Orbiting Quarantine Facility (OQF): The Antaeus Report
Donald L. DeVincenzi and John R. Bagby, editors. NASA SP-454, Washington, DC (1981).
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This report describes a NASA design study conducted in 1978 to examine the feasibility of construction, and operating a unique space-based laboratory – one dedicated, at least initially, to the isolation and analysis of potentially hazardous samples returned from Mars. This report does not argue that analysis of Mars samples should be done in space. Rather, it defines the characteristics of an orbiting laboratory should this be an option for active consideration for future MSR studies. Hence, a considerable effort was devoted to development of an appropriate series of tests to be performed on the sample (the quarantine protocol) and to design of the facility in which these tests would be conducted. The 10-week summer study involving 20 scientists and engineers was intended to be an intensive learning experience for the participants.
As a result of the Viking missions to Mars, a great deal of knowledge was gained about the surface features and composition the planet. However, one of the major questions that prompted the mission – Is there life on Mars? – was not conclusively answered. Because of that uncertainty, many scientists believed that the samples should be considered to be potentially hazardous until proven conclusively that they are not. This meant that adequate precautions need to be taken to protect the Earth’s biosphere until the samples are proved safe. Previously, consideration had been given to returning a sterilized sample. Alternatively, it had been suggested that the sample be held under quarantine in a maximum containment facility on Earth, possibly in a remote location, while undergoing analysis. No one had studied a third option, which was to perform hazard analysis of the sample before it was introduced into the terrestrial biosphere. Therefore, this summer study was convened in 1978 to examine the feasibility of receiving and analyzing returned Mars samples in an orbiting quarantine facility.
Mission objective: The purpose of the Orbiting Quarantine Facility (OQF) would be to detect the presence of biologically active agents – either life forms or uncontrolled (replicating) toxins – in the sample and to assess their potential impact on terrestrial systems. Only when the sample could be certified safe or controllable would it be transferred to laboratories on Earth for physical analysis.
The particular advantage of an orbiting facility over an Earth-based one is the flexibility it offers in the event that potentially pathogenic agents are present in the sample. With space as a buffer between such organisms and the terrestrial biosphere, the risk of terrestrial contamination is far lower. Complete characterization of the hazard such organisms might represent could thus be carried out without fear of a containment failure and possible contamination of the biosphere. Depending upon the results of testing, the options available for subsequent disposition of the sample would include: 1) unqualified release, 2) sterilization prior to release to Earth laboratories, 3) indefinite retention in orbit for prolonged study, and 4) in one extreme case, boosting the sample-containing facility into a distant orbit. A terrestrial quarantine facility could not offer such margins of security.
Mission scenario: The mission plan calls for the Space Shuttle to deliver the OQF, one or more components at a time, into near Earth orbit, where it will be assembled and manned. While awaiting the arrival of the Mars sample return vehicle (MSRV), the crew will conduct system tests and protocol review. The incoming MSRV, bearing the sample in a sealed canister in its crown, will be inserted into the same orbit in the vicinity of the OQF. An orbiting transfer vehicle comprised of an inertial upper stage engine (IUS) and remote teleoperated manipulator system (TELLE) will then link up with the MSRV, extract the sample canister, and deliver it to the OQF. Re-supply of the laboratory, replacement of crewmembers if necessary and eventual transport of the sample and crew to Earth will all be carried out via the Space Shuttle.
Modules: The proposed facility will consist of five Spacelab-derived modular units, each dedicated to a specific function or group of functions. The overall OQF will be free flying and will have a pinwheel configuration, with four of the cylindrical modules connected spoke-fashion to a central hub. Such a design produces low aerodynamic drag and is easy to assemble; it also allows efficient intermodule movement.
Central to the OQF mission is the Laboratory Module, in which the quarantine testing protocol will be carried out. This unit is equipped with a centrally located containment cabinet system for sample handling and processing. To obtain greater containment reliability than is offered by rubber gloves, specially designed metal bellows manipulative arms will be employed for access to the cabinets. Provision is made to maintain portions of the cabinetry under simulated martian environmental conditions, and a variety of other controlled environments required by the protocol can be produced. Clean air is continuously passed down the face of the cabinets, which are kept under negative pressure to eliminate leakage into the laboratory.
The high-hazard containment facility at the Centers for Disease Control and Prevention (CDC) served as a model for design of many of the physical features and procedures employed in the Laboratory Module. Based on CDC practices, the module itself acts as a barrier to contamination. All equipment and materials leaving the laboratory must be sterilized and packaged in leak-proof containers. Personnel entering or leaving the module must pass through a decontamination area, where they disrobe and take an air shower. The laboratory has independent life support, waste storage, and air filtration systems, and its atmospheric pressure is slightly lower than that of the other modules – all features that ensure effective containment. It is fully equipped for the performance of the quarantine protocol. A variety of microscopes, including scanning electron microscope, are provided. Cameras, spectrophotometers, centrifuge and vacuum devices, autoclaves, refrigerators, and all other necessary laboratory equipment and instruments are present as well.
Four other modules comprise the OQF. The Habitation Module is the crew’s living quarters. The OQF’s source of power is the Power Module. A general purpose Logistics Module provides storage for supplies and for waste materials generated in the Habitation Module (the Laboratory Module has independent waste storage). A Docking Module, serves as a common interface linking the other four.
Personnel: The crew would probably consist of five members: a commander (an astronaut/engineer) and four scientists (a medical doctor, a geobiologist, a biochemist, and a general biologist). Their tasks would be of two general types: facility operation and maintenance, and laboratory work. The allocation of functions and the scheduling of activities have been carefully worked out for each crewmember.
Experimental protocol: A number of factors impact the experimental design. For example, the protocol must take into account the limited amount of sample available for testing (probably about 100 g). In addition, it must ensure that the untested portion of the sample remains unaltered. It must include a sufficient range of tests to allow biologically active agents to be detected with a high degree of confidence. Equipment and experiments alike must be appropriate for use in the zero-g environment. The potential for human error must be minimal. And there must be enough flexibility designed into the protocol to permit a thorough characterization of life forms that might not closely resemble terrestrial forms.
Preliminary handling: The protocol begins with receipt of the sample canister from the IUS-TELLE. A collapsible structure in the OQF guides the transfer vehicle into position so that a trigger mechanism and clamp can acquire the canister and draw it into the OQF’s airlock. The sample canister is punctured with a needle and a sample of the gas within the canister is taken. A mechanism similar to a can opener then removes the bottom of the canister so that further gas sampling and removal of a subsample can take place. The subsample, consisting of approximately 100 g (or 10 percent) of the returned sample, is first analyzed for radioactivity and then transferred by a manipulator to a sample processing unit.
This unit is specially designed to permit the subsample to be manipulated in the absence of gravity, by means of centrifugal force. In the processing unit, the sample is sized and larger particles are viewed under a stereomicroscope to determine whether organisms or fossils are present. The larger-sized material is then evenly ground and the entire subsample is recombined and mixed. This mixture is dispensed to the five testing phases. Of the 100-g subsample, 46 g will be used in the various tests; 54 g will be held in reserve for possible further series of tests. The remaining 900 g of sample material is stored, unopened, under martian environmental conditions for later delivery to Earth (if approved).
Testing protocol: The five testing phases, and the specific experiments they include, are:
- Chemical analysis
- pH, Eh, and conductance tests
- aqueous extraction/element analysis
- organic mass spectrometry
- amino acid analysis
- stereomicroscopic examination
- scanning electron microscopy
- light microscope examination
- ultraviolet microscopy
- Metabolic testing
- gas exchange: dry
- CO 2 fixation: dry and moist
- enriched O 2 metabolism
- autoradiography of labeled samples
- Microbiological culturing
- growth on solid media
- Challenge culture
- The challenge culture phase involves the introduction of martian soil into cell cultures representing a cross section of terrestrial species. Although a number of organisms have already been tested in zero g to date, additional research is necessary to determine the most appropriate species to include in the challenge system. Such organisms must not only be representative of the Earth’s major phyla, but must also have a minimal reaction to zero g.
- If results of the preceding series of tests show no evidence of non-terrestrial life forms or replicating toxins, the sample will be approved for delivery to Earth, where more extensive physical, chemical, and biological studies will be undertaken. However, in the event that biological agents have been detected, second order tests would be initiated. The precise character of second-order testing cannot be established in advance. The type of tests would be determined on the basis of characteristics such organisms or toxins might possess.
Protocol planning: The protocol is a complex network of interdependent tests, with many activities being dependent upon the outcome of previous tests. To illustrate the sequence of events in the protocol, a tracking technique known as Graphical Evaluation and Review Technique (GERT) is used. GERT charts present test activities and information flows in their proper sequence, and use GERT ‘symbology’ to indicate the logic that determines each protocol step. By this means, it is possible to calculate the probabilities associated with different experimental outcomes, and thus to calculate the detection sensitivity of various tests. Detailed GERT charts are presented for each testing phase, along with tables of associated outcome probability analyses.
Conclusion: The facility and the experimental protocol described here offer a strong margin of protection against the possibility that a Mars sample would contain hazardous agents. They also offer a powerful hedge against the unknown, and against the fears that could easily develop if organisms showing signs of pathogenicity were detected in a sample undergoing study in a laboratory on Earth. With such a sample held in orbit, its disposition could be determined on the basis of analysis rather than emotion, and the scientific value of the returned sample could thus be maximized.