Results for “ISS Anomaly” — Page 5

NASA NTRS2010

The International Space Station Solar Alpha Rotary Joint Anomaly Investigation

The Solar Alpha Rotary Joint (SARJ) is a single-axis pointing mechanism used to orient the solar power generating arrays relative to the sun for the International Space Station (ISS). Approximately 83 days after its on-orbit installation, one of the two SARJ mechanisms aboard the ISS began to exhibit high drive motor current draw. Increased structural vibrations near the joint were also observed. Subsequent inspections via Extravehicular Activity (EVA) discovered that the nitrided case-hardened steel bearing race on the outboard side of the joint had extensive damage to one of its three rolling surfaces. A farreaching investigation of the anomaly was undertaken. The investigation included metallurgical inspections, coupon tests, traction kinematics tests, detailed bearing measurements, and thermal and structural analyses. The results of the investigation showed that the anomaly had most probably been caused by high bearing edge stresses that resulted from inadequate lubrication of the rolling contact. The profile of the roller bearings and the metallurgical properties of the race ring were also found to be significant contributing factors. To mitigate the impact of the damage, astronauts cleaned and lubricated the race ring surface with grease. This corrective action led to significantly improved performance of the mechanism both in terms of drive motor current and induced structural vibration.

Harik, Elliot P.↗

NASA NTRS2010

The International Space Station Solar Alpha Rotary Joint Anomaly Investigation

The Solar Alpha Rotary Joint (SARJ) is a single-axis pointing mechanism used to orient the solar power generating arrays relative to the sun for the International Space Station (ISS). Approximately 83 days after its on-orbit installation, one of the two SARJ mechanisms aboard the ISS began to exhibit high drive motor current draw. Increased structural vibrations near the joint were also observed. Subsequent inspections via Extravehicular Activity (EVA) discovered that the nitrided case hardened steel bearing race on the outboard side of the joint had extensive damage to one of its three rolling surfaces. A far-reaching investigation of the anomaly was undertaken. The investigation included metallurgical inspections, coupon tests, traction kinematics tests, detailed bearing measurements, and thermal and structural analyses. The results of the investigation showed that anomaly had most probably been caused by high bearing edge stresses that resulted from inadequate lubrication of the rolling contact. The profile of the roller bearings and the metallurgical properties of the race ring were also found to be significant contributing factors. To mitigate the impact of the damage astronauts cleaned and lubricated the race ring surface with grease. This corrective action led to significantly improved performance of the mechanism both in terms of drive motor current and induced structural vibration.

Harik, Elliot P.↗

NASA NTRS2010

Root Cause Investigation of the Starboard Solar Alpha Rotary Joint Anomaly on the International Space Station

The Solar Alpha Rotary Joint (SARJ) is a single-axis pointing mechanism used to orient the solar power generating arrays relative to the sun for the International Space Station (ISS). Approximately 83 days after its on-orbit installation, one of the two SARJ mechanisms aboard the ISS began to exhibit high current draw. Later inspections via Extravehicular Activity (EVA) discovered that the case hardened steel race ring on the outboard side of the joint had extensive damage to one of its three rolling surfaces. A far-reaching investigation of the anomaly was undertaken, comprising metallurgical inspections, coupon tests, traction kinematics tests, detailed bearing measurements, and thermal and structural analyses. The investigation found that the race ring damage had been caused by high bearing edge stresses that resulted from inadequate lubrication of the rolling contact. The profile of the roller bearings and the metallurgical properties of the race ring were also found to be significant contributing factors.

Taylor, Deneen↗

NASA NTRS2018

International Space Station Spacecraft Charging Environments: Modeling, Measurement and Implications for Future Human Space Flight Programs

Spacecraft charging analysis and migration is an interdisciplinary subject combining aspects of electrostatics, plasma physics, ionizing radiation, and materials science, as well as electronic system electromagnetic interference and compatibility (EMI/EMC) effects. Spacecraft charging hazards are caused by the accumulation of electrical charge on spacecraft and spacecraft components produced by interactions with space plasmas, energetic charged particles, and solar UV photons as well as spacecraft electrical power and propulsion systems operations. Spacecraft charging hazard effects include both hard and soft avionics and electrical power system anomalies and have led to the partial or complete loss of numerous spacecraft. The International Space Station (ISS) orbital altitude and inclination (~400 km and 51.6o) determined the dominant natural environment factors affecting ISS spacecraft charging; high speed flight through the geomagnetic field and electrical power system interaction with the cold, high-density ionospheric plasma. In addition ISS is exposed to energetic auroral electrons at high latitude. In this paper we present the results of ISS spacecraft charging modeling and measurements and compare the measurements with numerical modeling of ISS charging processes. ISS is a large metallic structure and flight through the geomagnetic field at orbital speed dominates ISS charging. Collection of ionospheric electrons by the large 160V PV arrays is the next largest contributor. Charging by auroral electrons is detectable but makes a relatively minor contribution. Finally we report the observation of short duration (~ 1 sec) rapid charging peaks associated with shunt/un-shunt operations of the 160V PV arrays, a phenomena not predicted before flight. ISS spacecraft charging environments are radically different from those encountered at higher altitudes in Earth?s magnetosphere and in cis-Lunar space. We present a brief review of those charging environments and an assessment of the applicability of ISS spacecraft charging management and experience to future human spaceflight programs beyond LEO.

Koontz, Steven L.↗

NASA NTRS2017

A PCR Based Microbial Monitoring Alternative Method of Detection and Identification of Microbes Aboard ISS

Previous research has shown that microorganisms and potential human pathogens have been detected on the International Space Station (ISS) with additional introduction of new microflora occurring with every exchange of crew or addition of equipment and supplies. These microbes are readily transferred between crew and subsystems (i.e. ECLSS, environmental control and life support systems). As this can be detrimental to astronaut health and optimal performance of ISS systems, monitoring of systems such as ECLSS to include identification of microbial contaminants could prevent adverse effects on human health and life support systems. Current monitoring on ISS is laborious and utilizes culture based methods followed by sample return to Earth for complete analysis. Future, long-distance spaceflight missions will require real-time monitoring capabilities that enable efficient and rapid assessments of the microbial environment allowing for expedited decisions and more targeted response to cope with anomalies. Polymerase chain reaction (PCR), a molecular microbial monitoring method was chosen and numerous PCR instruments investigated for their potential to perform in microgravity conditions. Using ISS as a test bed for PCR verification in microgravity will enable NASA to assess whether molecular based microbiological sensors may be components of reliable, closed-loop life support and habitation systems in spacecraft, enhancing infrastructure capabilities through increased efficiency, reliability, and time savings by enabling sample analysis on orbit. NASA selected the Water Monitoring Suite as one of the rapid spaceflight hardware demonstration activities utilizing a streamlined process to minimize the time required to fly experimental flight hardware. The RAZOR EX (BioFire Defense, Salt Lake City, UT) system was part of the water monitoring suite and is a commercial off-the-shelf (COTS) real-time PCR instrument designed for field work. The RAZOR EX was originally designed for Department of Defense (DoD) under a small business innovative research (SBIR) grant and is ruggedized, compact and provides a rapid, sample to answer in less than an hour. PCR assays using a fluorescent probe were optimized and spiked with known concentrations of DNA (Pseudomonas aeruginosa) ranging from 0.002 to 20 ng. PCR reagents were lyophilized and configured in customized pouches and tested for flight readiness. Three types of water were used to rehydrate the reagents and demonstrate the fidelity of the PCR reaction in microgravity. Molecular grade deionized water served as a control while filtered and unfiltered ISS potable water served to test for chemical or biological inhibitors. All three types were compared to parallel ground test results. Nine tests were run on ISS (3 of each water type) and the critical threshold cycle (Ct) was compared to parallel ground tests completed at Kennedy Space Center, FL and Johnson Space Center, TX. All concentrations of Pseudomonas aeruginosa DNA were detected. A comparison of the Ct produced in real time PCR indicated similarity between flight and ground samples. There appeared to be no significant difference between flight or ground PCR reactions or between any of the three water types. This testing demonstrated the ability to perform molecular testing during spaceflight operations with similar sensitivity. It will allow for future ground development of molecular protocols and minimize the need for spaceflight testing. Future testing will include development of additional targets including environmental and health related organisms.

Christina Khodadad↗

NASA NTRS2008

Radiation Measured during ISS-Expedition 13 with Different Dosimeters

Radiation in low Earth orbit (LEO) is mainly composed of Galactic Cosmic Rays (GCR), solar energetic particles and particles in SAA (South Atlantic Anomaly). The biological impact of space radiation to astronauts depends strongly on the particles linear energy transfer (LET) and is dominated by high LET radiation. It is important to measure the LET spectrum for the space radiation field and to investigate the influence of radiation on astronauts. At present, the preferred active dosimeters sensitive to all LET are the tissue equivalent proportional counter (TEPC) and silicon detectors in various configurations; the preferred passive dosimeters are thermoluminescence dosimeters (TLDs) and optically stimulated luminescence dosimeters (OSLDs) sensitive to low LET as well as CR-39 plastic nuclear track detectors (PNTDs) sensitive to high LET. The TEPC, CR-39 PNTDs, TLDs and OSLDs were used to investigate the radiation exposure for the ISS mission Expedition 13 (ISS-12S) in LEO. LET spectra and radiation quantities (fluence, absorbed dose, dose equivalent and quality factor) were measured for the space mission with different dosimeters. This paper introduces the operational principles for the dosimeters, describes the method to combine the results measured by TLDs/OSLDs and CR-39 PNTDs, and presents the LET spectra and the radiation quantities measured. Keywords: space radiation; cosmic rays; active and passive dosimeters; LET spectra

Zhou, D.↗

NASA NTRS2014

Ionosphere Plasma State Determination in Low Earth Orbit from International Space Station Plasma Monitor

A plasma diagnostic package is deployed on the International Space Station (ISS). The system - a Floating Potential Measurement Unit (FPMU) - is used by NASA to monitor the electrical floating potential of the vehicle to assure astronaut safety during extravehicular activity. However, data from the unit also reflects the ionosphere state and seems to represent an unutilized scientific resource in the form of an archive of scientific plasma state data. The unit comprises a Floating Potential probe and two Langmuir probes. There is also an unused but active plasma impedance probe. The data, at one second cadence, are collected, typically for a two week period surrounding extravehicular activity events. Data is also collected any time a visiting vehicle docks with ISS and also when any large solar events occur. The telemetry system is unusual because the package is mounted on a television camera stanchion and its data is impressed on a video signal that is transmitted to the ground and streamed by internet to two off center laboratory locations. The data quality has in the past been challenged by weaknesses in the integrated ground station and distribution systems. These issues, since mid‐2010, have been largely resolved and the ground stations have been upgraded. Downstream data reduction has been developed using physics based modeling of the electron and ion collecting character in the plasma. Recursive algorithms determine plasma density and temperature from the raw Langmuir probe current voltage sweeps and this is made available in real time for situational awareness. The purpose of this paper is to describe and record the algorithm for data reduction and to show that the Floating probe and Langmuir probes are capable of providing long term plasma state measurement in the ionosphere. Geophysical features such as the Appleton anomaly and high latitude modulation at the edge of the Auroral zones are regularly observed in the nearly circular, 51 deg inclined, 400 km altitude ISS orbit. Evidence of waves in the ion collection current data is seen in geographic zones known to exhibit the spread‐F phenomenon. An anomaly in the current collection characteristic of the cylindrical probe appears also too be organized by the geomagnetic field.

Kramer, Leonard↗

NASA NTRS2011

Integration of In-Flight and Post-Flight Water Monitoring Resources in Addressing the U.S. Water Processor Assembly Total Organic Carbon (TOC) Anomaly

Beginning in June of 2010, the total organic carbon (TOC) concentration in the U.S. Water Processor Assembly (WPA) product water started to increase. A surprisingly consistent upward TOC trend was observed through weekly ISS total organic carbon analyzer (TOCA) monitoring. As TOC is a general organic compound indicator, return of water archive samples was needed to make better-informed crew health decisions on the specific compounds of concern and to aid in WPA troubleshooting. TOCA-measured TOC was more than halfway to the health-based screening limit of 3,000 g/L before archive samples were returned. Archive samples were returned on 22 Soyuz in September 2010 and on ULF5 in November of 2010. The samples were subjected to extensive analysis. Although TOC was confirmed to be elevated, somewhat surprisingly, none of the typical target compounds were detected at high levels. After some solid detective work, it was confirmed that the TOC was associated with a compound known as dimethylsilanediol (DMSD). DMSD is believed to be a breakdown product of siloxanes which are thought to be ubiquitous in the ISS atmosphere. A toxicological limit was set for DMSD and a forward plan was developed for conducting operations in the context of understanding the composition of the TOC measured in flight. This required careful consideration of existing ISS flight rules, coordination with ISS stakeholders, and development of a novel approach for the blending of inflight TOCA data with archive results to protect crew health. Among other challenges, team members had to determine how to utilize TOCA readings when making decisions about crew consumption of WPA water. This involved balancing very real concerns associated with the assumption that TOC would continue to be comprised of only DMSD. Demonstrated teamwork, multidisciplinary awareness, and innovative problem-solving were required to respond effectively to this anomaly.

Straub, John E., II↗

NASA NTRS2006

Cassini Camera Contamination Anomaly: Experiences and Lessons Learned

We discuss the contamination 'Haze' anomaly for the Cassini Narrow Angle Camera (NAC), one of two optical telescopes that comprise the Imaging Science Subsystem (ISS). Cassini is a Saturn Orbiter with a 4-year nominal mission. The incident occurred in 2001, five months after Jupiter encounter during the Cruise phase and ironically at the resumption of planned maintenance decontamination cycles. The degraded optical performance was first identified by the Instrument Operations Team with the first ISS Saturn imaging six weeks later. A distinct haze of varying size from image to image marred the images of Saturn. A photometric star calibration of the Pleiades, 4 days after the incident, showed stars with halos. Analysis showed that while the halo's intensity was only 1 - 2% of the intensity of the central peak of a star, the halo contained 30 - 70% of its integrated flux. This condition would impact science return. In a review of our experiences, we examine the contamination control plan, discuss the analysis of the limited data available and describe the one-year campaign to remove the haze from the camera. After several long conservative heating activities and interim analysis of their results, the contamination problem as measured by the camera's point spread function was essentially back to preanomaly size and at a point where there would be more risk to continue. We stress the importance of the flexibility of operations and instrument design, the need to do early infight instrument calibration and continual monitoring of instrument performance.

Cassini↗

NASA NTRS2009

Biennial Research and Technology Development Report

Various articles for the Biennial Research and Technology Development Report of the Johnson Space Center include: Automating ISS File Management using Agent-Based Systems Integration; International Space Station Operations; Planning and Monitoring ISS Solar Array Operations; Water Egress and Survival Trainer; Search and Relationship -- Mining of Heterogeneous Flight Control Documents; and Anomaly Monitoring Inductive Software System.

Taylor, Elizabeth↗

NASA NTRSDate not supplied

Development, Build and Certification of the Alternate Fecal Canister (AFC) Hardware for the NASA Exploration Toilet

On longer range exploration missions, the mass and volume of critical hardware and consumables that will be needed to support crew will pose a big stowage challenge. This includes the hardware needed for the collection and storage of human metabolic waste. The amount of stowage needed for this hardware both before (empty) and after (full) use will be a significant burden on the overall spacecraft habitable volume, layout, and design. To help with this challenge, the National Aeronautics and Space Administration (NASA) has developed a collapsible canister for the collection and containment of fecal deposits. The Alternate Fecal Canister (AFC) is an alternative to the exploration toilet hard-sided fecal canister. The AFC is collapsible in its empty state which is a volume benefit to smaller vehicles on longer missions. In addition, the use of lighter-weight materials provides a reduction in mass of the overall container. This paper will provide a summary of the AFC design including final flight design and build, acceptance and qualification testing completed, final certification and delivery and forward plans for a technology demonstration with the exploration toilet on the International Space Station (ISS). In addition, a summary of issues and final resolution encountered during flight build and testing will also be provided. As part of the acceptance and certification process for AFC, the hardware was also put into several rounds of odor testing with the support of the White Sands Test Facility (WSTF). The details, planning and anomalies identified during odor testing will also be summarized in this paper. Finally, a brief overview of potential future design upgrades including changes to address any crew feedback from the ISS demonstration will be discussed.

Fecal Canister↗

NASA NTRSDate not supplied

Development, Build and Certification of the Alternate Fecal Canister (AFC) Hardware for the NASA Exploration Toilet

On longer range exploration missions, the mass and volume of critical hardware and consumables that will be needed to support crew will pose a big stowage challenge. This includes the hardware needed for the collection and storage of human metabolic waste. The amount of stowage needed for this hardware both before (empty) and after (full) use will be a significant burden on the overall spacecraft habitable volume, layout, and design. To help with this challenge, the National Aeronautics and Space Administration (NASA) has developed a collapsible canister for the collection and containment of fecal deposits. The Alternate Fecal Canister (AFC) is an alternative to the exploration toilet hard-sided fecal canister. The AFC is collapsible in its empty state which is a volume benefit to smaller vehicles on longer missions. In addition, the use of lighter-weight materials provides a reduction in mass of the overall container. This paper will provide a summary of the AFC design including final flight design and build, acceptance and qualification testing completed, final certification and delivery and forward plans for a technology demonstration with the exploration toilet on the International Space Station (ISS). In addition, a summary of issues and final resolution encountered during flight build and testing will also be provided. As part of the acceptance and certification process for AFC, the hardware was also put into several rounds of odor testing with the support of the White Sands Test Facility (WSTF). The details, planning and anomalies identified during odor testing will also be summarized in this paper. Finally, a brief overview of potential future design upgrades including changes to address any crew feedback from the ISS demonstration will be discussed.

Fecal Canister↗

NASA NTRSDate not supplied

Development, Build and Certification of the Alternate Fecal Canister (AFC) Hardware for the NASA Exploration Toilet

On longer range exploration missions, the mass and volume of critical hardware and consumables that will be needed to support crew will pose a big stowage challenge. This includes the hardware needed for the collection and storage of human metabolic waste. The amount of stowage needed for this hardware both before (empty) and after (full) use will be a significant burden on the overall spacecraft habitable volume, layout, and design. To help with this challenge, the National Aeronautics and Space Administration (NASA) has developed a collapsible canister for the collection and containment of fecal deposits. The Alternate Fecal Canister (AFC) is an alternative to the exploration toilet hard-sided fecal canister. The AFC is collapsible in its empty state which is a volume benefit to smaller vehicles on longer missions. In addition, the use of lighter-weight materials provides a reduction in mass of the overall container. This paper will provide a summary of the AFC design including final flight design and build, acceptance and qualification testing completed, final certification and delivery and forward plans for a technology demonstration with the exploration toilet on the International Space Station (ISS). In addition, a summary of issues and final resolution encountered during flight build and testing will also be provided. As part of the acceptance and certification process for AFC, the hardware was also put into several rounds of odor testing with the support of the White Sands Test Facility (WSTF). The details, planning and anomalies identified during odor testing will also be summarized in this paper. Finally, a brief overview of potential future design upgrades including changes to address any crew feedback from the ISS demonstration will be discussed.

Fecal Canister↗

NASA NTRS2014

Human Exploration Science Office (KX) Overview

The Human Exploration Science Office supports human spaceflight, conducts research, and develops technology in the areas of space orbital debris, hypervelocity impact technology, image science and analysis, remote sensing, imagery integration, and human and robotic exploration science. NASA's Orbital Debris Program Office (ODPO) resides in the Human Exploration Science Office. ODPO provides leadership in orbital debris research and the development of national and international space policy on orbital debris. The office is recognized internationally for its measurement and modeling of the debris environment. It takes the lead in developing technical consensus across U.S. agencies and other space agencies on debris mitigation measures to protect users of the orbital environment. The Hypervelocity Impact Technology (HVIT) project evaluates the risks to spacecraft posed by micrometeoroid and orbital debris (MMOD). HVIT facilities at JSC and White Sands Test Facility (WSTF) use light gas guns, diagnostic tools, and high-speed imagery to quantify the response of spacecraft materials to MMOD impacts. Impact tests, with debris environment data provided by ODPO, are used by HVIT to predict risks to NASA and commercial spacecraft. HVIT directly serves NASA crew safety with MMOD risk assessments for each crewed mission and research into advanced shielding design for future missions. The Image Science and Analysis Group (ISAG) supports the International Space Station (ISS) and commercial spaceflight through the design of imagery acquisition schemes (ground- and vehicle-based) and imagery analyses for vehicle performance assessments and mission anomaly resolution. ISAG assists the Multi-Purpose Crew Vehicle (MPCV) Program in the development of camera systems for the Orion spacecraft that will serve as data sources for flight test objectives that lead to crewed missions. The multi-center Imagery Integration Team is led by the Human Exploration Science Office and provides expertise in the application of engineering imagery to spaceflight. The team links NASA programs and private industry with imagery capabilities developed and honed through decades of human spaceflight, including imagery integration, imaging assets, imagery data management, and photogrammetric analysis. The team is currently supporting several NASA programs, including commercial demonstration missions. The Earth Science and Remote Sensing Team is responsible for integrating the scientific use of Earth-observation assets onboard the ISS, which consist of externally mounted sensors and crew photography capabilities. This team facilitates collaboration on remote sensing and participates in research with academic organizations and other Government agencies, not only in conjunction with ISS science, but also for planetary exploration and regional environmental/geological studies. Human exploration science focuses on science strategies for future human exploration missions to the Moon, Mars, asteroids, and beyond. This function provides communication and coordination between the science community and mission planners. ARES scientists support the operation of robotic missions (i.e., Mars Exploration Rovers and the Mars Science Laboratory), contribute to the interpretation of returned mission data, and translate robotic mission technologies and techniques to human spaceflight.

Calhoun, Tracy A.↗

NASA NTRSDate not supplied

Lessons Learned from Astrobee Operations on the International Space Station

Since its launch in 2019, NASA has been operating three Astrobee free-flying robots providing an autonomous and adaptable research platform aboard the International Space Station (ISS). These robots have not only facilitated a myriad of national and international research endeavors in microgravity but have also served as a STEM outreach platform for student competitions aboard the ISS. Amidst its extensive operational tenure, spanning over five years and exceeding 1200 hours of cumulative free-flyer operation as of April 2024, the Astrobee robots have encountered software and hardware anomalies. Despite its inherent design for on-orbit repair or replacement, certain anomalies have proven to be complex, necessitating remote resolution via software and firmware updates or, in extreme cases, hardware replacements or the return of faulty units to NASA's ground facilities for repair. Such challenges underscore the delicate balance between the autonomous functionality of Astrobee and the occasional need for human intervention to maintain optimal performance. One recurring point of failure identified during Astrobee's operational lifespan has been the SD card, a critical component utilized by the different Astrobee processors and the Dock Station. The occurrence of SD card anomalies, both on orbit and within ground units, has provided invaluable insights into the improvement of Astrobee's systems and mitigation to future faults. This presentation will focus on four key areas: 1. Overview of Faults and Anomalies: A comprehensive examination of the diverse array of faults and anomalies encountered by Astrobee and its associated systems both in orbit and on the ground. From software glitches to hardware malfunctions, this section provides insights into the challenges faced during Astrobee's operational tenure. 2. Resolution Processes and Procedures: An in-depth discussion of the methodologies and procedures implemented to resolve the encountered anomalies. This includes remote troubleshooting, software patches, firmware updates, and, when necessary, the logistics involved in hardware replacements or down-massing for repair. 3. Implementation of Software Updates and Hardware Upgrades: A detailed exploration of the strategies employed to mitigate the risk of recurring anomalies through the implementation of software updates and hardware upgrades. This section highlights the iterative nature of Astrobee's development, emphasizing the continuous pursuit of robustness and reliability. 4. Lessons Learned and Future Directions: Reflecting on the insights gained from addressing anomalies, this section examines the lessons learned and outlines future directions for enhancing Astrobee's robustness and resilience. It underscores the iterative nature of space exploration and the importance of adaptability and continuous improvement in the pursuit of scientific discovery. Through a nuanced examination of Astrobee's operational challenges and the strategies employed to overcome them, this presentation sheds light on the complexities of operating autonomous robotic systems in the ISS environment. It underscores NASA's commitment to pushing the boundaries of exploration and innovation while navigating the inherent challenges of space exploration.

Astrobee↗

NASA NTRSDate not supplied

Lessons Learned from Astrobee Operations on the International Space Station

Since its launch in 2019, NASA has been operating three Astrobee free-flying robots providing an autonomous and adaptable research platform aboard the International Space Station (ISS). These robots have not only facilitated a myriad of national and international research endeavors in microgravity but have also served as a STEM outreach platform for student competitions aboard the ISS. Amidst its extensive operational tenure, spanning over five years and exceeding 1200 hours of cumulative free-flyer operation as of April 2024, the Astrobee robots have encountered software and hardware anomalies. Despite its inherent design for on-orbit repair or replacement, certain anomalies have proven to be complex, necessitating remote resolution via software and firmware updates or, in extreme cases, hardware replacements or the return of faulty units to NASA's ground facilities for repair. Such challenges underscore the delicate balance between the autonomous functionality of Astrobee and the occasional need for human intervention to maintain optimal performance. One recurring point of failure identified during Astrobee's operational lifespan has been the SD card, a critical component utilized by the different Astrobee processors and the Dock Station. The occurrence of SD card anomalies, both on orbit and within ground units, has provided invaluable insights into the improvement of Astrobee's systems and mitigation to future faults. This presentation will focus on four key areas: 1. Overview of Faults and Anomalies: A comprehensive examination of the diverse array of faults and anomalies encountered by Astrobee and its associated systems both in orbit and on the ground. From software glitches to hardware malfunctions, this section provides insights into the challenges faced during Astrobee's operational tenure. 2. Resolution Processes and Procedures: An in-depth discussion of the methodologies and procedures implemented to resolve the encountered anomalies. This includes remote troubleshooting, software patches, firmware updates, and, when necessary, the logistics involved in hardware replacements or down-massing for repair. 3. Implementation of Software Updates and Hardware Upgrades: A detailed exploration of the strategies employed to mitigate the risk of recurring anomalies through the implementation of software updates and hardware upgrades. This section highlights the iterative nature of Astrobee's development, emphasizing the continuous pursuit of robustness and reliability. 4. Lessons Learned and Future Directions: Reflecting on the insights gained from addressing anomalies, this section examines the lessons learned and outlines future directions for enhancing Astrobee's robustness and resilience. It underscores the iterative nature of space exploration and the importance of adaptability and continuous improvement in the pursuit of scientific discovery. Through a nuanced examination of Astrobee's operational challenges and the strategies employed to overcome them, this presentation sheds light on the complexities of operating autonomous robotic systems in the ISS environment. It underscores NASA's commitment to pushing the boundaries of exploration and innovation while navigating the inherent challenges of space exploration.

Astrobee↗

NASA NTRS2010

Radiation Measured with Different Dosimeters for ISS-Expedition 18-19/ULF2 on Board International Space Station during Solar Minimum

Radiation field of particles in low Earth orbit (LEO) is mainly composed of galactic cosmic rays (GCR), solar energetic particles and particles in SAA (South Atlantic Anomaly). GCR are modulated by solar activity, at the period of solar minimum activity, GCR intensity is at maximum and the main contributor for space radiation is GCR. At present for space radiation measurements conducted by JSC (Johnson Space Center) SRAG (Space Radiation Analysis Group), the preferred active dosimeter sensitive to all LET (Linear Energy Transfer) is the tissue equivalent proportional counter (TEPC); the preferred passive dosimeters are thermoluminescence dosimeters (TLDs) and optically stimulated luminescence dosimeters (OSLDs) sensitive to low LET as well as CR-39 plastic nuclear track detectors (PNTDs) sensitive to high LET. For the method using passive dosimeters, radiation quantities for all LET can be obtained by combining radiation results measured with TLDs/OSLDs and CR-39 PNTDs. TEPC, TLDs/OSLDs and CR-39 detectors were used to measure the radiation field for the ISS (International Space Station) - Expedition 18-19/ULF2 space mission which was conducted from 15 November 2008 to 31 July 2009 - near the period of the recent solar minimum activity. LET spectra (differential and integral fluence, absorbed dose and dose equivalent) and radiation quantities were measured for positions TEPC, TESS (Temporary Sleeping Station, inside the polyethylene lined sleep station), SM-P 327 and 442 (Service Module - Panel 327 and 442). This paper presents radiation LET spectra measured with TEPC and CR-39 PNTDs and radiation dose measured with TLDs/OSLDs as well as the radiation quantities combined from results measured with passive dosimeters.

Zhou, Dazhuang↗

NASA NTRS2015

November 2013 Analysis of High Energy Electrons on the Japan Experimental Module (JEM: Kibo)

Albedo (precipitating/splash) electrons, created by galactic cosmic rays (GCR) interaction with the upper atmosphere move upwards away from the surface of the earth. In the past validation work these particles were often considered to have negligible contribution to astronaut radiation exposure on the International Space Station (ISS). Estimates of astronaut exposure based on the available Computer Aided Design (CAD) models of ISS consistently underestimated measurements onboard ISS when the contribution of albedo particles to exposure were neglected. Recent measurements of high energy electrons outside ISS Japan Experimental Module (JEM) using Exposed Facility (EF), Space Environment Data Acquisition Equipment - Attached Payload (SEDA-AP) and Standard DOse Monitor (SDOM), indicates the presence of high energy electrons at ISS altitude. In this presentation the status of these energetic electrons is reviewed and mechanism for the creation of these particles inside/outside South Atlantic Anomaly (SAA) region explained. In addition, limited dosimetric evaluation of these electrons at 600 MeV and 10 GeV is presented.

Badavi, Francis F.↗