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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.

Diesel engine ash emissions are composed of the non-combustible portions of diesel particulate matter derived mainly from lube oil, and over time can degrade diesel particulate filter performance. This paper presents results from a high temperature oxidation method (HTOM) used to estimate ash emissions, and engine oil consumption in real-time. Atomized lubrication oil and diesel engine exhaust were used to evaluate the HTOM performance. Atomized fresh and used lube oil experiments showed that the HTOM reached stable particle size distributions and concentrations at temperatures above 700°C. The HTOM produced very similar number and volume weighted particle size distributions for both types of lube oils. The particle number size distribution was unimodal, with a geometric mean diameter of about 23 nm. The volume size distribution had a geometric volume mean diameter of about 65 nm.

NASA's proposed lunar lander, Altair, will be exposed to vastly different external temperatures following launch till its final destination on the moon. In addition, the heat rejection is lowest at the lowest environmental temperatures (0.5 kW @ 4K) and highest at the highest environmental temperature (4.5 kW @ 215K). This places a severe demand on the radiator design to handle these extreme turn-down requirements. A radiator with digital turn-down capability is currently under study at JPL as a robust means to meet the heat rejection demands and provide freeze protection while minimizing mass and power consumption. Turndown is achieved by independent control of flow branches with isolating latch valves and a gear pump to evacuate the isolated branches. A bench-top test was conducted to characterize the digital radiator concept. Testing focused on the demonstration of proper valve sequencing to achieve turn-down and recharge of flow legs.

Negative Valve Overlap (NVO) is a potential control strategy for enabling Low-Temperature Gasoline Combustion (LTGC) at low loads. While the thermal effects of NVO fueling on main combustion are well-understood, the chemical effects of NVO in-cylinder fuel reforming have not been extensively studied. The objective of this work is to examine the effects of fuel molecular structure on NVO fuel reforming using gas sampling and detailed speciation by gas chromatography. Engine gas samples were collected from a single-cylinder research engine at the end of the NVO period using a custom dump-valve apparatus. Six fuel components were studied at two injection timings: (1) iso-octane, (2) n-heptane, (3) ethanol, (4) 1-hexene, (5) cyclohexane, and (6) toluene. All fuel components were studied neat except for toluene - toluene was blended with 18.9% nheptane by liquid volume to increase the fuel reactivity.

A fully flexible valve actuation (FFVA) system was developed for a single cylinder research engine to investigate high efficiency clean combustion (HECC) in a diesel engine. The main objectives of the study were to examine the emissions, performance, and combustion characteristics of the engine using late intake valve closing (LIVC) to determine the benefits and limitations of this strategy to meet Tier 2 Bin 5 NOx requirements without after-treatment. The most significant benefit of LIVC is a reduction in particulates due to the longer ignition delay time and a subsequent reduction in local fuel rich combustion zones. More than a 95% reduction in particulates was observed at some operating conditions. Combustion noise was also reduced at low and medium loads due to slower heat release. Although it is difficult to assess the fuel economy benefits of LIVC using a single cylinder engine, LIVC shows the potential to improve the fuel economy through several approaches.

During an ExtraVehicular Activity (EVA), both the heat generated by the astronaut's metabolism and that produced by the Portable Life Support System (PLSS) must be rejected to space. The heat sources include the heat of adsorption of metabolic CO2, the heat of condensation of water, the heat removed from the body by the liquid cooling garment, the load from the electrical components and incident radiation. Although the sublimator hardware to reject this load weighs only 1.58 kg (3.48 lbm), an additional 3.6 kg (8 lbm) of water are loaded into the unit, most of which is sublimated and lost to space, thus becoming the single largest expendable during an eight-hour EVA. Using a radiator to reject heat from the astronaut during an EVA can reduce the amount of expendable water consumed in the sublimator. Radiators have no moving parts and are thus simple and highly reliable. However, past freezable radiators have been too heavy.

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.

During an ExtraVehicular Activity (EVA), both the heat generated by the astronaut's metabolism and that produced by the Portable Life Support System (PLSS) must be rejected to space. The heat sources include the heat of adsorption of metabolic CO2, the heat of condensation of water, the heat removed from the body by the liquid cooling garment and the load from the electrical components. Although the sublimator hardware to reject this load weighs only 1.58 kg (3.48 lbm), an additional 3.6 kg (8 lbm) of water are loaded into the unit, most of which is sublimated and lost to space, thus becoming the single largest expendable during an eight-hour EVA. Using a radiator to reject heat from the astronaut during an EVA can reduce the amount of expendable water consumed in the sublimator. Last year we reported on the design and initial operational assessment tests of a novel radiator designated the Radiator And Freeze Tolerant heat eXchanger (RAFT-X).

Shortly after installation of the service and performance heat exchanger (SPCU HX) in 2001, samples collected from the coolant fluid indicated the presence of nickel accompanied by a subsequent decrease in phosphate concentration along with a high microbial load. When the SPCU HX was replaced and evaluated post-flight, it was expected that the heat exchanger would have significant biofilm and corrosion present given the composition of the coolant fluid; however, there was no evidence of either. Early results from two experiments imply that the heat exchanger materials themselves are inhibiting biofilm formation. This paper discusses the results of one set of experiments and puts forward the inhibition of quorum sensing as a possible mechanism for the lack of biofilm formation.

Exhaust particulate emissions from a 4-cylinder, 2.25 liter spark ignition engine were measured and characterized. A single-stage ejector-diluter system was used to dilute and cool the exhaust sample for measurement. The particulate measurement equipment included a condensation nucleus counter and a scanning mobility particle sizer. Exhaust measurements were made both upstream and downstream of the catalytic converter using three different fuels. Unlike particulate emissions in diesel engines, spark ignition exhaust particle emissions were found to be highly unstable. Typically, a stable “baseline” concentration on the order of 105 particles/cm3 is emitted. Occasionally, however, a “spike” in the exhaust particle concentration is observed. The exhaust particle concentrations observed during these spikes can increase by as much as two orders of magnitude over the baseline concentration.

Exhaust particle number concentrations and size distributions were measured from the exhaust of a 1995 direct injection, Diesel engine. Number concentrations ranged from 1 to 7.5×107 particles/cm3. The number size distributions were bimodal and log-normal in form with a nuclei mode in the 7-15 nm diameter range and an accumulation mode in the 30-40 nm range. For nearly all operating conditions, more than 50% of the particle number, but less than 1% of the particle mass were found in the nuclei mode. Preliminary indications are that the nuclei mode particles are solid and formed from volatilization and subsequent nucleation of metallic ash from lubricating oil additives. Modern low emission engines produce low concentrations of soot agglomerates. The absence of these agglomerates to act as sites for adsorption or condensation of volatile materials makes nucleation and high number emissions more likely.

Combustion aerosols consist mainly of elemental and organic carbon (EC and OC). Since EC strongly absorbs light and thus affects atmospheric visibility and radiation balance, there is great interest in its measurement. To this end, the National Institute for Occupational Safety and Health (NIOSH) published a standard method to determine the mass of EC and OC on filter samples. Another common method of measuring carbon in aerosols is the aethalometer, which uses light extinction to measure “black carbon” or BC, which is considered to approximate EC. A third method sometimes used for estimating carbon in submicron combustion aerosols, is to measure particle size distributions using a scanning mobility particle sizer (SMPS) and calculate mass using the assumptions that the particles are spherical, carbonaceous and of known density.

The effects of fuel sulfur content and dilution conditions on diesel engine PM number emissions have been researched extensively through steady state testing. Most results show that the concentration of nuclei-mode particles emitted increases with fuel sulfur content. A few studies further observed that fuel sulfur content has little effect on the emissions of heavily-used engines. It has also been found that primary dilution conditions can have a large impact on the size and number distribution of the nuclei-mode particles. These effects, however, have not yet been fully understood through transient testing, the method used by governments worldwide to certify engines and regulate emissions, and a means of experimentation which generates realistic conditions of on-road vehicles by varying the load and speed of the engine.

Long duration NASA-Mir program missions, and the planned International Space Station missions, have given impetus for NASA to implement an operational program of psychological preparation, monitoring, and support for its crews. For exploration missions measured in years, the importance of psychological issues increases exponentially beyond what is currently done. Psychologists' role should begin during the vehicle design and crew selection phases. Extensive preflight preparation must focus on individual and team adaptation, and leadership. Factors such as lack of resupply options and communication delays will alter in-flight monitoring and support capabilities, and require a more self-sufficient crew. Involvement in postflight recovery will also be necessry to ensure appropriate reintegration to the family and job.

A new methodological tool was developed consisting of a patchwork thermal cool/warm grid with great flexibility to manipulate the temperature on different areas of the body. Through conflicting temperatures on the body surface, it is possible to direct heat current to different distal or proximal areas. The effectiveness of the use of a cooled hood, gloves, socks on the overheated body was evaluated as countermeasures for balancing heat exchange. Temperature in the magistral vessels was the main source of information for understanding the mechanism of the relationship between core and shell, and shell and distal parts of the limb.

Scientists and engineers at NASA are currently developing flight instruments which will demonstrate oxygen production on the Moon and Mars. REGA will extract oxygen from the lunar regolith, measure implanted solar wind and indigenous gases, and monitor the lunar atmosphere. MIP will demonstrate oxygen production on Mars, along with key supporting technologies including filtration, atmospheric acquisition and compression, thermal management, solar cell performance, and dust removal.

When a permanent human outpost is established on the Moon, various methods may be used to reject the heat generated by the base. One proposed concept is the use of a heat pump operating with a vertical, flow-through thermal radiator mounted on a Space Station type habitation module [1]. Since the temperature of the lunar surface varies over the day, the vertical radiator sink temperatures can reach much higher levels than the comfort and even survivability requirements of a habitation module. A high temperature lift heat pump will not only maintain a comfortable habitation module temperature, but will also decrease the size of the radiators needed to reject the waste heat. Thus, the heat pump will also decrease the mass of the entire thermal system. Engineers at the Johnson Space Center (JSC) have tested a High Lift Heat Pump design and are developing the next generation heat pump based on information and experience gained from this testing.

An integrated water recovery system was operated for 91 days in support of the Lunar Mars Life Support Test Project (LMLSTP) Phase III test. The system combined both biological and physical-chemical processes to treat a combined wastewater stream consisting of waste hygiene water, urine, and humidity condensate. Biological processes were used for primary degradation of organic material as well as for nitrification of ammonium in the wastewater. Physical-chemical systems removed inorganic salts from the water and provided post-treatment. The integrated system provided potable water to the crew throughout the test. This paper describes the water recovery system and reviews the performance of the system during the test.

The potential of controlling human body thermal status through monitoring temperature and heat flux indices of the fingers was evaluated. A cooling/warming suit was used that provided a range of uniform and nonuniform temperature regimes on the body surface. Temperature changes on the skin surface changed body comfort significantly but did not affect core temperature. However, under different imposed thermal conditions, peripheral temperature, particularly the fingers, closely followed the thermal conditions either within or on the surface of the body. The fingers appear to have considerable potential as a key site in developing an automatic thermal feedback system in the EVA suit.