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S C Moudy

Publications and source records attributed to S C Moudy.

10 records
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Operational Implications from Field Test Results: Sensorimotor Guidelines for Exploration Missions

Two key sensorimotor objectives of the joint NASA-Russian Field Test (FT) study were (1) to quantify functional performance on long duration crewmembers as close to landing as possible, and (2) to develop a recovery timeline back to preflight baseline. The purpose of this presentation is to provide an overview of the FT results and discuss the operational implications for future exploration missions. The NASA and Russian teams conducted a total of 48 Field Tests, including 18 using a reduced Pilot FT (PFT) protocol. The combined PFT/FT cohort included 14 first-time fliers, 4F, and nine cosmonauts who repeated FT during a second mission. The mission durations were 185 ± 42 days, mean ± std. Nominally, the initial postflight session was performed in the medical test at the Soyuz landing site or at the nearby airport (R+2.2 ± 1.3 hrs, mean ± std), and then repeated multiple times throughout the postflight recovery. The common tasks performed across PFT and full FT protocols included sit-to-stand, recovery from fall (prone to stand) and tandem walk, performed in that order of increasing difficulty. The full FT protocol also included seated tasks (eccentric gaze, dysmetria finger to nose, eye-hand coordination on a tablet, grip force discrimination), a standing posture test with an upper body perturbation, a timed up and go mobility test with obstacles, and a dynamic visual acuity task during vertical oscillations. While there was considerable variability in the postflight outcome measures across crewmembers, the level of vestibular/cerebellar and sensorimotor impairment was greater than previously observed during shorter spaceflight missions. Most striking was the higher incidence of motion sickness even without constraining the standard medical interventions. Motion sensitivity prevented some crewmembers from attempting and/or completing the early testing. The recovery timeline varied with task complexity, generally taking longer when either the basis of support was limited (e.g., tandem walk) or visual cues were deprived (eyes closed). Based on this evidence, mission planners need to expect a range of response across individuals and tasks following G-transitions. Individual health assessments are recommended along with development of pre-worked, prioritized content and timelines, with the ability to change roles depending on crew readiness. Handholds and balance aids are recommended to help stabilize the crewmembers to perform specific tasks (e.g., touch screen selection) or to allow the crewmember the ability to rest with onset of symptoms. Based on anecdotal reports and performance on computerized dynamic posturography, multiple testing on landing day appeared to be beneficial for some participants, while others may have pushed beyond their motion tolerance limit in an effort to complete more FT objectives. Instead of delaying planetary surface operations to allow for recovery, our results suggest that early mobility may be important. Early active self-administered retraining, individualized based on the level of initial impairment and motion sensitivity, will enable a more efficient motor learning and enhance crew performance.

S J Wood↗
NASA NTRSDate not supplied

Validation of A Sensorimotor Disorientation Ground Analog

INTRODUCTION Simulating the sensorimotor disorientation effects of gravity transitions after prolonged stays in microgravity is exceedingly challenging on Earth. In a previous study [1], a Sensorimotor Disorientation Analog (SDA) was developed based on subjective feedback from previously flown astronauts. The purpose of this study was to validate this SDA by comparing performance in movement tasks that have a wealth of spaceflight data against task performance while using the SDA. METHODS Thirty healthy non-astronaut subjects (17 males, 13 females; Mean ± SD, Age: 33.5 ± 7.2 years, Height: 68.0 ± 3.4 in, Weight: 164 ± 26 lbs.) volunteered to participate in this study. Subjects performed three movement tasks: computerized dynamic posturography (CDP), obstacle walk, and tandem walk. For CDP, subjects maintained an upright stance for 20s with eyes closed on an unstable pitch sway-referenced platform with head erect (sensory organization test (SOT)-5) and with head pitch ±20° to an auditory cue(SOT-5M). The obstacle walk involved a sit-to-stand with 10s of quiet stance followed by walking to and around a cone placed 4m away while navigating a 30cm obstacle to the cone and back. The tandem walk involved walking heel-to-toe for approximately 10-12 steps with eyes open and eyes closed. Subjects performed the three movement tasks under three levels of the SDA replicating different time points of recovery: none (preflight), low (Return (R)+24- 48hours), and high (R+0- 24hours). The SDA included galvanic vestibular stimulation (GVS) to disorient the vestibular system and a weighted suit (trunk, wrists, and ankles) to alter proprioceptive feedback and replicate subjective heaviness. RESULTS As the SDA magnitude increased, overall performance outcomes decreased. However, the ability of the SDA to replicate the range of astronaut postflight performance was task dependent. CDP SOT-5 performance across SDA levels closely replicated astronaut performance at all time points. SOT-5M, however, had minimal performance changes across SDA levels and was unable to replicate astronaut performance. The obstacle walk showed performance changes across SDA levels and matched astronaut performance preflight and at R+24-48hrs (low). Obstacle walk performance at the high SDA level was reduced in comparison to the low level; however, it was not replicative of astronaut performance immediately after landing. Last, tandem walk had distinct groupings of performance across SDA levels and was able to elicit a high level of disorientation consistent with R+0-24 hours (high) postflight performance for eyes open and eyes closed. The low SDA level for both eyes open and eyes closed was more disruptive than previous crewmember performance at the R+24-48 hours timepoint. CONCLUSION The SDA was developed to replicate postflight sensorimotor disruptions. However, it is well-known that immediately post-landing, astronauts can experience motion sickness, dehydration, fatigue, orthostatic intolerance, illusory sensations, lumbar pain, etc. This multi-system response to return to 1G varies widely across astronauts and, as such, it was not unexpected that the extreme ends of responses in the R+0-24hrs time period were the most difficult to replicate. These results suggest that the SDA levels are able to elicit distinct performance groupings and, although not able to perfectly replicate R+0-24hrs, the SDA did replicate a large range of performance after return to Earth.

S C Moudy↗
NASA NTRSDate not supplied

Standard Measures During Spaceflight

The goal of the Spaceflight Standard Measures project is to ensure that a set of measures, representing the Human Research Program’s key risks and acquired with minimal impact on time and resources, is consistently captured from crewmembers through the end of the International Space Station (ISS) Program. Data collected under the Spaceflight Standard Measures project include assessments of sleep/wake cycles, cognition, immune status and function, general blood and urine chemistry (urine is collected only before flight and after landing), microbiome composition (gastrointestinal tract, saliva, and body surface), cardiovascular structure and function (carotid intima-media thickness, orthostatic responses), sensorimotor function, sleep quality, and team processes. Data is collected once or twice before the flight (180 and 90 days before launch), twice during the 6-month missions (flight day 30 and 30 days before return to Earth) with the exception of actigraphy, which is recorded during two-week periods before, during, and after the mission. In this presentation, we will review the data collected to date on 31 ISS crewmembers. These data are placed in the NASA Life Sciences Portal (NLSP) and are available for occupational surveillance (using non-identifiable data), Institutional Review Board-approved data sharing requests, and retrospective data requests. This data repository enables high-level monitoring of the effectiveness of countermeasures and meaningful interpretation of health and performance outcomes for various mission durations. The knowledge gained from this project informs and supports future hypothesis-driven research that will enable the success of planetary missions.

G R Clement↗
NASA NTRSDate not supplied

Validation of a Sensorimotor Disorientation Ground Analog

Simulating the sensorimotor disorientation effects of gravity transitions after prolonged stays in microgravity is exceedingly challenging on Earth. In a previous study, a Sensorimotor Disorientation Analog (SDA) was developed based on subjective feedback from previously flown astronauts.

S C Moudy↗
NASA NTRSDate not supplied

Optimizing Postural Control Assessment in Astronauts and Head-Down Bedrest Subjects

In space, astronauts undergo physiological adaptations, such as changes in sensorimotor processing, to acclimate to microgravity conditions. However, these adaptations pose challenges upon astronauts’ return to Earth, particularly in postural control. Astronauts struggle with balance and coordination during the early post-flight period. Understanding these adaptations and their implications is key for optimizing astronaut health and performance, especially in anticipation of upcoming Artemis lunar missions. Head-down bedrest (HDBR) is a ground-based spaceflight analog that allows for additional research to be conducted into this adaptation and recovery period to test potential countermeasures before spaceflight. This research aims to delve into the assessment of postural control in both HDBR subjects and astronauts, providing insights essential for mission preparedness and the development of effective countermeasures.

H E Gustafson↗
NASA NTRSDate not supplied

Development and Validation of Sensorimotor Assessment Tasks Using Spaceflight Analogs

INTRODUCTION Exploration class missions will require a new level of crew autonomy to self-assess and treat their sensorimotor dysfunction around periods of gravitational transition, where sensorimotor disturbances are at their highest. There is a need to define sensorimotor assessment thresholds that indicate when performance in early extravehicular activities (EVAs) might be impacted or unsafe. The purpose of this study was to develop and validate a set of assessment tasks using sensorimotor spaceflight analogs including the Sensorimotor Disorientation Analog (SDA) and +3G x sustained centrifugation. METHODS For the SDA, forty-one healthy non-astronaut subjects (21 males, 20 females; Mean ± SD, Age: 34.0 ± 7.8 years) volunteered to participate in this study. Subjects attended two testing sessions: 1) familiarization to the tasks and baseline data collection, and 2) tasks completed under two levels of sensorimotor disorientation. Subjects performed a series of seven sensorimotor assessment tasks followed by two operationally relevant EVA analog tasks. The sensorimotor assessments tasks, ordered from least to most provocative of the sensorimotor system, included: postural stability, step test, prone/supine recovery from fall (RFF), four-square-step-test, obstacle negotiation with turns (OTT), kneel-and-reach, and augmented reality full-body coordination. The operational analog tasks included a top-hatch capsule egress and a 5-minute EVA traversal. Disorientation was applied via the SDA which utilized galvanic vestibular stimulation and weighted trunk, wrists, and ankles to target the vestibular and proprioceptive systems such that performance while wearing the SDA mimicked astronaut postflight performance at R+0 and R+1. Sixteen healthy non-astronaut subjects (10 males, 6 females; Age: 35.0 ± 9.5 years) completed +3G x 60-minute sustained centrifugation as an established spaceflight analog replicating the vestibular disruptions seen postflight. Subjects completed a pre-session which included familiarization to the tasks and a 5-minute centrifuge spin. The data collection session included, in order, a baseline data collection, 60-minute centrifuge spin, immediate post-centrifuge data collection, 45-minute seated recovery, and a final data collection. The same assessment and operational analog tasks were conducted as described above. RESULTS Pearsons’ correlation r-values were calculated between assessment and operational analog tasks. The two assessment tasks with the strongest correlations to the operational analog tasks were the RFF (SDA: r≥ 0.57, Centrifuge: r ≥0.55) and OTT (SDA: r≥ 0.66, Centrifuge: r ≥ 0.49). For brevity, repeated measures ANOVA with follow-up paired t-tests are discussed for these two assessment tasks. The SDA found significant differences between all three levels of disorientation for both RFF and OTT (p < 0.001). Significant differences were also found between baseline and immediate post centrifuge testing for both the RFF (p≤ 0.011) and OTT (p = 0.001). Additional results are forthcoming for both disorientation paradigms. DISCUSSION These validation studies provide evidence for down-selection of the assessment tasks that were able to distinguish between levels of sensorimotor disorientation and correlate to performance in operationally relevant tasks for use in upcoming Artemis missions.

S C Moudy↗