The Planetary Protection Independent Review Board (PPIRB) report1 includes 34 major or supporting findings and 43 major or supporting recommendations. This chapter reviews those findings and recommendations for their consistency with the 2018 report of the National Academies of Sciences, Engineering, and Medicine, Review and Assessment of Planetary Protection Policy Development Processes2 (hereinafter the “2018 report”). The PPIRB report organized its findings and recommendations into seven categories. The first category, “General/Overarching,” includes 15 findings and 19 recommendations. The section includes items regarding the changing context of planetary protection, development of planetary protection requirements, and compliance enforcement, among others.
The PPIRB organized its remaining findings and recommendations in the following six categories:
- Planetary protection categorization,
- Human spaceflight,
- Private sector initiatives and missions,
- Robotic Mars sample return,
- Ocean Worlds exploration, and
- Committee on Space Research (COSPAR).
In the sections below, the committee presents the PPIRB’s findings and recommendations in italics, followed by the committee’s analysis of those conclusions. For ease of reference, the committee has assigned sequential numbers to the PPIRB’s findings and recommendations (see Appendix C), which appear in square brackets in this report. In keeping with its statement of task, the committee reviewed whether the PPIRB’s findings and recommendations are consistent with the 2018 report. In cases where the PPIRB report considered issues not addressed in
1 Planetary Protection Independent Review Board (PPIRB), NASA Planetary Protection Independent Review Board (PPIRB): Report to NASA/SMD: Final Report, NASA, Washington, D.C., 2019, https://www.nasa.gov/sites/default/files/atoms/files/planetary_protection_board_report_20191018.pdf.
2 See National Academies of Sciences, Engineering, and Medicine (NASEM), Review and Assessment of Planetary Protection Policy Development Processes, The National Academies Press, Washington, D.C., 2018.
the 2018 report, the committee drew on other reports from the National Academies, briefings to the committee, or other publicly available information to assess consistency with the content of the 2018 report or determine whether the committee agrees with the PPIRB’s conclusions. Because many of the PPIRB’s findings and recommendations came with no supporting information or explanation that provided insight into how the board reached its conclusions or worded its statements, the committee based its review as much as possible on reasonable interpretations of the PPIRB’s findings and recommendations.
The PPIRB’s first seven findings and recommendations consider the advent of new types of private-sector missions, the evolution of the scope of planetary protection policy, scientific and technological advancements, and the need for independent, outside advice to NASA on planetary protection issues.
Major Finding: With the advent of private sector robotic and human planetary missions, as well as new ultralowcost (e.g., CubeSatclass) planetary missions, the context in which PP is conducted is profoundly and rapidly changing. 
Major Finding: For planetary missions involving locations of high astrobiological potential, it is essential that forward and backward contamination consideration be integral to mission implementation. This applies to both government and private sector missions. 
Supporting Finding: The PPIRB did not assess planetary exploration historical site preservation or the implications of the human modification of celestial bodies in the Solar System, for example, for resource recovery. 
The PPIRB and 2018 reports are fundamentally in agreement on these issues. However, the 2018 report noted that planetary protection policy does not involve “significant actions beyond documentation and inventory of organic materials for the vast majority of ongoing and planned private-sector space activities,”3 with the possible exception of potential private-sector missions to Mars (see below).
Supporting Finding: The scope of Planetary Protection landscape is complex, broad, nuanced, sometimes politically charged. The PPIRB could only evaluate it at a top level in the time and resources allocated for our review. 
The statement of task for the 2018 study mandated that the report examine all aspects of planetary protection policy development—from policy formulation to the policy implications of implementing planetary protection requirements. The committee responsible for the 2018 report had sufficient time to complete this top-to-bottom study of planetary protection policy development processes.
Major Recommendation: Because of advances in knowledge and technologies since the Viking era, NASA’s PP [planetary protection] policies and implementation procedures should be reassessed.4 
Major Recommendation: Owing to the changing PP context and the rapid advancement of scientific, technological, and private sector planetary mission capabilities, NASA should reassess its PP guidelines at least twice per decade with an IRBlike body that includes representatives of all major stakeholder communities. 
3 See NASEM, 2018, p. 86.
4 Some PPIRB findings and recommendation are accompanied by brief supporting text. For the sake of conciseness, the committee has not reproduced the supporting text for those items.
Major Recommendation: NASA should establish a standing forum for the discussion and resolution of emergent PP issues that includes input from government, private sector, and perhaps even nonU.S. private sector enterprises. 
These three major recommendations are consistent with recommendations in the 2018 report, with one possible exception. The PPIRB’s Major Recommendation  appears to envision a forum that would be involved in the “resolution” of issues. The committee understands that “resolution” can have different meanings, but it notes that final disposition of policy questions or disputes is a government responsibility. More centrally, both reports emphasize the need for planetary protection efforts to reassess continually and, where appropriate, utilize new scientific and technological advances. In particular, the 2018 report included five relevant recommendations, as follows:
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.
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 in deep space operations in the years ahead.
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.
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.
Recommendation 4.3: The SSB and NASA should pursue new mechanisms to anticipate emerging issues in planetary protection, respond more rapidly, and address new dimensions such as private-sector missions and human exploration.
The PPIRB report has one major finding and one major recommendation that focus on the NASA Office of Planetary Protection (OPP):5
Major Finding: The PPIRB applauds SMD’s [Science Mission Directorate’s] and OSMA’s [Office of Safety and Mission Assurance’s] recent revamping of the PPO and the work of the new PP Officer, which has increased communication, clarity, and responsiveness to community needs and concerns. 
Major Recommendation: NASA should establish explicit processes such as an ongoing process of independent review to ensure that PPO policies and procedures are consistently applied regardless of specific PPO personnel. 
The 2018 and PPIRB reports are consistent in supporting both the OPP’s move from NASA’s Science Mission Directorate (SMD) to the Office of Safety and Mission Assurance (OSMA) and the need that missions have for
5 The PPIRB report uses “PPO” for Planetary Protection Office. However, the organization’s correct title is Office of Planetary Protection (OPP). This report and NASEM, 2018, use the latter terminology and reserve “PPO” as the acronym for the planetary protection officer. In practice, OPP and PPO are virtually synonymous.
consistency in the application of planetary protection policy, requirements, and processes. Two recommendations in the 2018 report addressed these points explicitly:
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.
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 in deep space exploration in the years ahead.
Both reports agree that planetary protection policy should apply equally to governmental and private-sector space activities. The PPIRB report contains six findings or recommendations regarding the clarity and timeliness of the development and implementation of planetary protection requirements. With respect to clarity, the report states as follows:
Major Finding: There is a general lack of clarity concerning PP requirements and implementation processes, particularly for nonNASA missions; this impedes the development of private sector planetary exploration. 
The PPIRB and 2018 reports are consistent in recognizing a lack of clarity in the planetary protection requirements and implementation processes for non-NASA, private-sector missions. Indeed, the 2018 report identified a critical need for the federal government to clarify where legal and regulatory authority rests for overseeing planetary protection issues implicated by private-sector space activities that have no NASA participation. This “regulatory gap” is discussed in detail later in this chapter.
Major Recommendation: NASA should clarify its policy for exercising PP authority over primarily nonNASA space activities that have some level of NASA involvement. 
The 2018 report did not analyze how NASA implements its planetary protection policies concerning non-NASA space activities that involve some NASA participation. However, the policy is clear. For space activities that NASA sponsors or that utilize NASA resources, NASA requires all aspects of those activities—whether undertaken by a foreign government or a private-sector entity—to comply with NASA’s planetary protection requirements. In fact, NASA’s documents state the formal policy in NPD8020.12D (section 2.2.2):
NASA shall provide hardware, services, data, funding, and other resources to non-NASA missions (including but not limited to resources provided through international agreements, contracts, Space Act agreements, grants, and cooperative agreements) only if the recipient organization(s), whether governmental or private entity, demonstrate adherence to appropriate policies, regulations, and laws regarding planetary protection that are generally consistent with the COSPAR Planetary Protection Policy and Guidelines.
The committee—and both reports—agree that planetary protection policy be clear.
Major Recommendation: To further encourage the development of private sector planetary activities, NASA should offer a greater degree of PP expertise and tools to new and emerging actors in planetary exploration. 
The 2018 report did not discuss whether NASA could support possible new entrants into the exploration and use of space, but the committee agrees that such NASA support would be appropriate. Having NASA share
planetary protection expertise and tools with private-sector entities would be similar to NASA’s traditional role in working with the private sector in aeronautics.
The PPIRB report offers one major finding and two recommendations about the importance of timely completion of planetary protection requirements.
Major Finding: The late addition of PP requirements to some projects has been costly and inefficient to implement. 
Major Recommendation: To reduce project inefficiencies, PP requirements should be finalized early in mission formulation and should avoid past practices of adding new or unexpected PP requirements, including in categorization letters. 
Major Recommendation: PP requirements on missions should be written to define PP intent, rather than detailed implementation methods, thereby allowing projects to select and/or develop implementations most suitable to meet their PP requirements from a systems standpoint. 
This finding and these recommendations are consistent with the 2018 report, which included two relevant findings and a recommendation:
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 (2018 report, p. 58).
Finding: The NASA Office of Planetary Protection and the mission project teams have not been following standard NASA spaceflight program and project management and systems engineering practices. In particular the PPO has been issuing level-1 requirements informally through letters, email, and verbal direction, and the project teams have 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 (2018 report, pp. 58-59).
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…. 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.
The 2018 report made clear its view that it is more appropriate to define planetary protection requirements by their intended goal and not by specific implementation methods in its discussion of the European Space Agency’s (ESA’s) approach to planetary protection. That discussion concluded with a finding and recommendation for an approach very similar to that advocated for in the PPIRB’s major recommendation :
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 (2018 report, p. 66)
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.
The PPIRB report includes one finding and recommendation regarding NASA’s legal authority over nongovernmental missions:
Major Finding: Although NASA is not a regulatory agency, the Agency can likely affect control over nonNASA U.S. missions by linking PP compliance to eligibility for current or future NASA business or NASA support. However, overreaching application of such control could result in reduced opportunities for collaboration with private sector missions. 
Supporting Recommendation: Policy regarding such application of Agency authority to affect PP implementation should be carefully reviewed above the PPO level. 
The 2018 report also noted that NASA is not a regulatory agency, but that the agency uses contracts or other formal agreements to require non-NASA missions that involve NASA participation or use NASA resources to follow NASA’s planetary protection requirements. When requested, NASA advises the Federal Aviation Administration (FAA) on planetary protection when the latter conducts payload reviews of proposed launches of non-NASA missions (e.g., as happened with Moon Express, SpaceX, and SpaceIL missions). However, the 2018 report did not discuss whether NASA could make private-sector compliance with NASA planetary protection policy for missions not involving NASA participation a condition for NASA to enter into future contracts and agreements with such entities.
The “General/Overarching” section of the PPIRB report presents one finding and one recommendation pertaining to COSPAR. The finding states:
Supporting Finding: COSPAR PP guidelines have evolved to be an internationally recognized, voluntary standard for protection of scientific interests in celestial bodies. Adherence to the COSPAR guidelines has been considered an acceptable mechanism for establishing a State party’s compliance with the harmful contamination aspects in Article IX of the OST [Outer Space Treaty]. Adherence to COSPAR PP guidelines have constituted one type of mechanism for establishing compliance with Article IX, but this is not the only such compliance mechanism; other mechanisms that may be more appropriate also exist. 
The 2018 report also found that, while COSPAR guidelines are not legally binding, they have become widely recognized international standards used by all spacefaring countries to guide compliance with Article IX of the Outer Space Treaty (OST):
Finding: For five decades, the states parties to the Outer Space Treaty have used COSPAR policy as part of complying with their planetary protection obligations under the treaty and, thus, have made COSPAR interdependent with their respective national rules, institutions, and processes on planetary protection.
Finding: All spacefaring nations, including new entrants to space exploration, have declared they will comply with COSPAR guidance on planetary protection. Such commitment highlights the importance of the COSPAR planetary policy development process to the behavior of spacefaring nations, including state party efforts to comply with their planetary policy obligations in the Outer Space Treaty.
The 2018 report identified no international mechanism other than COSPAR that states parties to the OST have used, or proposed to use, for guiding compliance with Article IX.
This history raises questions about what the PPIRB meant when it claimed in Supporting Finding  that “more appropriate” mechanisms “also exist” for “establishing compliance with Article IX.” In response to questions from the committee, the chair of the PPIRB stated that, in formulating Supporting Finding , the PPIRB had in mind the UN Committee on the Peaceful Uses of Outer Space (COPUOS), which connects to the PPIRB’s recommendation on this issue:
Supporting Recommendation: Whenever updating U.S. PP policy and implementation practices, the U.S. government should work with the United Nations (UN) Committee on the Peaceful Uses of Outer Space (COPUOS) to communicate new U.S. PP approaches to the international community, share best practices, and encourage the international community to address such issues. 
The combination of Supporting Finding  and Supporting Recommendation  suggests that the PPIRB is advising the U.S. government to transition its involvement in international cooperation on planetary protection from COSPAR to COPUOS.
Such an approach is not consistent with the 2018 report, which focused on improving COSPAR as the international forum for cooperation on planetary protection policy.6 The approach also departs from how the U.S. government has engaged in international cooperation on planetary protection policy development in the 50 years since the adoption of the OST.
As the 2018 report described, the practice of the U.S. government has involved NASA, with input from the Space Studies Board of the National Academies, developing new planetary protection approaches and taking those approaches, and the supporting scientific information, to COSPAR for international cooperation involving other countries and the scientific communities involved in planetary protection. COPUOS has not been directly involved in planetary protection issues since the late 1950s. In 2017, COPUOS itself identified “COSPAR as the appropriate international authority for creating consensus planetary protection guidelines.”7 The 2018 report observed that “COSPAR and COPUOS have discussed” the possibility of a “closer relationship” between COSPAR and the United Nations but “concluded that it was not appropriate at this time.”8 The PPIRB report contained no information or explanation for why the board believed that COPUOS was a more appropriate international forum for cooperation on planetary protection than COSPAR. Nor does it explain advantages accruing from bringing planetary protection issues within the scope of COPUOS activities.
As mentioned in Chapter 1 of this report and discussed in the 2018 report, COSPAR has reorganized its Panel on Planetary Protection (PPP) in order to make it more effective in developing policies that reflect the changing complexion of planetary exploration.9 The PPP’s most recent terms of reference state that these policies “should be based upon the principle that COSPAR planetary protection policies should enable the exploration and use of the solar system, not prohibit it. It is not the purpose of the Panel to specify the means by which adherence to the COSPAR planetary protection policy is achieved; the best and most cost effective means to adhere to the COSPAR planetary protection requirements is reserved to the engineering judgment of the organization responsible for the planetary mission.”10
After Supporting Finding  on COSPAR, the first section of the PPIRB report turns to three findings and three recommendations addressing the scientific basis of planetary protection requirements. The findings are as follows:
Supporting Finding: For many of NASA’s scientifically driven planetary exploration missions to astrobiologically relevant targets, scientific cleanliness requirements often exceed PP bioburden requirements. 
Supporting Finding: Anachronistic, and sometimes unrealistic, PP requirements (e.g., delivery of <1 viable organism to Europan liquid water for Europa Clipper) have driven a great deal of costly and sometimes questionable effort, often involving requirements or implementation waivers. 
Supporting Finding: The PPIRB applauds and encourages flexible ways to address PP intent using novel methods. 
6 See NASEM, 2018, pp. 72-76 and 89.
7 See NASEM, 2018, p. 42.
8 See NASEM, 2018, p. 76.
9 See NASEM, 2018, pp. 73-76.
10 COSPAR Planetary Protection Panel Terms of Reference approved by the COSPR Bureau, March 21, 2019. Available at https://cosparhq.cnes.fr/scientific-structure/panels/panel-on-planetary-protection-ppp.
The 2018 report did not discuss whether mission science requirements are often more stringent than planetary protection bioburden requirements. That is, are there situations in which the biological or organic cleanliness requirements for a scientific instrument to meet its performance objectives are more demanding than the requirements for planetary protection? The PPIRB report does not cite any examples of such cases, but the committee is aware that such cases have happened and may occur again.11
The two reports are consistent in that both identify cases in which planetary protection requirements that have been levied on missions are unrealistically demanding and costly, and that evidence-based openness to flexibility and innovation in implementing planetary protection requirements is desirable in preventing such situations from causing delays and unneeded mission costs.
Three recommendations in this section of the PPIRB report build on the idea of being open to new techniques and approaches for meeting both forward and back contamination objectives:
Supporting Recommendation: The PPO should exploit new discoveries and new technologies to better categorize exploration targets, create better forward and backward PP implementation protocols, and lower PP cost and schedule impacts on projects. 
Supporting Recommendation: For forward contamination, NASA PP policy should move beyond exclusive adherence to spore counts, which is an outdated legacy of the 1970s Viking era. PP policy should encourage the use of proven modern techniques and wellestablished genomic tools for monitoring and characterization of bioburden of cleanroom facilities and flight hardware. NASA should also encourage the broader use of probabilistic models of the risk of “harmful” forward contamination based on likely scenarios and acceptable risk outcomes. 
Supporting Recommendation: For both forward and backward contamination requirements, NASA should continue to allow novel approaches, such as crediting for time spent in the harsh space environment or on harsh planetary surfaces (e.g., UV, radiation, temperature extremes, lack of liquid water). To enable this, NASA should support quantitative laboratory studies of such approaches to demonstrate quantitative PP credits. 
All three recommendations are consistent with the 2018 report, which recommended that NASA recognize relevant advances in biotechnology and engage the broader scientific community in capitalizing on those developments:
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.12
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.”
11 For an example in the case of the Mars 2020 mission, see NASEM, 2018, p. 50. A better example is the very stringent organic (and associated bioburden) requirements levied on the OSIRIS REx asteroid sample-return mission to satisfy the scientific objectives of measuring organic compounds on a pristine, but abiotic, body.
12 See NASEM, 2018, p. 64.
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.
Both reports addressed the need for clear requirements that are developed through a participative process and communicated clearly to mission teams. The PPIRB report recommended the following:
Supporting Recommendation: NASA’s PP requirements should be completely specified in NASA Procedural Requirements (NPRs)/NASA Policy Directives (NPDs) so that projects subject to NASA PP requirements know what to expect and can better plan in advance to a known, fixed set of project requirements. 
Supporting Recommendation: The PPO should implement both welldocumented and transparent PP requirements and requirements waiver processes for all missions with NASA involvement. 
Supporting Recommendation: NASA should provide external stakeholders with clear information and better insight and outreach on its PP standards and processes. This should include a rollout plan for new PP processes, followed by regular stakeholder engagement opportunities to ensure widespread awareness and understanding of PP standards and processes. 
The related recommendations in the 2018 report similarly emphasized the importance of broad stakeholder engagement in developing and communicating planetary protection policies and requirements:
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. … 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.
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 in deep space exploration in the years ahead.
The PPIRB report devotes one finding and recommendation to concerns about streamlining planetary protection measures for ultra-low-cost missions, as follows:
Supporting Finding: Without further changes to streamline lowcost mission PP implementation, ultralowcost planetary missions (e.g., CubeSats) will likely have a PP implementation cost burden that is a larger percentage of their total budget than larger missions, which in turn could threaten their low cost, particularly for those missions beyond PP Category II. 
Supporting Recommendation: NASA should assess how to streamline PP implementation for ultralowcost planetary missions. 
The 2018 report did not address ultra-low-cost missions, and, therefore, the two reports are not directly comparable on this issue. Subsequent to publication of the 2018 report, interest in small, low-cost planetary mission
concepts (e.g., SmallSats and CubeSats) has increased.13 For example, SmallSat concepts comprise a significant portion of responses to a recent call for future flight mission ideas from the Mars science community.14 The committee addresses the issues of small, low-cost missions below in the section on categorization and again in Chapter 3.
However, the committee notes, first, that providing basic spacecraft information, such as a master equipment list, is required to obtain NASA or FAA launch approval and would suffice for planetary protection purposes for most missions, especially for Category I missions, and possibly for Category II missions (see Appendix E). Thus, only missions to Mars and the icy moons of Jupiter and Saturn (and, by extension, the other ocean worlds) may have substantial planetary requirements that would add unique efforts or costs.
Second, the committee emphasizes that all missions are required to respect planetary protection objectives by ensuring space activities take into account the cost of implementing applicable planetary protection measures. Finally, the committee notes that, as a general rule, all missions can benefit from approaches designed to streamline implementation of planetary protection measures and minimize their costs.
The PPIRB report has findings and recommendations regarding enforcement of reporting requirements and contractual requirements for planetary protection. The finding and associated recommendation addressing enforcement state:
Supporting Finding: It is impractical for launch providers or satellite hosts to definitively determine the biological content of every payload. Biological materials intentionally added by a bad actor are especially challenging for launch providers to monitor or report, as they can be further obscured by falsified verification or inaccurate documentation. 
Supporting Recommendation: Breaches of PP reporting or other requirements should be handled via sanctions that hold the root perpetrator accountable, rather than increasing the verification and regulatory burden on all actors. 
This finding and recommendation arise from PPIRB’s evaluation of the rule-breaking incident associated with the Beresheet mission. Built by SpaceIL,15 an Israeli nonprofit organization, and launched by SpaceX, this commercial lunar lander carried a variety of payloads, including a laser retroreflector experiment supplied by NASA via an agreement with the Israeli Space Agency.16 Unbeknownst to SpaceIL, SpaceX, or NASA (which also provided tracking and communications support), another payload aboard Beresheet contained undisclosed organisms and, possibly, other biological materials.17 As such, this was a clear case of a payload owner not providing the launch operator or NASA with full information about the payload’s biological content. This incident happened after publication of the 2018 report, so that report contained no discussion of the issues the incident generated.
The committee addresses the implications of the SpaceIL incident in Chapter 3, because the incident connects to persistent questions about the legal authority and rules applicable to private-sector space activities conducted with or without NASA participation that implicate planetary protection.
Supporting Finding: Space Act Agreements and some NASA contracts require NASA 8020.12 PP compliance, which in turn invokes COSPAR policy/guidelines. 
13 For background information concerning CubeSats and SmallSats, see, for example, https://www.nasa.gov/content/what-are-smallsatsand-cubesats.
17 C.D. Johnson, D. Porras, C.M Hearsey, and S. O’Sullivan, “The Curious Case of the Transgressing Tardigrades (Part 1),” The Space Review, August 26, 2019; and C.D. Johnson, D. Porras, C.M Hearsey, S. O’Sullivan, and M. Vidauri, “The Curious Case of the Transgressing Tardigrades (Part 2),” The Space Review, September 3, 2019. Both available at https://www.thespacereview.com.
Supporting Recommendation: These contractual requirements should be reviewed by NASA to simplify compliance where possible and to avoid overconstraining the means of meeting NASA intent. 
The 2018 report mentioned that NASA includes its planetary protection requirements in contracts or agreements with non-NASA entities for missions that involve NASA participation or that use NASA resources. NASA planetary protection requirements in NPD (NASA Policy Directive) 8020.12 are consistent with COSPAR guidelines, and, as noted above, all spacefaring nations use COSPAR guidelines in their efforts to comply with Article IX of the OST. Given that NASA participates in the activities under such contracts or agreements, NASA complies with its planetary protection requirements in activities the agency undertakes. It would not be appropriate for such contracts or agreements to permit private-sector entities to work under less rigorous planetary protection requirements or processes than would NASA personnel. However, the 2018 report did not analyze whether Space Act agreements or NASA contracts that include requirements for compliance with NASA planetary protection requirements (1) impose unnecessary burdens on private-sector entities working with NASA or (2) could include simplified means of planetary protection compliance for space companies.
The PPIRB report has one finding and four recommendations specific to the categorization of missions to the Moon, Mars, or small solar system bodies for planetary protection purposes. The finding states:
Major Finding: As more is learned about each celestial body, more detailed and tailored approaches to forward contamination become advisable. These include variable categorization based on surface/subsurface location, where and how many times past missions have investigated the body, and the survivability and propagation of terrestrial organisms in the body’s environments. 
The 2018 report similarly concluded that more scientific information is needed to inform future approaches to planetary protection. The 2018 report described how planetary protection policy has, in fact, changed significantly over time in light of new scientific information about solar system bodies.
However, the PPIRB report perpetuates confusion about planetary protection terminology. The report suggests that much of the Moon can be re-defined as Category I, while areas of Mars may be reassigned to Category II (see Appendix E). However, in planetary protection policy, missions are categorized and not planetary bodies and their surfaces. NASA OPP typically reviews a mission’s objectives and provides the mission with a categorization letter, and the assigned category determines the planetary protection requirements for the mission.
As scientific understanding progresses, certain missions to the Moon, Mars, ocean worlds, and small bodies could receive a categorization that imposes fewer planetary protection requirements. The space exploration community is moving away from treating planets and other solar system bodies as monoliths and toward viewing them potentially as entities with diverse areas of interest for different purposes.18 This evolution of mission categorization would benefit not only the traditional planetary science community but also private-sector activities and human-exploration missions. Indeed, the question of mission categorization is a cross-cutting topic that touches on the affordability of entrepreneurial space missions as well as the feasibility of human “exploration zones.” The committee believes that the proper way to address a categorization decision is to evaluate the science or other objectives for visiting a given area and thus assigning whichever mission category may be appropriate.
The PPIRB report makes a specific recommendation concerning the planetary protection categorization of lunar missions:
18 See, for example, NASEM, 2018, pp. 79-81.
Major Recommendation: NASA should study how much of the Moon’s surface and subsurface could be designated PP Category I versus Category II. Establishing different categories for different locations on the Moon could significantly simplify and enhance exploration opportunities for both the civil and private sectors. 
The 2018 report did not address whether NASA could study how many missions to the Moon could be designated Category I rather than Category II (see Appendix E). However, the Moon has been called a “witness plate” of near-Earth impact history over the last 4 billion years or more. The record of meteoritic and cometary strikes since the Moon was formed comprise an important piece of planetary evolution that has been lost or severely eroded on Earth. What this historical record reveals has direct bearing on understanding the astrobiology of the early Earth, the rise of life after the period of heavy bombardment, and the possibility that certain permanently shadowed regions may retain a record of volatile materials, including water ice, from billions of years of meteoritic and cometary impacts. Subsequent to the discovery of water ice in permanently shadowed regions of the Moon, NASA OPP has classified lunar missions to be Category II.
The differences between Category I and Category II would appear to be minimal for any experienced space hardware developer. Category I missions require no planetary protection documentation, and Category II missions require only brief documentation and an inventory of organic compounds in excess of 1 kg for lunar missions.19 In the case of fleets of CubeSats, NASA’s current requirement is for an inventory of organics in excess of 10 g per element. NASA OPP has developed a single-page organic inventory template to reduce the workload for lunar CubeSat teams.20 Therefore, the lunar Category II requirement does not, at first blush, seem onerous. As a practical matter, even a student-led CubeSat mission will have a so-called master equipment list and a simple project plan that would satisfy or nearly satisfy the Category II requirements. However, the committee believes that a more rigorous scientific evaluation of the appropriate number for the organic inventory for CubeSats is required (see Chapter 3).
However, according to the OPP,21 planetary protection policy includes requirements associated with trajectory calculations and landing-site analyses for impacts, pre-launch and post-launch assessments, and the like. During the committee’s first meeting, the PPO described the burden faced by small satellite entrepreneurs and academics when required to demonstrate at some level of statistical confidence that a spacecraft would not inadvertently impact an object, such as Mars. The committee foresees that under certain circumstances, a secondary SmallSat payload developer might not have the budgetary capability to conduct all required pre- and post-launch analyses. In addition, the PPIRB chair stated to the committee that the PPIRB sensed that there might be some irreducible cost for meeting planetary protection measures that even the smallest and simplest spacecraft would have to bear.
In the time available, the committee could not verify whether planetary protection requirements impose such a minimum cost and, therefore, suggests that the OPP undertake a study to see if such a cost exists and, if so, at what level. NASA’s own Commercial Lunar Payload Services program may afford an opportunity to evaluate this question.22 As a possible solution to be considered for the small spacecraft community, the committee notes that NASA, through the OPP, might provide some analytic support for trajectory calculations and impact analyses. The committee will return to the need for further study of both appropriate guidelines for organic inventories and planetary protection costs for small spacecraft missions in Chapter 3.
19 See, “Guidelines on the implementation of an organic inventory” in G. Kminek, C. Conley, V. Hipkin, H. Yano, “COSPAR’s Planetary Protection Policy,” Space Research Today, Number 200, December 2017, https://cosparhq.cnes.fr/assets/uploads/2019/12/PPPolicyDecember-2017.pdf.
20 Private communication from J. Andy Spry to G. Scott Hubbard, January 8, 2020. The current organic inventory threshold for NASA’s Artemis program is 1 kg, but for 13 individual CubeSats carried as secondary payloads on Artemis 1, “the inventorying is at the 10 gram level of fidelity, to allow for meaningful aggregation into the Artemis system totals.”
21 See, for example, the OPP website, https://sma.nasa.gov/sma-disciplines/planetary-protection.
22 For more information about NASA’s Commercial Lunar Payload Services program see, for example, https://www.nasa.gov/content/commercial-lunar-payload-services.
At the other end of the size-and-cost spectrum, current U.S. government initiatives, such as the Artemis program, contemplate human missions to the surface of the Moon for “long-term exploration and utilization.”23 Such missions could produce scientific and commercial activities on the lunar surface that include mining regolith for in situ resource utilization (ISRU). In these circumstances, providing an inventory of organics greater than 1 kg will be essentially impossible given the presence of humans and the widespread civil engineering machinery required. Such an effort would justify Category I requirements for lander missions to regions of interest, provided such regions had been previously explored and evaluated for their scientific value.
Therefore, the committee concurs with the PPIRB that action on the part of NASA and the lunar science community is required to study the possibility that some lunar lander missions could be subject to Category I requirements. For example, a properly constituted expert group, such as the NASA Lunar Exploration Analysis Group or the SSB Committee on Astrobiology and Planetary Science, could review the data from Apollo as well as more recent missions (e.g., Lunar Prospector, Lunar Reconnaissance Orbiter, and LCROSS) to determine whether the contemplated regions are sufficiently well explored and documented so that activities such as a human landing base or ISRU would not burden future science.
Furthermore, the lunar science community needs to know whether remote sensing measurements of the presence of approximately 30 percent (by weight) water ice in certain shadowed regions on the Moon are correct. Previous studies have considered how a mission to examine these ice deposits could be executed.24 Any such endeavor contacting the lunar surface will remain at least a Category II mission until the organic and chemical composition is known and the astrobiological implications are assessed, before ultimately determining whether the resources might be declared available for ISRU.
Finally, the incident involving SpaceIL’s Beresheet lunar lander has drawn widespread attention to the organic inventory currently required for a Category II mission. However, if missions intended to land anywhere in large areas of the Moon could receive a Category I, spacecraft such as Beresheet would have a logical destination where the payload was of no consequence.
The PPIRB report makes two recommendations and offers one finding concerning the planetary protection categorization of Mars missions:
Major Recommendation: NASA should reconsider how much of the Martian surface and subsurface could be Category II versus IV by revisiting assumptions and performing new analysis of transport, survival and amplification in order to reassess the risk of survival and propagation of terrestrial biota on Mars. 
Major Recommendation: NASA should consider establishing (i) high priority astrobiology zones, i.e., regions considered to be of high scientific priority for identifying extinct or extant life, and (ii) human exploration zones, i.e., regions where the larger amounts of biological contamination inevitably associated with human exploration missions, as compared to robotic scientific missions, will be acceptable. 
23 Executive Office of the President, “Presidential Memorandum on Reinvigorating America’s Human Space Exploration Program,” The White House, Washington, D.C., December 11, 2017, https://www.whitehouse.gov/presidential-actions/presidential-memorandumreinvigorating-americas-human-space-exploration-program.
24 See, for example, NASEM, Vision and Voyages for Planetary Science in the Decade 20132022, The National Academies Press, Washington, D.C., 2011, pp. 359-360. See also, https://www.nasa.gov/feature/new-viper-lunar-rover-to-map-water-ice-on-the-moon.
Supporting Finding: Various scientific studies25suggest that the survival and amplification of terrestrial biota are unlikely on the Martian surface, which would support classification of much of the Martian surface as Category II. 
As the 2018 report discussed, the exploration of Mars presents a far more complex planetary protection challenge than the Moon. Mars has a thin atmosphere, at least 44 distinct geologic units,26 significant amounts of water ice distributed at a variety of latitudes, possible liquid water aquifers below the surface, complex organics, and unexplained methane releases. As such, Mars is a very complex world containing multiple environments that could potentially harbor evidence of extinct or extant life.
Categorization of Mars missions as either III, IV, or restricted sample return V (see Appendix E) is grounded in scientific data collected over the past 50 years, but particularly in the last 20 years of the “follow the water” Mars Exploration Program. Now, however, Mars is an attractive object for not only scientific exploration but also commercial space ventures and human exploration.
The 2018 report noted that commercial interests want to minimize uncertainty and expense and that human exploration faces particular planetary protection challenges. That report did not recommend moving some missions (i.e., Mars landers) to Category II, but it did recommend that “NASA’s process for developing a human Mars exploration policy should include examination of alternative planetary protection scenarios and should have access to the necessary research that informs these alternatives.”27
Human explorers can never be cleaned like robotic spacecraft, and space suits and human habitats will leak or may have catastrophic blowouts. To accommodate the competing interests of robotic science and human exploration missions, so-called “exploration zones” have been proposed. Both the human exploration and science communities have participated in initial workshops in recent years to identify potential exploration zones.28
The research citations noted in the PPIRB report (see Supporting Finding ) are an interesting, albeit inconclusive, addition to the discussion of what constitutes a so-called “Special Region” or an exploration zone. The current state of research does not yet appear to be adequate to determine whether there are regions on Mars where human explorers or commercial missions might land with minimal planetary protection implications.
Through information obtained from past and future Mars missions and complementary research, some regions may have sufficiently low risk of forward or back contamination so that a lander would only be required to follow the current Category II requirements. Human exploration mission planners require access to the necessary research that informs the categorization of missions to Mars.29
The committee agrees with the PPIRB report concerning the need for more research to provide a basis for a more flexible approach to mission categorization for Mars. In that regard, the committee emphasizes in particular the suggestions in the 2018 report that research concerning Mars is needed to address the following questions:30
25 A.A. Pavlov, G. Vasilyev, V.M. Ostryakov, A.K. Pavlov, and P. Mahaffy, 2012, Degradation of the organic molecules in the shallow subsurface of Mars due to irradiation by cosmic rays, Geophysical Research Letters 39(13); C.L. Khodadad, G.M. Wong, L.M. James, P.J. Thakrar, M.A. Lane, J.A. Catechis, and D.J. Smith, 2017, Stratosphere conditions inactivate bacterial endospores from a Mars spacecraft assembly facility, Astrobiology 17(4):337-350; R.F. Shotwell, L.E. Hays, D.W. Beaty, Y. Goreva, T.L. Kieft, M.T. Mellon, G. Moridis, L.D. Peterson, and N. Spycher, 2019, The potential for an off nominal landing of a multimission radioisotope thermoelectric generator-powered spacecraft on Mars to induce an artificial special region, Astrobiology (in press) 19(11), DOI: 10.1089/ast.2017.1688; J.D. Rummel, D.W. Beaty, M.A. Jones, C. Bakermans, N.G. Barlow, P.J. Boston, V.F. Chevrier, et al., 2014, A new analysis of Mars “special regions”: Findings of the second MEPAG Special Regions Science Analysis Group (SR-SAG2), Astrobiology 14(11):887-968.
26 K.L. Tanaka, J.A. Skinner Jr., J.M. Dohm, R.P. Irwin III, E.J. Kolb, et al., Geologic Map of Mars, Scientific Investigations Map 3292, U.S. Geological Survey, Flagstaff, Ariz., 2014.
27 See NASEM, 2018, Recommendation 5.1.
28 See, for example, https://www.nasa.gov/journeytomars/mars-exploration-zones.
29 See NASEM, 2018, Recommendation 5.1.
30 See NASEM, 2018, pp. 83-84.
- Because some releases of gases, dust, or other emissions from a human landing site or base are inevitable, how far would such contamination travel in the very thin atmosphere of Mars? Would it be diluted extensively and/or sterilized before reaching the science region of interest?
- If a human habitat on Mars were to suffer a catastrophic blowout event and release microbes from the astronauts, how far would the contamination travel and what effect could it have on the scientific exploration regions?
- Using the current knowledge of Mars and modern biological expertise, is there credible evidence that any terrestrial microbes would survive in the harsh radiation and dry, oxidizing conditions on the surface of Mars?
- To what extent might modern genomic techniques be applied to assessing contamination and possibly even eliminate the need for some contamination control requirements?
Previous OPP and COSPAR planning documents have recommended research on these topics, but such studies have not yet been funded.31 Answers to these and related questions would advance the needs of future science, commercial activities, and human exploration.
The PPIRB report makes one recommendation and offers one finding concerning the planetary protection categorization of missions to small bodies in the solar system:
Supporting Recommendation: In cases of missions to Solar System destinations where there is a large population of similar Category I and II objects (e.g., comets, asteroids, Kuiper Belt Objects), NASA should allow classification of individual objects as Category I to simplify missions to them. 
The PPIRB report makes a population argument for classifying missions to some small bodies as Category I:
[J]ust as the lunar and Martian surfaces in their entirety do not need to bear the same planetary protection classification, in the case of small bodies where there are numerous potential targets, the contamination of any individual does not cause significant contamination to the class as a whole. If chemical evolution or origin of life experiments are planned for such objects, there are myriad to choose from that will not have been previously visited by robotic probes.
Most missions to such small bodies fall under Category II, and some asteroid missions are already assigned to Category I. As with the Moon, a small mission might not be able to satisfy the trajectory and launch analyses required to obtain a Category II designation. However, a planetary protection advisory committee could survey the small bodies’ community and assess whether the population argument in the PPIRB report holds across the solar system. That is, are there enough similar asteroids and comets with prebiotic composition such that, if one is contaminated, significant scientific knowledge is not lost?
31 See, for example: M.S. Race, J.E. Johnson, J.A. Spry, B. Siegel, and C.A. Conley (eds.), Planetary Protection Knowledge Gaps for Human Extraterrestrial Missions—Final Report, DAA_TN36403, NASA Human Exploration and Operations Mission Directorate and NASA Planetary Protection Office, Washington, D.C., 2015; G. Kminek, B.C. Clark, C.A. Conley, M.A. Jones, M. Patel, M.S. Race, M.A. Rucker, O. Santolik, B. Siegel, and J.A. Spry (eds.), Report of the COSPAR Workshop on Refining Planetary Protection Requirements for Human Missions, NASA Science Mission Directorate and Human Exploration and Operations Mission Directorate, Washington, D.C., 2016; and M.S. Race, J.A. Spry, B. Siegel, C.A. Conley, and G. Kminek (eds.), Final Report of the Second COSPAR Workshop on Refining Planetary Protection Requirements for Human Missions and COSPAR Work Meeting on Developing Payload Requirements Addressing PP Gaps on Natural Transport of Contamination on Mars, COSPAR, Paris, France, 2019. All three documents are available at https://sma.nasa.gov/sma-disciplines/planetary-protection.
The PPIRB report has much to say about human missions to Mars that is consistent with the 2018 report. The first major PPIRB finding on human spaceflight states:
Major Finding: Human missions to Mars will create new opportunities for science and exploration. 
Previous studies of the U.S. human spaceflight program, such as the Augustine report, noted that “science can be enhanced by human exploration, particularly of complex environments, and by providing the ability to service scientific facilities in space.”32 The decadal survey for solar system exploration added, “On the basis of the importance of questions relating to life, the committee concluded that for the more distant future, human explorers with robotic assistance may contribute more to the scientific exploration of Mars than they can to any other body in the solar system.”33
Eight PPIRB findings and recommendations then deal with the immaturity of planetary protection policy for human exploration and the need to develop the policy expeditiously. Those findings and recommendations address forward contamination, crew return and back contamination, national policy, and communications with the public, as follows:
Major Finding: PP planning for human missions to Mars and the communication of those plans to the public are presently immature. 
Major Recommendation: NASA should expeditiously develop PP guidelines for human missions to Mars, whether those missions are conducted by NASA, other international agencies, or private entities. 
Major Recommendation: NASA should begin planning for the public communication of all aspects of PP planning for human missions to Mars sooner rather than later, and should pay special attention to public PP concerns, similarly to NASA’s proactive treatment of NASA missions involving radioisotope power systems. 
Major Finding: Human missions to Mars will inevitably introduce orders of magnitude more terrestrial microorganisms to Mars than robotic missions have done or will do. 
Major Finding: NASA’s current policies for robotic Category V Restricted Earth Return from Mars appear to be unachievable for human missions returning from Mars. 
Major Recommendation: Regarding the return of humans and equipment from Mars, NASA should invest in developing more informed, backward contamination PP criteria, considering protection of Earth’s biosphere, the feasibility of mission implementation, and the potential for in situ hazard characterization on Mars. 
Supporting Recommendation: In considering crew return from Mars, NASA should assess the acceptability of the multimonth return trajectory as a PP quarantine and evaluation period, potentially simplifying terrestrial quarantine scenarios, requirements, and timescales. 
32 Review of U.S. Human Spaceflight Plans Committee [a.k.a. Augustine report], Seeking a Human Spaceflight Program Worthy of a Great Nation, Office of Science and Technology Policy, Washington, D.C., 2009, https://www.nasa.gov/pdf/396093main_HSF_Cmte_FinalReport.pdf, p. 78.
33 NASEM, Vision and Voyages for Planetary Science in the Decade 20132022, The National Academies Press, Washington, D.C., 2011, pp. 56-63.
Supporting Recommendation: NASA should review COSPAR’s humans to Mars principles and guidelines to assess which should be followed, discarded, or updated for NASA’s first human Mars expedition. 
Both the PPIRB and 2018 reports generally agree on these topics. However, a previous National Academies’ report has questioned the utility of the suggestion of using long-return flights to mitigate back-contamination concerns, as suggested in Supporting Recommendation .34 Moreover, return flight times may not always be long, given appropriate technological advances. The 2018 report noted that neither NASA nor COSPAR has developed policies that deal with planetary protection for human exploration of Mars and that current “principles and guidelines may be impossible in any practical manner for human missions” and that “[t]he planetary protection challenges generated by human missions to Mars will require policy makers to adapt existing approaches and develop new strategies.”35
The committee reiterates a point in the 2018 report that scientific studies are especially needed to provide a basis for:36
- Establishing exploration zones (perhaps through an international process) where humans are allowed to explore;
- Setting requirements for human missions that are relaxed from current COSPAR standards based on realistic engineering considerations and the outcome of the research and technologies studies addressing specific items in COSPAR policy; and
- Delineating, through international agreement, areas of scientific interest that human missions cannot access and ensure that these zones have sufficient buffers to protect the scientific endeavors from human contamination until scientific studies are completed.
The scientific issues that underpin decisions about how to organize areas of Mars for future robotic and human exploration constitute a strategic need for the next phase of planetary protection policy to which the committee returns in Chapter 3.
The 2018 report did not address communications with the public about potential public concerns over human missions to Mars.37 However, the 2018 report did note that the formal interagency review process by which the U.S. government reviews and approves space activities that could potentially have large-scale adverse environmental effects on Earth was established through a presidential directive issued in 1977.38 The 2018 report found that this directive is out of date and recommended that it be revisited “in light of NASA plans for Mars sample-return missions and human-crewed missions to Mars and revise or replace its provisions for engaging relevant federal agencies in developing back-contamination protection policies.”39
The PPIRB report also recommends paying more attention to how to conduct astrobiological studies in the presence of human activities:
Major Recommendation: Special attention should be paid to assess how astrobiological research can be carried out in the presence of human activities. 
34 National Research Council, Scientific Prerequisites for the Human Exploration of Space, National Academy Press, Washington, D.C., 1993, pp. 30-31.
35 See NASEM, 2018, p. 79.
36 See NASEM, 2018, p. 83.
37 See PPIRB, 2019 .
38 The White House, “Scientific or Technical Experiments with Possible Large-Scale Adverse Environmental Effects and Launch of Nuclear Systems into Space,” Presidential Directive NSC-25, December 14, 1977. Available at https://fas.org/irp/offdocs/pd/pd25.pdf.
39 See NASEM, 2018, Recommendation 3.1.
40 See NASEM, 2018, p. 83.
41 See NASEM, 2018, p. 92.
As noted in the discussion below of future studies, this approach assumes exploration activities can protect large parts of Mars for scientific study and that contamination from the human habitats will not expand into these other regions of interest.
The feasibility and limitations of a policy that allows for protected science zones or unprotected human exploration zones depend on the extent to which contaminants can be transported across Mars. After many decades of intensive scientific Mars exploration, the only known truly global phenomena are dust storms. … it is conceivable that some release of contaminants might be (or might have been in the past) carried a significant distance by those dust storms.
As noted earlier in the committee’s discussion of categorizing missions to Mars, important studies are required to address questions of atmospheric transport of contaminants, the survivability of terrestrial microbes on the surface of Mars, and the utility of modern genomic techniques for monitoring contamination control.
Finally, PPIRB Major Recommendation  and Supporting Finding  deal with related topics. In text accompanying Major Recommendation , the PPIRB report says Mars sample return “policies should take into consideration current understanding of the ongoing natural transport of material from Mars to Earth since the formation of the planets ~4.5 billion years ago.”
Scientists have identified more than 220 meteorites on Earth that are believed to have originated on Mars because of their unique isotopic signatures and the presence of trapped gases matching those found in the martian atmosphere but not in Earth’s. Analyses of such objects have led to claims of the detection of organic compounds and even controversial claims concerning the presence of ancient martian “microfossils.”42 While the case for the presence of organic compounds of martian origin have stood the test of time, meteorite experts and astrobiologists now discount the findings about microfossils as contamination from impact on Earth, misinterpretation of surface morphology, and inorganic processes. In any event, the Mars meteorites on Earth have no identifiable context because their region of origin on Mars is unknown. This fact limits the scientific utility of such objects. Further, the rocks have been altered by being subject to unknown and extreme conditions as they traveled from Mars to Earth. While one cannot discount all possibilities, the notion that life on Earth was “seeded” from Mars is speculative and does not eliminate the need to exercise due care and diligence when handling samples brought back to Earth taken from formerly habitable areas on Mars.
Regarding forward contamination of Mars, the PPIRB report provides the following finding:
Supporting Finding: Terrestrial biology has been transported to Mars by previous robotic missions at discrete locations, although at low levels as compared to what is likely on future crewed and crewrelated missions. The impact that these already transported organisms have had on any global Mars ecosystem is unknown but is likely to be minimal. 
The PPIRB and 2018 reports are not comparable on the issue considered in Supporting Finding . The 2018 report did not address what impact the transport of terrestrial organisms to Mars by robotic missions has had on the martian ecosystem. Spacecraft since the dawn of planetary exploration have been cleaned according to the standards in place at the time. The overarching concept was that, even with a crash landing, the chance that an Earth organism would be released on Mars was less than 1/10,000. As the 2018 report described, the history of the U.S. space program is one of diligence and, in the case of the Viking missions to Mars, significant expenditure to assure planetary protection integrity.
The 2018 report also documented what is known about other spacecraft that have landed or crashed on the Red Planet. Although available records indicate that the Soviets followed planetary protection guidelines in their missions to Mars,43 no process to verify Soviet claims of compliance existed. Thus, “dirtier” spacecraft could have created some contamination. Indeed, several studies cited in the PPIRB report indicate that normal Earth organisms
42 D.S. McKay, E.K. Gibson Jr., K.L. Thomas-Keprta, H. Vali, C.S. Romanek, et al., Search for past life on Mars: Possible relic biogenic activity in Martian Meteorite ALH84001, Science 273:924-930, 1996.
43 See NASEM, 2018, pp. 28-31.
would not survive for any significant length of time on the martian surface.44 However, as described above, the type of studies, experiments, and analysis recommended for human exploration will help answer questions about the transport and survival of Earth organisms on Mars.
This section of the PPIRB report includes eight findings and recommendations,45 beginning with a statement about expanding private-industry interests in planetary missions:
Major Finding: In addition to NASA’s worldleading civil space exploration capabilities, the United States now has a vibrant, highly capable private space sector. Through rapid innovation and cuttingedge technology, this space sector is expanding access to space for both private and government users, unleashing new robotic and crewed exploration opportunities in the Solar System. 
The 2018 report also noted “the emergence of private-sector interest in new types of space activities,” which fall within what is variously called “space entrepreneurship” and “new space,” and added:46
These new activities include delivering crew and cargo to the International Space Station, launching and operating remote sensing technologies, plans for asteroid mining, interest in space tourism, transport to the lunar surface, and missions to Mars. The only ‘new space’ areas that implicate serious planetary protection concerns are missions to Mars.
Thus, both the PPIRB and 2018 reports recognize the importance for planetary protection policy of the entry of private industry into planetary exploration and other uses of space. Private-sector interest in missions to the Moon and Mars, including human missions, has developed over the last decade and has become more pressing as companies pursue such missions. Lunar and martian missions planned or proposed by private-sector entities underscore the needs to undertake the following:
- Involve space companies in planetary protection policy discussions;
- Consider private-sector interests that go beyond science; and
- Clarify the legal and regulatory framework for private-sector space missions that do not involve NASA participation or use NASA resources.
In terms of the legal and regulatory framework, the PPIRB report stated:
Major Finding: Through existing authorization mechanisms under current Federal regulatory frameworks, the U.S. Government licenses the launch and reentry of private space vehicles, including those for beyond Earth orbit activities. Regarding PP, these licensing mechanisms could be improved to relieve administrative burdens and address misperceptions of legal uncertainty for private sector space activities, including private sector robotic and human planetary missions that do not have significant NASA involvement. 
By contrast, the 2018 report found that the legal problems facing planetary protection in connection with private-sector space activities having no NASA involvement went beyond “misperceptions of legal uncertainty” about federal “regulatory frameworks.” The 2018 report noted that the FAA questioned whether its legal authority
44 See PPIRB report Supporting Finding  and associated citations.
45 A number of the PPIRB report’s other findings and recommendations are also relevant to private sector missions, specifically, the following findings or recommendations: [1, 6, 7, 10-12, 16, 17, 25, 27, 30, 31, 33]. In developing policy for private-sector actors, the combined set of findings and recommendations from the PPIRB report should be considered.
46 See NASEM, 2018, p. 85.
to approve launches and review launch payloads encompassed the ability to regulate planetary protection issues. The 2018 report also observed that:47
No federal regulatory agency has the jurisdiction to authorize and continually supervise on-orbit activities undertaken by private-sector entities, including activities that could raise planetary protection issues. The committee heard from numerous experts that this regulatory gap is a serious problem in U.S. space law.
However, the PPIRB report also included a recommendation that more closely tracked the conclusions of the 2018 report on legal and regulatory issues:
Supporting Recommendation: For space activities without significant NASA involvement (including private sector robotic and human planetary missions), NASA should work with the Administration, the Congress, and private sector space stakeholders to identify the appropriate U.S. Government agency to implement a PP regulatory framework. 
The 2018 report raised similar points:48
Finding: A regulatory gap exists in U.S. federal law and poses a problem for U.S. compliance with the OST’s obligations on planetary protection with regard to private sector enterprises. The OST requires states parties, including the United States, to authorize and continually supervise nongovernmental entities, including private sector enterprises, for any space activity that implicates the treaty, including its planetary protection requirements.
Recommendation 6.2: Congress should address the regulatory gap by promulgating legislation that grants jurisdiction to an appropriate federal regulatory agency to authorize and supervise private-sector space activities that raise planetary protection issues. The legislation should also ensure that the authority granted be exercised in a way that is based upon the most relevant scientific information and best practices on planetary protection.
The persistence of uncertainty concerning, questions about, and problems with the legal and regulatory framework that applies to private-sector space activities not involving NASA participation elevates this issue as a strategic need for the next phase of planetary protection policy. The committee returns to this issue in Chapter 3.
The PPIRB report also recommends minimizing costs and burdens of planetary protection on private-sector activities:
Major Recommendation: PP–related authorization and supervision across the U.S. government should be implemented in a transparent, timely, and predictable manner, minimizing costs and burdens on private sector activities where possible. 
The 2018 report’s focus on legal issues arose, in part, from the uncertainty, transparency problems, and potential delays and additional costs that lack of clarity about federal regulation of private-sector activities for planetary protection purposes can create. The 2018 report emphasized the importance for all space missions that planetary protection requirements be set early and implemented according to established project management and engineering protocols. The 2018 report also stressed that appropriate planetary protection policies apply equally to relevant government-sponsored and private-sector space missions.
Thus, the two reports are consistent in stressing that the federal legal power to authorize and continually supervise nongovernmental entities for planetary protection purposes be exercised in a clear and transparent manner and in ways that permit timely, predictable, and cost-efficient outcomes.
Two PPIRB report recommendations recognize that different players have diverse objectives for planetary missions and that national space policy supports both scientific exploration and commercial uses of space:
47 See NASEM, 2018, pp. 86-87.
48 See NASEM, 2018, Recommendation 6.2.
Major Recommendation: In addition to balancing the needs of science and exploration, PP policy should also recognize that it is both a NASA and a national objective to encourage private sector space initiatives and commercial robotic and human planetary missions. 
Major Recommendation: Regarding PP, NASA should work in support of the Administration’s efforts, and as appropriate with the Congress and private sector stakeholders, to enable private sector space initiatives that do not have significant NASA involvement. 
The 2018 report does not have comparable conclusions, but the report is not inconsistent with the PPIRB’s recommendations. The 2018 report underscored that the purpose of planetary protection policy is “to enable, not inhibit, space exploration and the search for life.”49 The committee adds that the space community need not think of having to balance planetary protection and various mission objectives as if they were competing aims. Rather, the aim is to devise ways to permit exploration and other uses of space to go forward in light of planetary protection rationales.
The PPIRB report identified the growing importance of private-sector interest in space activities and the planetary protection implications of that interest:
Supporting Finding: Several private space companies are rapidly advancing technologies and plans for robotic and human planetary missions, including plans to land cargo and humans on the surface of the Moon and Mars. These developments provide important considerations for updating NASA and other U.S. government PP policy. 
Supporting Recommendation: The U.S. should continue to encourage international PP forums to include private sector stakeholder participation. 
Similarly, the 2018 report concluded that engaging the private sector in discussions and advisory activities regarding formulation and implementation of planetary protection policy was needed:50
Finding: To date, planetary protection policy development at national and international levels has not involved significant participation from the private sector. The lack of private sector participation creates potential challenges for policy development, because private-sector actors need to be able to understand and embrace appropriate planetary protection measures.
Recommendation 6.3: NASA should ensure that its policy-development processes, including new mechanisms (e.g., a revitalized external advisory committee focused on planetary protection), make appropriate efforts to take into account the views of the private sector in the development of planetary protection policy. NASA should support the efforts of COSPAR officials to increase private-sector participation in the COSPAR process on planetary protection.
In the international context, the 2018 report highlighted efforts that COSPAR officials are making to increase the participation of the private sector in the organization’s planetary protection processes. The PPIRB report’s apparent interest in using COPUOS rather than COSPAR for international cooperation on planetary protection (see Supporting Finding  and Supporting Recommendation  above) would shift such cooperation into an intergovernmental body within the United Nations. Typically, intergovernmental bodies do not allow nongovernmental entities to participate directly in their meetings or have a say in their decisions. If increasing private-sector participation in international cooperation on planetary protection is a policy objective, then COPUOS would not be
49 See NASEM, 2018, p. 9.
50 See NASEM, 2018, Recommendation 6.3.
an optimal forum in which to pursue that objective. For more on the relative roles of COSPAR and COPUOS see “Areas of Inconsistency and Concern” in Chapter 3.
The findings and recommendations of the PPIRB report are broadly consistent with the 2018 report and previous NASA reports on Mars sample return. Planning for the 2020 Mars sample collection mission is well advanced, and NASA is already implementing some of the PPIRB’s recommendations on Mars sample return.
This part of the PPIRB report begins with a finding and recommendation about materials the Earth has already received from Mars over the history of the solar system:
Major Finding: Martian material has been naturally transported to Earth for billions of years. 
Major Recommendation: NASA’s MSR PP approach should take into account the findings of the recent National Academies’ Consensus Study Report on sample return from the Martian moons. 
The 2018 report did not focus on the transport of material from Mars to Earth, so these findings are not comparable to the 2018 report. This topic is addressed in previous National Academies’ reports and other studies.51 The committee finds that the naturally occurring transport of martian materials to Earth is not a scientifically compelling reason to alter planetary protection policies for returned samples from Mars. The committee notes that, while the Earth regularly receives meteorites from Mars (estimated to be about 1 ton per year of rock fragments 10 cm or more in diameter), the meteorites are mostly igneous, basaltic rocks that are tough enough to survive ejection from Mars and transport to Earth, which makes them a biased sample. Martian meteorite collections contains few or no examples of significantly aqueously altered rocks of sedimentary or altered igneous types that might provide,52 or might have provided, habitats for living organisms. Samples that might yield signs of life would come from subsurface rock formations affected by water.
Although theoretical models suggest that martian meteorites originate close to the surface (within about 10 m for craters about 10 km in diameter),53 there is currently no evidence that they accumulated cosmogenic isotopes before launch from the surface of Mars,54 so they were unlikely to have been sterilized by cosmic radiation before launch. However, natural transfer from Mars to Earth usually requires hundreds of thousands to millions of years of exposure to the severe space radiation environment, although more rapid transfers are possible, but much less likely.55 Nevertheless, until it is clear that martian material poses no threat to the Earth’s environment, strenuous efforts will be required to quarantine martian samples, especially those from the subsurface, from contact with Earth’s biosphere by effective barriers in both the return spacecraft and in the sample receiving facility.
The joint report of the National Academies and the European Science Foundation on sample return from the martian moons (mentioned in the PPIRB report’s Major Recommendation ) concluded that “after considering the body of work conducted by the SterLim and JAXA teams, the effect of desiccation on the surfaces of the martian moons, and the relative flux of meteorite-to-spacecraft-mediated transfer to Earth, the committee recommends that samples returned from the martian moons be designated unrestricted Earth return.”56 This conclusion was specifically based on the following factors:
51 See, for example, NASEM, Assessment of Planetary Protection Requirements for Mars Sample Return Missions, The National Academies Press, Washington, D.C., 2009, and references therein.
52 Out of approximately 220 Martian meteorites catalogued as of 9 January 2019, there is only one example, so far, of a sedimentary rock, NWA 7034 (a basaltic breccia).
53 J.N. Head, H.J. Melosh, and B.A. Ivanov, Martian meteorite launch: High-speed ejecta from small craters, Science 298:1752-1756, 2002.
54 O. Eugster, D.F. Herzog, K. Marti, and M.W. Caffee, “Irradiation Records, Cosmic-ray Exposure Ages, and Transfer Times of Meteorites,” pp. 829–851 in Meteorites and the Early Solar System II, 2006.
55 B. Gladman and J.A. Burns, Martian meteorite transfer. Simulation, Science 274:161-162, 1996.
56 NASEM and European Science Foundation, Planetary Protection Classification of Sample Return Missions from the Martian Moons, The National Academies Press, Washington, D.C., 2019, pp. 3 and 41.
- The random, impact-based sampling of the martian surface that contributes material to the martian moons;
- The inhospitable conditions at the martian surface, during impact, during collision with Phobos, and on Phobos; and
- The bias inherent in samples that survive impact ejection.
For these reasons, the U.S.-European martian moons report found that “the content of this report and, specifically, the recommendations presented in it do not apply to future sample return missions from Mars itself.”57 Therefore, the committee does not agree with the PPIRB report that compelling scientific evidence exists to change the planetary protection requirements for Mars sample return based on martian meteorites.
The next PPIRB finding on Mars sample return states as follows:
Major Finding: As the first restricted Earth return since Apollo, MSR will be a uniquely high profile mission. 
The 2018 report likewise recognized the importance of the Mars sample return mission for planetary protection policy by including a case study on Mars 2020.58 This case study highlighted the significance of the Mars sample return project for planetary protection policy on back contamination. The two reports are consistent in identifying the importance of the Mars sample return mission for planetary protection policy on back contamination.
The PPIRB report next addressed the Mars Sample Receiving Facility:
Major Recommendation: Planning for a Mars Sample Receiving Facility (MSRF) should be accelerated, or at least maintained on schedule, and should also be kept as pragmatic and streamlined as possible so that it does not unduly drive the schedule or cost of MSR. 
Supporting Finding: Significant work is being done to study the MSRF and whether an entirely new facility should be built, and where, or whether the MSRF should be an addon to an existing Biosafety Level 4 (BSL4) facility. 
The 2018 report identified the lack of planetary protection requirements for the Mars Sample Receiving Facility and activities that will take place in it. In particular, the 2018 report noted that “planetary protection requirements for the sample containment, verification of containment, return vehicle, and sample receiving facility are not yet in place” and the need to develop such requirements as a key part of the overall Mars sample return mission.59 The two reports are, thus, consistent in emphasizing the need for further work on planetary protection policy planning and implementation for the Mars Sample Receiving Facility. The 2018 report did not address the specific plans or details concerning the building of the Mars Sample Return Facility, but other reports from the National Academies have done so, albeit not recently.60
The PPIRB report also focused on the need for a public outreach strategy in connection with the Mars sample return mission:
Major Recommendation: NASA should begin work with other government agencies to develop a MSR PP public outreach, communications, and engagement plan. 
The 2018 report focused attention on the need to adapt planetary protection policy and its implementation for Mars sample return within NASA and across the federal government in order to assure that bringing samples back
57 NASEM and European Science Foundation, Planetary Protection Classification of Sample Return Missions from the Martian Moons, The National Academies Press, Washington, D.C., 2019, pp. 5 and 44-45.
58 See NASEM, 2018, pp. 46-52.
59 See NASEM, 2018, p. 52.
60 See, for example, National Research Council, The Quarantine and Certification of Martian Samples, National Academy Press, Washington, D.C., 2002.
from Mars proceeds as smoothly as possible politically, diplomatically, and scientifically. Therefore, the two reports are consistent in recommending the development of interagency and diplomatic plans to address the challenges of returning samples from Mars, including public outreach, communications, and engagement.
The PPIRB report next addressed sterilization techniques in connection with the Mars sample return mission:
Supporting Finding: Some types of sterilization of Mars samples are antagonistic to many important types of scientific measurements. 
Supporting Recommendation: NASA should carefully trade the implications of the degree and types of PP sterilization techniques for Mars samples with the implications for various types of science measurements. 
Supporting Recommendation: NASA should continue to engage experts from the medical, pharmaceutical, and personal care industries to advise on effective sterilization protocols. 
The 2018 report did not discuss sterilization of Mars samples. The 2018 report is also silent on the effect of such sterilization on the science conducted on the samples and on the appropriate expertise required to advise NASA on sample sterilization protocols. However, PPIRB Supporting Recommendation  does follow from one in the 2018 report, which reads:
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.
The PPIRB report had one major finding, one major recommendation, and one supporting finding and recommendation regarding the exploration of Europa, Enceladus, Titan, and the other ocean worlds. The major finding and major recommendation state:
Major Finding: The fraction of terrestrial microorganisms in spacecraft bioburdens that has potential to survive and amplify in ocean worlds is likely to be extremely small.61Further, any putative indigenous life in subsurface oceans on Europa, Enceladus, or Titan is highly unlikely to have a common origin with terrestrial life. 
Major Recommendation: The PP requirements for ocean worlds exploration should be reassessed in light of this finding. 
Although the 2018 report included a case study of the planetary protection policy and implementation issues associated with the Europa Clipper mission,62 it did not address or reach scientific conclusions about the following topics:
- The potential of terrestrial organisms on spacecraft to survive and amplify in the oceans of icy bodies;
- Whether any indigenous life in the subsurface oceans of Europa, Enceladus, or Titan is unlikely to share a common origin with terrestrial organisms; or
61 M.T. La Duc, A.E. Dekas, S. Osman, C. Moissl, D. Newcombe, and K. Venkateswaran, Isolation and characterization of bacteria capable of tolerating the extreme conditions of clean-room environments, Applied Environmental Microbiology 73:2600-2611, 2007; and National Research Council, Assessment of Planetary Protection Requirements for Spacecraft Missions to Icy Solar System Bodies, The National Academies Press, Washington, DC, 2012, https://doi.org/10.17226/13401.
- Whether the current bioburden requirements for missions to Europa, Enceladus, or other ocean worlds are appropriate.
Subsequent to publication of the 2018 report, the Europa Clipper project and the NASA PPO reached agreement on a realistic approach to achieving a responsible thousand-fold reduction in the spacecraft’s bioburden, with an understanding that flexibility will be granted for hardware that cannot withstand the protocol. By concentrating on being able to estimate that less than one viable microorganism could reach the ocean (after accounting for impact survivability, likelihood of landing on an active region of the surface, ocean transport processes, and probability of hitting Europa in the first place), the project devised the means to ensure a very low probability of contamination of a Europan ocean.63
The PPIRB report’s supporting finding and recommendation on ocean worlds are as follows:
Supporting Finding: Category IV is currently assigned to landed ocean world missions when there is a significant probability of contamination of the liquid interior oceans. However, the situation for each ocean world environment is very different and limited information exists for each of these worlds regarding ice shell composition and thickness, ocean composition and habitability, interfaces/communication between the surface and ocean, and any transport of material across the surface. 
Supporting Recommendation: NASA should study transport, survival and amplification mechanisms of contamination individually for each ocean world. 
The 2018 report did not address the use of Category IV (see Appendix E) for missions that land spacecraft on the surface of icy bodies with subsurface oceans. The 2018 report identified the need for more research to inform missions to such icy bodies that come after Europa Clipper:
The formulation of planetary protection policies for such missions will need to be informed by new research. In particular the scientific question of whether a single organism, deposited on the surface, could contaminate Europa’s entire ocean within a reasonable period of biological exploration needs to be revisited.64
The committee agrees that mission categorization be based on the best available scientific knowledge and supports the PPIRB report’s recommendation for further study of transport, survival, and amplification potential of terrestrial microorganisms within the oceans of icy bodies. The committee notes that the available scientific knowledge is incomplete with regard to the following: the ability of introduced microorganisms to survive and propagate in an ocean world environment (despite temperatures and pressures comparable to those found in Earth’s deep ocean) and whether or not such life forms would be readily distinguishable from indigenous life. Further, as the OST requires that states parties avoid “harmful contamination” of celestial bodies, the committee does not agree with the contention in Major Finding  that any potential ability to distinguish terrestrial contaminants from indigenous life negates concerns over potential contamination of ocean worlds with replicating terrestrial microorganisms.
The final five PPIRB findings and recommendations address topics related to the OST, the role of COSPAR, and the semantics of planetary protection—all grouped under the heading of “COSPAR.”
Major Finding: There is a lack of consensus as to how and when the Outer Space Treaty has legal relevance to nongovernmental entities. 
63 January 6, 2020, email from Europa Clipper Project Scientist to committee.
64 See NASEM, 2018, pp. 56-57.
In contrast to the PPIRB report, the 2018 report did not identify confusion about how, under the OST, states parties make Article IX legally relevant for nongovernmental entities by fulfilling their Article VI obligation to authorize and supervise the space activities of such entities. The 2018 report’s analysis of the OST focused on the treaty’s obligations on states parties (governments) to do the following:
- Conduct space exploration so as to avoid harmful contamination of the Moon and other celestial bodies and adverse changes in Earth’s environment and to adopt appropriate measures for these purposes,65 and
- Authorize and continually supervise space activities of nongovernmental entities (private companies).66
Under international law, the OST is clear that it becomes legally relevant for nongovernmental entities when OST states parties fulfill their treaty obligations to authorize and supervise the space activities of nongovernmental entities, including activities that have planetary protection implications.
On the other hand, the two reports are consistent in that both highlight the need to identify, in domestic law, a federal agency to regulate nongovernmental entities on planetary protection (or, in OST terms, the agency that will authorize and supervise the space activities of nongovernmental entities for planetary protection purposes). The question whether the OST directly applies to nongovernmental entities, without the need for domestic legislation implementing the treaty, is a question of national law. Put differently, the U.S. government is required to make Article IX legally relevant for nongovernmental entities by fulfilling its Article VI obligation to authorize and supervise such entities. The 2018 report concluded that, at the level of domestic law, the United States has a “regulatory gap” because no federal agency has the explicit authority to regulate planetary protection issues. The PPIRB report also noted the need to identify an appropriate federal agency to regulate the private sector in the planetary protection domain (see Supporting Recommendation  in the discussion of private-sector initiatives above).
Major Finding: The process for incorporating recommendations from this report that NASA accepts into COSPAR guidelines is not well defined. 
The two reports are not consistent on this point. The 2018 report described the long-established process through which NASA has taken proposed planetary protection policy changes to COSPAR, how COSPAR considers and adopts changed or new policies, and how the restructured COSPAR Panel on Planetary Protection will deal with changes in the future.67 The committee agrees, however, that while the process may actually be well defined, it is not well understood outside the community of planetary protection experts.
Supporting Finding: The term “Planetary Protection” has been used by different communities to include a variety of topics. This has caused confusion with respect to the primary responsibility of governmental PP oversight and the intent of past practices. 
Supporting Recommendation: NASA should broadly communicate that its PP policy is consistent with COSPAR history, and is specifically focused on reducing biological forward contamination that could interfere with future astrobiological investigations and backward contamination that might have adverse impacts on Earth’s biosphere. 
If the intent of the PPIRB finding was to suggest replacing the term “planetary protection,” then the two reports are not consistent because the 2018 report provided nothing to indicate that use of “planetary protection” has produced confusion. Replacing “planetary protection” after many decades of successful international use
65 From Article IX of the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies, opened for signature January 27, 1967, 18 U.S.T. 2410, 610 U.N.T.S. 205. Hereafter the OST.
66 From Article VI of the OST.
67 See NASEM, 2018, pp. 72-76.
could very probably lead to confusion that the PPIRB may have wished to avoid. The 2018 committee identified the following:68
Two goals for planetary protection that NASA, international, and Space Studies Board documents have reflected for decades:
- The control of forward contamination, defined by NASA as “the control of terrestrial microbial contamination associated with robotic space vehicles intended to land, orbit, fly-by, or otherwise encounter extraterrestrial solar system bodies; and
- The control of back contamination, defined by NASA as “the control of contamination of the Earth and the Moon by extraterrestrial material collected and returned by robotic missions.
On the other hand, the PPIRB recommendation for communicating COSPAR’s long-established role and relationship to NASA is consistent with the 2018 report’s description of the history of planetary protection policy. The 2018 report observed that “NASA science and policy have, to date, provided the basis for practically all substantive COSPAR guidelines.”69 Put differently, history of the development of COSPAR’s planetary protection policies is the story of the international adoption of Space Studies Board science and NASA policy.70 As noted above, NASA has consistently defined planetary protection policy to focus on forward contamination to protect astrobiological science’s search for extraterrestrial life and prebiotic chemical evolution and backward contamination to protect Earth’s environment from potential harm by replicating extraterrestrial organisms.
Supporting Recommendation: To reduce confusion, NASA should develop and then use a standard glossary of PP related terminology, including for example “spacecraft cleanliness,” “forward biological transport,” and “backward biological transport.” 
The 2018 report did not identify any serious planetary protection policy problems that arose from confusion about what “planetary protection” means or from the lack of standardized terminology. Nevertheless, having a NASA document that presents a standard glossary could be helpful for new entrants (e.g., human and private-sector missions) as they become part of the solar system exploration milieu.
68 See NASEM, 2018, p. 9.
69 See NASEM, 2018, p. 17.
70 See NASEM, 2018, pp. 76-78.