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NASA NTRS2023

The Trash Compaction Processing System (TCPS) Technology Demonstrations Science Objectives and Requirement Definitions

Throughout the Next STEP Phase A and Phase B, the Trash Compaction Processing System (TCPS) is being developed for a technology demonstration (TD) on the International Space Station (ISS) in 2025. For Phase A, two contractors built proof-of-concept hardware. One contractor was chosen to build the TD hardware for Phase B. Both Phase A lessons learned and risk reduction activities at Ames Research Center (ARC) were used to write the TD science objectives, scope, and requirements. The work at ARC aims to retire technical risks and provide design data to TCPS developers and the ISS system integrators. This paper will summarize the lessons learned from the proof-of-concept hardware, the risk reduction activities, and how these lessons learned form the basis of the TD requirement matrix.

TCPS↗
NASA NTRS2013

Practical Application of PRA as an Integrated Design Tool for Space Systems

This paper presents the application of the first comprehensive Probabilistic Risk Assessment (PRA) during the design phase of a joint NASA/NOAA weather satellite program, Geostationary Operational Environmental Satellite Series R (GOES-R). GOES-R is the next generation weather satellite primarily to help understand the weather and help save human lives. PRA has been used at NASA for Human Space Flight for many years. PRA was initially adopted and implemented in the operational phase of manned space flight programs and more recently for the next generation human space systems. Since its first use at NASA, PRA has become recognized throughout the Agency as a method of assessing complex mission risks as part of an overall approach to assuring safety and mission success throughout project lifecycles. PRA is now included as a requirement during the design phase of both NASA next generation manned space vehicles as well as for high priority robotic missions. The influence of PRA on GOES-R design and operation concepts are discussed in detail. The GOES-R PRA is unique at NASA for its early implementation. It also represents a pioneering effort to integrate risks from both Spacecraft (SC) and Ground Segment (GS) to fully assess the probability of achieving mission objectives. PRA analysts were actively involved in system engineering and design engineering to ensure that a comprehensive set of technical risks were correctly identified and properly understood from a design and operations perspective. The analysis included an assessment of SC hardware and software, SC fault management system, GS hardware and software, common cause failures, human error, natural hazards, solar weather and infrastructure (such as network and telecommunications failures, fire). PRA findings directly resulted in design changes to reduce SC risk from micro-meteoroids. PRA results also led to design changes in several SC subsystems, e.g. propulsion, guidance, navigation and control (GNC), communications, mechanisms, and command and data handling (C&DH). The fault tree approach assisted in the development of the fault management system design. Human error analysis, which examined human response to failure, indicated areas where automation could reduce the overall probability of gaps in operation by half. In addition, the PRA brought to light many potential root causes of system disruptions, including earthquakes, inclement weather, solar storms, blackouts and other extreme conditions not considered in the typical reliability and availability analyses. Ultimately the PRA served to identify potential failures that, when mitigated, resulted in a more robust design, as well as to influence the program's concept of operations. The early and active integration of PRA with system and design engineering provided a well-managed approach for risk assessment that increased reliability and availability, optimized lifecyc1e costs, and unified the SC and GS developments.

Kalia, Prince↗
NASA NTRS2016

The Spacecraft Fire Experiment (Saffire) - Objectives, Development and Status

Since 2012, the Spacecraft Fire Experiment (Saffire) has been under development by the Spacecraft Fire Safety Demonstration (SFS Demo) project that is funded by NASA's Advanced Exploration Systems Division in the Human Exploration and Operations Mission Directorate. The overall objective of this project is to reduce the uncertainty and risk associated with the design of spacecraft fire safety systems for NASA's exploration missions. This is accomplished by defining, developing, and conducting experiments that address gaps in spacecraft fire safety knowledge and capabilities identified by NASA's Fire Safety System Maturation Team. This paper describes the three Spacecraft Fire Experiments (Saffire-I, -II, and -III) that were developed at NASA-GRC and that will conduct a series of material flammability tests in low-gravity and at length scales that are realistic for a spacecraft fire. The experiments will be conducted in Orbital ATK's Cygnus vehicle after it has unberthed from the International Space Station. The tests will be fully automated with the data downlinked at the conclusion of the test and before the Cygnus vehicle reenters the atmosphere. The objectives of these experiments are to (1) determine how rapidly a large scale fire grows in low-gravity and (2) investigate the low-g flammability limits compared to those obtained in NASA's normal gravity material flammability screening test. The hardware for these experiments has been completed and is awaiting their respective launches, all planned for 2016. This paper will review the objectives of these experiments and how they address several of the knowledge gaps for NASA's exploration missions. The hardware development will be discussed including several novel approaches that were taken for testing and evaluation of these series payloads. The status of the missions and operational status will also be presented.

combustion↗
NASA NTRS2015

Developing Probabilistic Safety Performance Margins for Unknown and Underappreciated Risks

Probabilistic safety requirements currently formulated or proposed for space systems, nuclear reactor systems, nuclear weapon systems, and other types of systems that have a low-probability potential for high-consequence accidents depend on showing that the probability of such accidents is below a specified safety threshold or goal. Verification of compliance depends heavily upon synthetic modeling techniques such as PRA. To determine whether or not a system meets its probabilistic requirements, it is necessary to consider whether there are significant risks that are not fully considered in the PRA either because they are not known at the time or because their importance is not fully understood. The ultimate objective is to establish a reasonable margin to account for the difference between known risks and actual risks in attempting to validate compliance with a probabilistic safety threshold or goal. In this paper, we examine data accumulated over the past 60 years from the space program, from nuclear reactor experience, from aircraft systems, and from human reliability experience to formulate guidelines for estimating probabilistic margins to account for risks that are initially unknown or underappreciated. The formulation includes a review of the safety literature to identify the principal causes of such risks.

Safety Performance Margin↗
NASA NTRS2005

GO/NO-GO - When is medical hazard mitigation acceptable for launch?

Medical support of spaceflight missions is composed of complex tasks and decisions that dedicated to maintaining the health and performance of the crew and the completion of mission objectives. Spacecraft represent one of the most complex vehicles built by humans, and are built to very rigorous design specifications. In the course of a Flight Readiness Review (FRR) or a mission itself, the flight surgeon must be able to understand the impact of hazards and risks that may not be completely mitigated by design alone. Some hazards are not mitigated because they are never actually identified. When a hazard is identified, it must be reduced or waivered. Hazards that cannot be designed out of the vehicle or mission, are usually mitigated through other means to bring the residual risk to an acceptable level. This is possible in most engineered systems because failure modes are usually predictable and analysis can include taking these systems to failure. Medical support of space missions is complicated by the inability of flight surgeons to provide "exact" hazard and risk numbers to the NASA engineering community. Taking humans to failure is not an option. Furthermore, medical dogma is mostly comprised of "medical prevention" strategies that mitigate risk by examining the behaviour of a cohort of humans similar to astronauts. Unfortunately, this approach does not lend itself well for predicting the effect of a hazard in the unique environment of space. This presentation will discuss how Medical Operations uses an evidence-based approach to decide if hazard mitigation strategies are adequate to reduce mission risk to acceptable levels. Case studies to be discussed will include: 1. Risk of electrocution risk during EVA 2. Risk of cardiac event risk during long and short duration missions 3. Degraded cabin environmental monitoring on the ISS. Learning Objectives 1.) The audience will understand the challenges of mitigating medical risk caused by nominal and off-nominal mission events. 2.) The audience will understand the process by which medical hazards are identified and mitigated before launch. 3.) The audience will understand the roles and responsibilities of all the other flight control positions in participating in the process of reducing hazards and reducing medical risk to an acceptable level.

Hamilton, Douglas R.↗
NASA NTRS2009

Renal Stone Risk During Spaceflight: Assessment and Countermeasure Validation

This viewgraph presentation describes the risks of renal stone formation in manned space flight. The contents include: 1) Risk; 2) Evidence; 3) Nephrolithiasis -A Multifactorial Disease; 4) Symptoms/signs; 5) Urolithiasis and Stone Passage; 6) Study Objectives; 7) Subjects; 8) Methods; 9) Investigation Results; 10) Potassium Citrate; 11) Calcium Balance; 12) Case Study; 13) Significant Findings; 14) Risk Mitigation Strategies and Recommended Actions; and 15) Future Potential.

Pietrzyk, Robert A.↗
NASA NTRS2011

Immune System Dysregulation and Herpesvirus Reactivation Persist During Long-Duration Spaceflight

This poster presentation reviews a study that is designed to address immune system dysregulation and the risk to crewmembers in long duration exploration class missions. This study will address these objectives: (1) Determine the status of adaptive immunity physiological stress, viral immunity, latent herpesvirus reactivation in astronauts during 6 month missions to the International Space Station; (2) determine the clinical risk related to immune dysregulation for exploration class spaceflight; and (3) determine an appropriate monitoring strategy for spaceflight-associated immune dysfunction that could be used for the evaluation of countermeasures. The study anticipates 17 subjects, and for this presentation, (midpoint study data) 10 subjects are reviewed.

Crucian, B. E.↗
NASA NTRS2004

Malaria Modeling using Remote Sensing and GIS Technologies

Malaria has been with the human race since the ancient time. In spite of the advances of biomedical research and the completion of genomic mapping of Plasmodium falciparum, the exact mechanisms of how the various strains of parasites evade the human immune system and how they have adapted and become resistant to multiple drugs remain elusive. Perhaps because of these reasons, effective vaccines against malaria are still not available. Worldwide, approximately one to three millions deaths are attributed to malaria annually. With the increased availability of remotely sensed data, researchers in medical entomology, epidemiology and ecology have started to associate environmental and ecological variables with malaria transmission. In several studies, it has been shown that transmission correlates well with certain environmental and ecological parameters, and that remote sensing can be used to measure these determinants. In a NASA project, we have taken a holistic approach to examine how remote sensing and GIs can contribute to vector and malaria controls. To gain a better understanding of the interactions among the possible promoting factors, we have been developing a habitat model, a transmission model, and a risk prediction model, all using remote sensing data as input. Our objectives are: 1) To identify the potential breeding sites of major vector species and the locations for larvicide and insecticide applications in order to reduce costs, lessen the chance of developing pesticide resistance, and minimize the damage to the environment; 2) To develop a malaria transmission model characterizing the interactions among hosts, vectors, parasites, landcover and environment in order to identify the key factors that sustain or intensify malaria transmission, and 3) To develop a risk model to predict the occurrence of malaria and its transmission intensity using epidemiological data and satellite-derived or ground-measured environmental and meteorological data.

Kiang, Richard↗
NASA NTRS2007

Detection of Orbital Debris Collision Risks for the Automated Transfer Vehicle

In this paper, we present a general collision risk assessment method, which has been applied through numerical simulations to the Automated Transfer Vehicle (ATV) case. During ATV ascent towards the International Space Station, close approaches between the ATV and objects of the USSTRACOM catalog will be monitored through collision rosk assessment. Usually, collision risk assessment relies on an exclusion volume or a probability threshold method. Probability methods are more effective than exclusion volumes but require accurate covariance data. In this work, we propose to use a criterion defined by an adaptive exclusion area. This criterion does not require any probability calculation but is more effective than exclusion volume methods as demonstrated by our numerical experiments. The results of these studies, when confirmed and finalized, will be used for the ATV operations.

Peret, L.↗
NASA NTRS2013

TPSAS-NF1676L-17243-DND

This presentation captures ERA Project's effort in using integrated cost-schedule-risk analysis tool, identifying and capturing explicit relationships between program funds, schedule, and discrete risks. The project team merged a myriad of cost and schedule data for timely, objective, uncertainty analysis of the ITD's budget and schedule. The project team conducted detailed schedule uncertainty analysis showing schedule activities and how their interrelationships were impacted, representing an impressive advance beyond routine Gantt charts. Furthermore, the ERA Project collected discrete risk events including their impacts to costs and/or schedule and interwove these risks into cost and schedule logic networks, providing the foundation to conduct cost and schedule analyses. The team integrated this data into the analysis model, providing probabilistic results that were then used by the ERA Project's senior management for decision-making purposes. The ERA Project management team, through technical and pathfinder expertise in integrating cost, schedule, risk, and technical content, consistently provided risk-informed recommendations to Implementing Centers and ISRP senior management which ultimately ensured the successful ARMD Key Decision Point (KDP) review of the ERA Phase 2 ITD Portfolio and increased the likelihood of achieving technical objectives within cost and schedule constraints.

Gaudy M Bezos-O'Connor↗
NASA NTRSDate not supplied

Metrics on Predictive Probability of Collision Assessments Reliant on Object State Updates

The probability of collision (Pc) metric is the dominant method of risk charac-terization for evaluating satellite close approaches, and has become of particular interest following major debris production incidents. However, confidence in the use of Pc for actionability has been questioned due in part due to its non-intuitive and often significant corrections following messaging updates. This paper assesses predictively computed probabilities and confidence bounds on Pc values corresponding to orbit determination updates by comparing these predic-tive values to observed operational values. This paper also presents use cases for this methodology in assessing event actionability.

conjunction assessment↗
NASA NTRS1976

A comparison of spacecraft penetration hazards due to meteoroids and manmade earth-orbiting objects

The ability of a typical double-walled spacecraft structure to protect against penetration by high-velocity incident objects is reviewed. The hazards presented by meteoroids are compared to the current and potential hazards due to manmade orbiting objects. It is shown that the nature of the meteoroid number-mass relationship makes adequate protection for large space facilities a conceptually straightforward structural problem. The present level of manmade orbiting objects (an estimated 10,000 in early 1975) does not pose an unacceptable risk to manned space operations proposed for the near future, but it does produce penetration probabilities in the range of 1-10 percent for a 100-m diameter sphere in orbit for 1,000 days. The number-size distribution of manmade objects is such that adequate protection is difficult to achieve for large permanent space facilities, to the extent that future restrictions on such facilities may result if the growth of orbiting objects continues at its historical rate.

Brooks, D. R.↗
NASA NTRS1987

Antenna Technology Shuttle Experiment (ATSE)

Numerous space applications of the future will require mesh deployable antennas of 15 m in diameter or greater for frequencies up to 20 GHz. These applications include mobile communications satellites, orbiting very long baseline interferometry (VLBI) astrophysics missions, and Earth remote sensing missions. A Lockheed wrap rip antennas was used as the test article. The experiments covered a broad range of structural, control, and RF discipline objectives, which is fulfilled in total, would greatly reduce the risk of employing these antenna systems in future space applications. It was concluded that a flight experiment of a relatively large mesh deployable reflector is achievable with no major technological or cost drivers. The test articles and the instrumentation are all within the state of the art and in most cases rely on proven flight hardware. Every effort was made to design the experiments for low cost.

Freeland, R. E.↗
NASA NTRS1991

Space Station Freedom/lunar transfer vehicle propellant operation hazard analysis

Space Station Freedom (SSF), as a transportation node for Space Exploration Initiative missions, would involve the assembly and refurbishing of lunar and Mars transfer vehicles. This includes operations involving cryogenic propellants (LH2 7 LO2) such as storing and handling of loaded propellant tanks, assembly onto the vehicle, and propellant transfer. Cryogenic propellants dictate rigorous safety precautions and impose unique requirements to ensure flight safety to both personnel and SSF elements. The objective of this study is to identify potential hazards and risks associated with cryogenic propellants. This involves identification of pertinent system design features and operational procedures. Criticality of identified risks/hazards shall be assessed and those that fall in the catastrophic and critical categories shall include mitigating solutions.

Dominick, Sam↗
NASA NTRS1992

High speed rotorcraft propulsion concepts to control power/speed characteristics

Recent NASA sponsored rotorcraft airframer studies have demonstrated the desire for constant power over a wide range of output speed for turboshaft propulsion systems. This study interrogated several different concepts aimed at maintaining constant power over a speed variation from 100-50 percent with minimum increase in fuel consumption. The baseline engine was an advanced technology 8000 shp, fixed turbine geometry, turboshaft engine. The concepts investigated included variable geometry turbines, variable geometry compressors, power transfer from the HP to LP shafts, counterrotating power turbine with a combiner gearbox, and variable speed transmission integrated with the baseline turboshaft engine. The concept that best satisfies the program objectives with superior engine performance and with the least technical risk is the baseline (fixed geometry turbines) turboshaft engine integrated with the variable speed transmission.

Bettner, J. L.↗
NASA NTRS1994

The natural space environment: Effects on spacecraft

The effects of the natural space environments on spacecraft design, development, and operation are the topic of a series of NASA Reference Publications currently being developed by the Electromagnetics and Environments Branch, Systems Analysis and Integration Laboratory, Marshall Space Flight Center. This primer provides an overview of the natural space environments and their effect on spacecraft design, development, and operations, and also highlights some of the new developments in science and technology for each space environment. It is hoped that a better understanding of the space environment and its effect on spacecraft will enable program management to more effectively minimize program risks and costs, optimize design quality, and successfully achieve mission objectives.

James, Bonnie F.↗
NASA NTRS2003

A Review of LOX/Kerosene Combustion Instability in American and Russian Combustion Devices in Application to Next-Generation Launch Technology

The Next-Generation Launch Technology (NGLT) project was introduced with its objectives. To meet the objectives, NASA has directed aerospace industry to perform advances and risk reduction of relevant technologies, including propulsion. Originally, the propulsion industry focused on producing both LOWLH2 and LOWkerosene flight engine technology demonstrators. These flight engine technology demonstrators were briefly reviewed. NASA recently redirected this focus to Lowkerosene only. Discussion of LOWkerosene combustion devices was and is prefaced by grave concerns about combustion instability. These concerns have prompted a review of LOWkerosene combustion instability in American and Russian combustion devices. In the review of the Russian propulsion industry's experience in eliminating LOWkerosene combustion instabilities, the history of principal Russian rocket scientists and their role in the development of LOXkerosene combustion devices is presented. The innovative methods implemented by the Russians of eliminations combustion instabilities in LOXkerosene combustion devices were reviewed. The successful elimination of these combustion instabilities has resulted in two generations of Russian-produced, high-performance LOWkerosene combustion devices.

Rocker, Marvin↗
NASA NTRS2004

Ignition Characterization Tests of the LOX/Ethanol Propellant Combination

A series of contracts have been issued by the Marshall Space Flight Center (MSFC) of the National Aeronautics and Space Administration (NASA) to explore candidate technologies considered to be important for the Next Generation Launch Technology (NGLT) effort. One aspect of the NGLT effort is to explore the potential of incorporating non-toxic propellants for Reaction Control Subsystems (RCS). Contract NAS8-01109 has been issued to Aerojet to develop a dual thrust Reaction Control Engine (RCE) that utilizes liquid oxygen and ethanol as the propellants. The dual thrust RCE incorporates a primary thrust level of 870 lbf, and a vernier thrust level of 10 - 30 lbf. Aerojet has designed and tested a workhorse LOX igniter to determine LOX/Ethanol ignition characteristics as part of a risk mitigation effort for the dual thrust RCE design. The objective of the ignition testing was to demonstrate successfid ignition from GOX to LOX, encompassing potential two-phase flow conditions. The workhorse igniter was designed to accommodate the full LOX design flowrate, as well as a reduced GOX flowrate. It was reasoned that the initial LOX flow through the igniter would flash to GOX due to the inherent heat stored in the hardware, causing a reduced oxygen flowrate because of a choked, or sonic, flow condition through the injection elements. As LOX flow continued, the inherent heat of the test hardware would be removed and the hardware would chill-in, with the injected oxygen flow transitioning from cold GOX through two-phase flow to subcooled LOX. Pressure and temperature instrumentation permitted oxygen state points to be determined, and gas-side igniter chamber thermocouples provided chamber thermal profile characteristics. The cold flow chamber pressure (P(sub c)) for each test was determined and coupled with the igniter chamber diameter (D(sub c)) to calculate the characteristic quench parameter (P(sub c) x D(sub c)), which was plotted as a function of core mixture ratio, MR(sub c). Ignition limits were determined over a broad range of valve inlet conditions, and ignition was demonstrated with oxygen inlet conditions that ranged from subcooled 173 R LOX to 480 R GQX. Once ignited at cold GOX conditions, combustion was continuous as the hardware chilled in and the core mixture ratio transitioned from values near 1.0 to over 12.5.

Popp, Christopher G.↗