Under U.S. policy and international treaty, the goals of planetary protection are to avoid both adverse changes in Earth’s environment caused by introducing extraterrestrial matter and harmful contamination of solar system bodies in order to protect their biological integrity for scientific study.1 The United States has long cooperated with other countries and relevant scientific communities through the Committee on Space Research (COSPAR) of the International Council for Science in developing planetary protection guidance for different categories of space missions.2 In the past, achieving planetary protection objectives through science-based, international-consensus guidelines proved relatively straightforward because a small number of spacefaring nations explored the solar system, predominantly through government-led and scientifically focused robotic missions.
However, interest in, and the capabilities to undertake, exploration and uses of outer space are evolving and expanding. More countries are engaging in space activities. Private-sector involvement is increasing. Planning is under way for human as well as robotic missions. As recent advisory reports have highlighted, the changes in the nature of space activities create unprecedented challenges for planetary protection.3
These challenges for planetary protection are apparent in growing government and commercial interest in human and robotic missions to the Moon.4 For example, the United States plans to return
1 See NASA, 1999, “NASA Policy Directive on Biological Contamination Control for Outbound and Inbound Planetary Spacecraft,” NPD 8020.7G, February 19; NASA, 2017, “NASA Interim Directive on Planetary Protection Provisions for Robotic Extraterrestrial Missions,” NID 8020.109A, March 30; and “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 (Outer Space Treaty), Article IX. NASA and the international community have used this definition of planetary protection throughout the history of solar system exploration. Other forms of contamination that might have abiotic chemical, mechanical, esthetic, or ethical consequences can also occur during planetary missions. See, for example, National Academies of Sciences, Engineering, and Medicine (NASEM) 2018, Review and Assessment of Planetary Protection Policy Development Processes, The National Academies Press, Washington, DC, pp. 11-12 (discussing ethical issues and planetary protection policy). In keeping with the traditional definition of planetary protection, the committee focuses in this report on effects that can interfere with research relating to the origin of life.
2 See Appendix B for the COSPAR policy and categories. For a brief historical summary of relationship between NASA and COSPAR, see NASEM, 2018, pp. 17-19.
3 NASEM, 2018, p. 85-89 (discussing the impact of private-sector space activities on planetary protection policy development); Planetary Protection Independent Review Board (PPIRB), 2019, NASA Planetary Protection Independent Review Board (PPIRB): Report to NASA/SMD: Final Report, NASA, Washington, DC, p. 9 (finding that the context in which planetary protection “is conducted is profoundly and rapidly changing); and NASEM, 2020, Assessment of the Report of NASA’s Planetary Protection Independent Review Board, The National Academies Press, Washington, DC, p. 17 (noting agreement between the NASEM 2018 report and the PPIRB report on the changing nature of planetary protection policy development and implementation).
4 According to the International Space Exploration Coordination Group, as many as seven national and international space agencies are planning in the next 5 years more than a dozen missions to the Moon—many of which will be to the lunar poles. See International Space Exploration Coordination Group, 2020, Global Exploration Roadmap Supplement, August 28, https://www.globalspaceexploration.org/?p=1049.
humans to the lunar surface through its Artemis Program. Space companies are exploring the Moon’s commercial possibilities, including in situ resource utilization and lunar tourism. The intensifying focus on the Moon raises important planetary protection issues for scientific communities, commercial enterprises, spacefaring nations, and international cooperation on peaceful uses of outer space.
Following the Apollo missions in the late 1960s and early 1970s, scientists concluded that the Moon is a sterile body that posed no risk for backward contamination of Earth’s biosphere. Scientists recognized the Moon as an important source of information about the chemical evolution of solar system materials, but, post-Apollo, the Moon was not considered biologically important. Under this perspective, lunar missions would not result in forward contamination that would harm the potential for studying potential biological activity (or prebiotic chemical evolution). Under these scientific conclusions, missions to the Moon did not have to satisfy any planetary protection requirements (Category I), and the return of lunar material to the Earth was not subject to restrictions (Category V (unrestricted)).
However, further scientific research on the Moon produced possible evidence that the lunar poles, and especially some permanently shadowed regions (PSRs), contain surface and subsurface water in the form of ice deposits. This development renewed biological interest in these areas of the Moon, because the water ice could be important for the study of the evolution of biologically relevant chemical compounds. To reflect these scientific analyses, the planetary protection approach to lunar missions changed in 2008 to require an inventory of organic materials carried on spacecraft (Category II with organic inventory).5 Subsequent lunar missions, including the Lunar Reconnaissance Orbiter, Lunar Prospector, and Chandrayaan-1 confirmed the presence of water ice on the Moon.
The water ice deposits at the lunar poles and in PSRs are prominently featured in the increased governmental and commercial interest in the Moon. Much remains unknown about these water ice deposits, including uncertainty about the abundance, distribution, and physical form of water and other volatiles in the PSRs and at the lunar poles. Lunar missions being planned by NASA, other national space agencies, and private-sector entities in different countries are targeting these areas on the Moon. In its 2019 report, the Planetary Protection Independent Review Board (PPIRB) established by NASA recommended that
NASA should study how much of the Moon’s surface and subsurface could be designated [planetary protection] 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.6
NASA asked the National Academies of Sciences, Engineering, and Medicine to review the PPIRB report and compare it to the conclusions of the National Academies’ 2018 report, Review and Assessment of Planetary Protection Policy Development Processes,7 that reviewed and assessed planetary protection policy development processes. In response to the PPIRB’s recommendation that NASA study whether some lunar missions could be Category I rather than Category II for planetary protection purposes, the National Academies’ report Assessment of the Report of NASA’s Planetary Protection Independent Review Board stated in April 2020:
5 COSPAR’s most recent guidelines specify that “A spacecraft organic inventory includes a listing of all organic materials carried by a spacecraft which are present in a total mass greater than 1 kg. A complete inventory should include organic products that may be released into the environment of the protected solar system body by propulsion and life support systems (if present), and include a quantitative and qualitative description of major chemical constituents and the integrated quantity of minor chemical constituents present.” See COSPAR, 2020, Policy on Planetary Protection, June 17, p. 4.
6 PPIRB, 2019, p. 13.
7 NASEM, 2018.
[T]he 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…could … determine whether the contemplated regions are sufficiently well explored and documented so that activities such as a human landing base or ISRU [in situ resource utilization]…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. … 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.8
In July 2020, NASA issued a new interim directive establishing NASA planetary protection requirements for both robotic and crewed missions to the Moon (hereafter, the Lunar NID).9 Before issuing this directive, NASA did not complete the formal study on planetary protection categorization of lunar missions that the PPIRB recommended in 2019 and that the National Academies report supported in 2020. The Lunar NID changed NASA’s planetary protection policy for lunar missions by creating two planetary protection categories for missions to the Moon: Category I-L (no planetary protection requirements) and Category II-L (a modified version of Category II’s requirement for an inventory of a spacecraft’s materials). (See Table 1.1.)
Under the Lunar NID, NASA designates all lunar missions as Category I-L except for missions to locations having (a) PSRs (i.e., areas south of 79°S and areas north of 86°N10) and (b) Apollo landing and other historic lunar sites.11 NASA designates missions to these two locations as Category II-L, requiring an inventory of biological materials (living and dead) included in spacecraft hardware and payloads. Under Category II-L, crewed missions must also list the amount and disposition of biological waste that will remain in the lunar environment.
The Lunar NID applies to robotic and crewed lunar missions with NASA involvement, including “NASA-controlled missions, commercial missions sponsored by NASA, joint missions in which NASA participates, and NASA support of non-NASA missions to the extent specified or referenced in the applicable contracts, grants, or agreements.”12 The Lunar NID does not apply to commercial lunar missions conducted without such NASA involvement or participation.13 Unless extended, the Lunar NID terminates on July 9, 2021.
8 NASEM, 2020, p. 28.
9 NASA, 2020, “NASA Interim Directive on Planetary Protection Categorization for Robotic and Crewed Missions to the Earth’s Moon,” NID 8715.128, July 9 (hereafter, the Lunar NID).
10 Some PSRs are also found at lower latitudes than those specified in the Lunar NID.
11 The inclusion of Apollo landing and other historic lunar sites in the Lunar NID departs from the traditional, narrow focus of planetary protection policy on backward and forward contamination. See Chapter 5.
12 Lunar NID, p. 2.
13 Under article VI of the Outer Space Treaty, states parties must authorize and continually supervise the space activities of non-governmental entities. Recent National Academies and PPIRB reports on planetary protection identified uncertainties about how the U.S. government can fulfill its planetary protection obligations under the Outer Space Treaty in connection with private-sector space activities that do not involve NASA participation. See NASEM, 2018, p. 87 (discussing how the Outer Space Treaty becomes legally relevant for non-governmental entities); PPIRB, p. 22 (finding that “[t]here is a lack of consensus as to how and when the Outer Space Treaty has legal relevance to non-governmental entities”); and NASEM, 2020, p. 42 (identifying how the Outer Space Treaty becomes legally relevant for non-governmental entities). The NASA interim directive on Mars—issued with the Lunar NID—states that NASA recognizes that the Outer Space Treaty “sets forth legal requirements on U.S. governmental and non-governmental entities to prevent . . . forward and backward harmful biological contamination.” NASA 2020, “NASA Interim Directive, Biological Planetary Protection for Human Missions to Mars,” NID 8715.129, July 9, p. 2. The Lunar NID does not include this statement. See Chapter 5.
TABLE 1.1 NASA Interim Planetary Protection Categories for Lunar Missions
|Lunar Target Sensitivity||Mission Planetary Protection Category|
|Not of direct interest for understanding the process of chemical evolution or where exploration will not be jeopardized by terrestrial contamination. No protection of such regions is warranted.||I-L|
|Of significant interest relative to the process of chemical evolution but only a remote chance that biological contamination by spacecraft could compromise future investigations. Reporting of biological materials is warranted.||II-L|
SOURCE: NASA Interim Directive 8715.128, July 9, 2020, p. 5.
In spring 2020, the COSPAR Panel on Planetary Protection conducted a survey of the lunar exploration community’s interests and concerns regarding the scientific importance of, and the contamination risk to the study of, lunar volatiles. The NASA Lunar Exploration Assessment Group (LEAG) organized a response from approximately 40 U.S. stakeholders,14 with 90 experts from other countries also participating in the survey. The overall response to the survey showed a very strong interest in the relevance of volatiles from PSRs for studying prebiotic chemistry as a precursor to life in the solar system and a comparably strong level of concern over how contamination could compromise future research.15
A majority of the approximately 130 total survey respondents expressed support for some combination of characterization of volatiles released from spacecraft propellants, inventories of spacecraft organic materials lists, or establishment of PSR protected areas as approaches to contamination mitigation. Representatives of the COSPAR Panel on Planetary Protection noted for the committee that the survey’s results appeared to be consistent with current COSPAR policy for the Moon, but it indicated that there might be a rationale for reducing the organic inventory requirements by focusing on volatile products of spacecraft propulsion and life support systems.
CHARGE TO THE COMMITTEE AND STRUCTURE OF THE REPORT
In 2020, NASA asked the National Academies’ Space Studies Board to establish a standing Committee on Planetary Protection (CoPP) to advise NASA on important matters relating to planetary protection.16 In fulfilling this mandate, the CoPP will
Carry out its charge at its in-person and virtual meetings by gathering evidence from experts, deliberating, and, when necessary, by preparing short assessment reports detailing progress in
14 NASA Lunar Exploration Analysis Group, 2020, Rapid Response Specific Action Team in Response to COSPAR Planetary Protection Inquiry, May 8. Responses came from members of the LEAG and CAPTEM (Curation and Analysis Planning Team for Extraterrestrial Materials) groups, as well as from members of the Lunar List Serv, which provides a community forum for scientists, engineers, mission designers, and others interested in lunar issues.
15 Briefing to the committee by Athena Coustenis, Gerhard Kminek, and Niklas Hedman, September 23, 2020.
16 NASA’s action implemented recommendations made by the reports issued by NASEM in 2018 and 2020 and the PPIRB in 2019 for the establishment of a standing advisory body on planetary protection.
areas relating to NASA’s planetary protection guidelines or new scientific and technical developments. Such reports may include findings and discussion of key activities undertaken by NASA as well as the status of its actions that relate to the state of implementation of priority missions and programs.
For its first task, NASA asked the CoPP to prepare a short report on the impact of human activities on polar volatile materials (e.g., water, carbon dioxide, and methane) and the scientific value of protecting the surface and subsurface regions of the Moon from organic and biological contamination. This report responds to the NASA request and is based on briefings and discussions during the committee’s three virtual open meetings in September 2020 and the committee’s review of publicly available material.
The report is organized along the lines of the statement of task for the study. (See Appendix A for the full statement of task.) Chapter 2 presents the committee’s findings about the current scientific understanding, value, and potential threat of contamination by lunar missions to (1) studies of solar system evolution and (2) studies of the chemical evolution of life. Chapter 3 discusses spacecraft transfer of volatiles to the lunar poles and PSRs. Chapter 4 presents the committee’s findings about lunar regions that warrant protection from organic and biological contamination.