Engineering topics
Publications and source records attributed to Jones, Jeffrey A..
Given the high physiological and functional demands of operating in a self-contained EVA or training suit in various gravity fields and system environments, there is a possibility that crew injury can occur and physiological and functional performance may be comprised.
It has long been recognized that path-integrated attenuation (PIA) can be used to improve precipitation estimates from high-frequency weather radar data. One approach that provides an estimate of this quantity from airborne or spaceborne radar data is the surface reference technique (SRT), which uses measurements of the surface cross section in the presence and absence of precipitation. Measurements from the dual-frequency precipitation radar (DPR) on the Global Precipitation Measurement (GPM) satellite afford the first opportunity to test the method for spaceborne radar data at Ka band as well as for the Ku-band-Ka-band combination. The study begins by reviewing the basis of the single- and dual-frequency SRT. As the performance of the method is closely tied to the behavior of the normalized radar cross section (NRCS or sigma(0)) of the surface, the statistics of sigma(0) derived from DPR measurements are given as a function of incidence angle and frequency for ocean and land backgrounds over a 1-month period. Several independent estimates of the PIA, formed by means of different surface reference datasets, can be used to test the consistency of the method since, in the absence of error, the estimates should be identical. Along with theoretical considerations, the comparisons provide an initial assessment of the performance of the single- and dual-frequency SRT for the DPR. The study finds that the dual-frequency SRT can provide improvement in the accuracy of path attenuation estimates relative to the single-frequency method, particularly at Ku band.
Human space travelers experience a unique environment that affects homeostasis and physiologic adaptation. Spaceflight-related changes have been reported in the musculo-skeletal, cardiovascular, neurovestibular, endocrine, and immune systems. The spacecraft environment further subjects the traveler to noise and gravitational forces, as well as airborne chemical, microbiological contaminants, and radiation exposure. As humans prepare for longer duration missions effective countermeasures must be developed, verified, and implemented to ensure mission success. Over the past ten years, synthetic biology has opened new avenues for research and development in areas such as biological control, biomaterials, sustainable energy production, bioremediation, and biomedical therapies. The latter in particular is of great interest to the implementation of long-duration human spaceflight capabilities. This article discusses the effects of spaceflight on humans, and reviews current capabilities and potential needs associated with the health of the astronauts where synthetic biology could play an important role in the pursuit of space exploration.
We investigate the spatial variability of the normalized radar cross section of the surface (NRCS or Sigma(sup 0)) derived from measurements of the TRMM Precipitation Radar (PR) for the period from 1998 to 2009. The purpose of the study is to understand the way in which the sample standard deviation of the Sigma(sup 0) data changes as a function of spatial resolution, incidence angle, and surface type (land/ocean). The results have implications regarding the accuracy by which the path integrated attenuation from precipitation can be inferred by the use of surface scattering properties.
During extra-vehicular activities (EVAs) or spacewalks astronauts over use their fingertips under pressure inside the confined spaces of gloves/space suits. The repetitive hand motion is a probable cause for discomfort and injuries to the fingertips. We describe a new wireless fiber-optic probe that can be integrated inside the astronaut glove for noninvasive blood perfusion measurements in distal fingertips. In this preliminary study, we present blood perfusion measurements while performing hand-grip exercises simulating the use of space tools.
There are currently several physiological monitoring requirements for EVA in the Human-Systems Interface Requirements (HSIR) document. There are questions as to whether the capability to monitor heart rhythm in the lunar surface space suit is a necessary capability for lunar surface operations. Similarly, there are questions as to whether the capability to monitor heart rhythm during a cabin depressurization scenario in the launch/landing space suit is necessary. This presentation seeks to inform space medicine personnel of recommendations made by an expert panel of cardiovascular medicine specialists regarding in-suit ECG heart rhythm monitoring requirements during lunar surface operations. After a review of demographic information and clinical cases and panel discussion, the panel recommended that ECG monitoring capability as a clinical tool was not essential in the lunar space suit; ECG monitoring was not essential in the launch/landing space suit for contingency scenarios; the current hear rate monitoring capability requirement for both launch/landing and lunar space suits should be maintained; lunar vehicles should be required to have ECG monitoring capability with a minimum of 5-lead ECG for IVA medical assessments; and, exercise stress testing for astronaut selection and retention should be changed from the current 85% maximum heart rate limit to maximal, exhaustive 'symptom-limited' testing to maximize diagnostic utility as a screening tool for evaluating the functional capacity of astronauts and their cardiovascular health.
Bisphosphonates as a Countermeasure to Space Flight Induced Bone Loss (Bisphosphonates) will determine whether antiresorptive agents, in conjunction with the routine inflight exercise program, will protect ISS crewmembers from the regional decreases in bone mineral density documented on previous ISS missions.
Introduction: In an effort to determine the human performance limits for vibration in spacecraft being developed by NASA, astronauts were evaluated during a simulated launch profile in a centrifuge/vibration environment and separate vibration-only simulation. Current USAF and Army standards for return to flight following centrifuge exposures require 12-24 hours to pass before a crewmember may return to flying duties. There are no standards on vibration exposures and return to flying duties. Based on direct observation and provocative neurological testing of the astronauts, a new standard for return to flying duties following centrifuge and/or vibration exposures was established. Methods: 13 astronaut participants were exposed to simulated launch profiles in a + 3.5 Gx bias centrifuge/vibration environment and separately on a vibration table at the NASA-Ames Research Center. Each subject had complete neurological evaluations pre- and post-exposure for the centrifuge/vibration runs with the NASA neurological function rating scale (NFRS). Subjects who participated in the vibration-only exposures had video oculography performed with provocative maneuvers in addition to the NFRS. NFRS evaluations occurred immediately following each exposure and at 1 hour post-run. Astronauts who remained symptomatic at 1 hour had repeat NFRS performed at 1 hour intervals until the crewmember was asymptomatic. Results: Astronauts in the centrifuge/vibration study averaged a 3-5 point increase in NFRS scores immediately following exposure but returned to baseline 3 hours post-run. Subjects exposed to the vibration-only simulation had a 1-3 point increase following exposure and returned to baseline within 1-2 hours. Pre- and post- vibration exposure video oculography did not reveal any persistent ocular findings with provocative testing 1 hour post-exposure. Discussion: Based on direct observations and objective measurement of neurological function in astronauts following simulated launch profiles, asymptomatic individuals are allowed to return to flying duties within 3 hours following centrifuge/vibration and 2 hours after vibration-only exposures.
NASA is currently the leader, in conjunction with our Russian counterpart co-leads, of the Multilateral Medical Policy Board (MMPB), the Multilateral Medical Operations Panel (MMOP), which coordinates medical system support for International Space Station (ISS) crews, and the Multilateral Space Medicine Board (MSMB), which medically certifies all crewmembers for space flight on-board the ISS. These three organizations have representatives from NASA, RSA-IMBP (Russian Space Agency- Institute for Biomedical Problems), GCTC (Gagarin Cosmonaut Training Center), ESA (European Space Agency), JAXA (Japanese Space Agency), and CSA (Canadian Space Agency). The policy and strategic coordination of ISS medical operations occurs at this level, and includes interactions with MMOP working groups in Radiation Health, Countermeasures, Extra Vehicular Activity (EVA), Informatics, Environmental Health, Behavioral Health and Performance, Nutrition, Clinical Medicine, Standards, Post-flight Activities and Rehabilitation, and Training. Each ISS Expedition has a lead Crew Surgeon from NASA and a Russian Crew Surgeon from GCTC assigned to the mission. Day-to-day issues are worked real-time by the flight surgeons and biomedical engineers (also called the Integrated Medical Group) on consoles at the MCC (Mission Control Center) in Houston and the TsUP (Center for Flight Control) in Moscow/Korolev. In the future, this may also include mission control centers in Europe and Japan, when their modules are added onto the ISS. Private medical conferences (PMCs) are conducted regularly and upon crew request with the ISS crew via private audio and video communication links from the biomedical MPSR (multipurpose support room) at MCC Houston. When issues arise in the day-to-day medical support of ISS crews, they are discussed and resolved at the SMOT (space medical operations team) meetings, which occur weekly among the International Partners. Any medical or life science issue that is not resolved at the SMOT can be taken to the Mission Management Team meeting, which occurs biweekly from MCC-Houston. This meeting includes the other International Partners and all flight support and console position representatives via teleconference. ISS Crew Surgeons have handled many medical conditions on orbit; including skin rashes, dental abscesses, lacerations, and STT segment EKG changes. Fortunately to date, there have not been any forced medical evacuations from the ISS. This speaks well for the implementation of the primary, secondary and even tertiary prevention strategies invoked by the Integrated Medical Group, as there were several medical evacuations during the previous Russian space stations.
Medullary Sponge Kidney (MSK) is a benign disorder associated with renal stones in 60% of patients. Patients frequently have episodic painless hematuria but are otherwise asymptomatic unless renal calculi or infections complicate the disease. Nephrolithiasis is a relative, but frequently enforced, contraindication to space or other high performance flight. Two case reports of asymptomatic NASA flight crew with MSK and three cases of military aviators diagnosed with MSK are reviewed, all cases resulted in waiver and return to flight status after treatment and a vigorous follow up and prophylaxis protocol. MSK in aviation and space flight necessitates a highly case-by-case dependent evaluation and treatment process to rule out other potential confounding factors that might also contribute to stone formation and in order to re-qualify the aviator for flight duties.
Medical requirements for the future Crew Exploration Vehicle (CEV), Lunar Surface Access Module (LSAM), advanced Extravehicular Activity (EVA) suits and Lunar habitat are currently being developed. Crews returning to the lunar surface will construct the lunar habitat and conduct scientific research. Inherent in aggressive surface activities is the potential risk of injury to crewmembers. Physiological responses to and the operational environment of short forays during the Apollo lunar missions were studied and documented. Little is known about the operational environment in which crews will live and work and the hardware that will be used for long-duration lunar surface operations.Additional information is needed regarding productivity and the events that affect crew function such as a compressed timeline. The Space Medicine Division at the NASA Johnson Space Center (JSC) requested a study in December 2005 to identify Apollo mission issues relevant to medical operations that had impact to crew health and/or performance. The operationally oriented goals of this project were to develop or modify medical requirements for new exploration vehicles and habitats, create a centralized database for future access, and share relevant Apollo information with the multiple entities at NASA and abroad participating in the exploration effort.
This viewgraph presentation is a course that reviews the diagnostic imaging techniques available for medical support on the future moon missions. The educational objectives of the course are to: 1) Update the audience on the curreultrasound imaging in space flight; 2) Discuss the unique aspects of conducting ultrasound imaging on ISS, interplanetary transit, ultrasound imaging on ISS, interplanetary transit, and lunar surface operations; and 3) Review preliminary data obtained in simulations of medical imaging in lunar surface operations.
During Neutral Buoyancy Lab (NBL) training sessions, a large amount of moisture accumulates in the EVA gloves. The glove design restricts the extension of the EVA suit s ventilation/cooling system to the hand. Subungual redness and fingernail pain develops for many astronauts following their NBL training sessions with subsequent oncholysis occurring over succeeding weeks. Various attempts have been made to reduce or avoid this problem. The causal role of moisture has yet to be defined. Methods: To determine the contribution that moisture plays in the injury to the fingers and fingernails during EVA training operations in NBL, the current Extravehicular Mobility Unit (EMU), with a Portable Life Support System (PLSS) was configured with a ventilation tube that extended down a single arm of the crewmember during the test and compared with the unventilated contralateral arm; with the ventilated hand serving as the experimental condition (E) and the opposite arm as the control (C). A cross-over design was used with opposite handedness for the vent tube on a subsequent NBL training run. Moisture content measures were conducted at six points on each hand with three types of moisture meters. A questionnaire was administered to determine subjective thermal hand discomfort, skin moisture perception, and hand and nail discomfort. Photographs and video were recorded. Measures were applied to six astronauts pre- and post-run in the NBL. Results: The consistent trends in relative hydration ratios at the dorsum, from 3.34 for C to 2.11 for E, and first ring finger joint locations, from 2.46 for C to 1.96 for E, indicated the extended vent tube promoted skin drying. The experimental treatment appeared to be more effective on the left hand versus the right hand, implying an interaction with hand anthropometry and glove fit. Video analyses differentiated fine and gross motor training tasks during runs and will be discussed. Conclusions: This potential countermeasure was effective in reducing the risks of hand and nail discomfort symptoms from moderate to low in two of six subjects. Improved design in the ventilation pattern of such a countermeasure is expected to improve the countermeasure s efficiency.
Ionizing radiation is a major health risk of long-term space travel, the biological consequences of which include genetic and oxidative damage. In this study, we propose an original mechanism by which high doses of ionizing radiation induce acute toxicity. We identified biological components that appear in the lymphatic vessels shortly after gamma irradiation. These radiation-induced toxins, which we have named specific radiation determinants (SRD), were generated in the irradiated tissues and then collected and circulated throughout the body via the lymph circulation and bloodstream. Depending on the type of SRD elicited, different syndromes of acute radiation sickness (ARS) were expressed. The SRDs were developed into a vaccine used to confer active immunity against acute radiation toxicity in immunologically naive animals. Animals that were pretreated with SRDs exhibited resistance to lethal doses of gamma radiation, as measured by increased survival times and survival rates. In comparison, untreated animals that were exposed to similar large doses of gamma radiation developed acute radiation sickness and died within days. This phenomenon was observed in a number of mammalian species. Initial analysis of the biochemical characteristics indicated that the SRDs were large molecular weight (200-250 kDa) molecules that were comprised of a mixture of protein, lipid, carbohydrate, and mineral. Further analysis is required to further identify the SRD molecules and the biological mechanism by which the mediate the toxicity associated with acute radiation sickness. By doing so, we may develop an effective specific immunoprophylaxis as a countermeasure against the acute effects of ionizing radiation.
Spaceflight-induced microgravity appears to be a risk factor for the development of urinary calculi due to skeletal calcium liberation and other undefined factors, resulting in stone disease in crewmembers during and after spaceflight. Calcifying nanoparticles, or nanobacteria, reproduce at a more rapid rate in simulated microgravity conditions and create external shells of calcium phosphate in the form of apatite. The questions arises whether calcifying nanoparticles are niduses for calculi and contribute to the development of clinical stone disease in humans, who possess environmental factors predisposing to the development of urinary calculi and potentially impaired immunological defenses during spaceflight. A case of a urinary calculus passed from an astronaut post-flight with morphological characteristics of calcifying nanoparticles and staining positive for a calcifying nanoparticle unique antigen, is presented.
Sonography is the only medical imaging modality aboard the ISS, and is likely to remain the leading imaging modality in future human space flight programs. While trauma sonography (TS) has been well recognized for terrestrial trauma settings, the technique had to be evaluated for suitability in space flight prior to adopting it as an operational capability. The authors found the following four-phased evaluative approach applicable to this task: 1) identifying standard or novel terrestrial techniques for potential use in space medicine; 2) developing and testing these techniques with suggested modifications on the ground (1g) either in clinical settings or in animal models, as appropriate; 3) evaluating and refining the techniques in parabolic flight (0g); and 4) validating and implementing for clinical use in space. In Phase I of the TS project, expert opinion and literature review suggested TS to be a potential screening tool for trauma in space. In Phase II, animal models were developed and tested in ground studies, and clinical studies were carried out in collaborating trauma centers. In Phase III, animal models were flight-tested in the NASA KC-135 Reduced Gravity Laboratory. Preliminary results of the first three phases demonstrated potential clinical utility of TS in microgravity. Phase IV studies have begun to address crew training issues, on-board imaging protocols, and data transfer procedures necessary to offer the modified TS technique for space use.
Randall initially described calcified subepithelial papillary plaques, which he hypothesized as nidi for kidney stone formation. The discovery of calcifying nanoparticles (CNP) in many calcifying processes of human tissues has raised another hypothesis about their possible involvement in urinary stone formation. This research is the first attempt to investigate the potential association of these two hypotheses. We collected renal papilla and blood samples from 17 human patients who had undergone laparoscopic nephrectomy due to neoplasia. Immunohistochemical staining (IHS) was applied on the tissue samples using monoclonal antibody 8D10 (mAb) against CNP. Homogenized papillary tissues and serum samples were cultured for CNP. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis were performed on fixed papillary samples. Randall's plaques were visible on gross inspection in 11 out of 17 collected samples. IHS was positive for CNP antigen in 8 of these 11 visually positive samples, but in only 1 of the remaining 6 samples. SEM revealed spherical apatite formations in 14 samples, all of which had calcium and phosphate peaks detected by EDS analysis. From this study, there was some evidence of a link between the presence of Randall's plaques and the detection of CNP, also referred to as nanobacteria. Although causality was not demonstrated, these results suggest that further studies with negative control samples should be made to explore the etiology of Randall's plaque formation, thus leading to a better understanding of the pathogenesis of stone formation.
Medical requirements for the future Crew Exploration Vehicle (CEV), Lunar Surface Access Module (LSAM), advanced Extravehicular Activity (EVA) suits and Lunar habitat are currently being developed. Crews returning to the lunar surface will construct the lunar habitat and conduct scientific research. Inherent in aggressive surface activities is the potential risk of injury to crewmembers. Physiological responses and the operational environment for short forays during the Apollo lunar missions were studied and documented. Little is known about the operational environment in which crews will live and work and the hardware will be used for long-duration lunar surface operations. Additional information is needed regarding productivity and the events that affect crew function such as a compressed timeline. The Space Medicine Division at the NASA Johnson Space Center (JSC) requested a study in December 2005 to identify Apollo mission issues relevant to medical operations that had impact to crew health and/or performance. The operationally oriented goals of this project were to develop or modify medical requirements for new exploration vehicles and habitats, create a centralized database for future access, and share relevant Apollo information with the multiple entities at NASA and abroad participating in the exploration effort.