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Technical Paper

ISS Internal Active Thermal Control System (IATCS) Coolant Remediation Project - 2006 Update

2006-07-17
2006-01-2161
The IATCS coolant has experienced a number of anomalies in the time since the US Lab was first activated on Flight 5A in February 2001. These have included: 1) a decrease in coolant pH, 2) increases in inorganic carbon, 3) a reduction in phosphate concentration, 4) an increase in dissolved nickel and precipitation of nickel salts, and 5) increases in microbial concentration. These anomalies represent some risk to the system, have been implicated in some hardware failures and are suspect in others. The ISS program has conducted extensive investigations of the causes and effects of these anomalies and has developed a comprehensive program to remediate the coolant chemistry of the on-orbit system as well as provide a robust and compatible coolant solution for the hardware yet to be delivered.
Technical Paper

Guidance for Trade Studies of Flight-Equivalent Hardware

2007-07-09
2007-01-3223
Spacecraft hardware trade studies compare options primarily on mass while considering impacts to cost, risk, and schedule. Historically, other factors have been considered in these studies, such as reliability, technology readiness level (TRL), volume and crew time. In most cases, past trades compared two or more technologies across functional and TRL boundaries, which is an uneven comparison of the technologies. For example, low TRL technologies with low mass were traded directly against flight-proven hardware without consideration for requirements and the derived architecture. To provide for even comparisons of spacecraft hardware, trades need to consider functionality, mission constraints, integer vs. real number of flight hardware units, and mass growth allowances by TRL.
Technical Paper

Recent Operational Experience with the Internal Thermal Control System Dual-Membrane Gas Trap

2004-07-19
2004-01-2428
A dual-membrane gas trap is currently used to remove gas bubbles from the Internal Thermal Control System (ITCS) coolant on board the International Space Station. The gas trap consists of concentric tube membrane pairs, comprised of outer hydrophilic tubes and inner hydrophobic fibers. Liquid coolant passes through the outer hydrophilic membrane, which traps the gas bubbles. The inner hydrophobic fiber allows the trapped gas bubbles to pass through and vent to the ambient atmosphere in the cabin. The gas removal performance and operational lifetime of the gas trap have been affected by contamination in the ITCS coolant. However, the gas trap has performed flawlessly with regard to its purpose of preventing gas bubbles from causing depriming, overspeed, and shutdown of the ITCS pump. This paper discusses on-orbit events over the course of the last year related to the performance and functioning of the gas trap.
Technical Paper

Effects of Surfactant Contamination on the Next Generation Gas Trap for the ISS Internal Thermal Control System

2004-07-19
2004-01-2429
The current dual-membrane gas trap is designed to remove gas bubbles from the Internal Thermal Control System (ITCS) coolant on board the International Space Station (ISS). To date it has successfully served its purpose of preventing gas bubbles from causing depriming, overspeed, and shutdown of the ITCS pumps. However, contamination in the ITCS coolant has adversely affected the gas venting rate and lifetime of the gas trap, warranting a development effort for a next-generation gas trap. Previous testing has shown that a hydrophobic-only design is capable of performing even better than the current dual-membrane design for both steady-state gas removal and gas slug removal in clean deionized water. This paper presents results of testing to evaluate the effects of surfactant contamination on the steady-state performance of the hydrophobic-only design.
Technical Paper

Development of Optical Trace Gas Monitoring Technology for NASA Human Space Flight

2004-07-19
2004-01-2266
Investigators from three institutions have partnered in a Rapid Technology Development Team whose goal will be the deployment of laser-based sensors for air-constituent measurements on board spacecrafts. The sensors will eventually be based on Type II Interband Cascade (IC) lasers being developed at the Jet Propulsion Laboratory. These lasers will be used in implementations of both photo acoustic spectroscopy based on the use of quartz tuning fork oscillators as a resonant acoustic sensor (QE-PAS) and cavity ring down spectroscopy (CRDS). In the first year of the program, work at Rice and George Washington Universities has focused on the development of both QEPAS and CRDS sensors for ammonia using near infrared lasers. Simultaneously, the JPL portion of the team has fabricated both Fabry Perot and distributed feedback lasers in the mid infrared that can be used for formaldehyde detection.
Technical Paper

Task Efficiency Results for Desert Rats 2007

2008-06-29
2008-01-2061
The Desert Research and Technology Studies 2007 testing events included three test scenarios which were each tested using extravehicular activity (EVA), autonomous rover and teleoperated rover modes of operation. Task time efficiency data was collected for each mode for comparison. The site survey scenarios consisted of rover travel through a grid of Global Positioning System waypoints with data collection occurring at each waypoint. The total elapsed time for each waypoint was, on average, smallest for the autonomous mode and comparable for the EVA and teleoperated modes. The solar power unit cable deploy scenario task times were comparable between all three modes.
Technical Paper

Human-rating Automated and Robotic Systems — How HAL Can Work Safely with Astronauts

2009-07-12
2009-01-2527
Long duration human space missions, as planned in the Vision for Space Exploration, will not be possible without applying unprecedented levels of automation to support the human endeavors. The automated and robotic systems must carry the load of routine “housekeeping” for the new generation of explorers, as well as assist their exploration science and engineering work with new precision. Fortunately, the state of automated and robotic systems is sophisticated and sturdy enough to do this work — but the systems themselves have never been human-rated as all other NASA physical systems used in human space flight have. Our intent in this paper is to provide perspective on requirements and architecture for the interfaces and interactions between human beings and the astonishing array of automated systems; and the approach we believe necessary to create human-rated systems and implement them in the space program.
Technical Paper

Life Support Requirements and Technology Challenges for NASA's Constellation Program

2008-06-29
2008-01-2018
NASA's Constellation Program, which includes the mission objectives of establishing a permanently-manned lunar Outpost, and the exploration of Mars, poses new and unique challenges for human life support systems that will require solutions beyond the Shuttle and International Space Station state of the art systems. In particular, the requirement to support crews for extended durations at the lunar outpost with limited resource resupply capability will require closed-loop regenerative life support systems with minimal expendables. Planetary environmental conditions such as lunar dust and extreme temperatures, as well as the capability to support frequent and extended-duration Extra-vehicular Activity's (EVA's) will be particularly challenging.
Technical Paper

Development of the Next Generation Gas Trap for the Space Station Internal Thermal Control System

2003-07-07
2003-01-2566
The current dual-membrane gas trap is designed to remove non-condensed gases (NCG) from the Internal Thermal Control System (ITCS) coolant on board the International Space Station (ISS). To date it has successfully served its purpose of preventing depriming, overspeed, and shutdown of the ITCS pump. However, contamination in the ITCS coolant has adversely affected the gas venting rate and lifetime of the gas trap, warranting a development effort for a next-generation gas trap. Design goals are to meet or exceed the current requirements to (1) include greater operating ranges and conditions, (2) eliminate reliance on the current hydrophilic tube fabrication process, and (3) increase operational life and tolerance to particulate and microbial growth fouling.
Technical Paper

A Two-Phase Fluid Pump for Use in Microgravity Environments

1999-07-12
1999-01-1979
The two-phase pump assembly (TPPA) supports advanced thermal control systems (TCS) being developed for future orbital and deep space missions that continuously demand technological advancements to reduce cost, schedule, size, and weight. The TCS provides cooling to onboard personnel and systems by utilizing a coolant in which the working fluid undergoes vaporization and condensation while circulating in the coolant fluid loop. The considerable latent heat associated with these liquid-vapor phase transitions allows the working fluid to absorb and transport a given amount of heat energy with a significantly reduced coolant flow rate resulting in a smaller system size, volume, and mass. Properly designed heat exchangers which utilize boiling and condensation phase transitions can be made smaller and lighter than single-phase systems for a given heat dissipation load.
Technical Paper

Mir Leak Detection Using Fluorescent Tracer Gases

1999-07-12
1999-01-1938
On June 25, 1997 a docking mishap of a Progress supply ship caused the Progress vehicle to crash into an array of solar panels and puncture the hull of the Spektr module. The puncture was small enough to allow the crew to seal off the Spektr module and repressurize the rest of the station. The Progress vehicle struck the Spektr module several times and the exact location, size, and number of punctures in the Spektr hull was unknown. Russian cosmonauts donned space suits and went inside the Spektr module to repair some electrical power cables and look for the location of the hull breach, they could not identify the exact location of the hole (or holes). The Spektr module was pressurized with Mir cabin air twice during the STS-86 fly around in an attempt to detect leakage (in the form of ice particles) from the module. Seven particles were observed within a 36 second time span, but tracking the path of the individual particles did not pinpoint a specific leak location.
Technical Paper

Solid Polymer Electrolyte Oxygen Generator Assembly Life Testing at MSFC - The First Year

1997-07-01
972376
A two year test program has been initiated to evaluate the effects of extended duration operation on a solid polymer electrolyte Oxygen Generator Assembly (OGA); in particular the cell stack and membrane phase separators. As part of this test program, the OGA was integrated into the Marshall Space Flight Center (MSFC) Water Recovery Test (WRT) Stage 10, a six month test, to use reclaimed water directly from the water processor product water storage tanks. This paper will document results encountered and evaluated thus far in the life testing program.
Technical Paper

Diode-Laser Spectral Absorption-Based Gas Species Sensor for Life Support Applications

1997-07-01
972388
We present the development of a semiconductor diode laser spectral absorption based gas species sensor for oxygen concentration measurements, intended for life support system monitoring and control applications. Employing a novel self-compensating, noise cancellation detection approach, we experimentally demonstrate better than 1% accuracy, linearity, and stability for monitoring breathing air conditions with 0.2 second response time. We also discuss applications of this approach to CO2 sensing.
Technical Paper

A Thermal Control System Dual-Membrane Gas Trap for the International Space Station

1997-07-01
972410
The dual membrane gas trap filter is utilized in the internal thermal control system (ITCS) as part of the pump package assembly to remove non-condensed gases from the ITCS coolant. This improves pump performance and prevents pump cavitation. The gas trap also provides the capability to vent air that is Ingested into the ITCS during routine maintenance and replacement of the International Space Station (ISS) system orbital replacement units. The gas trap is composed of two types of membranes that are formed into a cylindrical module and then encased within a titanium housing. The non-condensed gas that is captured is then allowed to escape through a vent tube in the gas trap housing.
Technical Paper

Columbus Orbital Facility Condensing Heat Exchanger and Filter Assembly

1997-07-01
972409
Space environmental control systems must control cabin temperature and humidity. This can be achieved by transferring the heat load to a circulating coolant, condensing the humidity, and separating the condensate from the air stream. In addition, environmental control systems may be required to remove particulate matter from the air stream. An assembly comprised of a filter, a condensing heat exchanger, a thermal control valve, and a liquid carryover sensor, is used to achieve all these requirements. A condensing heat exchanger and filter assembly (CHXFA) is being developed and manufactured by SECAN/AlliedSignal under a contract from Dornier Daimler-Benz as part of a European Space Agency program. The CHXFA is part of the environmental control system of the Columbus Orbital Facility (COF), the European laboratory module of the International Space Station (ISS).
Technical Paper

The Continuing Evolution of the C-130 Environmental Control System

1999-07-12
1999-01-2163
The vast array of C-130 applications demand a variety of air conditioning solutions to meet the specific needs of each variant and its user. Existing C-130′s are often reconfigured for special use such as airborne early warning and control (AEW&C), electronic surveillance, or armed reconnaissance, or just upgraded to current flight standards where new equipment is added to the aircraft that significantly increases the heat load on the air conditioning system. These factors dictate the need for high-, middle-, and low-end solutions to deliver the increased cooling capacity required at a price each user can afford. This paper will recap the evolution of the C-130 environmental control system (ECS) to date, summarize current improvement efforts, and suggest future ECS developments.
Technical Paper

A Novel Repair Technique for the Internal Thermal Control System Dual-Membrane Gas Trap

2005-07-11
2005-01-3079
A dual-membrane gas trap is currently used to remove gas bubbles from the Internal Thermal Control System (ITCS) coolant on board the International Space Station (ISS). The gas trap consists of concentric tube membrane pairs, comprised of outer hydrophilic tubes and inner hydrophobic fibers. Liquid coolant passes through the outer hydrophilic membrane, which traps the gas bubbles. The inner hydrophobic fiber allows the trapped gas bubbles to pass through and vent to the ambient atmosphere in the cabin. The gas trap was designed to last for the entire lifetime of the ISS, and therefore was not designed to be repaired. However, repair of these gas traps is now a necessity due to contamination from the on-orbit ITCS fluid and other sources on the ground as well as a limited supply of flight gas traps. This paper describes a novel repair technique that has been developed that will allow the refurbishment of contaminated gas traps and their return to flight use.
Technical Paper

Assessment of Microbiologically Influenced Corrosion Potential in the International Space Station Internal Active Thermal Control System Heat Exchanger Materials: A 6-Month Study

2005-07-11
2005-01-3077
The fluid in the Internal Active Thermal Control System (IATCS) of the International Space Station (ISS) is water based. The fluid in the ISS Laboratory Module and Node 1 initially contained a mix of water, phosphate (corrosion control), borate (pH buffer), and silver sulfate (Ag2SO4) (microbial control) at a pH of 9.5±0.5. Over time, the chemistry of the fluid changed. Fluid changes included a pH drop from 9.5 to 8.3 due to diffusion of carbon dioxide (CO2) through Teflon® (DuPont) hoses, increases in dissolved nickel (Ni) levels, deposition of silver (Ag) to metal surfaces, and precipitation of the phosphate (PO4) as nickel phosphate (NiPO4). The drop in pH and unavailability of a antimicrobial has provided an environment conducive to microbial growth. Microbial levels in the fluid have increased from <10 colony-forming units (CFUs)/100 mL to 106 CFUs/100 mL.
Technical Paper

Advanced Fiber-Optic Monitoring System for Space-flight Applications

2005-07-11
2005-01-2877
Researchers at Luna Innovations Inc. and the National Aeronautic and Space Administration's Marshall Space Flight Center (NASA MSFC) are developing an integrated fiber-optic sensor system for real-time monitoring of chemical contaminants and whole-cell bacterial pathogens in water. The system integrates interferometric and evanescent-wave optical fiber-based sensing methodologies to provide versatile measurement capability for both micro- and nano-scale analytes. Sensors can be multiplexed in an array format and embedded in a totally self-contained laboratory card for use with an automated microfluidics platform.
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