33 items pinned
Mars Before the Space Age
Abstract: Mars has surely been scrutinised since the dawn of humankind. In the 16th century Tycho Brahe made accurate observations of the position of Mars that enabled Johannes Kepler to obtain his first two laws of planetary motion. In the 17th century the first telescope observations were made, but very little surface detail could be discerned. Throughout the 18th and 19th centuries telescopes improved, revealing many dark areas on the red tinted surface. After the close opposition of 1877 Giovanni Schiaparelli announced about 40 canali on Mars. This led to the saga of the canals of Mars, laid to rest in 1971 when Mariner 9 made observations from Martian orbit showing that the canali/canals of Mars do not exist. Belief that there was life on Mars was widespread in the 19th century, including the view that the dark areas were some form of plant life. This view persisted until Mariner 4 flew past Mars in 1965 and discovered a far thinner atmosphere than previously thought, with impact craters dominating the images. It was Mariner 9 that revealed much more promising landscapes. Thus, the contemporary era of Mars exploration began. Our picture of Mars today is not only much more complete that that before Mariner 4, in several ways it is quite different. The belief however, that there may be life on Mars persists - subsurface life cannot be ruled out and, failing that, there might be ancient fossils on Mars.
Pub.: 14 Jan '09, Pinned: 09 Sep '16
The MARS2013 Mars analog mission.
Abstract: We report on the MARS2013 mission, a 4-week Mars analog field test in the northern Sahara. Nineteen experiments were conducted by a field crew in Morocco under simulated martian surface exploration conditions, supervised by a Mission Support Center in Innsbruck, Austria. A Remote Science Support team analyzed field data in near real time, providing planning input for the management of a complex system of field assets; two advanced space suit simulators, four robotic vehicles, an emergency shelter, and a stationary sensor platform in a realistic work flow were coordinated by a Flight Control Team. A dedicated flight planning group, external control centers for rover tele-operations, and a biomedical monitoring team supported the field operations. A 10 min satellite communication delay and other limitations pertinent to human planetary surface activities were introduced. The fields of research for the experiments were geology, human factors, astrobiology, robotics, tele-science, exploration, and operations research. This paper provides an overview of the geological context and environmental conditions of the test site and the mission architecture, in particular the communication infrastructure emulating the signal travel time between Earth and Mars. We report on the operational work flows and the experiments conducted, including a deployable shelter prototype for multiple-day extravehicular activities and contingency situations.
Pub.: 16 May '14, Pinned: 09 Sep '16
Robust, affordable, semi-direct mars mission
Abstract: A new architecture is proposed for the first manned Mars mission, based on current NASA developments (SLS and Orion), chemical propulsion for interplanetary transit, aerocapture for all vehicles, a split strategy, and a long stay on the surface. Two important choices make this architecture affordable and appropriate for the first mission. The first is splitting the Earth return vehicle into two parts that are launched separately and dock in Mars orbit. This is necessary to make aerocapture feasible and efficient, which considerably reduces mass. The second is reducing the crew to 3 astronauts. This simplifies the mission and reduces the SLS payload mass under the 45-metric ton limit for a direct TMI (trans-Mars injection) burn without LEO assembly. Only 4 SLS launches are required. The first takes the Mars ascent vehicle and in situ resource utilization systems to the planet’s surface. The second takes the first part of the Earth return vehicle, the habitat, into Mars orbit. Two years later, two further SLS launches take a dual-use habitat (outbound trip and surface), Orion, and an enhanced service module to LEO, and then into Mars orbit, followed by the landing of the habitat on the surface. Transit time is demonstrated to be easily reduced to less than 6 months, with relatively low impact on propellant mass and none at all on the architecture.
Pub.: 02 Jun '16, Pinned: 09 Sep '16
Earth--Mars Transfers with Ballistic Capture
Abstract: We construct a new type of transfer from the Earth to Mars, which ends in ballistic capture. This results in a substantial savings in capture $\Delta v$ from that of a classical Hohmann transfer under certain conditions. This is accomplished by first becoming captured at Mars, very distant from the planet, and then from there, following a ballistic capture transfer to a desired altitude within a ballistic capture set. This is achieved by manipulating the stable sets, or sets of initial conditions whose orbits satisfy a simple definition of stability. This transfer type may be of interest for Mars missions because of lower capture $\Delta v$, moderate flight time, and flexibility of launch period from the Earth.
Pub.: 27 Oct '14, Pinned: 09 Sep '16
Comparison of Four Space Propulsion Methods for Reducing Transfer Times of Manned Mars Mission
Abstract: We assess the possibility of reducing the travel time of a manned mission to Mars by examining four different propulsion methods, and keeping the mass at departure under 2,500 tonnes, for a fixed architecture. We evaluated representative systems of three different state of the art technologies (chemical, nuclear thermal, and electric), and one advance technology, the "Pure Electro-Magnetic Thrust" (PEMT) concept (proposed by Rubbia). A mission architecture mostly based on the Design Reference Architecture 5.0 is assumed in order to estimate the mass budget, that influences the performance of the propulsion system. Pareto curves of the duration of the mission and time of flight versus mass of mission are drawn. We conclude that the ion engine technology, combined with the classical chemical engine, yields the shortest mission times for this architecture with the lowest mass, and that chemical propulsion alone is the best to minimise travel time. The results obtained using the PEMT suggest that it could be a more suitable solution for farther destinations than Mars.
Pub.: 26 Nov '15, Pinned: 09 Sep '16
EMMI - Electric Solar Wind Sail Facilitated Manned Mars Initiative
Abstract: The novel propellantless electric solar wind sail concept promises efficient low thrust transportation in the Solar System outside Earth's magnetosphere. Combined with asteroid mining to provide water and synthetic cryogenic rocket fuel in orbits of Earth and Mars, possibilities for affordable continuous manned presence on Mars open up. Orbital fuel and water enable reusable bidirectional Earth-Mars vehicles for continuous manned presence on Mars and allow smaller fuel fraction of spacecraft than what is achievable by traditional means. Water can also be used as radiation shielding of the manned compartment, thus reducing the launch mass further. In addition, the presence of fuel in the orbit of Mars provides the option for an all-propulsive landing, thus potentially eliminating issues of heavy heat shields and augmenting the capability of pinpoint landing. With this E-sail enabled scheme, the recurrent cost of continuous bidirectional traffic between Earth and Mars might ultimately approach the recurrent cost of running the International Space Station, ISS.
Pub.: 20 Feb '15, Pinned: 09 Sep '16
How safe is safe enough? Radiation risk for a human mission to Mars.
Abstract: Astronauts on a mission to Mars would be exposed for up to 3 years to galactic cosmic rays (GCR)--made up of high-energy protons and high charge (Z) and energy (E) (HZE) nuclei. GCR exposure rate increases about three times as spacecraft venture out of Earth orbit into deep space where protection of the Earth's magnetosphere and solid body are lost. NASA's radiation standard limits astronaut exposures to a 3% risk of exposure induced death (REID) at the upper 95% confidence interval (CI) of the risk estimate. Fatal cancer risk has been considered the dominant risk for GCR, however recent epidemiological analysis of radiation risks for circulatory diseases allow for predictions of REID for circulatory diseases to be included with cancer risk predictions for space missions. Using NASA's models of risks and uncertainties, we predicted that central estimates for radiation induced mortality and morbidity could exceed 5% and 10% with upper 95% CI near 10% and 20%, respectively for a Mars mission. Additional risks to the central nervous system (CNS) and qualitative differences in the biological effects of GCR compared to terrestrial radiation may significantly increase these estimates, and will require new knowledge to evaluate.
Pub.: 23 Oct '13, Pinned: 09 Sep '16
Review of NASA approach to space radiation risk assessments for Mars exploration.
Abstract: Long duration space missions present unique radiation protection challenges due to the complexity of the space radiation environment, which includes high charge and energy particles and other highly ionizing radiation such as neutrons. Based on a recommendation by the National Council on Radiation Protection and Measurements, a 3% lifetime risk of exposure-induced death for cancer has been used as a basis for risk limitation by the National Aeronautics and Space Administration (NASA) for low-Earth orbit missions. NASA has developed a risk-based approach to radiation exposure limits that accounts for individual factors (age, gender, and smoking history) and assesses the uncertainties in risk estimates. New radiation quality factors with associated probability distribution functions to represent the quality factor's uncertainty have been developed based on track structure models and recent radiobiology data for high charge and energy particles. The current radiation dose limits are reviewed for spaceflight and the various qualitative and quantitative uncertainties that impact the risk of exposure-induced death estimates using the NASA Space Cancer Risk (NSCR) model. NSCR estimates of the number of "safe days" in deep space to be within exposure limits and risk estimates for a Mars exploration mission are described.
Pub.: 01 Jan '15, Pinned: 09 Sep '16
Exercise in space: the European Space Agency approach to in-flight exercise countermeasures for long-duration missions on ISS.
Abstract: To counteract microgravity (µG)-induced adaptation, European Space Agency (ESA) astronauts on long-duration missions (LDMs) to the International Space Station (ISS) perform a daily physical exercise countermeasure program. Since the first ESA crewmember completed an LDM in 2006, the ESA countermeasure program has strived to provide efficient protection against decreases in body mass, muscle strength, bone mass, and aerobic capacity within the operational constraints of the ISS environment and the changing availability of on-board exercise devices. The purpose of this paper is to provide a description of ESA's individualised approach to in-flight exercise countermeasures and an up-to-date picture of how exercise is used to counteract physiological changes resulting from µG-induced adaptation. Changes in the absolute workload for resistive exercise, treadmill running and cycle ergometry throughout ESA's eight LDMs are also presented, and aspects of pre-flight physical preparation and post-flight reconditioning outlined.With the introduction of the advanced resistive exercise device (ARED) in 2009, the relative contribution of resistance exercise to total in-flight exercise increased (33-46 %), whilst treadmill running (42-33 %) and cycle ergometry (26-20 %) decreased. All eight ESA crewmembers increased their in-flight absolute workload during their LDMs for resistance exercise and treadmill running (running speed and vertical loading through the harness), while cycle ergometer workload was unchanged across missions.Increased or unchanged absolute exercise workloads in-flight would appear contradictory to typical post-flight reductions in muscle mass and strength, and cardiovascular capacity following LDMs. However, increased absolute in-flight workloads are not directly linked to changes in exercise capacity as they likely also reflect the planned, conservative loading early in the mission to allow adaption to µG exercise, including personal comfort issues with novel exercise hardware (e.g. the treadmill harness). Inconsistency in hardware and individualised support concepts across time limit the comparability of results from different crewmembers, and questions regarding the difference between cycling and running in µG versus identical exercise here on Earth, and other factors that might influence in-flight exercise performance, still require further investigation.
Pub.: 05 Aug '16, Pinned: 09 Sep '16
A voyage to Mars: Space radiation, aging, and nutrition
Abstract: On exploratory class missions, such as a voyage to Mars, astronauts will be exposed to doses and types of radiation that are not experienced in low earth orbit where the space shuttle and International Space Station operate. Astronauts who participate in exploratory class missions outside the magnetic field of the earth will be exposed to galactic cosmic rays which are composed of alpha particles, protons and particles of high energy and charge. Exposure to cosmic rays produces changes in neuronal and behavioral functioning which are characteristic of aged organisms. As has been observed with aging, maintaining rats on antioxidant berry diets can prevent/ameliorate the radiation-induced changes in neural and behavioral function. As such, these diets have the potential to provide protection to astronauts from the deleterious effects of exposure to space radiation. Content Type Journal ArticlePages 233-241DOI 10.3233/NUA-140045Authors Bernard M. Rabin, Department of Psychology, University of Maryland Baltimore County, Baltimore, MD, USABarbara Shukitt-Hale, Human Nutrition Research Center on Aging, USDA-ARS, Tufts University, Boston, MA, USA Journal Nutrition and AgingOnline ISSN 1879-7725Print ISSN 1879-7717 Journal Volume Volume 2 Journal Issue Volume 2, Number 4 / 2014 On exploratory class missions, such as a voyage to Mars, astronauts will be exposed to doses and types of radiation that are not experienced in low earth orbit where the space shuttle and International Space Station operate. Astronauts who participate in exploratory class missions outside the magnetic field of the earth will be exposed to galactic cosmic rays which are composed of alpha particles, protons and particles of high energy and charge. Exposure to cosmic rays produces changes in neuronal and behavioral functioning which are characteristic of aged organisms. As has been observed with aging, maintaining rats on antioxidant berry diets can prevent/ameliorate the radiation-induced changes in neural and behavioral function. As such, these diets have the potential to provide protection to astronauts from the deleterious effects of exposure to space radiation. Content Type Journal ArticlePages 233-241DOI 10.3233/NUA-140045Authors Bernard M. Rabin, Department of Psychology, University of Maryland Baltimore County, Baltimore, MD, USABarbara Shukitt-Hale, Human Nutrition Research Center on Aging, USDA-ARS, Tufts University, Boston, MA, USA Content Type Journal ArticleContent Type Journal ArticlePages 233-241DOI 10.3233/NUA-140045Authors Bernard M. Rabin, Department of Psychology, University of Maryland Baltimore County, Baltimore, MD, USABarbara Shukitt-Hale, Human Nutrition Research Center on Aging, USDA-ARS, Tufts University, Boston, MA, USA Authors Bernard M. Rabin, Department of Psychology, University of Maryland Baltimore County, Baltimore, MD, USABarbara Shukitt-Hale, Human Nutrition Research Center on Aging, USDA-ARS, Tufts University, Boston, MA, USA Bernard M. Rabin, Department of Psychology, University of Maryland Baltimore County, Baltimore, MD, USABarbara Shukitt-Hale, Human Nutrition Research Center on Aging, USDA-ARS, Tufts University, Boston, MA, USA Journal Nutrition and AgingOnline ISSN 1879-7725Print ISSN 1879-7717 Journal Volume Volume 2 Journal Issue Volume 2, Number 4 / 2014 Journal Nutrition and AgingOnline ISSN 1879-7725Print ISSN 1879-7717 Journal Nutrition and AgingJournal Nutrition and AgingNutrition and AgingOnline ISSN 1879-7725Online ISSN 1879-7725Print ISSN 1879-7717Print ISSN 1879-7717 Journal Volume Volume 2 Journal Volume Volume 2Journal Volume Volume 2 Journal Issue Volume 2, Number 4 / 2014 Journal Issue Volume 2, Number 4 / 2014Journal Issue Volume 2, Number 4 / 2014Volume 2, Number 4 / 2014
Pub.: 19 Jun '14, Pinned: 09 Sep '16
What happens to your brain on the way to Mars.
Abstract: As NASA prepares for the first manned spaceflight to Mars, questions have surfaced concerning the potential for increased risks associated with exposure to the spectrum of highly energetic nuclei that comprise galactic cosmic rays. Animal models have revealed an unexpected sensitivity of mature neurons in the brain to charged particles found in space. Astronaut autonomy during long-term space travel is particularly critical as is the need to properly manage planned and unanticipated events, activities that could be compromised by accumulating particle traversals through the brain. Using mice subjected to space-relevant fluences of charged particles, we show significant cortical- and hippocampal-based performance decrements 6 weeks after acute exposure. Animals manifesting cognitive decrements exhibited marked and persistent radiation-induced reductions in dendritic complexity and spine density along medial prefrontal cortical neurons known to mediate neurotransmission specifically interrogated by our behavioral tasks. Significant increases in postsynaptic density protein 95 (PSD-95) revealed major radiation-induced alterations in synaptic integrity. Impaired behavioral performance of individual animals correlated significantly with reduced spine density and trended with increased synaptic puncta, thereby providing quantitative measures of risk for developing cognitive decrements. Our data indicate an unexpected and unique susceptibility of the central nervous system to space radiation exposure, and argue that the underlying radiation sensitivity of delicate neuronal structure may well predispose astronauts to unintended mission-critical performance decrements and/or longer-term neurocognitive sequelae.
Pub.: 17 Jul '15, Pinned: 09 Sep '16
The story of 520 days on a simulated flight to mars
Abstract: The project Mars 500 was the first long-term simulation of a manned flight to Mars. We examined the ways crew members described their experiences and their life during simulation, what they saw as key episodes and key topics in simulation, as well as key problems and key benefits. The aim of this paper is to present the Mars 500 simulation in its complexity, from beginning to end, as a one narrative story.
Pub.: 29 Apr '16, Pinned: 09 Sep '16
Laminar and turbulent heating predictions for mars entry vehicles
Abstract: Laminar and turbulent heating rates play an important role in the design of Mars entry vehicles. Two distinct gas models, thermochemical non-equilibrium (real gas) model and perfect gas model with specified effective specific heat ratio, are utilized to investigate the aerothermodynamics of Mars entry vehicle named Mars Science Laboratory (MSL). Menter shear stress transport (SST) turbulent model with compressible correction is implemented to take account of the turbulent effect. The laminar and turbulent heating rates of the two gas models are compared and analyzed in detail. The laminar heating rates predicted by the two gas models are nearly the same at forebody of the vehicle, while the turbulent heating environments predicted by the real gas model are severer than the perfect gas model. The difference of specific heat ratio between the two gas models not only induces the flow structure's discrepancy but also increases the heating rates at afterbody of the vehicle obviously. Simple correlations for turbulent heating augmentation in terms of laminar momentum thickness Reynolds number, which can be employed as engineering level design and analysis tools, are also developed from numerical results. At the time of peak heat flux on the +3σ heat load trajectory, the maximum value of momentum thickness Reynolds number at the MSL's forebody is about 500, and the maximum value of turbulent augmentation factor (turbulent heating rates divided by laminar heating rates) is 5 for perfect gas model and 8 for real gas model.
Pub.: 25 Jul '16, Pinned: 09 Sep '16
Mars precision landing guidance based on model predictive control approach
Abstract: A precision landing guidance design for the Mars powered descent phase is proposed based on model predictive control (MPC) approach. Dynamics model used for the formulation are convexificated and linearized to adopt the convex optimization technique, which has been suggested by researchers of Jet Propulsion Laboratory. To employ the receding horizon frame and reduce the number of control inputs, the convex optimization problem is augmented with Laguerre functions. To represent the minimum fuel consumption or minimum landing error precisely unlike the optimal control theory, new cost function is designed by combining them with weighting factors. Moreover, the stability of the proposed guidance design for the independent control inputs calculated from each time step is verified by using Lyapunov stability analysis. Finally, numerical simulations are conducted to examine the suggested guidance formulation and to compare the performance with an optimal solution.
Pub.: 01 Aug '16, Pinned: 09 Sep '16
Landmark-based autonomous navigation for pinpoint planetary landing
Abstract: A landmark-based autonomous navigation scheme is presented for pinpoint planetary landing. The dynamic model is built on the basis of measurements from Inertial Measurement Unit. Measurement models of landmarks with known coordinates and landmarks with unknown coordinates extracted from sequential descent images are developed and used to calculated the state corrections in Extend Kalman Filter, respectively. Then, the corrections are fused by a covariance intersection fusion algorithm to perform state updates. The tight coupling of the two types of landmark observations yields accurate and robust state estimates. Extensive simulations are performed, which confirm the validity of the proposed navigation scheme and analyze the effects of factors, such as the horizonal position errors and the densities of landmarks with known coordinates and the roughness of the landing surface, on the navigation accuracy.
Pub.: 26 Aug '16, Pinned: 10 Oct '16
A beacon configuration optimization method based on Fisher information for Mars atmospheric entry
Abstract: The navigation capability of the proposed Mars network based entry navigation system is directly related to the beacon number and the relative configuration between the beacons and the entry vehicle. In this paper, a new beacon configuration optimization method is developed based on the Fisher information theory and this method is suitable for any number of visible beacons. The proposed method can be used for the navigation schemes based on range measurements provided by radio transceivers or other sensors for Mars entry. The observability of specific state is defined as its Fisher information based on the observation model. The overall navigation capability is improved by maximizing the minimum average Fisher information, even though the navigation system is not fully observed. In addition, when there is only one beacon capable of entry navigation and the observation information is relatively limited, the optimization method can be modulated to maximize the Fisher information of the specific state which may be preferred for the guidance and control system to improve its estimation accuracy. Finally, navigation scenarios consisted of 1–3 beacons are tested to validate the effectiveness of the developed optimization method. The extended Kalman filter (EKF) is employed to derive the state estimation error covariance. The results also show that the zero-Fisher information situation should be avoided, especially when the dynamic system is highly nonlinear and the states change dramatically.
Pub.: 13 Nov '16, Pinned: 21 Nov '16
Simulation and Spacecraft Design: Engineering Mars Landings.
Abstract: A key issue in history of technology that has received little attention is the use of simulation in engineering design. This article explores the use of both mechanical and numerical simulation in the design of the Mars atmospheric entry phases of the Viking and Mars Pathfinder missions to argue that engineers used both kinds of simulation to develop knowledge of their designs' likely behavior in the poorly known environment of Mars. Each kind of simulation could be used as a warrant of the other's fidelity, in an iterative process of knowledge construction.
Pub.: 26 Nov '15, Pinned: 09 Sep '16
Assessment of the Forward Contamination Risk of Mars by Clean Room Isolates from Space-Craft Assembly Facilities through Aeolian Transport - a Model Study
Abstract: The increasing number of missions to Mars also increases the risk of forward contamination. Consequently there is a need for effective protocols to ensure efficient protection of the Martian environment against terrestrial microbiota. Despite the fact of constructing sophisticated clean rooms for spacecraft assembly a 100 % avoidance of contamination appears to be impossible. Recent surveys of these facilities have identified a significant number of microbes belonging to a variety of taxonomic groups that survive the harsh conditions of clean rooms. These microbes may have a strong contamination potential, which needs to be investigate to apply efficient decontamination treatments. In this study we propose a series of tests to evaluate the potential of clean room contaminants to survive the different steps involved in forward contamination. We used Staphylococcus xylosus as model organism to illustrate the different types of stress that potential contaminants will be subjected to on their way from the spacecraft onto the surface of Mars. Staphylococcus xylosus is associated with human skin and commonly found in clean rooms and could therefore contaminate the spacecraft as a result of human activity during the assembling process. The path the cell will take from the surface of the spacecraft onto the surface of Mars was split into steps representing different stresses that include desiccation, freezing, aeolian transport in a Martian-like atmosphere at Martian atmospheric pressure, and UV radiation climate. We assessed the surviving fraction of the cellular population after each step by determining the integrated metabolic activity of the survivor population by measuring their oxygen consumption rate. The largest fraction of the starting culture (around 70 %) was killed during desiccation, while freezing, Martian vacuum and short-term UV radiation only had a minor additional effect on the survivability of Staphylococcus xylosus. The study also included a simulation of atmospheric transport on Martian dust, which did not significantly alter the metabolic potential of the cells. The high survival potential of skin microbes, which are not among the most robust isolates, clearly underlines the necessity for efficient decontamination protocols and of adequate planetary protection measures. Thus we propose a series of tests to be included into the description of isolates from spacecraft assembly clean rooms in order to assess the forward contamination potential of the specific isolate and to categorize the risk level according to the organisms survival potential. We are aware that the tests that we propose do not exhaust the types of challenges that the microbes would meet on their way and therefore the series of tests is open to being extended.
Pub.: 26 Jul '16, Pinned: 09 Sep '16
Water extraction on Mars for an expanding human colony.
Abstract: In-situ water extraction is necessary for an extended human presence on Mars. This study looks at the water requirements of an expanding human colony on Mars and the general systems needed to supply that water from the martian atmosphere and regolith. The proposed combination of systems in order to supply the necessary water includes a system similar to Honeybee Robotics' Mobile In-Situ Water Extractor (MISWE) that uses convection, a system similar to MISWE but that directs microwave energy down a borehole, a greenhouse or hothouse type system, and a system similar to the Mars Atmospheric Resource Recovery System (MARRS). It is demonstrated that a large water extraction system that can take advantage of large deposits of water ice at site specific locations is necessary to keep up with the demands of a growing colony.
Pub.: 11 Nov '15, Pinned: 09 Sep '16
Can plants grow on Mars and the moon: a growth experiment on Mars and moon soil simulants.
Abstract: When humans will settle on the moon or Mars they will have to eat there. Food may be flown in. An alternative could be to cultivate plants at the site itself, preferably in native soils. We report on the first large-scale controlled experiment to investigate the possibility of growing plants in Mars and moon soil simulants. The results show that plants are able to germinate and grow on both Martian and moon soil simulant for a period of 50 days without any addition of nutrients. Growth and flowering on Mars regolith simulant was much better than on moon regolith simulant and even slightly better than on our control nutrient poor river soil. Reflexed stonecrop (a wild plant); the crops tomato, wheat, and cress; and the green manure species field mustard performed particularly well. The latter three flowered, and cress and field mustard also produced seeds. Our results show that in principle it is possible to grow crops and other plant species in Martian and Lunar soil simulants. However, many questions remain about the simulants' water carrying capacity and other physical characteristics and also whether the simulants are representative of the real soils.
Pub.: 28 Aug '14, Pinned: 09 Sep '16
Microbial succession in an inflated lunar/Mars analog habitat during a 30-day human occupation.
Abstract: For potential future human missions to the Moon or Mars and sustained presence in the International Space Station, a safe enclosed habitat environment for astronauts is required. Potential microbial contamination of closed habitats presents a risk for crewmembers due to reduced human immune response during long-term confinement. To make future habitat designs safer for crewmembers, lessons learned from characterizing analogous habitats is very critical. One of the key issues is that how human presence influences the accumulation of microorganisms in the closed habitat.Molecular technologies, along with traditional microbiological methods, were utilized to catalog microbial succession during a 30-day human occupation of a simulated inflatable lunar/Mars habitat. Surface samples were collected at different time points to capture the complete spectrum of viable and potential opportunistic pathogenic bacterial population. Traditional cultivation, propidium monoazide (PMA)-quantitative polymerase chain reaction (qPCR), and adenosine triphosphate (ATP) assays were employed to estimate the cultivable, viable, and metabolically active microbial population, respectively. Next-generation sequencing was used to elucidate the microbial dynamics and community profiles at different locations of the habitat during varying time points. Statistical analyses confirm that occupation time has a strong influence on bacterial community profiles. The Day 0 samples (before human occupation) have a very different microbial diversity compared to the later three time points. Members of Proteobacteria (esp. Oxalobacteraceae and Caulobacteraceae) and Firmicutes (esp. Bacillaceae) were most abundant before human occupation (Day 0), while other members of Firmicutes (Clostridiales) and Actinobacteria (esp. Corynebacteriaceae) were abundant during the 30-day occupation. Treatment of samples with PMA (a DNA-intercalating dye for selective detection of viable microbial population) had a significant effect on the microbial diversity compared to non-PMA-treated samples.Statistical analyses revealed a significant difference in community structure of samples over time, particularly of the bacteriomes existing before human occupation of the habitat (Day 0 sampling) and after occupation (Day 13, Day 20, and Day 30 samplings). Actinobacteria (mainly Corynebacteriaceae) and Firmicutes (mainly Clostridiales Incertae Sedis XI and Staphylococcaceae) were shown to increase over the occupation time period. The results of this study revealed a strong relationship between human presence and succession of microbial diversity in a closed habitat. Consequently, it is necessary to develop methods and tools for effective maintenance of a closed system to enable safe human habitation in enclosed environments on Earth and beyond.
Pub.: 03 Jun '16, Pinned: 09 Sep '16
An ecological compass for planetary engineering.
Abstract: Proposals to address present-day global warming through the large-scale application of technology to the climate system, known as geoengineering, raise questions of environmental ethics relevant to the broader issue of planetary engineering. These questions have also arisen in the scientific literature as discussions of how to terraform a planet such as Mars or Venus in order to make it more Earth-like and habitable. Here we draw on insights from terraforming and environmental ethics to develop a two-axis comparative tool for ethical frameworks that considers the intrinsic or instrumental value placed upon organisms, environments, planetary systems, or space. We apply this analysis to the realm of planetary engineering, such as terraforming on Mars or geoengineering on present-day Earth, as well as to questions of planetary protection and space exploration.
Pub.: 04 Oct '12, Pinned: 09 Sep '16