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After several decades of human spaceflight, the community of space-faring nations has accumulated a diverse and sometimes harrowing history of toxicological events that have plagued human space endeavors almost from the very beginning. Some lessons have been learned in ground-based test beds and others were discovered the hard way - when human lives were at stake in space. From such lessons one can build a risk-management framework for toxicological events to minimize the probability of a harmful exposure, while recognizing that we cannot predict all possible events. Space toxicologists have learned that relatively harmless compounds can be converted by air revitalization systems into compounds that cause serious harm to the crew.

An EVA simulation with a medical contingency scenario was conducted in 2006 with the NASA Haughton-Mars and EVA Physiology System and Performance Projects, to develop medical contingency management and evacuation techniques for planetary surface exploration. A rescue/evacuation system to allow two rescuer astronauts to evacuate one incapacitated astronaut was evaluated. The rescue system was utilized effectively to extract an injured astronaut up a slope of15-25° and into a surface mobility rover for transport to a simulated habitat for advanced medical care. Further research is recommended to evaluate the effects of reduced gravity and to develop synergies with other surface systems for carrying out the contingency procedures.

Spacecraft radiators reject heat to their surroundings. Radiators can be deployable or mounted on the body of the spacecraft. NASA's Crew Exploration Vehicle is to use body mounted radiators. Coatings play an important role in heat rejection. The coatings provide the radiator surface with the desired optical properties of low solar absorptance and high infrared emittance. These specialized surfaces are applied to the radiator panel in a number of ways, including conventional spraying, plasma spraying, or as an appliqué. Not specifically designed for a weathering environment, little is known about the durability of conventional paints, coatings, and appliqués upon exposure to weathering and subsequent exposure to solar wind and ultraviolet radiation exposure. In addition to maintaining their desired optical properties, the coatings must also continue to adhere to the underlying radiator panel.

As part of preparing for the Crew Exploration Vehicle (CEV), the National Aeronautics and Space Administration (NASA) worked on developing the requirements to manage the fire risk. The new CEV poses unique challenges to current fire protection systems. The size and configuration of the vehicle resembles the Apollo capsule instead of the current Space Shuttle or the International Space Station. The smaller free air volume and fully cold plated avionic bays of the CEV requires a different approach in fire protection than the ones currently utilized. The fire protection approach discussed in this paper incorporates historical lessons learned and fire detection and suppression system design philosophy spanning from Apollo to the International Space Station.

Protecting astronauts from space radiation exposure is an important challenge for mission design and operations for future exploration-class and long-duration missions. Crew members are exposed to sporadic solar particle events (SPEs) as well as to the continuous galactic cosmic radiation (GCR). If sufficient protection is not provided the radiation risk to crew members from SPEs could be significant. To improve exposure risk estimates and radiation protection from SPEs, detailed evaluations of radiation shielding properties are required. A model using a modern CAD tool ProE™, which is the leading engineering design platform at NASA, has been developed for this purpose. For the calculation of radiation exposure at a specific site, the cosine distribution was implemented to replicate the omnidirectional characteristic of the 4π particle flux on a surface.

A reliable nutrient delivery system is essential for long-term cultivation of plants in space. At the Kennedy Space Center, a series of ground-based tests are being conducted to compare candidate plant nutrient delivery systems for space. To date, our major focus has concentrated on the Porous Tube Plant Nutrient Delivery System, the ASTROCULTURE™ System, and a zeoponic plant growth substrate. The merits of each system are based upon the performance of wheat supported over complete growth cycles. To varying degrees, each system supported wheat biomass production and showed distinct patterns for plant nutrient uptake and water use.

This paper present a summary of the design studies for the suit port proof of concept. The Suit Port reduces the need for airlocks by docking the suits directly to a rover or habitat bulkhead. The benefits include reductions in cycle time and consumables traditionally used when transferring from a pressurized compartment to EVA and mitigation of planetary surface dust from entering into the cabin. The design focused on the development of an operational proof of concept evaluated against technical feasibility, level of confidence in design, robustness to environment and failure, and the manufacturability. A future paper will discuss the overall proof of concept and provide results from evaluation testing including gas leakage rates upon completion of the testing program.

The 2001 Mars Odyssey spacecraft Martian Radiation Environment Experiment (MARIE) is a solid-state silicon telescope high-energy particle detector designed to measure galactic cosmic radiation (GCR) and solar particle events (SPEs) in the 20 – 500 MeV/nucleon energy range. In this paper we discuss the instrument design and focus on the observations and measurements of SPEs at Mars. These are the first-ever SPE measurements at Mars. The measurements are compared with the geostationary GOES satellite SPE measurements. We also discuss some of the current interplanetary particle propagation and diffusion theories and models. The MARIE SPE measurements are compared with these existing models.

The INTEGRITY Program will design and operate a test bed facility to help prepare for future beyond-LEO missions. The purpose of INTEGRITY is to enable future missions by developing, testing, and demonstrating advanced human space systems. INTEGRITY will also implement and validate advanced management techniques including risk analysis and mitigation. One important way INTEGRITY will help enable future missions is by reducing their risk. A risk analysis of human space missions is important in defining the steps that INTEGRITY should take to mitigate risk. This paper describes how a Probabilistic Risk Assessment (PRA) of human space missions will help support the planning and development of INTEGRITY to maximize its benefits to future missions. PRA is a systematic methodology to decompose the system into subsystems and components, to quantify the failure risk as a function of the design elements and their corresponding probability of failure.

The Equivalent System Mass (ESM) metric developed by NASA describes and compares individual system impact on a closed system in terms of a single parameter, mass. The food system of a Mars mission may encompass a large percentage of total mission ESM, and decreasing this ESM would be beneficial. Yeast breads were made using three methods (hand & oven, bread machine, mixer with dough hook attachment & oven). Flat breads were made using four methods (hand & oven, hand & griddle, mixer with dough hook attachment & oven, mixer with dough hook attachment & griddle). Two formulations were used for each bread system (scratch ingredients, commercial mix). ESM was calculated for each of these scenarios. The objective of this study was to compare the ESM of yeast and flat bread production for a Martian surface outpost. Method (equipment) for both types of bread production was demonstrated to be the most significant influence of ESM when one equipment use was assumed.

A thermal analysis of the compressible carbon dioxide (CO2) flow for the Portable Fire Extinguisher (PFE) system has been performed. A SINDA/FLUINT model has been developed for this analysis. The model includes the PFE tank and the Temporary Sleep Station (TeSS) nozzle, and both have an initial temperature of 72 °F. In order to investigate the thermal effect on the nozzle due to discharging CO2, the PFE TeSS nozzle pipe has been divided into three segments. This model also includes heat transfer predictions for PFE tank inner and outer wall surfaces. The simulation results show that the CO2 discharge rates and component wall temperatures fall within the requirements for the PFE system. The simulation results also indicate that after 50 seconds, the remaining CO2 in the tank may be near the triple point (gas, liquid and solid) state and, therefore, restricts the flow.

In applications that require space-suited crewmembers to traverse rough terrain, boot fit and mobility are of critical importance to the crewmember's overall performance capabilities. Current extravehicular activity (EVA) boot designs were developed for micro-gravity applications, and as such, incorporate only minimal mobility features. Recently three advanced space suit boot designs were evaluated at the National Aeronautics and Space Administration Johnson Space Center (NASA/JSC). The three designs included: 1) a modified Space Shuttle suit (Extravehicular Mobility Unit or EMU) boot, 2) the Modified Experiment Boot designed and fabricated by RD & PE Zvezda JSC, and 3) a boot designed and fabricated by the David Clark Company. Descriptions of each configuration and rationale for each boot design are presented.

Major improvements have recently been completed in the approach to spacecraft shielding analysis. A Computer-Aided Design (CAD)-based system has been developed for determining the shielding provided to any point within or external to the spacecraft. Shielding analysis is performed using a commercially available stand-alone CAD system and a customized ray-tracing subroutine contained within a standard engineering modeling software package. This improved shielding analysis technique has been used in several vehicle design projects such as a Mars transfer habitat, pressurized lunar rover, and the redesigned Space Station. Results of these analyses are provided to demonstrate the applicability and versatility of the system.

Over the last couple decades, there has been a growing interest in incorporating commercial off-the-shelf (COTS) technologies and open standards in the design of human-rated spacecraft. This approach is intended to reduce development and upgrade costs, lower the need for new design work, eliminate reliance on individual suppliers, and minimize schedule risk. However, it has not traditionally been possible for COTS solutions to meet the high reliability and fault tolerance requirements of systems implementing critical spacecraft functions. Byzantine faults are considered particularly dangerous to such systems because of their ability to escape traditional means of fault containment and disrupt consensus between system components. In this paper, we discuss the design of a voting protocol using Time-Triggered Ethernet capable of achieving data integrity in the presence of a single Byzantine fault.

Conceptual designs for a space suit Personal Life Support Subsystem (PLSS) were developed and assessed to determine if upgrading the system using new, emerging, or projected technologies to fulfill basic functions would result in mass, volume, or performance improvements. Technologies were identified to satisfy each of the functions of the PLSS in three environments (zero-g, Lunar, and Martian) and in three time frames (2006, 2010, and 2020). The viability of candidate technologies was evaluated using evaluation criteria such as safety, technology readiness, and reliability. System concepts (schematics) were developed for combinations of time frame and environment by assigning specific technologies to each of four key functions of the PLSS -- oxygen supply, waste removal, thermal control, and power. The PLSS concepts were evaluated using the ExtraVehicular Activity System Sizing Analysis Tool, software created by NASA to analyze integrated system mass, volume, power and thermal loads.

A small team of NASA engineers has been assembled at the Johnson Space Center, with the goal of developing an inexpensive space-capable vehicle. In order to minimize cost and development time of the experimental vehicle, it was desirable to build upon a previously-developed vehicle shape. The basic shape of the X-24A experimental lifting body was chosen for several reasons, and in the case of the Environmental Control and Life Support (ECLS), the de-orbit cross-range capability of this shape provides for a minimal on-orbit time while waiting for landing opportunities, which in turn simplifies the ECLS. Figure 1 shows the X-38 vehicle body shape. In keeping with the goal of rapidly developing an inexpensive and reliable vehicle, the ECLS was developed using simple, passive systems where practical. This paper provides an overview of the ECLS mission requirements and design, with emphasis on the philosophy used in its development.

Procedures for rapid microbiological analysis were performed during simulated surface extra-vehicular activity (EVA) at Meteor Crater, Arizona. The fully suited operator swabbed rock (‘unknown’ sample), spacesuit glove (contamination control) and air (negative control). Each swab sample was analyzed for lipopolysaccharide (LPS) and β-1, 3-glucan within 10 minutes by the handheld LOCAD PTS instrument, scheduled for flight to ISS on space shuttle STS-116. This simulated a rapid and preliminary ‘life detection’ test (with contamination control) that a human could perform on Mars. Eight techniques were also evaluated for their ability to clean and remove LPS and β-1, 3-glucan from five surface materials of the EVA Mobility Unit (EMU). While chemical/mechanical techniques were effective at cleaning smooth surfaces (e.g. RTV silicon), they were less so with porous fabrics (e.g. TMG gauntlet).

Meeting radiation protection requirements during EVA is predominantly an operational issue with some potential considerations for temporary shelter. The issue of spacesuit shielding is mainly guided by the potential of accidental exposure when operational and temporary shelter considerations fail to maintain exposures within operational limits. In this case, very high exposure levels are possible which could result in observable health effects and even be life threatening. Under these assumptions, potential spacesuit radiation exposures have been studied using known historical solar particle events to gain insight on the usefulness of modification of spacesuit design in which the control of skin exposure is a critical design issue and reduction of blood forming organ exposure is desirable.

As NASA is preparing to extend man's reach into space, it is expected that astronauts will be required to spend more and more time exposed to the hazards of performing Extra-Vehicular Activity (EVA). One of these hazards includes the risk of the space suit bladder being penetrated by hypervelocity micrometeoroid and orbital debris (MMOD) particles. Therefore, it has become increasingly important to investigate new ways to improve the protectiveness of the current Extravehicular Mobility Unit (EMU) against MMOD penetration. ILC Dover conducted a NASA funded study into identifying methods of improving the current EMU protection. The first part of this evaluation focused on identifying how to increase the EMU shielding, selecting materials to accomplish this, and testing these materials to determine the best lay-up combinations to integrate into the current thermal micrometeoroid garment (TMG) design.

This ground-based study compared the risk of microbubbles during decompression under simulated space extravehicular activities (EVA) after three days of six-degree head-down bed rest with three days of ambulatory control. Test subjects were exposed to a pressure of 44.8 kPa (6.5 psi), breathed 100% oxygen, and exercised at reduced pressure either in the supine (during experimental) or upright (control) position. Circulating microbubbles were monitored by a precordial Doppler ultrasound device, and were found in 52% (12/23) of control and 26% (6/23) of experimental exposures. Survival analysis using Cox proportional hazards regression showed that there was 0.22 times (95% confidence interval=0.07-0.68) reduction in the risk of high grade microbubbles after bed rest, compared to controls (p=0.004). This finding is of importance in evaluating the risk of DCS during EVA.