The committee’s statement of task calls for an examination of the current policy development processes from both a national and international perspective, including a review of the major players and stakeholders and their respective roles and responsibilities. The charge also asks for an assessment of how the current process takes into account relevant new scientific knowledge and technical developments. In addition, the charge asks the committee to consider how the current process attends to balancing the immediate planetary protection needs with the need to gather scientific information to support future studies. This chapter addresses those elements of the charge.
In assessing the effectiveness of the current process, the committee considered a number of best practices—for example, broad stakeholder engagement and participation, clarity of roles and responsibilities, transparency, access to new scientific and technical knowledge, timeliness, and consistency—that are important for effective policy development and implementation. Notwithstanding the successes achieved over many years, whether the current process will continue to function as well in the future will depend on how well the processes of planetary protection policy development embrace these practices. The committee’s recommendations are numbered according to the chapter and order in which they appear.
Planetary protection policy development involves a process that flows between national and international policy formulation and national policy implementation. Figure 3.1 is a simplified depiction of these processes and their interaction, and it provides context for this chapter’s more detailed analysis. Planetary protection policy development is grounded in the Outer Space Treaty (OST). As a state party to the treaty, the U.S. government has binding obligations under international law to comply with its planetary protection provisions, which are also federal law under the Constitution.
NASA policies satisfy this obligation for government-sponsored space activities. For private-sector space activities with planetary protection implications, a “regulatory gap” exists because Congress has not adopted legislation giving a federal agency jurisdiction over such activities (see Chapter 6).
NASA draws on scientific input from the Space Studies Board (SSB) of the National Academies of Sciences, Engineering, and Medicine, internal agency advisory groups, and consultants to the Office of Planetary Protection (OPP), to formulate policies to direct NASA activities that have planetary protection implications. This stage involves setting high-level objectives in NASA Policy Directives (NPDs) and requirements for specific types of
missions in NASA Procedural Requirements (NPRs). In NASA, the NPDs and NPRs are coupled such that the two types of directives together represent the policy.
NASA policy formulation affects, and is informed by, efforts to forge international consensus on planetary protection policies. The U.S. government supports the Committee on Space Research (COSPAR) in order to help achieve international consensus on science-based planetary protection policies. As noted in Chapter 2, NASA science and policy positions have historically determined the guidance COSPAR has produced. The United Nations Committee on the Peaceful Uses of Outer Space, of which the United States is a member, has endorsed COSPAR as the appropriate international authority for creating consensus planetary protection guidelines.1 However, the OST does not require the U.S. government to support COSPAR, participate in COSPAR, or adopt and implement COSPAR guidance. In this international harmonization step, nothing is incorporated in the NASA policy that does not have the agreement of NASA and the U.S. government.
In reality, the policy development process is not as simple as Figure 3.1 might suggest. Activities at one step can create a need for players lower in the process (e.g., in NASA) to revise or frame new policies to address issues that have not been addressed at higher levels in the flow (e.g., COSPAR), thereby acting as feedback loops. The discussion below will show that efforts to implement policies prescribed for controlling terrestrial contamination risks in the Mars 2020 mission’s sample collection systems (the policy implementation phase) have led to a need for NASA to refine its policies (the policy formulation phase). Similarly, experience with the Europa Clipper mis-
1 See paragraph 25 of United Nations Committee on the Peaceful Uses of Outer Space, “Space Science for Global Development: Report on the United Nations Office for Outer Space Affairs and Committee on Space Research coordination meeting in support of the preparations for UNISPACE+50,” Vienna, Austria, May 22-23, 2017. And paragraph 332 of United Nations, “Report of the Committee on the Peaceful Uses of Outer Space, Sixtienth (sic) Session (7-17 June 2017)” General Assembly, Official Records, Seventy-second Session, Supplement No. 20., http://www.unoosa.org/res/oosadoc/data/documents/2017/aac_1052017crp/aac_1052017crp_25_0_html/AC105_2017_CRP25E.pdf and http://www.unoosa.org/oosa/en/ourwork/copuos/2017/index.html.
sion provides an example of how efforts to develop planetary protection raised issues that players in the policy harmonization process (e.g., NASA, COSPAR, and the scientific community) would have done well to have anticipated in order to permit timely development of policies and requirements for the mission.
NASA implements planetary protection policies and requirements in NASA-led missions by translating the NASA procedural requirements into the design of spacecraft and mission activities. The translation process sometimes involves negotiations between OPP and the science and engineering teams. Policy implementation includes verifying that space missions comply with the applicable requirements. Experience with individual missions often provides lessons that can be applied to subsequent policy formulation and harmonization actions.
Overview of NASA Planetary Protection Policy Documents and Institutional Roles
NPDs establish NASA’s objectives and instruct agency officials and staff about what they are required to do to achieve these objectives. NPRs guide how officials and staff implement policy directives in the context of specific missions. These two sets of documents, taken together, define NASA’s policy. Occasionally, NASA issues a NASA Interim Directive (NID) that temporarily modifies policy directives or implementation requirements.2 (See Figure 3.2 on the structure of NASA policy documents.)
Current NASA planetary protection policy is contained in:
- One NPD, revalidated in 2013, that establishes the high-level objectives and defines agency office roles and responsibilities for planetary protection; and
- One NID, adopted in 2017, that provides the implementation requirements for robotic missions.3
Both documents appear to be silent on whether a particular individual or office has the responsibility to develop and maintain NASA’s planetary protection policies.4
To date, NASA has not developed procedural requirements for planetary protection concerning human missions to Mars, but the agency has issued a NASA Policy Instruction (NPI) that contains the policy guidelines for the development of an NPR for crewed planetary missions (see Chapter 5).
2 NIDs may replace NPDs or NPRs on a short-term basis (not to exceed 12 months) if an immediate change is warranted.
3 These implementation requirements include the COSPAR guidelines contained in the COSPAR Planetary Protection Policy.
4 In briefing the committee about NASA’s expectations for this study, both the former NASA chief scientist and the acting NASA chief scientist noted that one concern was the extent to which a separation of responsibilities between policy formulation, policy implementation, and implementation verification was advisable.
Formally, NASA assigns most of the responsibilities for administering the agency’s planetary protection policy to the planetary protection officer (PPO). (See Box 3.1 on the PPO’s responsibilities.) Other NASA officials and staff have specific responsibilities for implementing planetary protection policy. On November 30, 2017, NASA transferred responsibility for overall administration of its planetary protection policy from the Associate Administrator of the Science Mission Directorate to the Chief of the Office of Safety and Mission Assurance (OSMA). The Associate Administrator for the Human Exploration and Operations Mission Directorate and the Associate Administrator for the Space Technology Mission Directorate are designated to ensure that the NPD on planetary protection is incorporated into human spaceflight missions.5 The directors of NASA centers and their program/project managers are responsible for meeting the procedural requirements for planetary protection and for cooperating with the PPO’s administration of NASA planetary protection activities. Finally, NASA has had a standing Planetary Protection Subcommittee (PPS) of the NASA Advisory Council’s (NAC’s) Science Committee to provide
5 The administration’s fiscal year 2019 budget proposal to Congress includes a proposal to move the Space Technology Mission Directorate under the Human Exploration and Operations Mission Directorate.
advice and support to the PPO, NASA administrators, and mission directorates on planetary protection issues. However, NASA reorganized the NAC in late 2017, and the subcommittee was eliminated.6
NASA’s acting chief scientist explained to the committee that the decision to move the OPP from the Science Mission Directorate (SMD) to the OSMA would fit more effectively with OSMA’s role as a technical authority, which focuses on verification, validation, and compliance concerning mission requirements, including safety, reliability, and quality assurance. This move makes the Chief of the OSMA responsible for making final decisions on planetary protection policy issues.
With the move to OSMA, NASA plans to divide the planetary protection functions into two roles:
- The PPO for administering policy directives and procedural requirements; and
- A new planetary protection research manager, responsible for performing gap analyses, identifying and coordinating planetary protection research, identifying new and emerging planetary protection risks and uncertainties associated with human exploration missions to Mars and other planetary bodies, coordinating with appropriate agency organizations to develop risk mitigation methodologies, and maintaining cognizance of international advances in the state of the art and adaptations to new technologies, materials, processes and risks.
Whether or not the planetary protection research manager would be located in SMD or somewhere else in NASA was not clear to the committee. SMD has a clear charter, an established process, and a proven record of managing the agency’s space and Earth science programs. Given the close linkage between SMD’s astrobiology and planetary science programs and planetary protection research needs, SMD would be the obvious choice as the home for NASA’s planetary protection research program.
Current NASA Planetary Protection Policies
NASA’s overarching policy document for planetary protection is applicable to all spaceflight missions, including human spaceflight.7 This NPD explicitly incorporates its implementing requirements document,8 and consequently, the requirements document is considered a part of the NASA planetary protection policy.
The 2017 NID sets forth NASA’s biological and organic contamination control requirements applicable to robotic planetary flight programs and specifically addresses two topics. The first is the control of terrestrial microbial contamination associated with robotic space vehicles intended to land, orbit, flyby, or otherwise encounter extraterrestrial solar system bodies. The second is the control of contamination of Earth and the Moon by extraterrestrial material collected and returned by robotic missions. The NID also defines the following:
- Planetary protection categorization of missions;
- General mission requirements for NASA participation in non-NASA or non-U.S. missions;
- Detailed documentation and review requirements and their schedules;
- Process of monitoring and verification;
- Waivers and deviations; and
- Delegated responsibilities of the PPO.
The NID refers to a NASA handbook9 that describes uniform microbiological assay procedures that are to be used to assess the degree of microbiological contamination of intramural environments where spacecraft hardware is assembled, tested, and launched and to assess the level of microbial contamination on spacecraft hardware.
6 See, for example, December 15, 2017, memorandum from Thomas Zurbuchen, associate administrator, Science Mission Directorate to the chairs of the various NASA planetary science analysis/assessment groups.
7 NPD 8020.7G, Biological Contamination Control for Outbound and Inbound Planetary Spacecraft, (Revalidated 05/17/13 w/change 1).
8 NID 8020.109A, Planetary Protection Provisions for Robotic Extraterrestrial Missions.
9 HDBK 6022, NASA Standard Procedures for the Microbial Examination of Space Hardware.
Overview of NASA’s Process for Developing Planetary Protection Policy
Traditionally, NASA’s development of new or modified planetary protection policy has involved action, first within NASA, and second through international cooperation within COSPAR. The interdependence between the NASA-level activity and COSPAR efforts is reflected in how COSPAR policy statements and implementation guidance mirror NASA’s NPD and NID for planetary protection. As Chapter 2 described, NASA has been the lead actor in the development and revisions of COSPAR planetary protection guidance. This NASA leadership role has been driven by NASA’s need for new or additional policies for missions that have not yet been fully considered by COSPAR. Under this pattern, changes in NASA and COSPAR policy occur synergistically, although COSPAR has no authority to compel NASA to change NASA’s planetary protection policies. Chapter 4 describes how COSPAR operates, and the present subsection focuses on the NASA process for developing or modifying planetary protection policy.
NASA has a comprehensive process for creating new or revising existing NPDs and NPRs. Proposed changes typically emerge from the OPP, and, once a proposal has been formally drafted, any new or revised NPD, NPR, or NID is released to all affected NASA parties for review. The review involves extensive discussions on the proposal, including on implementation issues. NASA ensures that all questions and comments on the proposed change are addressed, and negotiations among affected NASA parties often produce revised proposals. All affected NASA parties are required to concur in changes that appear in a new or revised NPD, NPR, or NID. More recently, NASA has waited to update its planetary protection procedural requirements until the NPR comes up for renewal per NASA’s directives policy.
The committee understands that this comprehensive process is used whenever changes to NPDs and NPRs on planetary protection are proposed. This approach ensures that changes to the operative policy and requirement mandates within NASA are fully vetted by affected stakeholders in the agency.
However, questions can arise if COSPAR adopts changes to its planetary protection guidance that have not been comprehensively reviewed and approved within NASA beforehand. Although NASA has been the driving force behind changes in COSPAR guidance to date, COSPAR—as an international forum—can produce proposals and adopt recommendations for changes to its planetary protection guidance that do not originate within NASA and that have not been comprehensively vetted by all relevant NASA stakeholders. In other words, changes to COSPAR guidance could be adopted with the concurrence of only a few NASA officials who may be concurrently participating in COSPAR’s internal deliberative processes.
The adoption of new COSPAR guidance in these circumstances would not change any NPD, NPR, or NID, but NASA would then face conflict between its commitment to follow COSPAR guidance and its commitment to vet thoroughly within the agency any changes to NASA planetary protection directives and requirements. Rejection or revision of the new COSPAR guidance after internal NASA review would put the United States at odds with the international scientific consensus achieved in COSPAR and create potential problems for future policy harmonization efforts within COSPAR.
Often both the COSPAR policy and the NASA policy have been incomplete when it comes to new missions that are being proposed for the first time. That is the case for Mars 2020, which is the first stage of a possible Mars sample return campaign, and Europa Clipper, which is the first Category III (see Table 2.1) mission to an Ocean World. In cases such as these, the NASA PPO defines the missing policy requirements and provides them to SMD, its programs, and their new missions. This additional policy guidance and requirements were not available sufficiently early in the mission design process, and then it was provided to the mission teams by a variety of means including letters, email, and verbal directions. This process will be discussed further in the next sections.
The most recent planetary science decadal survey designated the highest-priority strategic mission to be initiating the first phase of a Mars sample return campaign by developing what at the time was called the Mars Astrobiology Explorer and Cacher (MAX-C), an in situ science rover with sample caching capability.10
10 National Research Council (NRC), Vision and Voyages for Planetary Science in the Decade 2013-2022, The National Academies Press, Washington, D.C., 2011.
Returning samples from Mars has remained a priority for the planetary science community for roughly 50 years because such a mission has the best chance of determining whether life emerged elsewhere in the solar system. Answering the big question of “Are we alone?” means that this is the next logical step in planetary science exploration and provides most science return for the investment.
While some may argue for intensified in situ missions, sample return has continued to be the implementation approach of choice for at least four reasons:
- Samples can be analyzed by many laboratories rather than by a single rover.
- Investigations may be conducted by hundreds of researchers sharing samples rather than a single set of investigators operating remote experiments.
- Advanced instrumentation can be utilized that is too large or complex for in situ missions.
- Alternate measurement routes can be followed as new data emerges so that one can pursue the pathways of discovery.
Mars 2020 and Planetary Protection
After several years of study and cost reductions, the first step toward a Mars sample return campaign was approval of a rover with the MAX-C science and caching capabilities but now known as Mars 2020 (see Figure 3.3).13 The mission presented several notable challenges for planetary protection.
First, because Mars 2020 will be the first phase of a sample return campaign, planetary protection regulations regarding restricted Earth return (see Table 2.1) become applicable. Thus, Mars 2020 becomes the first-ever mission to have to deal with samples returned from Mars and, therefore, moves NASA into a new planetary protection regime.
Second, when Mars 2020 received formal authority to proceed in 2013 (Key Decision Point A in Figure 3.4), the project was given a cost constraint of $2.1 billion (real-year dollars), including the cost of the launch vehicle. In part to meet the cost constraint, the project was required to maximize the use of hardware and software inherited from the Mars Science Laboratory (MSL) Curiosity mission. Moreover, NASA officials were unable to portray Mars 2020 as the first phase in a sample return campaign because the administration had not yet committed to the goal of returning samples from Mars. Indeed, NASA officials were enjoined from mentioning the possibility of returning samples from Mars to Earth prior to an August 28, 2017, presentation by NASA Associate Administrator Thomas Zurbuchen to the National Academies’ planetary science decadal survey’s midterm review committee.14 The reality of a sample return campaign became even more apparent in April 2018, when NASA and the European Space Agency (ESA) signed a statement of intent to develop a joint Mars sample return plan under which each agency would have lead responsibilities for specific mission elements. The statement added that “this endeavor may be in concert with other international or commercial partners.”15
11 See, for example, E.H. Hauri, T. Weinreich, A.E. Saal, M.C. Rutherford, and J.A. Van Orman, High pre-eruptive water contents preserved in lunar melt inclusions, Science 333:213-215, 2011.
12 See, for example, F.M. McCubbin, B.L. Jolliffc, H. Nekvasil, P.K. Carpenter, R.A. Zeigler, A. Steele, S.M. Elardoa, and D.H. Lindsley, Fluorine and chlorine abundances in lunar apatite: Implications for heterogeneous distributions of magmatic volatiles in the lunar interior, Geochimica et Cosmochimica Acta 75:5073-5093, 2011.
13 MAX-C was assessed by an independent cost and technical evaluation by the Aerospace Corporation as costing ~$3.5 billion in fiscal year (FY) 2015 dollars, which the planetary science decadal survey’s steering committee rejected as being too expensive. The decadal survey committee set the not-to-exceed cost threshold at ~$2.5 billion in FY2015 dollars. For details, see NRC, Vision and Voyages for Planetary Science in the Decade 2013-2022, The National Academies Press, Washington, D.C., 2011, pp. 268-271 and 340.
14 See, for example, National Academies of Sciences, Engineering, and Medicine (NASEM), Review of Progress Toward Implementing the Decadal Survey Vision and Voyages for Planetary Sciences, The National Academies Press, Washington, D.C., 2018 (in preparation).
15 Associate Administrator for Science Thomas Zurbuchen, NASA, and Director Human and Robotic Exploration Programmes David Parker, ESA, “Joint Statement of Intent between the National Aeronautics and Space Administration and the European Space Agency on Mars Sample Return,” April 26, 2018, https://mepag.jpl.nasa.gov/announcements/2018-04-26%20NASA-ESA%20SOI%20(Signed).pdf.
Prior to the August 28 presentation,16 Mars 2020 was officially a reflight of MSL with new science objectives, new instruments, and the ability to collect and cache samples that might or might not be collected and returned to Earth at a later time. As a result of this ambiguity, a conflict between the PPO and the mission implementation arose early in the Mars 2020 planning because MSL had not been subjected to the planetary protection requirements that the PPO believed would be needed for, what was in essence, the first phase of an officially unacknowledged sample return campaign.
Dry heat sterilization that had been used for Viking, for example, would likely damage Mars 2020 hardware irreparably or result in large amounts of organic outgassing. In addition, a new sampling and caching system for returnable samples was needed but had not yet been designed. While the project recognized from the start that planetary protection and scientific cleanliness would be a major issue, there emerged over a period of 3 years a fundamental disagreement between the project and the OPP both about level-1 requirements and about approaches in implementation. This 3-year period is outlined in Figure 3.4 and corresponds roughly to the time from authority to proceed in 2013 to the approval of the planetary protection plan in 2016.
The project took the position that planetary protection practices that worked for MSL would be acceptable for most hardware on Mars 2020 and that a systems approach would identify those specific parts that would require sterilization and that could be verified by appropriate modeling. The means of demonstrating the “sterility” of the parts requiring sterilization became a source of disagreement between the PPO and the project.
The in situ instruments, while not intended for life detection per se, would be sensitive to very small amounts of organic carbon, meaning they need to be very clean to avoid erroneous results produced by contamination on
16 T. Zurbuchen, NASA, presentation to the committee August 28, 2017, http://sites.nationalacademies.org/cs/groups/ssbsite/documents/webpage/ssb_181241.pdf.
the instruments. More challenging are the sample collection mechanism and canisters, which would be the first part of the Mars sample return campaign and thus be planetary protection Category V (restricted Earth return).
Several complex and contentious issues arose during the negotiations over planetary protection requirements and how they were to be applied to Mars 2020. Chief among those was tension between the goals of reducing potential contamination by viable organisms and total organic carbon. Meeting the two goals often proved mutually incompatible.
While the planetary protection community continues to hold Viking planetary protection procedures (i.e., sterilization by means of dry heat microbial reduction) as the gold standard, the cost constraint and required reuse of the MSL design effectively eliminated any full-spacecraft and most subsystem-level heat sterilization techniques. The cost for redesign of the spacecraft to withstand sterilization temperatures would have been prohibitive. Further, given the reuse of the MSL design, utilizing dry heat microbial reduction would have resulted in significant organic outgassing that would overwhelm the total organic carbon limits necessary to meet the mission’s science objectives.
In addition, a “round trip” science integrity contamination requirement on the hardware cleanliness became an issue. The requirement’s rationale, from a planetry perspective, was based on avoiding a “false positive” that might keep returned samples in containment permanently. Mars 2020 project officials objected to this rationale. As explained in the “Interim Report” section of Chapter 1, the committee concluded that there was no need for a separate round trip planetary protection requirement.
Finally, applying certain very prescriptive Viking era requirements (bake subsystem Z for X hours at temperature Y) into level-117 performance requirements that could require a new Mars 2020 design was a major hurdle.18 Such standard prescriptions do not translate well as new missions emerge with differing designs and objectives, and thus more innovative approaches to planetary protection goals are needed. The planetary protection requirements for surface cleanliness could be satisfied by alternative techniques, provided that the project demonstrates the efficacy of the alternative method.
Mars 2020 Planetary Protection Issue Resolution
Deliberations among the science community, NASA officials, and Mars 2020 project managers determined that controlling total organic carbon would be the driving requirement for the hardware design and cleanliness. The science team concluded that the number of viable organisms could be reduced by selective heating of specific parts such as the sample collection tubes. Given the importance of organic contamination, NASA constituted an Organic Contamination Panel (OCP) of experts that provided guidance to the project.
The OCP recommended a total organic carbon (TOC) baseline limit of 10 ppb with a threshold (not to exceed) of 40 ppb. NASA officials and project managers accepted the recommendations of the OCP, and NASA’s PPO endorsed these requirements. Organics were sorted into two categories to reflect the differing impact on science instrumentation and the relative importance of different sources of carbon.
With respect to round-trip cleanliness, both science and planetary protection objectives would benefit by minimizing the number of viable organisms in the sample tube, but a measurable (integer) value was needed as the level-1 requirement in order to determine specific allocations to the various potentially contaminating processes. Thus, the Mars 2020 team initially proposed a requirement of less than 10 culturable spores per sample. Following further discussions, a requirement of one viable organism per sample was proposed and eventually accepted by the OPP, and NASA headquarters officials established this limit as a level-1 requirement. However, the OPP still disagreed with the method by which the level of confidence in meeting that requirement was calculated, preferring to use a Viking era limit based on surface area of the sample tubes.19
In order to adapt the contamination control approach for Mars 2020 to produce an equivalent of Viking era post-sterilization cleanliness, the project instituted a systems engineering approach. By treating the sample contact hardware and associated instrumentation as elements of a much larger system with a total contamination budget, the project was able to vary the technique of sterilization and cleaning by functional element while still meeting the level-1 requirements. For example, while the sample collection tubes are baked at 350°C, other parts of the spacecraft and instruments were cleaned by alternative methods that were approved for MSL (e.g., treatment by chemicals, gasses, or lower temperature sterilization). According to the Mars 2020 project team’s measurements and modeling described to the committee, the systems engineering approach will permit them to meet the limits
17 The term “level-1” refers to NASA’s highest-level mission performance requirements. Level-1 requirements are usually set by NASA headquarters to define the top-level objectives that a mission is required to meet to be successful. Level-2, and lower, requirements are derived (flow down) from level-1, and they provide increasing levels of implementation detail to assist engineers to ensure that their subsystems designs will ultimately support the level-1 requirements.
18 Spaceflight mission engineers need high-level requirements—for example, “operate on Mars for one full year,” that they can then “flow down” to specific requirements for subsystems, instruments, parts selection, and so on.
19 While NASA resolved the dispute by approving the Mars 2020 team’s proposed limit, this disagreement highlights the difference between the ESA approach and NASA. Chapter 3 explains that in ESA the project manager is given broad latitude to determine how top-level requirements flow down to translate into implementation requirements at spacecraft system and subsystem levels.
on viable microorganisms by more than a factor of 16,000 and to meet the limits on TOC with a margin of at least 37 percent.20
NASA conducted extensive reviews of the Mars 2020 project’s approach to meet both planetary protection and returned sample contamination control requirements. The project conducted multiple independent peer reviews and subsystem reviews prior to critical design review and during Phase-C, and the Standing Review Board engaged at life cycle reviews and subsystem reviews. The NASA Headquarters Mars Program Office and SMD consulted additional experts at various points during development, including the Planetary Protection Subcommittee (PPS), the Returned Sample Science Board, an Independent Assessment Review, a Cache Cleanliness Science Study Team, and a Contamination Control and Planetary Protection Working Group.
Those reviews differed in content based on their particular focus and timing. However, according to the Mars 2020 program executive at NASA Headquarters, the review teams found the project team had a clear understanding of the technical challenges and had developed a credible approach that was compliant with requirements.21 No showstoppers were identified, and each review group provided useful insights, which NASA took seriously.
As noted earlier, some time passed after the original decision to proceed with Mars 2020 in 2013 before these reviews were initiated. The project engaged with the PPS in November 2014 and in June and December 2015; the IAR met in March and October 2015, with a follow-up teleconference in January 2016; the CCSST did a quick-look in April 2016; the RSSB has had ongoing engagement since its inception; and the CCPPWG was initiated in summer 2016 with ongoing engagement with the project throughout 2017.
NASA’s OPP objected to the project team’s approach for three reasons:
- The new approach does not comply with the OPP’s requirement for cleanliness of the sample hardware (equivalent to the Viking post-sterilization level);
- The systems approach cleanliness budget may not take into account all possible sources of contamination; and
- Modeling techniques such as computational fluid dynamics cannot be applied to organismal contaminants.
Nevertheless, NASA Headquarters approved this systems approach to contamination control. Although the long-running disagreement was eventually resolved by a NASA Headquarters decision, the committee found the failure to exercise a dispute resolution process sooner to be a troubling symptom of either a gap in NASA’s policy or a breakdown in utilizing policies that were available. For the reasons indicated in the section “The OPP’s Move to the OSMA” later in this chapter, the committee expects that the move to OSMA will engender a cleaner, dispute-resolution process.
Lessons Learned from Mars 2020 Planetary Protection Implementation
The 3-year long (from about mid-2013 until mid-2016) and often contentious discussion between the Mars 2020 project team and the OPP suggests several lessons for any new policy development:
- Early discussions and agreement between a given project team and PPOs, preferably at the mission definition stage, on the mission’s planetary protection requirements and approach are of paramount importance. In particular, if a mission is moving into scientific or programmatic territory not fully developed (e.g., Mars sample return, humans to Mars or putative missions to the internal oceans of icy bodies) much dialogue and research is clearly warranted.
- All planetary protection requirements imposed by NASA Headquarters need to reflect the agency’s standard project management and systems engineering protocols.
20 Mars 2020 project communication to committee. For an example of this new systems engineering process see I.G. Mikellides, A.D. Steltzner, B.K. Blakkolb, R.C. Matthews, K.A. Kipp, D.E. Bernard, M. Stricker, J.N. Benardini, P.S. Shah, and A. Robinson, The viscous fluid mechanical particle barrier for the prevention of sample containment on the Mars 2020 Mission, Planetary and Space Science 142:53-68, 2017.
21 George Tehu, Mars 2020 program executive, NASA Headquarters, personal Communications to committee member G. Scott Hubbard, March 2, 3, and 16, 2018.
Implementation of planetary protection policies to specific missions need to embrace the principles of flexibility, adaptability, and openness to innovation:
- Current and future missions will be cost constrained or cost capped with all the attendant complications (e.g., reuse of heritage hardware, instruments from worldwide labs, distributed systems). Responsibility for dealing realistically with the inherent conflicts between cost constraints and rigorous planetary protection is best shared by decision makers who set the cost constraints, planetary protection officials, and mission managers.
- Standardized or rote application of sterilization or contamination control mechanisms may not be feasible in a cost-capped, complex effort.
- Project teams need to be able to devise implementation approaches to meet planetary protection requirements; defining implementation approaches is not an appropriate role for the OPP.
- Project teams need to draw on the wealth of experience and expertise from the planetary protection community, via an independent advisory structure, to adequately formulate a reasonable and implementable mitigation strategy.
- The process of setting requirements needs to include independent outside expert review.
- Modeling techniques of contamination transport such as winds using computational fluid dynamics need to be further assessed by the OPP for ongoing application.
- Existing planetary protection standards need to be reviewed and revised on a continuing basis to reflect modeling and testing results that improve detection sensitivity and mission compliance requirements within a peer-review framework that includes outside/foreign party participation (i.e., COSPAR, ESA, etc.).
- Mechanisms for conflict resolution need to be understood, and utilized as early and often as necessary. The fact that the OPP has moved to OSMA, which has an established dispute resolution process, will help meet this need.
Finding: In connection with Mars sample return, planetary protection requirements for the sample containment, verification of containment, return vehicle, and sample receiving facility are not yet in place.
Recommendation 3.1: NASA’s process for developing planetary protection policy for sample return missions should include early consultation with mission developers and managers, mission and receiving facility science teams, and microbiologists and include providing a means to use the best available biological and technological knowledge about back contamination and containment.
The most recent planetary science decadal survey listed as its second highest priority a mission to Europa, the moon of Jupiter where the Galileo spacecraft identified the presence of a subsurface salty liquid water ocean, and thus a potential habitat for life.22 In 2011, after a series of reviews, NASA concluded that a Europa mission, named Europa Clipper (see Figure 3.5), could be executed for approximately $2 billion to achieve the science objectives of examining the putative ocean under Europa’s icy surface.
Europa Clipper and the Planetary Protection Process
Unlike Mars 2020, the Europa Clipper mission only requires an orbiter and will not involve any purposeful spacecraft contact with the icy moon. The Clipper mission is classified as planetary protection Category III (see Table 2.1), the key risk being the probability of accidental contact with Europa’s ice crust. Clipper’s orbits will take it very low (possibly as low as 25 km) above the icy surface, and that will increase the risk of a crash that could possibly contaminate a small part of the moon for future lander missions or, in the worst case, contaminate the
22 NRC, Vision and Voyages for Planetary Science in the Decade 2013-2022, The National Academies Press, Washington, D.C., 2011.
europan ocean. The project team has developed an approach to navigation, spacecraft propulsion, orbital dynamics, and risk mitigation that will ensure with a high degree of confidence that the spacecraft will not contact Europa.
As with other planetary exploration spacecraft, there is also an end-of-mission plan that calls for a planetary protection procedure to eliminate the potential for contaminants inside the spacecraft to touch Europa. In some cases, such as the Cassini (Saturn) or Galileo (Jupiter) orbiters, the spacecraft has been directed to dive into the planetary atmosphere, burning up as it does so. The currently planned end-of-mission plan for Europa Clipper is a disposal at the moon Callisto.23 The outermost of Jupiter’s four Galilean satellites, Callisto affords the energetically simplest solution (i.e., least demanding in terms of propulsion requirements) for disposal that satisfies the planetary protection requirements. Although Callisto likely has a liquid water ocean deep below its crust, there is no evidence that matter has been or is transferred between the ocean and the surface so that a spacecraft impact on the surface is not considered to be a forward contamination risk.
The icy body contamination requirement contained in NPR 8020.12D states the following: “The probability of inadvertent contamination of an ocean or other liquid water body must be less than 1×10−4 per mission.”24 The document defines icy body contamination as “the introduction of a single viable terrestrial microorganism into a liquid-water environment.” The 10−4 criterion was suggested by the SSB in 2000,25 but it can be traced back to rather arbitrary estimates made in the early 1960s.26 In order to address the 10−4 requirement, the Europa Clipper
23 T. Lamy, B.B. Buffington, S. Campagnolay, C. Scott, and M. Ozimek, “A Robust Mission Tour for NASA’s Planned Europa Clipper Mission,” 2018 Space Flight Mechanics Meeting, doi:10.2514/6.2018-0202, p. 6, https://www.researchgate.net/publication/322314079_A_Robust_Mission_Tour_for_NASA%27s_Planned_Europa_Clipper_Mission.
24 Although NID 8020.109 is currently the approved directive, the Europa Clipper mission is subject to the previous version NPR 8020.12D per its level-1 requirements.
25 NRC, Preventing the Forward Contamination of Europa, National Academy Press, Washington, D.C., 2000, pp. 2 and 22-23.
26 See, for example, B. Sherwood, A. Ponce, and M. Waltemathe, “Forward Contamination of Oceans Worlds: A Stakeholder Conversation,” conference paper IAC-17.A1.6.1x40187, 68th International Astronautical Congress, Adelaide, Australia, 2017.
project has developed a mathematical Icy Bodies Planetary Protection Probabilistic Model (IBPPPM) for calculating the probability of icy body contamination and deriving allowable initial bioburden (bioburden on the spacecraft at launch) such that the requirement is satisfied.27 The IBPPPM has been designed to demonstrate compliance with regard to Europa, Ganymede, and Callisto. Some of the key questions the model answers are the following:
- What is the probability (Pc) of icy body contamination?
- What is the probability of impacting Europa, Ganymede, or Callisto?
- What are feasible initial bioburden allocations (by bioregion)?
- What regions of the flight system are driving Pc?
- What groups or types of organism are driving Pc?
- What environmental factors (e.g., ionizing radiation) have the most effect on Pc?
- What are the effects of a given cleaning protocol on Pc?
This model has been provisionally accepted by the PPO. Figure 3.6 shows graphically how the model works, representing the Europa contamination event tree, and is intended to be an illustration that communicates the various events considered in the model. It is not intended for direct use in mathematical calculations.
In the committee’s discussion with the Europa Clipper project staff about their approach, several issues emerged that are relevant to future policy development. These issues included the following:
- NASA’s NPR 8020.12D contains some of the parameters and their supporting rationale required for this model, and these are level-1 requirements imposed on the project. However, these level-1 requirements do not contain all of the essential parameters needed for the model. As a result, the project has been evaluating
27 M. DiNicola, K. McCoy, C. Everline, K. Reinholtz, and E. Post, “A Mathematical Model for Assessing the Probability of Contaminating Europa,” 978-1-5386-2014-4/18/, IEEE Aerospace Conference, 2018.
- The PPO has directed the project to use specific values for these missing parameters without following standard NASA protocols for flowing level-1 requirements to the project. These parameters have been specified by letter, email, or verbally. Box 3.2 describes some of the most important parameters that have been imposed on the project by the PPO, the method of their imposition, their source, and an analysis of their validity.
the scientific evidence for these additional parameters and has used their results to specify the missing parameters as part of the project’s definition of level-2 requirements, a normal project function. Although the PPO tentatively approved the model, disagreements have remained over some of these assumptions and parameters, particularly regarding the levels and efficacy of jovian radiation belt exposure for sterilization of the spacecraft and the transport of viable microorganisms from Europa’s surface to the ocean.
It appears that a conflict resolution process has either been lacking or not implemented. That is, the PPO’s and the project’s current understanding of how planetary protection requirements are imposed has not included the ability to disagree with the PPO’s specification of parameters.
These issues illuminate important lessons learned that are relevant to future planetary protection policy development and the need for an orderly process for developing and peer reviewing requirement details for missions for which there is no prior experience.
- Lesson 1. The absence of a complete set of planetary protection requirements can cause a major disruption to project development, particularly if these subsequently are imposed late in the project life cycle. Early definition of requirements is essential to effective project implementation.
- Lesson 2. The imposition of any requirements, including planetary protection requirements, on spaceflight missions needs to follow standard system engineering protocols to ensure that every appropriate requirement is properly understood, implemented, and can be adequately verified.
- Lesson 3. NASA’s conflict resolution process is essential in executing spaceflight missions, and its use is required when disagreements between technical authorities and projects occur. This ensures that senior NASA management understands the risks, benefits, and consequences of decisions when accepting any particular position by either party.
- Lesson 4. The early establishment of requirements, including those for planetary protection, has been shown to minimize the risk and uncertainty of future design changes and thus increased cost for the missions. Future research into the important parameters for these missions, including reevaluating legacy requirements such as those from Viking, will likely reduce the cost of these missions while still meeting U.S. obligations under Article IX of the OST.
Future Ocean World Missions
There is a chance that the Clipper mission will be followed in the future by a lander and maybe even an ocean-exploring Europa submarine. The Jet Propulsion Laboratory is currently studying a Europa lander (see Figure 3.7),28 and an initial mission concept was presented at a Mission Concept Review in June 2017. At the request of the NASA SMD, the Jet Propulsion Laboratory is now investigating additional options. If this and any other follow-on missions were to be implemented, the planetary protection requirements that apply to landing on a body potentially capable of supporting life will surely come into play. The formulation of planetary protection policies for such missions will need to be informed by new research. In particular the scientific question of whether
28 NASA, Report of the Europa Lander Science Definition Team, JPL D-97667, Jet Propulsion Laboratory, Pasadena, California, 2017, https://europa.nasa.gov/resources/58/europa-lander-study-2016-report.
a single organism, deposited on the surface, could contaminate Europa’s entire ocean within a reasonable period of biological exploration needs to be revisited.
NASA recently selected two finalists for the next mission in its New Frontiers Program and two missions for further technology development. One of the former missions is Dragonfly (see Figure 3.8),29 a rotorcraft lander designed to study Titan’s habitability and methane cycle. One of the latter missions is the Enceladus Life Signatures and Habitability, a plume fly-through spacecraft, which will receive funds to develop cost-effective techniques that limit spacecraft contamination and thereby enable life detection measurements on cost-capped missions. Although not apparently directly related to planetary protection research, this technology funding will help enable future planetary protection measures. As with Europa Clipper, this will be a flyby mission and will not attempt to land on the surface of Enceladus. However, very similar issues to Europa Clipper will exist including the ones listed in Box 3.2.
Assessment of NASA Planetary Protection Policies
While NASA’s formal policy documents define the authority of NASA officials, including the PPO for planetary protection, for establishing top-level (i.e., level-1) program requirements,30 the committee did not find these
30 Top-level requirements are labeled as level-1 requirements by the SMD and contained in an appendix to a mission’s parent program plan.
documents to be either clear or explicit about how top-level requirements to deal with first-of-a-kind situations are to be developed or about how authority for establishing lower-level requirements is delegated from headquarters down to project officials. As described in the next section, the NPR policy requirements were insufficient, and new additional level-1 requirements for recent projects such as Mars 2020 and Europa Clipper were not adequately defined early in the projects’ lifetimes. Consequently, there were situations in which the OPP needed to levy additional requirements intermittently during the project. In a more orderly project planning and development process, the committee would have expected that level-1 requirements would be sufficiently complete at the outset so that translation to level-2 and lower requirements would be easily traceable to the higher-level requirements very early in project formulation. Failure to do so represents a shortcoming in NASA’s planetary protection policy development processes.
As an example of where the current policies fail to contain all the requirements that are necessary to implement planetary protection within a spaceflight mission, the current policy does not specify a period of biological exploration for the icy moons of the outer solar system.31 Typically, the PPO issues a categorization letter that defines the planetary protection category for that mission. This letter may include additional requirements to be imposed on the project that are not contained in the NASA NPR.32 In the case of Mars 2020 and Europa Clipper, the OPP also used other more informal methods for imposing these requirements (i.e., either verbally or via email, or, in extreme cases, by rejecting project-level planetary protection documents rather than providing specific guidance) for which there did not appear to be a solid scientific basis.
This ad hoc process raises an issue concerning how to impose previously undefined planetary protection policy and requirements. Ad hoc requirements can also create conflict between the OPP and the mission project team, particularly if the basis of the requirements are not mutually agreed. When a situation like this occurs, NASA has a standard conflict resolution process defined in NPD 1000.0 and NPR 7120.5 that can be used to resolve such disagreements. NASA’s process expects that each requirement will have a scientific and/or engineering and/or policy basis that is understood by the relevant stakeholders. Furthermore, using letters, verbal direction, and non-approval are not in accordance with these policies or with good systems engineering practices. (See Appendix C for a description of NASA’s policies on good program and project management and systems engineering practices.) As noted above for Mars 2020, this standard approach was only recently used to resolve differences between the OPP and the mission project team.
The committee learned that NASA SMD recently began instituting a more orderly process by establishing some planetary protection requirements as part of their normal definition of the top-level requirements for the mission. This more formal process is in accordance with NASA’s requirements for project management and systems engineering. However as noted above, some planetary protection requirements were being imposed without adequate review and concurrence. The recent efforts in SMD to ensure a more systematic process are expected to continue with the transfer of the OPP to OSMA, however as the committee discusses below, the lack of an established advisory committee means that there is still no platform for independent expert review.
Finding: Because NASA planetary protection policies have been incomplete with respect to unique aspects of new, first-of-a-kind missions, requirements for these spaceflight missions have not always been clearly defined at the beginning of a project or communicated to projects in accordance with NASA’s standard protocols for imposing headquarters-level requirements.
Finding: The NASA OPP and the mission project teams have not been following standard NASA spaceflight program and project management and systems engineering practices. In particular the OPP has been issuing level-1 requirements informally through letters, email, and verbal direction, and the project teams have
31 An NRC 2012 report, Assessment of Planetary Protection Requirements for Spacecraft Missions to Icy Solar System Bodies (The National Academies Press, Washington, D.C.), recommended 1,000 years.
32 As an example, the Europa Clipper categorization letter, dated September 30, 2016, contains a requirement that the probability of transferring a viable organism from the surface of Europa to its sub ocean is 1, even though the current best estimate on the age of Europa’s ice is millions of years.
accepted this practice even though this methodology is inconsistent with normal NASA practices. NASA officials delayed unnecessarily in taking advantage of NASA’s established conflict resolution process.
Recommendation 3.2: NASA should assess the completeness of planetary protection policies and initiate a process to formally define the planetary protection requirements that are missing. NASA should ensure that all future headquarters planetary protection requirements imposed on spaceflight missions follow NASA standard project management and systems engineering protocols for review, approval, and flow-down of requirements and, when disagreements occur, ensure that NASA’s conflict resolution process is followed. For future new situations such as private-sector missions to other bodies or human exploration of Mars, the policies and their potential impacts should be evaluated and examined well in advance of a mission start.
As noted in the section “Overview of NASA’s Process for Developing Planetary Protection Policy” above, COSPAR can make a change to planetary protection guidance without the concurrence of relevant NASA stakeholders; something not done for other types of NASA internal policy and procedural directives. For example, the COSPAR Bureau approved changes in its planetary protection policy for Mars Special Regions (Appendix B) in March 2017.33 These changes originated as a result of discussions held at a COSPAR planetary protection colloquium held in September 2015.34 These changes had not been vetted by all affected NASA stakeholders. As examples, these changes modified COSPAR planetary protection guidance concerning human activities on Mars that had not been reviewed or concurred with by the NASA human spaceflight community.35 Moreover, there is additional language on required analyses of Mars landing site ellipses that was not vetted by the NASA organizations responsible for assessing landing sites. Notably, only 26 people, with 2 people representing NASA and 2 the Jet Propulsion Laboratory, attended this colloquium at which the new language was suggested. This small number of participants hardly represents the breadth of international or U.S. stakeholders. Once approved internationally, affected organizations in NASA will find it difficult to disagree with the proposed NASA updates to its internal policies. However, it could be argued that changes in COSPAR planetary protection guidelines proposed in September 2015 could have been vetted by NASA and international stakeholders in the 18 months leading up the March 2017 meeting of the COSPAR Bureau. Furthermore, changes to COSPAR’s policy with respect to Enceladus also were proposed during the same September 2015 colloquium and also were approved by the COSPAR Bureau at its meeting in March 2017.36
Finding: The COSPAR process can approve international guidance on planetary protection without such guidance being reviewed and agreed upon in advance by the range of NASA stakeholders that participate in making NASA policy on planetary protection.
Recommendation 3.3: NASA should ensure that in assessing changes to COSPAR planetary protection policies and requirements there is a process to engage the full breadth of NASA stakeholders, including the spaceflight mission and science communities. This process should be at least as disciplined as the process NASA uses to review, concur, and approve changes to its own policies.
33 G. Kminek, C. Conley, V. Hipkin, and H. Yano, COSPAR Planetary Protection Policy, Space Research Today, No. 200, December 2017, pp. 12-24.
34 G. Kminek, V.J. Hipkin, A.M. Anesio, J. Barengoltz, P.J. Boston, B.C. Clark, et al. Meeting Report: COSPAR Panel on Planetary Protection Colloquium, Bern, Switzerland, September 2015, Space Research Today, No. 195, pp. 42-51.
35 A reviewer informed the committee that “a representative of NASA human spaceflight” participated in the 2016 business meeting of COSPAR’s Panel on Planetary Protection at which the report of the September 2015 colloquium was discussed and the recommendation to change the COSPAR policy was formulated.
36 G. Kminek, C. Conley, V. Hipkin, and H. Yano, COSPAR Planetary Protection Policy, Space Research Today, No. 200, December 2017, pp. 12-24.
The OPP’s Move to OSMA
Based on the information NASA provided the committee on its decision to move the OPP to OSMA from SMD, the committee believes this change is well founded and can improve how NASA manages planetary protection policy. Under the former arrangement in which the OPP resided in SMD, there was an inherent conflict of interest because the dispute resolution official was directly responsible for science missions as well as planetary protection. As a part of OSMA, the OPP can function more like a NASA technical authority, and disagreements between the OPP and flight projects on planetary protection issues can be resolved through formal OSMA conflict resolution procedures that have worked well in other areas within OSMA’s purview.37
The OPP’s move to OSMA could also help alleviate staffing challenges the OPP has faced in the past. The small size of the OPP (typically no more than two NASA civil servants plus occasional consultants and contractors) is inadequate for the new challenges planetary protection policy faces. As a part of OSMA, the OPP can take advantage of OSMA’s practice of delegating verification activities to OSMA offices in NASA centers responsible for executing space missions. However, NASA has not completed the OPP’s transition to OSMA, and a number of issues remain unclear. For example, NASA officials could not yet tell the committee where the OPP’s research and technology function will be located in NASA and how it will operate.
Three pending developments will create a need for planetary protection policies that go beyond the demands of the past several decades:38
- A Mars sample return campaign and a mission to land and explore the ocean under the ice of Europa, both of which will include life detection objectives;
- Human spaceflight to Mars possibly in the late 2030s; and
- Potential Mars missions by space entrepreneurs, such as SpaceX.
Developing planetary protection policies that encompass these initiatives will require negotiations that cross international boundaries (possibly via COSPAR for international planetary protection policy), federal agency lines (e.g., with the Federal Aviation Administration for private-sector space missions and U.S. health and environmental agencies for sample returns), and multiple NASA directorates for human spaceflight and science. Such a breadth of responsibility may be better placed at the level of the NASA Administrator’s office, perhaps through the NASA Chief Scientist, rather than in OSMA or in any individual mission directorate.
Finding: NASA has not finalized all issues related to transferring the OPP from SMD to OSMA or revised its policy directives, procedural requirements, and advisory structure to reflect this important change.
Recommendation 3.4: NASA should expeditiously complete the transition of the OPP to OSMA and clarify the remaining issues concerning roles, responsibilities, resources, and locations of OPP functions. The Chief of the Office of Safety and Mission Assurance should complete the Science Mission Directorate’s move toward instituting a formal method for imposing planetary protection requirements that are in accordance with standard NASA systems engineering practices.
37 The transfer of the PPO from SMD is consistent with a prior National Academies recommendation concerning Mars sample return: “There is a critical need for . . . the office of NASA’s planetary protection officer to be formally situated within NASA in a way that will allow for the verification and certification of adherence to all planetary protection requirements. . . . Clear lines of accountability and authority at the appropriate levels with NASA should be established for . . . the planetary protection officer, in order to maintain accountability and avoid any conflict of interest with science and mission efforts.” For more details, see, NRC, Assessment of Planetary Protection Requirements for Mars Sample Return Missions, The National Academies Press, Washington, D.C., 2009, p. 69.
38 A fourth potential issue was raised by Lisa Pratt, NASA’s new planetary protection officer during a presentation to the SSB’s Committee on Astrobiology and Planetary Science on March 28, 2018. Dr. Pratt noted that CubeSats and other small spacecraft, whether flown singly or as adjuncts to traditional (large) missions, present new planetary protection concerns for ensuring that they are compliant with all necessary planetary protection requirements. Additional discussion of this topic is beyond the scope of the current study.
Recommendation 3.5: NASA should develop an agency-wide strategic plan for managing the planetary protection policy development challenges that sample return and human missions to Mars are creating.
An Independent Planetary Protection Advisory Committee
Throughout its history and across its missions, NASA has routinely solicited independent advice from formally constituted advisory bodies consisting of experts drawn from among national and international scientific and technical communities. The members of these advisory bodies are drawn, typically, from both within and outside of government, independent stakeholders, and representatives of other agencies with overlapping responsibilities, as well as, when appropriate, individuals with special expertise in space law, ethics, and public communication.
The OPP had long been advised by such a body encompassing all these components, owing to the breadth, potential impact, and likely broad public interest and concerns that planetary protection issues could engender. Over the past approximately two decades, this independent advisory apparatus operated originally as a Planetary Protection Advisory Committee (PPAC) of the NAC, and, more recently, as a subcommittee (PPS) of the NAC’s Science Committee.39 For a variety of reasons, the PPAC/PPS experienced occasional hiatuses in its authorization to meet or to appoint members. The PPS had not met for a year or more when, in late 2017, it was formally disbanded by NASA.
Agency officials have final authority in decision making, as well as final accountability for the outcomes of their decisions. Nonetheless, it has long been accepted that decision making is improved, both in the formulation of policies and the implementation of policies, if the issues are thoughtfully aired and analyzed by committed independent experts. Moreover, engaging independent experts drawn broadly from the involved communities, provides an effective mechanism to promote communication and understanding in both directions. And, ultimately, the scientific, technical, and space-industry communities will be more likely to accept and take ownership of decisions in which they—through representation—have a role in formulating and influencing final decisions.
In the past, at least post-Apollo, planetary protection has been centered mainly in the Science Mission Directorate and its predecessor organizations and focused on issues of forward contamination. In the few instances of returned-sample missions, the samples originated on bodies only remotely contemplated as having the possibility of deleteriously contaminating Earth.40 Thus, for those missions, backward contamination did not loom as large as might be the case going forward. For many missions currently contemplated, the stakes of contamination are higher in all dimensions, not only involving forward contamination, primarily a scientific concern, but also including dimensions that have the potential to engender significant public concerns, even alarm, around the possibility bringing extraterrestrial organisms to Earth.
Additionally, the potential stakeholders within NASA encompass a much larger range than heretofore of NASA mission directorates. At the same time, the cast of actors in deep space may be expanding to including nongovernmental entities. These factors, the committee argues, suggests that a planetary protection advisory group might most effectively be constituted at a level of the agency having broad, cross-cutting purview—perhaps at the Administrator or Chief Scientist level within NASA.
Finding: The development and implementation of planetary protection policy at NASA has benefited in the past from a formally constituted independent advisory process and body. As this report is written, both the advisory body and process are in a state of suspension.
Recommendation 3.6: NASA should reestablish an independent and appropriate advisory body and process to help guide formulation and implementation of planetary protection adequate to serve the best interests of the public, the NASA program, and the variety of new entrants that may become active
39 During the period 2012-2015, the PPS provided advice to NASA regarding the need to develop planetary protection requirements for human exploration missions, assess planetary protection lessons learned from the MSL mission, develop bioburden accounting software for future Mars sample return missions, and establish interactions between the OPP and OSMA.
40 The Genesis mission collected samples of the solar wind and the Stardust mission collected particles from the tail of a comet.
in deep space operations in the years ahead. The advisory body and process should involve a formal Federal Advisory Committe Act committee and interagency coordination, as well as ad hoc advisory committees, if and as circumstances dictate. This advisory apparatus should be situated and engage within NASA at a level commensurate with the broad cross-cutting scope of its purview and the potentially broad interests that the involved issues may engender.
The roles of the advisory body include the following:
- Serve as a sounding board and source of input to assist in development of planetary protection requirements for new missions and U.S. input to the deliberations of COSPAR’s Panel on Planetary Protection;
- Provide advice on opportunities, needs, and priorities for investments in planetary protection research and technology development; and
- Act as a peer review forum to facilitate the effectiveness of NASA’s planetary protection activities.
Capturing Scientific Advances in the Development of Planetary Protection Policy
The science that underpins planetary protection policies has always involved some uncertainty and debate about the basis for estimates of likelihood of viable organisms on a spacecraft or on a solar system body. Many factors that influenced forward contamination mitigation strategies in the late 1950s and early 1960s, such as estimates of the allowable bioburden on or the probabilities of contamination of a spacecraft, used statistical estimates that were sometimes little more than educated guesses.41,42,43 These approaches were adopted well before the genome era of microbiology.
With a relatively limited budget (see next section below), NASA’s OPP has funded research to begin to apply new advances in biotechnology and approaches to bioload reduction to planetary protection procedures. Work on the former has led to acceptance of certain biochemical assay techniques on a case-by-case basis, namely ATP (adenosine triphosphate) and LAL (limulus amebocyte lysate) assays, as supplements to the so-called NASA Standard Assay.44 Additionally, molecular techniques have been adapted to inventory the microbial burden in clean rooms and on spaceflight hardware45 and used during spacecraft assembly campaigns and on the International Space Station.46
With respect to approaches to bioload reduction beyond the standard dry-heat, microbial reduction used for the Viking spacecraft, NASA has certified the use of hydrogen peroxide vapor as a means to sterilize exposed surfaces. However this technique does not impact organisms within enclosed volumes or encapsulated in other materials. Other techniques that have been used at the subsystem or component level by NASA and other space agencies include the following:47
- Autoclaving for tubing and cleanroom materials
- Gamma radiation for the sterilization of the parachute for the Beagle-2 Mars lander
- Low-temperature hydrogen peroxide plasma for the batteries and electronic assemblies of the Beagle-2 Mars lander
41 C. Sagan and S. Coleman, Spacecraft sterilization standards and contamination of Mars, Journal of Astronautics and Aeronautics 3(5):22-27, 1965.
42 C. Sagan and S. Coleman, “Decontamination Standards for Martian Exploration Programs,” pp. 470-481 in NRC, Biology and the Exploration of Mars, National Academy of Sciences, Washington, D.C., 1966.
43 S. Schalkowski and R.C. Kline, Jr., “Analytical Basis for Planetary Quarantine,” pp. 9-26, in L.B. Hall (ed.), Planetary Quarantine, Gordon and Breach, London, U.K., 1971.
45 M.T. La Duc, K. Venkateswaran, and C.A. Conley, A genetic inventory of spacecraft and associated surfaces, Astrobiology 14:15-23, 2014
46 Lang et al., A microbial survey of the International Space Station (ISS), PeerJ 5:e4029; doi:10.7717/peerj.4029, 2017.
The communities now involved in modern biological sciences are exploding with more new discoveries—for example, about extremophiles, biofilms, prions, and genomics—that are likely to be relevant to planetary protection science. For example, genome sequencing of environmental samples (e.g., permafrost, sand, and feces) has made a dramatic change in how life is detected now on Earth.48 Modern genomic analysis of extreme environments on Earth generates detailed lists of which particular bacterial species and which particular genes are necessary to thrive in the terrestrial environments that are the closest analogues to Mars or icy bodies, such as polar or desert desiccated environments or frozen oceans, etc. The organisms that thrive on human skin or the soles of shoes of spacecraft assembly technicians are not the same organisms found in Antarctic oceans, dry valleys, or in the stratosphere that are the closest analogues to the environments where Mars or icy satellite landers would explore. The organisms from spacecraft cleanrooms would not be predicted to grow and reproduce on Mars or icy bodies. Consequently, rather than treating every bacterial species as a potential growing pathogen for Mars and elsewhere, a more nuanced view about which microbes to avoid bringing to Mars or icy bodies might be to specify the particular microbes that are found in the particular Earth regions most like landing sites on Mars or icy bodies, and to survey spacecraft assembly rooms for those particular organisms.49,50 If developments such as these prove feasible, they could have profound impacts on the way planetary protection is implemented in the future. For example, information about the abundances of microbes with known environmental tolerances might permit credit to be taken for environmental exposure, when implementing a probabilistic approach for missions to the outer planets.
The science of planetary protection will need to keep pace with the latest advances in biological science and technology.51 However, the field is relatively narrow—a niche field—compared to the extraordinarily broad field of biology in which it resides. Based on data supplied to the committee by NASA’s OPP, there are a few dozen very active participants in recent COSPAR planetary protection science meetings.52 Meeting organizers have had mixed success at recruiting microbiologists to participate in meetings where new scientific findings are considered for their implications for planetary protection policy. For example, scientists affiliated with the NASA Astrobiology Institute, which have been active in studies relating to extremophile microbes on Earth and what sorts of biochemistry they use and on origin of life, have not been substantially represented in such meetings. Practical considerations—for example, availability of support for travel to COSPAR meetings, especially those outside the United States—are a major reason for the limited participation in planetary protection workshops and colloquia.
There are several reasons that planetary protection science has attracted only a small minority of scientists. First, until recent years with expanding ambitions for Mars missions and new plans for missions to the icy moons of Jupiter or Saturn, there have been few solar system exploration missions that would require little more than the most basic planetary protection procedures. Second, planetary protection is an operational activity that does not naturally attract scientists who are more interested in pushing the frontiers of their fields. There have also been difficulties in translating latest technologies from the bench into workable procedures that enable NASA to effectively render planetary protection requirements.
These factors may help explain the difficulty in engaging forefront researchers in translating new advances into planetary protection practice, but they do not reduce the need. Studies, workshops, and brainstorming sessions organized by NASA, other space agencies (e.g., ESA and JAXA), the SSB, and COSPAR to advise planetary protection policy makers need to reach out internationally to a sufficiently broad range of microbiologists (e.g., including molecular genomic scientists). Furthermore, astrobiologists who explore diverse types of life on Earth are best qualified to advise on which organisms are likely to grow on Mars or icy bodies and, thus, require surveillance on spacecraft and which do not require surveillance. While most attention to date has been directed
48 For example, there are 4500 references in PubMed with keywords “metagenomic” and “environmental sample.”
49 See, for example, F. Abreu, A. Carolina, V. Araujo, P. Leão, K.T. Silva, F.M. Carvalho, O.L. Cunha, et al., Culture-independent characterization of novel psychrophilic magnetotactic cocci from Antarctic marine sediments, Environmental Microbiology 18:4426-4441, 2016.
50 See, for example, Y.M. Shtarkman, Z.A. Koçer, R. Edgar, R.S. Veerapaneni, T. D’Elia P.F. Morris, and S.O. Rogers, Subglacial Lake Vostok (Antarctica) accretion ice contains a diverse set of sequences from aquatic, marine and sediment-inhabiting bacteria and eukarya, PLoS One, 2013, https://doi.org/10.1371/journal.pone.0067221.
51 While biology is an important field for planetary protection, many other areas are also important. For example, recent research on recurring slope lineae on Mars illustrates the relevance of geology and hydrology to planetary protection science.
toward studies of so-called terran life (i.e., life as we know it), it is not too soon to begin to begin to identify issues relevant to non-terran life, if it exists.53 Exploration of the diversity or organisms, terran and non-terran would be an area of interest and assessment by the new planetary protection research manager and an appropriate role for the NASA Astrobiology Institute.
Finding: The field of planetary protection science fills a rather small sector of modern science, and it has not been able to engage a substantial number of scientists who have been leading in important areas of modern sciences. For example, while the field of biology has made enormous advances in recent years many of those advances that could be applicable to improving approaches to planetary protection have not yet been fully integrated into the development of planetary protection policy or translated into practical approaches to implement policies.
Recommendation 3.7: NASA should engage the full range of relevant scientific disciplines in the formulation of its planetary protection policies. This requires that scientific leaders outside of the standard planetary protection community in NASA participate in revisions to NASA and COSPAR planetary protection policies and requirements.
Research and Technology Development for Planetary Protection
As NASA transfers the OPP to OSMA, a new planetary protection research manager, working separately from the PPO, will provide strategic guidance on research and technology needs. This role, as described in the NASA Decision Memorandum, is to “focus on tools and techniques for the avoidance of organic-constituent and biological contamination in NASA’s current and future human and robotic exploration missions.”54 The details of how the new research manager will coordinate with the mission directorates regarding planning and funding are still being developed at NASA.
The OPP’s total budget has remained approximately constant at some $2 million to $2.5 million per year since 2006 (see Appendix D). Of the total, approximately one-half is devoted to principal investigator–initiated, peer-reviewed research awarded via the Planetary Protection Research program, a component of NASA’s Research Opportunities in Space and Earth Sciences (ROSES) activity. The remainder funds directed research in support of specific programmatic needs, contractor support, and the day-to-day operations of the OPP.
NASA uses its annual ROSES solicitation to request proposals for planetary protection research. The objective of solicited research is to improve NASA’s understanding of the potential for both forward and backward contamination, how to minimize it, and to set standards in these areas for spacecraft preparation and operating procedures. Improvements in technologies and methods for evaluating the potential for life in returned samples are also of interest. Many of these research areas derive directly from recent SSB recommendations on planetary protection. As a complement to the ROSES Exobiology program, the Planetary Protection Research program solicits research in laboratory simulations and Earth analogs of planetary environments, modeling planetary environmental conditions and transport processes, modern molecular analytical methods, and new or improved methods, technologies, and procedures for spacecraft sterilization.
During the last 10 years (2006 to 2017), NASA has only funded planetary protection research proposals submitted via ROSES in 7 of those years: 2006 (four funded), 2007 (six funded), 2008 (two funded), 2010 (one funded), 2011 (five funded), 2012 (one funded), and 2014 (four funded and three partially funded). See Appendix D for a list of funded projects. In 2015 it appears no proposals were selected. These proposals are generally funded at a level of $300,000 to $500,000 and can take up to 4 years to complete. Given the scope of issues facing planetary protection, such a modest investment would appear to be far less than optimal. However, even after leveraging
53 For a more complete discussion of non-terran life see, for example, NRC, The Limits of Organic Life in Planetary Systems, The National Academies Press, Washington, D.C., 2007.
54 Agency Program Management Council Decision Memorandum, “Planetary Protection Authority Transition,” May 17, 2017, approved May 22, 2017.
research conducted under NASA’s larger Astrobiology program, the limited Planetary Protection Research funding level noted above has been inadequate to support a critical-mass number projects in any planetary protection research area.
NASA has used the SSB to perform specialized studies, for specific scientific areas of planetary protection interest and organize topical workshops to explore a variety of planetary protection issues. Many of the recent reports from the SSB and NASA’s advisory groups have included recommendations for research that is necessary to advance planetary protection’s ability to understand and verify potential biological contamination. The 2012 report on icy solar system bodies contained eight specific research recommendations;55 the 2015 Joint European Science Foundation/NAS Review of the Mars Exploration Program Analysis Group’s (MEPAG’s) Report on Special Regions had 17 specific recommendations;56 and the MEPAG report, itself, had 14 recommendations.57 Many of these recommendations have not yet been acted upon. Discussions with the NASA PPO suggest that funding has just not been available to support all of this recommended research. As a result of these shortcomings, the missions have been forced to conduct their own planetary protection research, construct their own models, and carry out their own analyses. Mars 2020 is but one example where the project used advanced computational methods to evaluate contamination. This budget-driven outcome has resulted in the project offices possibly being better informed on mission-specific planetary protection issues than the OPP itself.
As discussed in the previous section, the Planetary Protection Research program has been slow to take advantage of the recent significant advances in fields such as genomics. Research results have the potential to reduce the overall cost of planetary protection, and the committee believes that increasing research funding is a very good return on investment.
According to a presentation from the Aerospace Corporation,58 the costs of planetary protection are about 10 percent of total mission costs. Then for a total budget for NASA exploration programs of a few billion dollars, the cost of planetary protection will be about a few hundred million dollars. NRC studies have recommended that at least 10 percent of a program cost be invested in advanced research and technology.59 Thus, it could be argued that an agency budget for planetary protection research would be a few tens of millions of dollars.
Finding: NASA has not adequately funded the research necessary to advance approaches to implementing planetary protection protocols and verifying that those protocols satisfy NASA’s increasingly complex planetary protection requirements. For an agency program of solar system exploration and planning for human exploration missions, costing several billion dollars per year, an investment in relevant planetary protection research and technology of less than one-tenth of one percent of that total seems inadequate.
Recommendation 3.8: NASA should adequately fund both the Office of Planetary Protection and the research necessary to determine appropriate requirements for planetary bodies and to enable state-of-the-art planetary protection techniques for monitoring and verifying compliance with these requirements. The appropriate investment in this area should be based on a strategic assessment of the scientific advances and technology needs to implement planetary protection for likely future missions.
55 NRC, Planetary Protection Requirements for Spacecraft Missions to Icy Solar System Bodies, The National Academies Press, Washington, D.C., 2012, pp. 55-58.
56 NASEM and the European Science Foundation, Review of the MEPAG Report on Mars Special Regions, The National Academies Press, Washington, D.C., 2015, pp. 45-47.
57 J.D. Rummel, D.W. Beaty, M.A. Jones, C. Bakermans, et al., A new analysis of Mars “Special Regions”: Findings of the Second MEPAG Special Regions Science Analysis Group (SR-SAG2), Astrobiology 14:887-968, 2014.
58 D. Bearden and E. Mahr, “Cost of Planetary Protection Implementation,” presentation to the committee, June 28, 2017, http://sites.nationalacademies.org/cs/groups/ssbsite/documents/webpage/ssb_180771.pdf.
59 NRC, An Enabling Foundation for NASA’s Earth and Space Science Missions, The National Academies Press, Washington, D.C., 2010.
Comparing the ESA and NASA Planetary Protection Policy Process
The committee’s charge does not include an assessment of the ESA planetary protection policy development process, but it is helpful to consider whether aspects of the ESA process offer useful lessons for NASA. ESA’s fundamental objectives for planetary protection, the vesting of authority for the policy at the top level of the agency, the policy’s ties to compliance with the OST, and the linkage to COSPAR guidelines are all similar to NASA’s. ESA’s PPO resides in the Product Assurance and Safety (PA&S) Department, which is a technical authority, and thus the organizational arrangement is much like NASA’s placement of its OPP in OSMA. That arrangement reduces organizational conflicts of interest at ESA by separating lines of responsibility for formulating policy, establishing requirements, and implementing requirements. ESA uses an independent Planetary Protection Working Group, with members from outside ESA selected for their specific expertise, to provide advice and recommendations to support the head of PA&S. This arrangement seems similar to NASA’s Planetary Protection Advisory Subcommittee, although the latter has been disbanded.
There appears to be a notable difference in how NASA and ESA delegate execution of policy and requirements to individual flight missions. At ESA, individual mission project managers are responsible for identifying the planetary protection requirements specific to their projects and defining the planetary protection implementation and management approach for their missions. The extent of that delegation at NASA appears to fall short of that at ESA. Finally, ESA’s PPO performs inspections and reviews to ensure compliance with planetary protection requirements, just as at NASA, but the project manager appears to have more discretion in implementing recommendations from the reviews than is the case at NASA.60
Finding: ESA’s planetary protection process reduces organizational conflicts of interest by separating lines of responsibility for formulating policy, establishing requirements, and implementing requirements and by giving more authority to mission project managers to translate top-level requirements into implementation approaches.
Recommendation 3.9: NASA should evaluate the ESA process for planetary protection implementation and strongly consider incorporating the elements of that process that are effective and appropriate.
Defining the length of time over which a solar system body needs to be protected from contamination in order to permit unimpaired biological study—that is, the period of biological exploration—has been a difficult issue throughout the history of planetary protection policy. Several definitions of the term have been used. In the late 1960s, the period of biological exploration was set initially at 20 years, based on the optimistic assumption that in that time 100 flight missions to planets of biological interest would have been conducted successfully.61 Another definition referred to the time required to establish whether or not a planet has indigenous life and, if so, to characterize it.62 The 20-year time span was used again as the likely time required to answer the questions about life on a planet. During this period, unsterilized spacecraft would be prohibited from impacting a planetary body. This gave rise to the minimum orbital lifetime requirement. When it became obvious that the pace of exploration was far slower than originally imagined, the period of biological exploration was reevaluated on an individual-planet basis. For Mars, it became 50 years after the launch of a given spacecraft so that the end of the period moves forward indefinitely as long as spacecraft are headed to the Red Planet.
For the icy moons of Jupiter and Saturn, the timeframe is not clear. NASA’s PPO promulgated requirements on NASA missions, including Europa Clipper, which established the time to be infinite. However, an infinite
60 Examples of the separation of the roles of policy formulation and implementation/enforcement can be found in many U.S. governmental agencies. The U.S. Department of Agriculture, for example, sets meat and poultry-handling safety standards which are overseen and enforced by the Food Safety and Inspection Service.
61 COSPAR, COSPAR Decision No. 16, COSPAR Information Bulletin No. 50, July 1968, pp. 15-16.
62 NRC, Preventing the Forward Contamination of Mars, The National Academies Press, Washington, D.C., 2006.
period is not representative of the current scientific consensus. For example, the 2012 SSB report Assessment of Planetary Protection Requirements for Spacecraft Missions to Icy Solar System Bodies recommended a period of 1,000 years.63
A period of biological exploration has important legal as well as scientific implications. It involves the OST’s prohibition against national appropriation on a celestial body by means of claim, use, occupation, or any other means.64 To prevent having a period of biological exploration being construed as appropriation, there would need to be, at the very least, a clear relationship between the length of a period of biological exploration and its scientific objectives, as well as identification of a definite date by which the period will end.65
Finding: As the exploration of the icy moons rises in priority and plans for piloted missions to Mars emerge, it is necessary to reevaluate and clarify the period of biological exploration.
Recommendation 3.10: Given the implications with respect to the Outer Space Treaty, NASA and COSPAR should facilitate development of an international strategy for establishing periods of biological exploration. Such a strategy should ensure that individual nation states are all using the same values. Specification of this period is vital to the calculations of probability of contaminating a potential habitat on another world.
63 NRC, Assessment of Planetary Protection Requirements for Spacecraft Missions to Icy Solar System Bodies, The National Academies Press, Washington, D.C., 2012.
64 Outer Space Treaty, Article II.
65 A resolution of appropriate period of biological exploration will have the effect of establishing sunset clauses for planetary protection at bodies where non-scientific missions may occur in the future.