mission duration (e.g., crew exploration vehicle [CEV], the international space station [ISS] for 6 months, ISS for 1 year, moon for less than 14 days, a lunar habitat, and a Mars mission). The RMAT format is direct and informative, and it includes mitigation and cost-benefit issues that are of great relevance to engineering, safety, and mission assurance decision makers. It also illustrates the logic and relationships among the many steps involved in standard setting and risk mitigation. The documentation for the risk calculations in the

RMAT should be readily accessible to all interested stakeholders and updated as new data are incorporated into the risk assessment.

Although small sample size is often an issue due to the limited number of people who have experienced space flight, the committee believes that there are opportunities for greater pooling of data. The next 10 years of ISS operations offer an important opportunity for data collection, as do collaborations with other relevant research endeavors. Further, as emphasized in several recent reports (IOM, 2001b, 2006), increasingly sophisticated statistical methodologies are becoming available for addressing the issues with small sample sizes.

A paucity of data is the major challenge that faces risk assessments of space mission hazards, particularly for long-duration efforts such as lunar habitation or a Mars mission. Because the standards can only be as meaningful as the data from which they are generated, data-gathering efforts during space flight need to be as thorough as possible, and data from other sources need to be considered to the fullest extent possible. Knowledge is continually gained with each space flight, and multiple feedback loops need to be built into the standards development and research process. In an organization such as NASA, utilizing a life-cycle approach is key. This approach involves gathering all the available evidence that can be gained by looking both prospectively and retrospectively.

NASA is actively engaged in collaborations with other federal agencies, international partners, and numerous scientific associations and businesses. It is critical to continue and, if possible, expand efforts to use these collaborations to share best practices, lessons learned, sentinel events, and near-miss experiences that can contribute to refining the standards and improving the health outcomes and health-related quality of life for the space crew members. Just as consortia of hospitals combine to share best practices, knowledge of equipment failures, etc., NASA should continue to involve its military and scientific peers in the United States and internationally in action-oriented discussions that focus on areas of common concern. Some of this information will be qualitative, and NASA should work to incorporate increased use of qualitative data into its risk assessment methodologies and mitigation strategies.

Of utmost importance is increased in-flight testing and research. One of the truisms of management that is relevant to space flight risk assessment is, “you can’t manage what you don’t measure.” An expansion of data collection before, during, and after a flight is a priority that needs to be emphasized in plans for research budgets and crew and mission schedules. The use of valid and reliable quantifiable measures for both behavioral and physiological outcomes is essential. Feedback loops need to be in place that identify gaps in knowledge and provide the information back into the research and testing priorities and plans for future research funding.

Relevant data can also come from a number of other sources, including:

• current and former astronauts and cosmonauts: More feedback from the astronaut corps, particularly from former space flight crew members, is needed. A focus on collecting experiences from previous flight crews regarding behavioral health and crew compatibility issues could be particularly useful and could point toward issues that may not be included in clinical follow-up examinations. Continued efforts to examine the data on long-term health outcomes (through the Longitudinal Study of Astronaut Health) are important.

• analog environments and models: Data and experiences from military and civilian colleagues who work in environments of flight or isolation and confined spaces or who conduct research in comparable areas are particularly relevant.

• international perspectives: Space crew members and other scientists and experts from countries with relevant expertise should continue to provide important information for assessing acceptable risk.

• feedback from waivers: Any waiver that is granted to a standard should be an opportunity for learning from the results of that waiver and should be used to provide feedback to the standards-setting process.

The data from these sources and the analyses and publications based on the data should be widely disseminated and submitted to peer-reviewed journals for validation. Improving data availability and enhancing the opportunities for data sharing will strengthen the validity and integrity of the NASA standards-setting process. Continual care should be exercised to ensure that standard setting is data driven and that standards are not based on opinion unsupported by the appropriate research. When data do not exist, every effort should be made to generate them.

In the context of rapidly expanding knowledge about space flight and human health, NASA needs to be a nimble organization that can refine its standards and processes as quickly as possible to reflect newly received data. The standards-setting process should be designed from the outset so that updates are an integral part of the process, with specific mechanisms in place to make these changes in a timely manner. In addition, experience with appeals and waivers should be collected and clearly documented so that updates to existing standards are informed by the decisions actually made. In the extreme case, a standard that is commonly waived simply ceases to be a standard.

Not only will the standards be of greatest value if the process is iterative and continually refined, but there also is the potential for a significant return on investment that results from honing the standards to the most precise measures possible. By necessity, conservative limits are chosen to protect human health

when people are facing the unknown hazards of specific exposures. This caution can lead to the potential for overengineering the design and construction of space vehicles. The more precise the standards, the greater the opportunity to be more targeted and efficient in defining the requirements for the vehicle or spacesuits that are needed to maintain the health and well-being of flight crews.

As noted above, new information will be gained from a number of different sources. The updating of standards should be driven both by events, such as new relevant findings, and by calendar-based review cycles. In this regard, standards will necessarily be formatted as documents. However, they are best considered as a set of operational rules linked to and derived from a knowledge base that is in more or less continuous flux as science and operational experience progresses. Mechanisms that allow frequent updates to occur as needed are preferred, while acknowledging that this should not be a burdensome prospect. This need suggests that appropriate software, combined with timely ad hoc and systematic reviews, can foster prompt revisions while minimizing the administrative burden.

Similarly, there is a need to more fully document the processes for appeals to the standards themselves and waivers for their application to individuals. While some standards, particularly the permissible exposure limits, focus on issues that directly affect the spacecraft architecture, other standards, such as those regarding the outcome measures (e.g., aerobic capacity, muscular strength, microgravity-induced bone mineral loss) are more specific to individual crew members and may benefit from a tiered waiver system so that decisions can be made at the appropriate level depending on the severity of the variance.

Written mechanisms and processes for developing new standards and expanding existing standards also need careful consideration. The behavioral health standard is particularly relevant for this discussion. The current standard for behavioral health is focused on sleep duration and individual cognitive function. While these are important issues, they are only a fraction of the behavioral health considerations that should be incorporated into the standard. Previous committees’ recommendations regarding behavioral health in both the Safe Passage and the Bioastronautics Roadmap reports (IOM, 2001a, 2006) focused on interpersonal relationships, group interactions, and small social systems. The committee urges that the behavioral health standard be expanded to include measures of group dynamics and interpersonal relationships, using quantitative and qualitative behavioral health assessment methodologies. Further, the committee believes that documented mechanisms should be established for initiating new standards and expanding existing standards.

Crew health and safety involves interdependent systems, including the multiple human physiological systems (e.g., cardiovascular, respiratory, renal, endocrine, etc.), space craft architecture and environment, and planetary environments. As a result of that interdependence, changes in any one system may also affect other systems, sometimes in ways that are neither obvious nor anticipated. For example, an isolated minor change in cardiovascular, pulmonary, or renal function might have little or no impact on the overall health or performance of an astronaut, whereas combined minor decrements in all three systems might have serious consequences. Similarly, the granting of a waiver might be appropriate at one point in time, but could jeopardize crew health if space permissible exposure limits were altered subse-

quently. Thus the space flight standard setting process must be constantly vigilant for possible unanticipated interactions that could negatively impact crew health and performance.

The committee urges NASA to consider how the individual space flight health standards are interrelated and to address potential additive, synergistic, or aggregate effects that may result when physiological changes or decrements occur in multiple body systems or when there is the potential for multiple hazardous exposures. The knowledge base for this area is relatively scant, but as data become increasingly available, NASA should continue to reexamine individual standards while exploring the consequences of their interrelationships.

The committee finds that the initial standards-setting process developed by NASA is a carefully designed process that is evidence-based and involves input from relevant stakeholders. The process follows an occupational health model as recommended in several prior IOM reports and provides an analytical framework for enhancing the safety of human space flight. The recent establishment of the three technical authorities is a boon to enhancing mission and crew safety and provides the needed connection between engineering design, mission operations, and crew safety.

Improvements are an inherent component of these types of efforts, and the committee recommends that NASA: expand the opportunity for input and review; strengthen the evidence review; increase research and validation efforts; enhance updates, appeals, and the development of new standards; and use an integrated systems approach.

The IOM Committee to Review NASA’s Space Flight Health Standards appreciates the opportunity to provide input into NASA’s standards-setting process. We would be pleased to brief you and your staff regarding the findings and recommendations provided in this letter.

DAVID E. LONGNECKER (Chair), Association of American Medical Colleges

ALFRED F. CONNORS, JR., Case Western Reserve University

LOUIS ANTHONY COX, JR., Cox Associates

CHRISTOPHER A. HART, Federal Aviation Administration

DANIEL R. MASYS, Vanderbilt University Medical Center

VAN C. MOW, Columbia University

TOM S. NEUMAN, University of California, San Diego

SHARON-LISE NORMAND, Harvard School of Public Health

THOMAS F. OLTMANNS, Washington University

JAMES PAWELCZYK, Pennsylvania State University

RUSSELL B. RAYMAN, Aerospace Medical Association

CAROL SCOTT-CONNER, University of Iowa

RHEA SEDDON, Vanderbilt University Medical Center

MICHAEL SILVERSTEIN, University of Washington

GEORGE PEACH TAYLOR, JR., PricewaterhouseCoopers

WARREN M. ZAPOL, Harvard Medical School

CATHARYN T. LIVERMAN, Study Director

NORA HENNESSY, Research Associate

VILIJA TEEL, Senior Project Assistant (through December 2006)

JUDY ESTEP, Senior Project Assistant (from December 2006)

MELVIN H. WORTH, Scholar-in-Residence

ANDREW POPE, Director, Board on Health Sciences Policy

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Meeting of the Committee on NASA’s Space Flight Health Standards

November 13-14, 2006

Keck Center, Rooms 110 and 201

500 5th Street, NW, Washington, DC 20001

Monday, November 13th – Room 110

OPEN SESSION

Tuesday, November 14th – Room 201

OPEN SESSION

Subsequent to the November 2006 meeting, the committee received input on standards-setting processes regarding the U.S. Navy Submarine Service from Wayne Horn and Larry Garsha and on the U.S. Antarctic Program from Will Silva.

This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the NRC’s Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making its published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We wish to thank the following individuals for their review of this report:

Although the reviewers listed above have provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations nor did they see the final draft of the report before its release. The review of this report was overseen by Judith Swain, National University of Singapore and University of California, San Diego, appointed by the Institute of Medicine, who was responsible for making certain that an independent examination of this report was carried out in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this report rests entirely with the authoring committee and the institution.