Planetary Protection Knowledge Gap Closure Enabling Crewed Missions to Mars.

As focus for exploration of Mars transitions from current robotic explorers to development of crewed missions, it remains important to protect the integrity of scientific investigations at Mars, as well as protect the Earth's biosphere from any potential harmful effects from returned martian material. This is the discipline of planetary protection, and the Committee on Space Research (COSPAR) maintains the consensus international policy and guidelines on how this is implemented. Based on National Aeronautics and Space Administration (NASA) and European Space Agency (ESA) studies that began in 2001, COSPAR adopted principles and guidelines for human missions to Mars in 2008. At that point, it was clear that to move from those qualitative provisions, a great deal of work and interaction with spacecraft designers would be necessary to generate meaningful quantitative recommendations that could embody the intent of the Outer Space Treaty (Article IX) in the design of such missions. Beginning in 2016, COSPAR then sponsored a multiyear interdisciplinary meeting series to address planetary protection "knowledge gaps" (KGs) with the intent of adapting and extending the current robotic mission-focused Planetary Protection Policy to support the design and implementation of crewed and hybrid exploration missions. This article describes the outcome of the interdisciplinary COSPAR meeting series, to describe and address these KGs, as well as identify potential paths to gap closure. It includes the background scientific basis for each topic area and knowledge updates since the meeting series ended. In particular, credible solutions for KG closure are described for the three topic areas of (1) microbial monitoring of spacecraft and crew health; (2) natural transport (and survival) of terrestrial microbial contamination at Mars, and (3) the technology and operation of spacecraft systems for contamination control. The article includes a KG data table on these topic areas, which is intended to be a point of departure for making future progress in developing an end-to-end planetary protection requirements implementation solution for a crewed mission to Mars. Overall, the workshop series has provided evidence of the feasibility of planetary protection implementation for a crewed Mars mission, given (1) the establishment of needed zoning, emission, transport, and survival parameters for terrestrial biological contamination and (2) the creation of an accepted risk-based compliance approach for adoption by spacefaring actors including national space agencies and commercial/nongovernment organizations.

Planetary protection technologies for planetary science instruments, spacecraft, and missions: Report of the NASA Planetary Protection Technology Definition Team (PPTDT).

Planetary bodies like Mars, Europa, and Enceladus pose the question, "How to study them without contaminating them and destroying future prospects to detect life, if it is there?" The natural trade-off, of course, is that the cleaner your spacecraft, the more you can explore such a body without risk of contaminating it. As chartered by NASA Headquarters, the Planetary Protection Technology Definition Team (PPTDT) was asked to provide a report covering six different areas related to the engineering and technology challenges of implementing planetary protection requirements on solar system exploration missions.

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

This paper treats the very specific history of one aspect of space policy and how it, or more specifically its name, developed in the first two decades of the Space Age. The concepts of preventing the biological and organic contamination of other planetary bodies, which also protect the biosphere from the consequences of finding extraterrestrial life and returning it to Earth, were established in the late 1950s with the beginning of the Space Age. Within their first decade, those concepts were labeled "planetary quarantine," a name that suggested the concepts but unfortunately came with latent baggage of its own. Over time, that sobriquet was replaced by the more prosaic "planetary protection," which has less of a baggage problem and has come to be used in common parlance to describe this contamination avoidance within the spaceflight community. This paper does not duplicate material found in the "official" NASA history of planetary protection (Meltzer, 2011 ), which covered this specific subject only broadly, nor was the same material presented by Meltzer's predecessor (Phillips, 1974 ), who could not cover it because it had not happened yet.

It's Time to Develop a New "Draft Test Protocol" for a Mars Sample Return Mission (or Two ).

The last time NASA envisioned a sample return mission from Mars, the development of a protocol to support the analysis of the samples in a containment facility resulted in a "Draft Test Protocol" that outlined required preparations "for the safe receiving, handling, testing, distributing, and archiving of martian materials here on Earth" (Rummel et al., 2002 ). This document comprised a specific protocol to be used to conduct a biohazard test for a returned martian sample, following the recommendations of the Space Studies Board of the US National Academy of Sciences. Given the planned launch of a sample-collecting and sample-caching rover (Mars 2020) in 2 years' time, and with a sample return planned for the end of the next decade, it is time to revisit the Draft Test Protocol to develop a sample analysis and biohazard test plan to meet the needs of these future missions. Key Words: Biohazard detection-Mars sample analysis-Sample receiving facility-Protocol-New analytical techniques-Robotic sample handling. Astrobiology 18, 377-380.

Aspergillus penicillioides differentiation and cell division at 0.585 water activity.

Water availability acts as the most stringent constraint for life on Earth. Thus, understanding the water relations of microbial extremophiles is imperative to our ability to increase agricultural productivity (e.g., by enhancing the processing and turnover of dead organic matter in soils of arid regions), reduce human exposure to mycotoxins in buildings and our food-supply chain, prevent the spoilage of foods/animal feeds, books, museum specimens and artworks and better control microbiology of industrial fermentations. Only a small number of microbial systems can retain activity at <0.710 water activity (ISME J 2015 9: 1333-1351). It has long-been considered that the most resilient of these is Xeromyces bisporus, which inhabits sugar-rich substrates (Appl Environ Microbiol 1968 16: 1853-1858). The current study focused on germination of Aspergillus penicillioides, a xerophile which is also able to grow under low humidity and saline conditions. Investigations of germination differed from those reported earlier: firstly, aerially borne conidia were harvested, and then used for inoculations, in their dry condition; secondly, cultures were incubated at 24°C, i.e. below optimum germination temperature, to minimize the possibility of water loss from the substrate; thirdly, cultures remained sealed throughout the 73-day study period (microscopic examination was carried out directly 48 through the Petri plate lid); fourthly, the germination parameters determined were: rates and extent of conidial swelling, production of differentiated germination-structures and septate germlings, and subsequent development of mycelium and/or sporulation; fifthly, assessments were carried out over a range of water-activity values and time points to obtain a complete profile of the germination process. Conidia swelled, formed differentiated germination-structures and then produced septate germlings at a water-activity of just 0.585 (≡58.5% relative humidity), outside the currently understood thermodynamic window for life. Furthermore, analyses of these data suggest a theoretical water-activity minimum of 0.565 for germination of A. penicilliodes. In relation to astrobiology, these findings have an application in understanding the limits to life in extraterrestrial environments. In light of current plans for exploration missions to Mars and other places, and the need to safeguard martian scientific sites and potential resources (including water) for future human habitation, a knowledge-based and effective policy for planetary protection is essential. As it is, Mars-bound spacecraft may frequently be contaminated with aspergilli (including A. penicillioides) and other organisms which, when transported to other planetary bodies, pose a contamination risk. In crafting countermeasures to offset this, it is important to know as precisely as possible the capabilities of these potential interplanetary visitors.

Glycerol enhances fungal germination at the water-activity limit for life.

For the most-extreme fungal xerophiles, metabolic activity and cell division typically halts between 0.700 and 0.640 water activity (approximately 70.0-64.0% relative humidity). Here, we investigate whether glycerol can enhance xerophile germination under acute water-activity regimes, using an experimental system which represents the biophysical limit of Earth's biosphere. Spores from a variety of species, including Aspergillus penicillioides, Eurotium halophilicum, Xerochrysium xerophilum (formerly Chrysosporium xerophilum) and Xeromyces bisporus, were produced by cultures growing on media supplemented with glycerol (and contained up to 189 mg glycerol g dry spores-1 ). The ability of these spores to germinate, and the kinetics of germination, were then determined on a range of media designed to recreate stresses experienced in microbial habitats or anthropogenic systems (with water-activities from 0.765 to 0.575). For A. penicillioides, Eurotium amstelodami, E. halophilicum, X. xerophilum and X. bisporus, germination occurred at lower water-activities than previously recorded (0.640, 0.685, 0.651, 0.664 and 0.637 respectively). In addition, the kinetics of germination at low water-activities were substantially faster than those reported previously. Extrapolations indicated theoretical water-activity minima below these values; as low as 0.570 for A. penicillioides and X. bisporus. Glycerol is present at high concentrations (up to molar levels) in many types of microbial habitat. We discuss the likely role of glycerol in expanding the water-activity limit for microbial cell function in relation to temporal constraints and location of the microbial cell or habitat. The findings reported here have also critical implications for understanding the extremes of Earth's biosphere; for understanding the potency of disease-causing microorganisms; and in biotechnologies that operate at the limits of microbial function.

A new analysis of Mars "Special Regions": findings of the second MEPAG Special Regions Science Analysis Group (SR-SAG2).

A committee of the Mars Exploration Program Analysis Group (MEPAG) has reviewed and updated the description of Special Regions on Mars as places where terrestrial organisms might replicate (per the COSPAR Planetary Protection Policy). This review and update was conducted by an international team (SR-SAG2) drawn from both the biological science and Mars exploration communities, focused on understanding when and where Special Regions could occur. The study applied recently available data about martian environments and about terrestrial organisms, building on a previous analysis of Mars Special Regions (2006) undertaken by a similar team. Since then, a new body of highly relevant information has been generated from the Mars Reconnaissance Orbiter (launched in 2005) and Phoenix (2007) and data from Mars Express and the twin Mars Exploration Rovers (all 2003). Results have also been gleaned from the Mars Science Laboratory (launched in 2011). In addition to Mars data, there is a considerable body of new data regarding the known environmental limits to life on Earth-including the potential for terrestrial microbial life to survive and replicate under martian environmental conditions. The SR-SAG2 analysis has included an examination of new Mars models relevant to natural environmental variation in water activity and temperature; a review and reconsideration of the current parameters used to define Special Regions; and updated maps and descriptions of the martian environments recommended for treatment as "Uncertain" or "Special" as natural features or those potentially formed by the influence of future landed spacecraft. Significant changes in our knowledge of the capabilities of terrestrial organisms and the existence of possibly habitable martian environments have led to a new appreciation of where Mars Special Regions may be identified and protected. The SR-SAG also considered the impact of Special Regions on potential future human missions to Mars, both as locations of potential resources and as places that should not be inadvertently contaminated by human activity.

Carl Woese, Dick Young, and the roots of astrobiology.

The beginning of the space age in the late 1950s gave rise to innovative and interdisciplinary research concepts and perspectives, including the concept of "exobiology" as a way to approach the fundamental aspects of biology through a study of life outside of the Earth, if it existed. This concept was embodied by NASA into its formal Exobiology Program and into the philosophy of the program both before and after the Viking missions that were launched to Mars to search for signs of life in 1975. Due to both management flexibility and an acceptance of the interdisciplinary nature of the problem of "life in the universe," NASA program managers, and particularly Richard S Young who ran the Exobiology Program beginning 1967, have made some excellent investments in paradigm altering science of great use both on Earth and on future space missions. The work of Carl Woese is one such example, which has revolutionized our understanding of the microbial world and the relationships of all life on Earth.

A THEORY OF FAUNAL BUILDUP FOR COMPETITION COMMUNITIES.

Invasion-structured communities have more species than do coevolution-structured communities assembled using the same resource distribution. Species in invasion-structured communities are tightly packed, occupying the upper portion of the resource axis; species in coevolution-structured communities are more widely spaced, and most are located in the lower portion of the resource axis. As a consequence, coevolution-structured communities tend to be more stable than comparable invasion-structured communities, but more open to invasion. Both invasion-structured and coevolution-structured communities have niche separations that are significantly different than would be expected if species were assorted at random. Two-species communities formed by the invasion-only algorithm under asymmetric competition had the majority of their niche separations in the range 0-0.5. All other communities had niche separations that were greater than expected. The most common separations were in the range 1.0-3.5. Thus, while not a common feature of many communities, nicheseparation patterns similar to those described by Hutchinson (1959) appear as an "ensemble" property of many communities. The faunal-buildup graphs formed by the coevolutionary algorithm differ from those formed by the invasion-only algorithm, showing community cycling whenever asymmetric competition is present. Through this cycling behavior the coevolutionary faunal-buildup algorithm provides both a theoretical basis for Wilson's (1959) taxon cycle and a hypothesis explaining the distribution of Anolis lizards in the Lesser Antilles.