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NASA's Advanced Exploration Systems Logistics Reduction Project is developing technologies that reduce mission mass and volume for exploration. Recently there has been increasing interest in determining the quantity of consumable logistics and system spares necessary to ensure a certain level of reliability. This is influenced by a technology's criticality and degree of impact to the overall mission. Technologies that directly reduce mass (e.g. longer wear crew clothing) are relatively straightforward for calculating the savings and understanding the mission impacts. Waste management technologies that process waste can reduce mass, but spares and contingency modes are more interwoven with other vehicle systems, so assessment is more complex. This paper considers mission benefits while also considering impacts from hardware failures for technologies including: crew clothing, reusable cargo bags for habitat outfitting, automated RFID cargo tracking, trash processing/storage/repurposing, and high reliability toilets.

In an effort to help future spacecraft thermal control analysts understand the characteristics of one- and two-loop Active Thermal Control Systems (ATCS), a comparison was made between the one- and two-loop ATCS architectures officially proposed for the Crew Exploration Vehicle (CEV) in Design Analysis Cycle 1 (DAC1) and DAC2, respectively. This report provides a description of each design, along with mass and power estimates derived from their respective Master Equipment List (MEL) and Power Equipment List (PEL). Since some of the components were sized independent of loop architecture (ex. coldplates and heat exchangers), the mass and power for these components were based on the MEL and PEL of the most mature design (i.e. two-loop architecture). The mass and power of the two architectures are then compared and the ability of each design to meet CEV requirements is discussed.

In support of the Constellation Program, which will return humans to the moon and establish an Outpost, NASA has conducted an analysis of crew clothing and laundry options. Single-use or "disposable" clothing has been used from Apollo until International Space Station (ISS) missions, meaning that clothes were worn for the whole mission or thrown away when they became too dirty to wear any longer. This is justified for short duration missions; however, as the Constellation mission will last much longer and each individual Outpost mission is expected to last up to 180 days, mission goals and launch penalties for mass and volume may lead to a different conclusion. Furthermore, the habitat atmosphere pressure and therefore oxygen volume percentage will be different from ISS or Shuttle. Almost daily EVA sorties will be a norm during Outpost exploration missions. All of these factors will have impacts on selection of crew clothing and laundry options for Outpost missions. Mass and volume estimates for disposable crew clothing have been shown as a major penalty in long-duration manned space exploration missions in previous analyses. Assuming disposable clothing like ISS, Equivalent System Mass (ESM) of crew clothing and hygiene towels was estimated to be 11,000 kg or about 11% of total life support system ESM for a 10-year Lunar Outpost mission with 4 crew members. Ways to reduce this clothing penalty, which are discussed in this paper, include: a) Reduce clothing supply rate through using clothes made of advanced fabrics; b) Reduce daily usage rate by extending its use duration before disposing; and c) Use laundry and reusable clothing. The report summarizes recent research efforts in advanced clothing, proposed clothing supply rates for Exploration missions, results of a trade-off study between disposable clothing and laundry, and conclusions and suggestions for Constellation Program clothing.

The developmental environment can have lasting effects on posthatching phenotype in oviparous animals. Innate immune response is one important component of fitness in vertebrates because it provides a generalized defense against infection. In addition, because male vertebrates are at a higher risk of infection than females, males may benefit more from increased innate immunity than females. We determined the effects of incubation temperature on the innate immune response of hatchling map turtles (Graptemys) by incubating eggs at a range of male and female producing-temperatures and assessing plasma complement activity in the resulting hatchlings. We found a significant effect of incubation environment on circulating complement in hatchling Graptemys ouachitensis, with male-producing temperatures yielding the highest innate immune response. Most important, these results demonstrate that immune response is affected by developmental environment in a species with environmental sex determination, potentially resulting in sex differences in the ability to fend off pathogens.

Oestradiol application during embryonic development reverses the sex of male embryos and results in normal female differentiation in reptiles lacking heteromorphic sex chromosomes, but fails to do so in birds and mammals with heteromorphic sex chromosomes. It is not clear whether the evolution of heteromorphic sex chromosomes in amniotes is accompanied by insensitivity to oestradiol, or if the association between oestradiol insensitivity and heteromorphic sex chromosomes can be attributable to phylogenetic constraints in these taxa. Turtles provide an ideal system to examine the potential relationship between oestradiol insensitivity and sex chromosome heteromorphy, since there are species with heteromorphic sex chromosomes that are closely related to species lacking heteromorphic sex chromosomes. We investigated this relationship by examining the long-term effects of oestradiol-17β application on sex determination in Staurotypus triporcatus and Staurotypus salvinii , two turtle species with male heterogamety. After raising the turtles in the lab for 3 years, we found follicular and Müllerian duct morphology in oestradiol-treated turtles that was identical to that of untreated females. The lasting sex reversal suggests that the evolutionary transition between systems lacking heteromorphic sex chromosomes and those with heteromorphic sex chromosomes is not constrained by a fundamental mechanistic difference.

In turtles with temperature-dependent sex determination (TSD), estradiol applied to eggs incubated at male-producing temperatures produces female hatchlings. In other vertebrate taxa, estradiol administration during embryogenesis often induces only temporary or incomplete feminization, and sensitivity to estradiol can vary among taxonomic families. In the present study, we treated eggs of Kinosternon scorpiodes and Sternotherus odoratus incubated at male-producing temperatures with estradiol-17β and examined reproductive morphology of offspring. Furthermore, to determine whether sex reversal resulting from estradiol application in turtles with TSD is lasting, we maintained juvenile K. scorpiodes in the lab for up to three years prior to dissection. We found normal ovarian morphology and Mullerian duct development in a significantly greater proportion of the hatchling S. odoratus and juvenile K. scorpiodes that had been treated with estradiol during embryogenesis than in the untreated group. Resul...

Sex ratios of the American snapping turtleChelydraserpentina are female-biased at cool temperatures, male-biased at moderate temperatures, and only females are produced at warm temperatures. The laboratory incubation of eggs at several constant temperatures yields patterns of skewed sex ratios. In this study, incubated eggs represented regional samples of C. serpentina from six different latitudes. The sample from the highest latitude yielded malebiased sex ratios across the broadest range of cool temperatures. This male-biased zone and those of the other five samples collectively contributed to a nested arrangement that is approximately symmetrical around a temperature of 24.5 ◦ C. Two indices of temperature-dependent sex determination (TSD) patterns (MF pivotal temperature, width of the male-biased zone) were significantly associated with latitude and with published data on several climatic variables (e.g. sunshine and rainfall). At high latitudes, females nest in exposed locations, locally the warmest places. At low latitudes females place their nests in shaded locations. Such nest site selection renders high latitude nests warmer than low latitude nests, even if only intermittently. Given that constant conditions show faster embryogenesis in high vs low latitude eggs, exposed nest sites seem to be an additional adaptation to hasten embryogenesis in high latitude nests. At low latitudes, shading prevents nests from overheating. We propose that a trade-off between evolution, (1) to balance sex ratio and (2) to maintain male-biased sex ratios in a temperature range that favours male fitness, leads to the observed arrangement of concentric TSD patterns centred around male production at 24.5 ◦ C.

We document temperature-dependent sex determination (TSD) in the Pancake Tortoise (Malacochersus tornieri). The nesting season is biased toward a fall–winter pattern and the embryos have a postovipositional developmental arrest. Males initially grow faster than females, but females are the larger sex. The species does not readily conform to a hypothesis that TSD is adaptively maintained through a direct association of juvenile growth with adult sexual size dimorphism.

This study investigates the potential effects of maternally derived hormones present in the yolk of reptile eggs. Specifically, we ask when are these hormones utilized by developing red-eared slider turtles (Trachemys scripta elegans), a species with temperature-dependent sex determination (TSD). Eggs were incubated at 27 degrees C, a male-producing temperature, and at 31 degrees C, a female-producing temperature. Concentrations of progesterone, testosterone, and 17beta-estradiol were measured at four points during development: at oviposition, at the start of the temperature sensitive period (TSP), at the end of the TSP, and at hatching. No effects of incubation temperature on yolk hormone concentrations were detected. The highest concentrations of all three hormones were measured at oviposition. Hormone-specific patterns of decline occurred throughout development. Each hormone declined between oviposition and the early TSP. Although estradiol was present in detectable quantities at oviposition, it was virtually undetectable by the early TSP. Testosterone showed no further decline after the early TSP. Progesterone continued to decline between the early and post-TSP. These results demonstrate that maternally derived yolk hormones decline at different rates. Alternative explanations for the disappearance of these yolk hormones are presented.

Eggs of wild caught Trachemys scripta and Graptemys pseudogeographica kohnii, two emydine turtles known to have temperature-dependent sex determination, were incubated at 28.5°C in boxes aerated with one of four gas mixtures (two in G. p. kohnii). Across all eggs, elevated levels of carbon dioxide significantly feminized sex ratios in both species and also reduced hatching success. When eggs were grouped into clutches, all comparisons between 0% and elevated carbon dioxide showed feminization in the portions of the clutches at elevated carbon dioxide, a statistically significant result for T. scripta. Accumulation of biogenic carbon dioxide from embryonic respiration and other sources is thus likely to affect sex ratios in natural nests under some conditions, perhaps through an effect on some aspects of embryonic pH.

Human exploration missions under study are limited by the launch mass capacity of existing and planned launch vehicles. The logistical mass of crew items is typically considered separate from the vehicle structure, habitat outfitting, and life support systems. Although mass is typically the focus of exploration missions, due to its strong impact on launch vehicle and habitable volume for the crew, logistics volume also needs to be considered. NASA's Advanced Exploration Systems (AES) Logistics Reduction and Repurposing (LRR) Project is developing six logistics technologies guided by a systems engineering cradle-to-grave approach to enable after-use crew items to augment vehicle systems. Specifically, AES LRR is investigating the direct reduction of clothing mass, the repurposing of logistical packaging, the use of autonomous logistics management technologies, the processing of spent crew items to benefit radiation shielding and water recovery, and the conversion of trash to propulsion gases. Reduction of mass has a corresponding and significant impact to logistical volume. The reduction of logistical volume can reduce the overall pressurized vehicle mass directly, or indirectly benefit the mission by allowing for an increase in habitable volume during the mission. The systematic implementation of these types of technologies will increase launch mass efficiency by enabling items to be used for secondary purposes and improve the habitability of the vehicle as mission durations increase. Early studies have shown that the use of advanced logistics technologies can save approximately 20 m(sup 3) of volume during transit alone for a six-person Mars conjunction class mission.

The actions of circulating hormones, although relatively well understood for adults, are largely unknown for their developing embryos. Transfer of maternal hormones to the egg is known to occur in oviparous species, and recently the presence of hormonally heterogeneous yolk layers has been described in two avian species. To investigate the possibility of a similar phenomenon occurring in chelonian species, egg yolk layers were analyzed in the painted turtle (Chrysemys picta marginata) and the red-eared slider turtle (Trachemys scripta elegans), two species that exhibit temperature-dependent sex determination. There was a similar pattern of hormonally heterogeneous yolk layers in both species: concentrations of progesterone and testosterone were significantly higher in the external yolk layer while concentrations of 17beta-estradiol were significantly higher in the intermediate and internal layers. This pattern of hormone deposition concurs with previously published studies of plasma hormone profiles from females of temperate-zone turtle species. Yolks of freshly laid eggs were also sampled using a biopsy technique to examine the concordance of early yolk hormone concentrations and offspring sex. No relationship was found between yolk hormone concentrations and individual offspring sex. Previous work showing that maternally derived yolk estradiol concentrations are correlated with female-biased sex ratios was, however, replicated. These findings suggest that offspring sex is influenced, in part, by the maternal hormone environment.

Future space exploration missions will need to use less logistical supplies if humans are to live for longer periods away from our home planet. Anything that can be done to reduce initial mass and volume of supplies or reuse or recycle items that have been launched will be very valuable. Reuse and recycling also reduce the trash burden and associated nuisances, such as smell, but require good systems engineering and operations integration to reap the greatest benefits. A systems analysis was conducted to quantify the mass and volume savings of four different technologies currently under development by NASA s Advanced Exploration Systems (AES) Logistics Reduction and Repurposing project. Advanced clothing systems lead to savings by direct mass reduction and increased wear duration. Reuse of logistical items, such as packaging, for a second purpose allows fewer items to be launched. A device known as a heat melt compactor drastically reduces the volume of trash, recovers water and produces a stable tile that can be used instead of launching additional radiation protection. The fourth technology, called trash-to-gas, can benefit a mission by supplying fuel such as methane to the propulsion system. This systems engineering work will help improve logistics planning and overall mission architectures by determining the most effective use, and reuse, of all resources.

A spacecraft thermal control system must keep the vehicle, avionics and atmosphere (if crewed) within a defined temperature range. Water coolant loops are typically used to transport heat to or from the cabin of a crewed spacecraft via heat exchangers to the heat sink systems that reject the heat to space. Water is non-toxic and good for heat transport, but it has a high freeze point. Thus, there is concern that the water loop can freeze and damage the thermal control system unless a low freeze point intermediate fluid loop is included. Incorporating a freeze-tolerant water/ice heat exchanger can eliminate this risk and offers a novel approach to spacecraft thermal control, since parts of the heat exchanger can be selectively frozen to passively increase the turndown of the heat rejection rate. In addition, it has the potential to simplify the thermal control system (for example, a secondary loop between the coolant water loop and the radiator may no longer be needed) and thereby reduce its size and mass.

All human space missions, regardless of destination, require significant logistical mass and volume that is strongly proportional to mission duration. Anything that can be done to reduce initial mass and volume of supplies or reuse items that have been launched will be very valuable. Often, the logistical items require disposal and represent a trash burden. Utilizing systems engineering to analyze logistics from cradle-to-grave and then to potential reuse, can minimize logistics contributions to total mission architecture mass. In NASA's Advanced Exploration Systems Logistics Reduction and Repurposing Project , various tasks will reduce the intrinsic mass of logistical packaging, enable reuse and repurposing of logistical packaging and carriers for other habitation, life support, crew health, and propulsion functions, and reduce or eliminate the nuisances aspects of trash at the same time. Repurposing reduces the trash burden and eliminates the need for hardware whose function can be provided by use of spent logistic items. However, these reuse functions need to be identified and built into future logical systems to enable them to effectively have a secondary function. These technologies and innovations will help future logistic systems to support multiple exploration missions much more efficiently.

Among reptiles that show temperature-dependent sex determination, sex ratios vary across constant incubation temperatures in ways sufficiently predictable to allow classifica- tion into patterns. One common pattern shows low temperatures yielding only males and high temperatures yielding only females. Another common pattern has low as well as high tempera- tures yielding only or mostly females and some intermediate temperatures yielding mostly males. Patterns tend to be associated with the direction of sexual dimorphism in adult size, especially for species with strong dimorphism. Pivotal temperatures (those yielding 1:l sex ratios) within the best-documented species and genera tend to increase with both latitude and longitude across central and southern North America. These geographic trends probably reflect factors that affect nest temperatures (duration of grow- ing season, insolation, and prevailing amounts of shading by vegetation). Data from a population of the alligator snapping turtle (Macroclemys temminckii) suggest that some embryos are temperature-independent females because these individuals become females even when they are shifted among male-producing temperatures during development. These indi- viduals are also more frequent in clutches of small eggs. In this and several other species, no constant incubation temperatures yield more than 75% males. 0 1994 WiIey-Liss, Inc.

Two modes of sex determination occur in squamates: genotypic sex determination (GSD) and temperature-dependent sex determination (TSD). Within each of these two major modes, there are many different variants, or mechanisms. Male heterogamety, female heterogamety, mul- tiple sex chromosome systems, and homomorphic sex chromosome systems are all types of GSD found in squamates. Two patterns of TSD have been reported. Only three snakes have been investigated for their sex-determining mechanisms, each having GSD, although incubation temperature does cause differential mortality and affects post-hatching physiolom. Less than 50 lizard species have been investigated, but there is considerable diversity in the sex-determining mechanisms reported thus far. Apparently, TSD (and/or GSD) has evolved multiple times within a given taxon. Presently, both GSD and TSD are found in the Agamidae, Eublepharidae, and Gekkonidae, and possibly in the Iguanidae, Lacertidae, and Varanidae as well. Only GSD has been reported for the Scincidae and Teiidae. Correlations within the Eublepharidae suggest an adaptive explanation for the evolution of sex- determining mechanisms; a shift from male-larger dimorphism to female-larger (or no sexual size dimorphism) is accompanied by a shift in sex-determining mode. These shifts are in agreement with similar correlations observed in turtles. b 1994 WiIey-Liss, Inc. The sex-determining mechanisms of squamate reptiles are poorly known, relative to the large number of species in the group (2,267 snakes, 3,307 lizards (Duellman, '791). Only 16% of these species have been karyotyped (Olmo, '861, and the effects of multi-temperature incubations have been examined in only a few species. Even so, there is considerable diversity in the sex-deter- mining mechanisms reported thus far (note: here we use sex-determining mechanism as defined by Bull "831).

Incubation temperature is known to affect pigmentation in turtles and alligators, but the influence of other incubation parameters on pigmentation has not been reported previously. We examined the pigmentation of hatchling red-eared slider turtles, Trachemys scripta elegans, incubated under various temperatures and gaseous conditions in the course of three prior studies. Reduced levels of oxygen during embryogenesis did not affect pigmentation, although such levels had produced small significant changes in developmental time. Elevated levels of carbon dioxide during development had a greater influence on pigmentation than did incubation temperature without producing as great a lengthening of incubation time. Hence, the changes in pigmentation produced by temperature and carbon dioxide could not be simply a function of their effects on developmental time. The carbon dioxide and temperature produced parallel changes in plastral pattern. In contrast, carbon dioxide had marked effects on skin pigmentation that were not paralleled by those of temperature. In addition, there were some significant differences among clutches in the effects of incubation temperature and carbon dioxide on pigmentation. Some of the differences in pigmentation among incubation treatments for this species are similar in magnitude to those occurring naturally among related turtle species. The ability to alter various developmental sequences differentially by changes in incubation conditions will facilitate both developmental and comparative evolutionary studies.

The leopard gecko, Eublepharis macularius, has temperature-dependent sex determination (TSD). Previous reports have shown that females are produced predominantly at cool incubation temperatures and males are produced predominantly at warm incubation temperatures (Pattern Ib). We report here that incubation at even higher temperatures (34 and 35 degrees C) produces mostly females (Pattern II). The lethal maximum constant incubation temperature for this species appears to be just above 35 degrees C. Although a previous study indicated that females from a warm incubation temperature (32 degrees C) failed to lay eggs, we found that 12 of 14 mature females incubated at 32.5 degrees C, and 5 of 6 mature females incubated at 34 degrees C produced fertile eggs and viable hatchlings.

Exploration Life Support (ELS) is a current project under NASA's Exploration Systems Mission Directorate. The ELS Project plans, coordinates and implements the development of advanced life support technologies for human exploration missions in space. Recent work has focused on closed loop atmosphere and water systems for long duration missions, including habitats and pressurized rovers. But, what are the critical questions facing life support system developers for these and other future human missions? This paper explores those questions and how progress in the development of ELS technologies can help answer them. The ELS Project includes the following Elements: Atmosphere Revitalization Systems, Water Recovery Systems, Waste Management Systems, Habitation Engineering, Systems Integration, Modeling and Analysis, and Validation and Testing, which includes the Sub-Elements Flight Experiments and Integrated Testing. Systems engineering analysis by ELS seeks to optimize overall mission architectures by considering all the internal and external interfaces of the life support system and the potential for reduction or reuse of commodities. In particular, various sources and sinks of water and oxygen are considered along with the implications on loop closure and the resulting launch mass requirements. Systems analysis will be validated through the data gathered from integrated testing, which will demonstrate the interfaces of a closed loop life support system. By applying a systematic process for defining, sorting and answering critical life support questions, the ELS project is preparing for a variety of future human space missions

Spacecraft human life support systems can achieve ultra reliability by providing sufficient spares to replace all failed components. The additional mass of spares for ultra reliability is approximately equal to the original system mass, provided that the original system reliability is not too low. Acceptable reliability can be achieved for the Space Shuttle and Space Station by preventive maintenance and by replacing failed units. However, on-demand maintenance and repair requires a logistics supply chain in place to provide the needed spares. In contrast, a Mars or other long space mission must take along all the needed spares, since resupply is not possible. Long missions must achieve ultra reliability, a very low failure rate per hour, since they will take years rather than weeks and cannot be cut short if a failure occurs. Also, distant missions have a much higher mass launch cost per kilogram than near-Earth missions. Achieving ultra reliable spacecraft life support systems with acceptable mass will require a well-planned and extensive development effort. Analysis must determine the reliability requirement and allocate it to subsystems and components. Ultra reliability requires reducing the intrinsic failure causes, providing spares to replace failed components and having "graceful" failure modes. Technologies, components, and materials must be selected and designed for high reliability. Long duration testing is needed to confirm very low failure rates. Systems design should segregate the failure causes in the smallest, most easily replaceable parts. The system must be designed, developed, integrated, and tested with system reliability in mind. Maintenance and reparability of failed units must not add to the probability of failure. The overall system must be tested sufficiently to identify any design errors. A program to develop ultra reliable space life support systems with acceptable mass should start soon since it must be a long term effort.

In the red-eared slider turtle, Trachemys scripta, sex is determined by the incubation temperature of the egg: warm temperatures produce females, cool ones produce males, and a narrow range of intermediate temperatures produce both sexes. We asked whether the influence of temperature is modified by the effects of carbon dioxide. Under one current hypothesis, sex is more closely linked to total incubation time and than to temperature. Higher levels of carbon dioxide should lengthen total incubation time and thus mimic the longer incubation times produced by low incubation temperatures. By this hypothesis longer incubation times should increase the tendency to produce males. Trachemys scripta eggs were incubated in atmospheres containing various concentrations of carbon dioxide. While total incubation times were significantly lengthened with elevated carbon dioxide (as if mimicking cool temperatures), sex ratios were altered in favor of females (as if mimicking warm temperatures). This result is compatible with a hypothesis that pH changes affect sex in turtles with TSD. Turtles incubated at elevated levels of carbon dioxide absorbed less yolk, and had more residual yolk, and were somewhat smaller than turtles incubated at lower of carbon dioxide. In some cases, clutches were heterogeneous in their responses to the various levels of carbon dioxide. © 1992 Wiley-Liss, Inc.

The sex of painted turtles (Chrysemys picta) is determined by the incubation temperature of the egg. At high temperatures (> 30 °C), all females are produced, with a transition to all males at most lower temperatures (24–27 °C). However, two of three previous studies have reported that some females also result when incubation temperatures are low (20–22 °C). In this study C. picta eggs were incubated at low temperatures (21.5 and 22.5 °C); however, macroscopic and histological examination of both embryos and hatchlings did not confirm these reports. Thus, C. picta has, at least typically, the pattern of sex determination that is most common among the genera to which it is most closely allied.

The amount of oxygen consumption for crew extravehicular activity (EVA) in future lunar exploration missions will be significant. Eight technologies to provide high pressure EVA O2 were investigated. They are: high pressure O2 storage, liquid oxygen (LOX) storage followed by vaporization, scavenging LOX from Lander followed by vaporization, LOX delivery followed by sorption compression, water electrolysis followed by compression, stand-alone high pressure water electrolyzer, Environmental Control and Life Support System (ECLSS) and Power Elements sharing a high pressure water electrolyzer, and ECLSS and In-Situ Resource Utilization (ISRU) Elements sharing a high pressure electrolyzer. A trade analysis was conducted comparing launch mass and equivalent system mass (ESM) of the eight technologies in open and closed ECLSS architectures. Technologies considered appropriate for the two architectures were selected and suggested for development.

The development of the Advanced Life Support (ALS) Sizing Analysis Tool (ALSSAT) using Microsoft(Registered TradeMark) Excel was initiated by the Crew and Thermal Systems Division (CTSD) of Johnson Space Center (JSC) in 1997 to support the ALS and Exploration Offices in Environmental Control and Life Support System (ECLSS) design and studies. It aids the user in performing detailed sizing of the ECLSS for different combinations of the Exploration Life support (ELS) regenerative system technologies. This analysis tool will assist the user in performing ECLSS preliminary design and trade studies as well as system optimization efficiently and economically. The latest ALSSAT related publication in ICES 2004 detailed ALSSAT s development status including the completion of all six ELS Subsystems (ELSS), namely, the Air Management Subsystem, the Biomass Subsystem, the Food Management Subsystem, the Solid Waste Management Subsystem, the Water Management Subsystem, and the Thermal Control Subsystem and two external interfaces, including the Extravehicular Activity and the Human Accommodations. Since 2004, many more regenerative technologies in the ELSS were implemented into ALSSAT. ALSSAT has also been used for the ELS Research and Technology Development Metric Calculation for FY02 thru FY06. It was also used to conduct the Lunar Outpost Metric calculation for FY08 and was integrated as part of a Habitat Model developed at Langley Research Center to support the Constellation program. This paper will give an update on the analysis tool s current development status as well as present the analytical results of one of the trade studies that was performed.

With the Preliminary Design Review (PDR) for the Orion Crew Exploration Vehicle planned to be completed in 2009, Exploration Life Support (ELS), a technology development project under the National Aeronautics and Space Administration s (NASA) Exploration Technology Development Program, is focusing its efforts on needs for human lunar missions. The ELS Project s goal is to develop and mature a suite of Environmental Control and Life Support System (ECLSS) technologies for potential use on human spacecraft under development in support of U.S. Space Exploration Policy. ELS technology development is directed at three major vehicle projects within NASA s Constellation Program (CxP): the Orion Crew Exploration Vehicle (CEV), the Altair Lunar Lander and Lunar Surface Systems, including habitats and pressurized rovers. The ELS Project includes four technical elements: Atmosphere Revitalization Systems, Water Recovery Systems, Waste Management Systems and Habitation Engineering, and two cross cutting elements, Systems Integration, Modeling and Analysis, and Validation and Testing. This paper will provide an overview of the ELS Project, connectivity with its customers and an update to content within its technology development portfolio with focus on human lunar missions.

Oxygen (O2) is obviously essential for human space missions, but it is important to examine all the different ways it will be used and the potential sources that it may come from. This effort will lead to storage and delivery requirements and help to determine the optimum architecture from an overall systems engineering point of view. Accounting for all the oxygen in a Lunar Outpost mission includes meeting the metabolic needs of the crew while in the surface Habitat, leakage through the Habitat or Pressurized Rover walls, recharge of the space suit backpack and emergency situations. Current plans indicate that both primary and secondary O2 bottles for the space suit will be filled to a pressure of 20.7 MPa (3000 psia). Other uses of O2 require much lower pressure. Sources of O2 at a Lunar Outpost include compressed or liquefied O2 brought along specifically for life support, scavenged O2 from the Lander propulsion system, recovered O2 from waste water or exhaled carbon dioxide and O2 mined from the moon itself. Previously, eight technology options were investigated to provide the high pressure space suit O2. High pressure O2 storage was treated as the baseline technology and compared to the other seven. The other seven were cryogenic storage followed by high pressure vaporization, scavenging liquid oxygen (LOX) from Lander followed by vaporization, LOX delivery followed by sorption compression, low pressure water electrolysis followed by mechanical compression, high pressure water electrolysis, sharing a high pressure electrolyzer with a regenerative fuel cell power system, and making use of In- Situ Resource Utilization (ISRU). This system-level analysis was conducted by comparing equivalent system mass of the eight technologies in open and closed loop life support architectures. The most promising high pressure O2 generation technologies were recommended for development. Updates and an expansion of the earlier study have been made and the results are reported in this paper. Examples of recent analyses include feasibility of recovering space suit purge O2 in a Pressurized Rover and using sub-critical LOX for primary supply while using high-pressure gaseous O2 as the secondary supply for the space-suit. Preliminary analysis on scavenging LOX from the Lander and delivering it to the Habitat has also been incorporated into this integrated lunar fluids analysis

Exploration Life Support (ELS) is one of NASA's Exploration Technology Development Projects. ELS plans, coordinates and implements the development of new life support technologies for human exploration missions as outlined in NASA's Vision for Space Exploration. ELS technology development currently supports three major projects of the Constellation Program - the Orion Crew Exploration Vehicle (CEV), the Altair Lunar Lander and Lunar Surface Systems. ELS content includes Air Revitalization Systems (ARS), Water Recovery Systems (WRS), Waste Management Systems (WMS), Habitation Engineering, Systems Integration, Modeling and Analysis (SIMA), and Validation and Testing. The primary goal of the ELS project is to provide different technology options to Constellation which fill gaps or provide substantial improvements over the state-of-the-art in life support systems. Since the Constellation missions are so challenging, mass, power, and volume must be reduced from Space Shuttle and Space Station technologies. Systems engineering analysis also optimizes the overall architecture by considering all interfaces with the life support system and potential for reduction or reuse of resources. For long duration missions, technologies which aid in closure of air and water loops with increased reliability are essential as well as techniques to minimize or deal with waste. The ELS project utilizes in-house efforts at five NASA centers, aerospace industry contracts, Small Business Innovative Research contracts and other means to develop advanced life support technologies. Testing, analysis and reduced gravity flight experiments are also conducted at the NASA field centers. This paper gives a current status of technologies under development by ELS and relates them to the Constellation customers who will eventually use them.

In many species of reptiles, sex is determined by the incubation temperature of the egg. In the red-eared slider turtle (Trachemys scripta), warm incubation temperatures produce females, cool ones produce males, and a narrow range of intermediate temperatures produces both sexes. The mechanism of sex determination has not been established. Some investigators have postulated that both total incubation time and developmental rate during the first third of development are better predictors of sex than is incubation temperature. Here we consider whether various oxygen concentrations might influence sex determination by altering total incubation time. We incubated T. Scripta eggs at various oxygen concentrations, and found that while total incubation times were significantly influenced by oxygen, sex ratios were not. Very low oxygen concentrations inhibited survival to hatching, In addition, total incubation time and the number of days to internalize the yolk after hatching were significantly lengthened by lowered oxygen concentrations. There were also strong effects of clutch on sex determination and physiology, but these effects were apparently not mediated by an effect on total incubation time.

In preparation for the contract award of the Crew Exploration Vehicle (CEV), the National Aeronautics and Space Administration (NASA) produced two design reference missions for the vehicle. The design references used teams of engineers across the agency to come up with two configurations. This process helped NASA understand the conflicts and limitations in the CEV design, and investigate options to solve them.

Numerous studies of sea turtle nesting ecology have revealed that females exhibit natal homing, whereby they imprint on the nesting area from which they hatch and subsequently return there to nest as adults. Because freshwater turtles comprise the majority of reptiles known to display environmental sex determination (ESD), the study of natal homing in this group may shed light on recent evolutionary models of sex allocation that are predicated on natal homing in reptiles with ESD. We examined natal homing in Graptemys kohnii , a freshwater turtle with ESD, using mitochondrial sequencing, microsatellite genotyping and mark and recapture of 290 nesting females. Females showed high fidelity to nesting areas, even after being transplanted several kilometres away. A Mantel test revealed significant genetic isolation by distance with respect to nesting locations ( r =0.147; p

As humans explore space, we find even greater temperature extremes than on Earth. Apollo astronauts, for example, did not stay on the moon past noon when surface temperatures soar to over 100°C. As we have on Earth, future space explorers will likely turn to mechanical heating and cooling systems to maintain comfortable living spaces. Most locations in Earth’s neighborhood have an abundant natural energy source from the sun, thus the development effort has taken a systems engineering approach and tried to optimize the heat pump and solar power source together. Earlier studies have shown that vapor compression cycle heat pumps are the most mass and power efficient for space applications. Photovoltaic (PV) cells are the most mature solar power conversion technology to provide electricity to the vapor compressor in space. Hence, these two technologies have been integrated into a solar PV vapor compression heat pump. A “ground-test unit” Solar Heat Pump designed to provide 15 kilowatts of cooling was completed in 2002 and underwent preliminary testing at SunDanzer’s previous location in Nevada. Following buildup of a heat pump testbed that will allow simulation of radiator loop temperatures on the moon or Mars, a complete system evaluation will be conducted in 2005 at the Johnson Space Center. Following that, the gravity dependent components of the system, most notably the compressor, will be analyzed and upgraded for the required gravity environment(s). A gravity-independent approach would allow NASA mission designers the most flexibility to use heat pump technology in future mission scenarios, but technical challenges may lead to machines optimized for a particular application. Design data and analysis, as well as the preliminary test results, indicate that the Solar Heat Pump will achieve very good efficiency, near 45% of Carnot efficiency, at a temperature lift of 45°C. A novel motor controller and computer control software allow the heat pump to use solar power directly from the PV array at about 400 volts direct current. These features, referred to as “PV-direct”, along with a good thermodynamic design, form a solid basis for the design of a future space-qualified Solar Heat Pump.Copyright © 2005 by ASME

The development of the Advanced Life Support (ALS) Sizing Analysis Tool (ALSSAT) using Microsoft® Excel was initiated by the Crew and Thermal Systems Division (CTSD) of Johnson Space Center (JSC) in 1997 to support the ALS and Exploration Offices in Environmental Control and Life Support System (ECLSS) design and studies. It aids the user in performing detailed sizing of the ECLSS based on suggested default values or user inputs for different combinations of the ALS regenerative system technologies (Ref. 1, 2). This analysis tool will assist the user in performing ECLSS preliminary design and trade studies as well as system optimization efficiently and economically. Since ALSSAT's latest publication in ICES 2001 (Ref. 1) describing the development of ALSSAT with its Air Revitalization Subsystem (ARS), Water Management Subsystem (WMS), and Biomass Subsystem (Biomass) mass balance sheets, ALSSAT has been expanded to include mass balance and sizing models for the remaining three ALS subsystems, namely, the Solid Waste Management Subsystem (SWMS), the Food Management Subsystem (FMS), and the Thermal Control Subsystem (TCS). The external interfaces, including the Extravehicular Activities (EVA) and Human Accommodations (HA), were implemented into ALSSAT in 2002. The overall mass balance sheet, which integrates the six ALS subsystems and the external interfaces applicable to the ECLSS, was also developed. In 2003, ALSSAT was upgraded to include the consideration of redundancy and contingency options in the ECLSS, as well as more ALS regenerative technology selections. ALSSAT has been used for the Metric Calculation for FY02 and FY03 (Ref. 3). Several trade studies were conducted in 2003. The analytical results will be presented in this paper.

The transfer of hormones from a female to her offspring is known to occur in egg laying vertebrates, and the potential for these early, maternally derived hormones to influence sex determination in reptiles with temperature-dependent sex determination is intriguing. In the present study, we examine variation in the concentrations of progesterone, testosterone, and estradiol among three follicle size classes within a female painted turtle (Chrysemys picta) and among females across four periods that span the pre- to post-nesting season. Females were collected, and both follicles and shelled eggs (when present) were harvested for hormone analysis. Progesterone levels did not vary seasonally. However, the concentration of progesterone did vary among and within follicle classes, and was primarily dependent upon ovulatory state: Recently ovulated follicles (as yolks within shelled eggs) contained significantly more progesterone than unovulated follicles. Concentrations of testosterone were low and did not vary either among size classes or across the season. Estradiol levels decreased with increasing follicle size and were higher later in the nesting season. Thus, hormone concentrations varied among follicle sizes and states but in patterns that differed among hormones. This variation has the potential to influence sex determination.