From Planetary Quarantine to Planetary Protection: A NASA and International Story

The History and on

“Planetary quarantine” and its alias, “planetary protection,” are the names given to policies and practices that seek to avoid biological and organic chemical contamination during space exploration and use. These policies intend to avoid both the contamination of other celestial bodies (forward contamination) and the possible contamination of Earth's biosphere by extraterrestrial material (backward, or back contamination). Initiated at the beginning of the Space Age in the late 1950s, these policies have become an international endeavor, in part because of the provisions of the 1967 United Nations Outer Space Treaty (OST; United Nations, 1967) and the activities of the interdisciplinary Committee on Space Research (COSPAR) and the UN Committee on the Peaceful Uses of Outer Space (COPUOS).

Despite an understanding that organic and biological contamination in space exploration could be problematic, or even dangerous, in the early years there was a naturally occurring disparity between theory and practice. There was limited understanding of extraterrestrial environments; thus it was not known how clean a spacecraft had to be to avoid forward contamination. Early planetary quarantine provisions called for “spacecraft sterilization,” but with components often developed for other uses, early spacecraft had difficulty surviving the rigors of the space environment, let alone the rigors of various sterilization methods. In an effort to balance these factors, and lead its efforts in spacecraft sterilization and quarantine, in August 1963 NASA established the position of Planetary Quarantine Officer (PQO). The first person to be appointed to that position was Captain Lawrence B. Hall, a senior commissioned officer of the US Public Health Service (Phillips, 1974). See Fig. 1 for portraits of Hall and his successors.

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FIG. 1.

Former or current NASA Planetary Quarantine/Protection Officers (1963–2018): Larry Hall, Dick Young, Don DeVincenzi, John D. Rummel, Mike Meyer, Cassie Conley, and Lisa Pratt.

While NASA was trying to implement planetary quarantine effectively, there was an active interest on the part of the US National Academy of Science (NAS), through their Space Science Board (SSB), in both the potential to study life outside Earth and the control of contamination that could make that either impracticable or impossible. Under the charter of the NAS, the SSB was often consulted by NASA for studies and recommendations on planetary quarantine. During the period leading up to the Apollo Moon-landing missions, the SSB provided numerous recommendations to NASA on planetary quarantine, both for forward contamination avoidance and for the preparation of a quarantine of the Apollo astronauts and samples. That was done as part of NASA's efforts to contain back contamination and ensure the protection of Earth's biosphere under Article IX of the OST.

Among other things, in preparation for a possible breach of quarantine at the Manned Spacecraft Center (MSC), NASA entered into the Federal Register a regulation allowing the PQO to arrest and quarantine anyone who was “extraterrestrially exposed” within the confines of the MSC (CFR Title 34 Part 1211, 1969). The extraconstitutional aspects of this regulation were, in fact, largely responsible for the later move away from the term “quarantine” to describe efforts to control interplanetary contamination (cf. Robinson, 1971, 1992). In his published work and in his dissertation at the McGill University Institute of Air and Space Law, George Robinson, an associate counsel at the Smithsonian Institution, noted that NASA's regulation (known within NASA's directive system as NPD or NMI 8020.14) was quite likely unenforceable within the bounds of US constitutional law in that it involved depriving individuals of liberty and property without a demonstrable cause (exposure was presumptive) and without further due process. These themes may seem more familiar to US audiences today, with efforts to stem domestic terrorist attacks and regulations intended to prevent the spread of Ebola and similar medium-latency virus infections, but at the time such measures were more familiar to science-fiction film fans (e.g., The Andromeda Strain) than to international lawyers working in the science domain.

One result of Robinson's work was that the NASA Planetary Quarantine Officer who was appointed when Hall retired in 1976 (Richard S. Young, who had been the Viking Program Scientist, see Table 1) encouraged the term “Planetary Protection” to be used as a replacement for “Planetary Quarantine” in discussions about the subject (D.L. DeVincenzi, personal communication, 1986). Both were used by the SSB and/or within NASA until at least 1981 (cf. Barengoltz et al., 1981). Thereafter, NASA Headquarters switched to the term “Planetary Protection,” exclusively, in discussions of interplanetary contamination. When Donald L. DeVincenzi replaced Dick Young as PQO in 1979, he became the first Planetary Protection Officer (PPO) for NASA de facto, in 1981, even though that title had yet to be established by a NASA management instruction (Table 2).

While in the late 1960s much of the world's attention was focused on the “manned” Apollo missions, NASA was paying a great deal of attention to the planned robotic Viking missions to Mars. The expectation (and the final plan) was that the Viking landers would conduct life-detection experiments by trying to grow martian organisms and looking for organic compounds in the martian surface material. Thus, it was imperative that each lander spacecraft be thoroughly cleaned and then, to achieve the final, acceptable, level of microbial contamination for both planetary protection and science, given a terminal heat treatment before being paired with an orbiter and placed atop the Titan III launch vehicle. The severity of the final heat treatment was designed more to ensure that the planned Viking life-detection experiments would not inadvertently detect terrestrial life than for the protection of martian environments.

One of the aspects of NASA's planetary quarantine efforts that made the Viking missions successful was that NASA had made significant research investments into sterilization techniques and the appropriate values to be used in measuring potential planetary contamination. As an important adjunct to the PQO, those research investments were overseen by a “Planetary Quarantine Advisory Panel” (PQAP), which focused on the establishment of a base knowledge of planetary protection methods to allow the Viking lander missions to succeed. Much of the baseline data reviewed by PQAP is still in use by NASA (and others) today.

Because of the development of responsibilities under the OST, and an increasing desire to engender international cooperation in planetary exploration, NASA maintained a strong leadership role in establishing and maintaining the COSPAR biological contamination control policy. As a result, the NASA and COSPAR policies have been closely aligned from the beginning, even before the OST was signed. The recent recognition of “the long-standing role of COSPAR in maintaining the planetary protection policy as a reference standard for spacefaring nations and in guiding compliance with Article IX of the Outer Space Treaty” (COPUOS, 2017) is, in fact, indicative of NASA's success in forging an international consensus in this area (cf. Space Studies Board, 2018). Enabled by that forum, NASA maintained an ongoing colloquy with the Soviet Union on the subject of interplanetary contamination that was important to the original formation and maintenance of COSPAR activity in planetary quarantine.

The various efforts made by NASA in shaping COSPAR's policy include the proposal in the early 1980s, when then PQO/PPO Donald DeVincenzi and his colleagues looked for a way to modify the NASA planetary protection regulations and later the COSPAR Planetary Protection Policy, to remove the numerically rigid, pseudo-quantitative policy of the time and instead tailor the various planetary protection requirements to specific mission/target-body combinations, with the potential to address specific concerns about various target bodies in a flexible manner and continue to avoid situations in which spacecraft contaminants might invalidate current or future scientific exploration of a body. The proposal made by DeVincenzi et al. (1983) included the new overall policy for COSPAR, as well as the international adoption of the term “Planetary Protection.” The proposal was accepted by COSPAR in 1984. The new policy also addressed issues regarding backward contamination control for robotic missions. It would take until 2008 before the COSPAR policy would address both forward and backward contamination for human missions.

Other initiatives by NASA included the 1999 establishment by the COSPAR Bureau and Council of a new Panel on Planetary Protection, with PPO J.D. Rummel as Chair, and the Panel's subsequent establishment of a complete COSPAR Planetary Protection Policy at the World Space Congress in Houston, Texas, in 2002. (COSPAR had not had a unified Planetary Protection Policy document since 1964.) Regular updates have yielded the current policy document (Kminek et al., 2017).

One of the innovations that was novel in the 2002 policy was an initial definition for places on Mars “within which Earth-sourced organisms are likely to propagate” or are “interpreted to have high potential for extant martian life forms.” These “Special Regions” on Mars were not parameterized at the time, but subsequent work in the policy arena and on Mars has furthered and will continue to further their description and characterize their potential existence. For the most recent such study, see the work of Rummel et al. (2014).

Another aspect of international policy that needs to be established, as such, is planning for a protocol that can establish the safety of a sample returned to Earth from a potential life-site in the Solar System, such as Mars, Europa, or Enceladus. Such a protocol will have to be completed in containment on Earth, and there is a long-lead-time requirement for the establishment of the appropriate containment facility, including every aspect from planning to construction and practice. That planning can only be accomplished after establishing a strategy for returned sample analyses that will define the nature of any receiving laboratory required—an engaging task for future work (see, e.g., Rummel and Kminek, 2018).

Finally, the rapid increase of commercial interest in missions and activities in cis-lunar space and beyond will eventually be the subject of a dialogue that is sure to have an influence on not only the policy specifics but also the very foundation of planetary protection policies themselves. Future limitations on biological contamination cannot be based on not only the needs of science, but also on the needs of explorers, tourists, and even settlers as we go forward into the Solar System. For example, on Mars even the most basic attempts at local or later planetary-scale engineering can result in changes to the environment that could greatly affect the ability of Earth organisms to thrive there, as well as the prospects for interaction with any martian organisms that might be present. From an exobiology perspective, the past is full of lessons, and future policies will continue to depend on knowledge gained from today's spacecraft. Forward and backward contamination control measures “must hold until we have acquired the factual information from which we can assess with assurance the detrimental effects of free traffic and determine whether these are small enough to warrant the relaxation of these controls” (Lederberg, 1960).