Samples of the planet Mars are expected to be collected by robotic spacecraft and returned to Earth for scientific study early in this century, perhaps as soon as 2015. There is a possibility, although it is acknowledged to be remote, that the samples will contain specimens of microorganisms that have lived on Mars, perhaps even in a viable state. The samples must be collected and handled in a way that will protect the terrestrial environment from contamination by these hypothetical organisms and also protect the samples from contamination by terrestrial organisms and other contaminants.
An essential element of the plan to handle martian samples responsibly is a quarantine facility, into which the samples will be received as soon as they arrive on Earth. Such a facility will perform the dual role of protecting the terrestrial environment and safeguarding the scientific integrity of the returned samples. In other words, it must combine the functions of a biological containment laboratory and a clean room.
Initial examination of the samples, including testing for potential biohazards, will be carried out in this facility, and the samples will be held there until conditions are met that permit release of aliquots1 of the samples to the laboratories of investigators elsewhere in the United States and abroad who are qualified to carry out specialized studies of them, and who have been formally approved to do so.
COMPLEX has studied the time required to plan, build, and staff an adequate quarantine facility. The time needed is surprisingly long, 7 years (see Table 6.3 in Chapter 6). If Mars sample return and quarantine are to be taken seriously, this need must be addressed. It dictates the most important recommendation of this report:
Recommendation. It is imperative that planning and construction of the Mars Quarantine Facility be begun at least 7 years in advance of the anticipated return of Mars samples. This responsibility cannot be deferred without compromising the quarantine and study of the Mars samples. [Chapter 6]
OPERATIONS IN THE QUARANTINE FACILITY
COMPLEX considers that only the most basic operations should be conducted in the quarantine facility: unpacking, preliminary examination, baseline characterization, weighing, photography, splitting, repackaging,
and storage. Another important operation will be the preparation of heat- and/or radiation-treated samples for distribution to the scientific community. In addition, certain life-detection studies that cannot be made on sterilized2 samples—such as testing for biohazards—will have to be carried out in the quarantine facility. To try to bring other scientific studies with bulky, complex instrumentation into the containment facility, along with the personnel who conduct the studies, would unacceptably increase the complexity, cost, and potential for failure of the facility.
The Mars Quarantine Facility should be designed to the smallest and simplest possible scale consistent with its role as a biological containment and clean room facility. No scientific investigations should be carried out in the quarantine facility that can be executed on sterilized samples outside the facility. [Chapter 6]
Protocols should be developed that specify in detail the steps and procedures to be followed for handling Mars samples in the quarantine facility. Necessary protocols include those for inventorying and preliminary analyses of the samples, searching for evidence of biological activity, testing for biohazards, and preparing sterilized aliquots of the samples for distribution to the scientific community. [Chapter 6; see also Chapter 4.]
Because it cannot be carried out on sterilized samples, biohazard assessment should be performed in the quarantine facility prior to any release of samples from the facility. Elements of these studies might include culturing experiments; attempts to infect animals, plants, and cell cultures; and genome detection via the polymerase chain reaction or similar techniques. [Chapter 6; see also Chapter 4.]
In addition to studying the optimal properties of a quarantine facility, COMPLEX has also considered life-detection techniques to be employed within (and outside) it, and the means of sterilizing samples within the facility so they can be removed from it. One important approach to life detection involves the extraction of key organic compounds (biomarkers, diagnostic of life processes) from samples for analysis at specialized laboratories outside the quarantine facility. Removal of these extracts from the facility will be contingent upon demonstration that the effects of the extraction process would be more than adequate to kill any known terrestrial organism.
Recommendation. It is important that a program of research be conducted to determine the efficacy of supercritical fluids and commonly used organic solvents in killing organisms. It is highly desirable to be able to remove solvent extracts from quarantine without the damage to dissolved biomarker compounds that would be caused by heat or ionizing radiation. Sterilization probably is systematically achieved by the supercritical fluids used in making extracts, but this needs to be verified before extracts can be removed from the Mars Quarantine Facility. [Chapter 4]
Much of the program of life detection will depend on studies of organic compounds in samples that were sterilized so they could be removed from the quarantine facility. Unfortunately, COMPLEX’s recommended techniques for sterilization—treatment by heat and or gamma radiation to such a level as to kill any known terrestrial organism—damage organic compounds to some extent. The vulnerability of organic compounds to heat and gamma-ray treatment is only imperfectly known. It is important that studies be carried out to enlarge knowledge in this area.
Recommendation. A program of research should be initiated to determine the effects on organic compounds in rocky matrices, and also on microscopic morphological evidence of life, of varying degrees of application of heat and gamma irradiation. This research should be started well in advance of the return of the Mars samples, so that treatment protocols can be designed intelligently and data obtained from analyses of treated samples can be interpreted with minimal ambiguity. [Chapter 5]
The nature of the quarantine facility, which must satisfy dual and partly conflicting requirements, is an important topic of study.
Recommendation. A major obstacle to design of the Mars Quarantine Facility is the problem of combining biological containment with clean-room conditions. It is essential that work on the solution of this problem be started immediately, to include mockups of containment/clean-room combinations whose efficacy can be tested, so that the design of a quarantine facility can proceed. [Chapter 6]
COMPLEX considers that affiliation of the quarantine facility with an ongoing containment facility (e.g., the U.S. Army Medical Research Institute of Infectious Diseases, in Ft. Detrick, Maryland; the Centers for Disease Control and Prevention, in Atlanta, Georgia; or the Medical Branch of the University of Texas at Galveston, where a BSL-4 facility is being constructed) is preferable to independent construction, for several reasons. These include:
Institutional support. A collaborative agreement with a host institution would mean that the Mars Quarantine Facility could draw on that institution for personnel, training, experience, security, and specialized utilities.
Economy. Sharing the resources named under 1 above should effect a large economy in operation of the Mars Quarantine Facility.
Environmental impact. Clearing an environmental impact statement for a BSL-4 facility can take years. Ideally, the Mars Quarantine Facility would operate under the environmental impact statement of its host institution.
Recommendation. The Mars Quarantine Facility should be affiliated with an ongoing containment facility that has BSL-4 capability and should be physically part of it or proximate to it, but control of the Mars Quarantine Facility should be under the jurisdiction of NASA. [Chapter 6]
Several initiatives cited above should be begun prior to design of the quarantine facility and planning of quarantine protocols, i.e., immediately: research on the efficacy of supercritical fluids and commonly used organic solvents in killing organisms; on the effects of varying degrees of treatment by heat and by gamma irradiation on organic compounds; and on ways of combining biological containment with clean-room conditions. An oversight committee should be formed to monitor these activities (see below, “The Apollo Experience”).
It is possible that the Mars sample return program will be an international venture, with other nations playing an important role in flight operations. The role of international partners in a sample return program should be carefully defined. The potentially sizeable contribution of another nation to the Mars program raises questions of how the earliest access to and ultimate curation of the samples will be shared. It is beyond the scope of COMPLEX’s charge to comment on the ultimate curation of the samples, but the committee believes strongly that, for practical reasons, their preliminary examination, baseline description, cataloguing, and packaging should be carried out at a single quarantine facility in the United States.
Recommendation. All samples in the initial collection returned from Mars should be placed in a quarantine facility in the United States, at least until the preliminary examination of the samples has been completed. Management and operation of the Mars Quarantine Facility should be shared between the United States and major international partners that participated in the collection of martian samples. [Chapter 6]
RELEASE OF SAMPLES FROM THE QUARANTINE FACILITY
COMPLEX considered the possible results of initial searches for evidence of life3 in the martian samples, especially analyses of the samples for total organic carbon. The committee recommends the following:
If the samples returned from Mars contain evidence of life, or if evidence of life is equivocal (e.g., organic matter is present), aliquots that have been treated by the application of heat and/or gamma radiation to levels more than adequate to kill any known terrestrial organism (Chapter 5) should be certified for release from the Mars Quarantine Facility. [Chapter 4]
If the samples contain evidence of life, or if evidence of life is equivocal, removal of untreated aliquots from the Mars Quarantine Facility for transfer to approved containment laboratories elsewhere should not be excluded, on the condition that containers and transfer procedures conform to protocols established by a panel of experts (e.g., from the Centers for Disease Control and Prevention) in containment.
Here “approved containment facilities elsewhere” refers principally to the case where a major international partner in the Mars sample return program wishes to establish an independent BSL-4 facility in which to study untreated samples (see Chapter 6). [Chapter 4]
If the samples are shown to be altogether barren of organic matter, to contain no detectable organic carbon compounds and no other evidence of past or present biological activity, untreated aliquots of the samples should be released for study beyond the confines of the Mars Quarantine Facility. [Chapter 4]
The possibility that the martian samples will contain unequivocal evidence of life is very remote, and for this reason COMPLEX’s response is based on the far more likely contingency that evidence of life will be equivocal or absent altogether. Unequivocal evidence of life would dictate a very elaborate plan of handling, curation, and study, which COMPLEX has not attempted to develop.
Recommendation. If unmistakable evidence of life as we know it is found in the Mars samples, they should be dedicated to biological studies. Studies of the biosignatures in them should be minimal until an optimal study plan has been developed and an appropriate research facility set up and staffed. In the interim, no aliquots of the samples should be released from the confines of the Mars Quarantine Facility unless warranted by ongoing biological studies, and the samples are sterilized. [Chapter 4]
Historically (e.g., with Apollo and the Viking Landers) there has been a degree of competition between biological and physical scientists for access to planetary research materials, and COMPLEX anticipates that this competition may be particularly intense where the martian samples are concerned. The above recommendation concedes that discovery of life in the samples would be of such supreme importance that the wishes of physical scientists should be subordinated to biological studies of the samples if this happens.
However, the discovery of life in the martian samples is unlikely, and in the far more probable case that only equivocal evidence of life is found, COMPLEX recommends that (sterilized) aliquots of the samples be made available to both biological and physical scientists for study. (Potential life-detection studies are not wholly compromised by sterilization.) COMPLEX is concerned that distribution of these samples not wait on resolution of uncertainties in the evidence, which can take a very long time (years) to occur. Scientists who have prepared their laboratories and staffs to study the samples should be allowed to begin work on them, and the results of their studies will provide important feedback for the planning of later Mars missions. Moreover, the public would find it difficult to understand why the study of samples from a much-publicized mission would be deferred for a period of years.
Recommendation. In the likely event that initial examination of the Mars samples can neither prove nor definitively rule out evidence of life in them, plans should be in place to promptly sterilize aliquots of the samples and remove them from the Mars Quarantine Facility for biological and geochemical studies in specialized laboratories elsewhere. This action should not be deferred pending resolution of the question of whether the samples contain life or artifacts of life. [Chapter 4]
THE APOLLO EXPERIENCE
COMPLEX reviewed details of the Lunar Receiving Laboratory, a quarantine facility constructed and used during the Apollo program, and attempted to profit from its triumphs and failures. Lessons learned in the review (Chapter 7; see also Appendix B) led COMPLEX to make these recommendations:
Recommendation. It is essential that the design for the Mars Quarantine Facility be kept as simple as possible, consistent with the facility’s mission of protecting Earth’s environment and the samples. Although it may be feasible to store the samples at low temperatures, an effort to try to maintain a Mars environment (temperature, pressure) during sample handling would complicate the design and operation of the facility to a very large degree, probably unnecessarily, and it should not be attempted for the first Mars sample return. [Chapter 7]
Recommendation. A continuing committee of senior biologists and geochemists that includes appropriate international representation should be formed and charged with reviewing every step of the planning, construction, and employment of the Mars Quarantine Facility. The committee should be formed during the earliest stages of planning for a Mars sample-return mission. Members of the committee should also participate in the design of the spacecraft and those portions of the mission profile where biological contamination is a threat. [Chapter 6]