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![Shaded-relief map of Mars showing the distribution of the youngest volcanic rocks on Mars [map unit AEC 3 from Tanaka et al. (2005)]. These volcanics are of Late Amazonian age, which includes geologic time from the present to about 300-500 Ma. Although there is no current indication that any of these rocks are as young as 1,000 years, we cannot say with certainty that the activity in this volcanic region has ceased, and that future eruptions are impossible. (For base map details, see legend to Fig. 10.)](profile/Andrew-Schuerger/publication/230720199/figure/fig11/AS:647943560364032@1531493191460/Shaded-relief-map-of-Mars-showing-the-distribution-of-the-youngest-volcanic-rocks-on-Mars.png)
Shaded-relief map of Mars showing the distribution of the youngest volcanic rocks on Mars [map unit AEC 3 from Tanaka et al. (2005)]. These volcanics are of Late Amazonian age, which includes geologic time from the present to about 300-500 Ma. Although there is no current indication that any of these rocks are as young as 1,000 years, we cannot say with certainty that the activity in this volcanic region has ceased, and that future eruptions are impossible. (For base map details, see legend to Fig. 10.)
Source publication
Current planetary protection (PP) protection policy designates a categorization IVc for spacecraft
potentially entering into a “special region” of Mars that requires specific constraints on spacecraft development and operations. National Aeronautics and Space Administration (NASA) requested that Mars Exploration Program Analysis Group (MEPAG) chart...
Similar publications
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...
Citations
... − Lower limit for water activity: 0.5 − Lower limit for temperature: -28 • C" These values come from a robust review of literature and community consensus discussions over the last two decades, mostly in efforts to establish parameters for special regions on Mars (regions where terrestrial organisms are likely to propagate, or a region interpreted to have a high potential for the existence of extant martian life). Beaty et al. (2006) reported on the outcome of a MEPAG effort that found that experiments and field observations had failed to show microbial reproduction at temperatures below -15 • C. They further found that the lower limit of life with regards to water activity (A w ) was 0.62. ...
... In addition, part of the evaluation process is to model how the launched spacecraft bioburdens will survive the Earth-Mars transit Department of Plant Pathology, University of Florida, Space Life Sciences Lab, Exploration Park, Merritt Island, Florida, USA. and the surface environment once spacecraft land. Several studies have evaluated the biocidal nature of the martian surface and set limits for temperature, water activity, UV irradiation, ionizing radiation, and salt tolerance for expected microbial survival and growth on Mars (e.g., Schuerger et al., 2003Schuerger et al., , 2005Schuerger et al., , 2006Beaty et al., 2006;Kminek et al., 2010;Rummel et al., 2014;Cockell et al., 2016). In these studies, between 15 and 22 biocidal factors are listed that will work alone or in combination to inactivate landed bioburdens from Earth. ...
Modeling risks for the forward contamination of planetary surfaces from endemic bioburdens on landed spacecraft requires precise data on the biocidal effects of space factors on microbial survival. Numerous studies have been published over the preceding 60 years on the survival of diverse microorganisms exposed to solar heating, solar ultraviolet (UV) irradiation, vacuum, ionizing radiation, desiccation, and many other planetary surface conditions. These data were generated with diverse protocols that can impair the interpretations of the results due to dynamic experimental errors inherent in all lab protocols. The current study (1) presents data on how metal surfaces can affect spore adhesion, (2) proposes doping and extraction protocols that can achieve very high recovery rates (close to 100%) from aluminum coupons with four Bacillus spp., (3) establishes a timeline in which dried spores on aluminum coupons should be used to minimize aging effects of spore monolayers, (4) confirms that vacuum alone does not dislodge spores dried on aluminum coupons, and (5) establishes that multiple UV irradiation sources yield similar results if properly cross-calibrated. The protocols are given to advance discussions in the planetary protection community on how to standardize lab protocols to align results from diverse labs into a coherent interpretation of how space conditions will degrade microbial survival over time.
... NASA and other space agencies have consistently reported that Bacillus spores, subjected to years vacuum in space, cosmic radiation and extreme temperatures, can survive, if they are shielded by the exterior of a spacecraft. We refer readers to Beaty [6], Fischer et al. [23], Martinez and Renno [37], Summons et al. [46], Michalski [39] and Debus [18] for details. ...
The increase in readily available computational power raises the possibility that direct agent-based modeling can play a key role in the analysis of epidemiological population dynamics. Specifically, the objective of this work is to develop a robust agent-based computational framework to investigate the emergent structure of Susceptible-Infected-Removed/Recovered (SIR)-type populations and variants thereof, on a global planetary scale. To accomplish this objective, we develop a planet-wide model based on interaction between discrete entities (agents), where each agent on the surface of the planet is initially uninfected. Infections are then seeded on the planet in localized regions. Contracting an infection depends on the characteristics of each agent—i.e. their susceptibility and contact with the seeded, infected agents. Agent mobility on the planet is dictated by social policies, for example such as “shelter in place”, “complete lockdown”, etc. The global population is then allowed to evolve according to infected states of agents, over many time periods, leading to an SIR population. The work illustrates the construction of the computational framework and the relatively straightforward application with direct, non-phenomenological, input data. Numerical examples are provided to illustrate the model construction and the results of such an approach.
... In order for bacteria on spacecraft to survive and grow on Mars, numerous conditions must be present to permit metabolism, cell proliferation, and adaptation of Earth microorganisms. Various studies have discussed up to 22 biocidal or inhibitory factors that are likely present on Mars (reviewed in 1,[10][11][12][13]. Recent experiments with bacteria exposed to low-pressure (7 hPa), low-temperature (0 °C), and a CO 2 -enriched anoxic atmosphere (henceforth called low-PTA conditions) have demonstrated that at least 30 bacterial species from 10 genera are capable of metabolism and growth under Mars-relevant low-PTA conditions. ...
... Results suggest that many of the culturable chemoorganotrophic bacteria present on spacecraft at launch may not pose a significant risk for potential proliferation once transferred to Mars. Although we tested the effects of only three environmental factors and five different TSA media on the growth of 125 spacecraft bacteria under simulated low-PTA conditions, the case for the proliferation of spacecraft bacteria on Mars is less likely than described here because other biocidal and inhibitory factors are present on Martian surface (see 1,10 ). For example, up to 22 biocidal and inhibitory factors have been discussed in papers on the habitability of the Martian surface (e.g., 1,10-13 ). ...
To protect Mars from microbial contamination, research on growth of microorganisms found in spacecraft assembly clean rooms under simulated Martian conditions is required. This study investigated the effects of low atmospheric pressure on the growth of chemoorganotrophic spacecraft bacteria and whether the addition of Mars relevant anaerobic electron acceptors might enhance growth. The 125 bacteria screened here were recovered from actual Mars spacecraft. Growth at 7 hPa, 0 °C, and a CO2-enriched anoxic atmosphere (called low-PTA conditions) was tested on five TSA-based media supplemented with anaerobic electron acceptors. None of the 125 spacecraft bacteria showed active growth under the tested low-PTA conditions and amended media. In contrast, a decrease in viability was observed in most cases. Growth curves of two hypopiezotolerant strains, Serratia liquefaciens and Trichococcus pasteurii, were performed to quantify the effects of the added anaerobic electron acceptors. Slight variations in growth rates were determined for both bacteria. However, the final cell densities were similar for all media tested, indicating no general preference for any specific anaerobic electron acceptor. By demonstrating that a broad diversity of chemoorganotrophic and culturable spacecraft bacteria do not grow under the tested conditions, we conclude that there may be low risk of growth of chemoorganotrophic bacteria typically recovered from Mars spacecraft during planetary protection bioburden screenings.
... Mars has been of scientific interest with questions regarding its formation, evolution and potential cessation of life. Factors that appear to facilitate survival of primitive organisms include water availability, favourable chemical environment, suitable energy source for metabolism and favourable physical conditions including temperature, pressure and limited radiation exposure (15). Given the drive and inevitability of a manned mission to Mars, solutions must be found to maximise the safety of astronauts. ...
Aim
The purpose of this research was to employ radiobiological as well as physics principles to investigate materials for an intravehicular spacesuit and a “storm shelter” that might minimize radiation exposure to astronauts during a mission to Mars.
Methods
NASA’s OLTARIS space radiation modelling tool was used to investigate thirty-two potential shielding materials. Radiation exposure was estimated during a return transit to Mars of 360 days duration. We assessed each shielding material by its ability to decrease effective radiation dose received by a computerized phantom during the constant galactic cosmic radiation (GCR) and a single solar particle event (SPE). For the “storm shelter” a large liquid fuel tank was modelled adjacent to the phantom during a SPE.
Results
At standard conditions, graphene appeared to be a promising shielding material when comparing other materials including polyethylene and lithium. The shielding efficacy became comparable to polyethylene but inferior to lithium when materials were normalised to 10g/cm2, 20g/cm2 and 30g/cm2. The graphene around the phantom reduced effective dose from GCR compared with an unshielded transit by 34% (162mSv/yr vs 213.3mSv/yr). A “storm shelter” using a liquid fuel tank was positioned to create a barrier adjacent to the astronauts. The liquid barrier reduced effective dose by 98.8% (44mSv vs 3614mSv). Other mitigation strategies were deduced and divided into launch, transit and habitation considerations.
Conclusion
A graphene based intravehicular suit could decrease astronaut exposure to harmful radiation during transit to Mars. A storm shelter using fuel as a barrier also decreased radiation dose during a solar particle event.
... A Special Region on Mars is defined as an environment that has conditions to allow terrestrial life to propagate. This is currently defined as temperatures warm enough, and water activity high enough for reproduction (Beaty et al., 2006;Rummel et al., 2014). Although the focus of these two important Mars Exploration Program Analysis Group (MEPAG) studies was naturally occurring Special Regions, Rummel et al., 2014 also presented preliminary analysis of the possibility of what they called "Spacecraft-Induced Special Regions" (see especially their Finding 5.1). ...
The Joint Workshop on Induced Special Regions convened scientists and planetary protection experts to assess the potential of inducing special regions through lander or rover activity. An Induced Special Region is defined as a place where the presence of the spacecraft could induce water activity and temperature to be sufficiently high and persist for long enough to plausibly harbor life. The questions the workshop participants addressed were: (1) What is a safe stand-off distance, or formula to derive a safe distance, to a purported special region? (2) Questions about RTGs (Radioisotope Thermoelectric Generator), other heat sources, and their ability to induce special regions. (3) Is it possible to have an infected area on Mars that does not contaminate the rest of Mars? The workshop participants reached a general consensus addressing the posed questions, in summary: (1) While a spacecraft on the surface of Mars may not be able to explore a special region during the prime mission, the safe stand-off distance would decrease with time because the sterilizing environment, that is the martian surface would progressively clean the exposed surfaces. However, the analysis supporting such an exploration should ensure that the risk to exposing interior portions of the spacecraft (i.e., essentially unsterilized) to the martian surface is minimized. (2) An RTG at the surface of Mars would not create a Special Region but the short-term result depends on kinetics of melting, freezing, deliquescence, and desiccation. While a buried RTG could induce a Special Region, it would not pose a long-term contamination threat to Mars, with the possible exception of a migrating RTG in an icy deposit. (3) Induced Special Regions can allow microbial replication to occur (by definition), but such replication at the surface is unlikely to globally contaminate Mars. An induced subsurface Special Region would be isolated and microbial transport away from subsurface site is highly improbable.
... In 2005, NASA adopted COSPAR's concept of special regions into its planetary protection policy, defining specific parameters like duration (100 years), maximum spacecraft penetration depth (5 m into the crust), and survival limits for terrestrial life (−15°C temperature, or −20°C including margin; and 0.62 water activity, or 0.5 including margin) [15]. ...
A fundamental requirement for space missions designed to touch “potential habitats” is the single number 10⁻⁴, the allowable probability of a single Earth organism contaminating the potential habitat. Many aspects of a mission that affect its complexity and cost – hardware design and manufacture, assembly and test, and mission operations – are driven by this value, so it is important, on the threshold of an era of exploring ocean worlds, to have confidence in it. Yet despite its long pedigree and occasional reviews, we find that the current requirement lacks programmatically defensible justification. At issue are three weaknesses: 1) microbial biology, in particular the science of extremophiles, is a rapidly changing field; 2) forward contamination is both a scientific and an ethical issue, yet no ethics-based conversation is apparent within policy-setting circles; 3) because of these two factors, policy-setting cannot be static. We review the history of the requirement; how the evolving understanding of biology could drive it up or down; how the forward-contamination hazard relates to risk-management practice and to the ethics profession; and how a contemporary stakeholder conversation could adapt lessons already learned by other fields.
... Recent studies on planetary protection issues related to Special Regions on Mars have identified approximately 20 biocidal or inhibitory factors that might negatively impact the survival, metabolism, and growth of microorganisms on the martian surface ( Beaty et al., 2006;Rummel et al., 2014;Schuerger et al., 2013 ). Other studies have modeled environmental conditions, energy sources, and nutrient requirements that are likely required to promote the growth of Earth microorganisms on Mars http://dx.doi.org/10.1016/j.icarus.2017.02.023 0019-1035/© 2017 Elsevier Inc. ...
The search for an extant microbiota on Mars depends on exploring sites that contain transient or permanent liquid water near the surface. Examples of possible sites for liquid water may be active recurring slope lineae (RSL) and fluid inclusions in ice or salt deposits. The presence of saline fluids on Mars will act to depress the freezing points of liquid water to as low as ‒60 °C, potentially permitting the metabolism and growth of halophilic microorganisms to temperatures significantly below the freezing point of pure water at 0 °C. In order to predict the potential risks of forward contamination by Earth microorganisms to subsurface sites on Mars with liquid brines, experiments were designed to characterize the short-term survival of two bacteria in aqueous soil solutions from six analog soils. The term ‘‘soil’’ is used here to denote any loose, unconsolidated matrix with no implications for the presence or absence of organics or biology. The analog soils were previously described (Schuerger et al., 2012, Planetary Space Sci., 72, 91–101), and represented crushed Basalt (benign control), Salt, Acid, Alkaline, Aeolian, and Phoenix analogs on Mars. The survival rates of spores of Bacillus subtilis and vegetative cells of Enterococcus faecalis were tested in soil solutions from each analog at 24, 0, or ‒70 °C for time periods up to 28 d. Survival of dormant spores of B. subtilis were mostly unaffected by incubation in the aqueous extracts of all six Mars analogs. In contrast, survival rates of E. faecalis cells were suppressed by all soil solutions when incubated at 24 °C but improved at 0 and ‒70 °C, except for assays in the Salt and Acid soil solutions in which most cells were killed. Results suggest that Earth microorganisms that form spores may persist in liquid brines on Mars better than non-spore forming species, and thus, spore-forming species may pose a potential forward contamination risk to sites with liquid brines.
... Thus, while there exist test protocols to guard against such contamination, for example plans developed by the NASA Planetary Protection Office, concerns remain. We refer the reader to Beaty [3], Fischer et al. [4], Martinez and Renno [2], Summons et al. [5], Michalski [6] and Debus [7] for details. ...
The increase in readily available computational power raises the possibility that robust agent-based modeling can play a productive role in the analysis of population dynamics. Accordingly, the objective of this work is to develop a robust agent-based computational framework to investigate the emergent structure of initially intermeshed hostile, competing, populations on a global scale. Specifically, we develop a model based on discrete entities (agents), each with their own interaction rules with their immediate neighbors, innate skill sets, reproductive rates, mobility and lifespans to represent a population. The global population is then allowed to evolve according to these local rules over many generations. The biological systems-level applications are numerous, stemming from human conflict on the macroscale to microbes on the microscale. Numerical examples are provided to illustrate the model construction and the results of such an approach.
... The Mars Exploration Program Advisory Committee (MEPAG) identified "Special Regions" on Mars that would be of greatest interest to astrobiologists, while providing guidelines for protecting Mars and Earth from biological contamination. 6 The Phoenix Lander (located at 68.219 o North; 234.249 o East) 7 documented near-surface regions of ground ice within the accessible excavation area of its sample scoop ( 3 m 2 ), at a mean depth of 4.6 cm. When detected, the ice state varied considerably, ranging from what appeared to be nearly pure water ice, through various mixtures of ice, salts and regolith. ...
... The Phoenix data motivated a re-examination of the earlier Mars Special Regions report. 6,10 The revised MEPAG protocols acknowledge that during cold humid nights, deliquescence can occur on hardware surfaces that have been contaminated by indigenous perchlorate salt debris. 11 In order to avoid biological contamination, they recommended that efforts be made to minimize in situ heating of regolith to temperatures above 255 K (considered to be the nominal temperature below which most brine solutions freeze). ...
