Allison P. Anderson

Acute effects of changes to the gravitational vector on the eye

Intraocular pressure (IOP) initially increases when an individual enters microgravity compared with baseline values when an individual is in a seated position. This has been attributed to a headward fluid shift that increases venous pressures in the head. The change in IOP exceeds changes measured immediately after moving from seated to supine postures on Earth, when a similar fluid shift is produced. Furthermore, central venous and cerebrospinal fluid pressures are at or below supine position levels when measured initially upon entering microgravity, unlike when moving from seated to supine postures on Earth, when these pressures increase. To investigate the effects of altering gravitational forces on the eye, we made ocular measurements on 24 subjects (13 men, 11 women) in the seated, supine, and prone positions in the laboratory, and upon entering microgravity during parabolic flight. IOP in microgravity (16.3 ± 2.7 mmHg) was significantly elevated above values in the seated (11.5 ± 2.0 mmHg) and supine (13.7 ± 3.0 mmHg) positions, and was significantly less than pressure in the prone position (20.3 ± 2.6 mmHg). In all measurements,P< 0.001. Choroidal area was significantly increased in subjects in a microgravity environment (P< 0.007) compared with values from subjects in seated (increase of 0.09 ± 0.1 mm(2)) and supine (increase of 0.06 ± 0.09 mm(2)) positions. IOP results are consistent with the hypothesis that hydrostatic gradients affect IOP, and may explain how IOP can increase beyond supine values in microgravity when central venous and intracranial pressure do not. Understanding gravitational effects on the eye may help develop hypotheses for how microgravity-induced visual changes develop.

Relaxation with Immersive Natural Scenes Presented Using Virtual Reality

INTRODUCTION Virtual reality (VR) can provide exposure to nature for those living in isolated confined environments. We evaluated VR-presented natural settings for reducing stress and improving mood. METHODS There were 18 participants (9 men, 9 women), ages 32 ± 12 yr, who viewed three 15-min 360° scenes (an indoor control, rural Ireland, and remote beaches). Subjects were mentally stressed with arithmetic before scenes. Electrodermal activity (EDA) and heart rate variability measured psycho-physiological arousal. The Positive and Negative Affect Schedule and the 15-question Modified Reality Judgment and Presence Questionnaire (MRJPQ) measured mood and scene quality. RESULTS Reductions in EDA from baseline were greater at the end of the natural scenes compared to the control scene (-0.59, -0.52, and 0.32 μS, respectively). The natural scenes reduced negative affect from baseline ( 1.2 and 1.1 points), but the control scene did not ( 0.4 points). MRJPQ scores for the control scene were lower than both natural scenes (4.9, 6.7, and 6.5 points, respectively). Within the two natural scenes, the preferred scene reduced negative affect ( 2.4 points) more than the second choice scene ( 1.8 points) and scored higher on the MRJPQ (6.8 vs. 6.4 points). DISCUSSION Natural scene VR provided relaxation both objectively and subjectively, and scene preference had a significant effect on mood and perception of scene quality. VR may enable relaxation for people living in isolated confined environments, particularly when matched to personal preferences.Anderson AP, Mayer MD, Fellows AM, Cowan DR, Hegel MT, Buckey JC. Relaxation with immersive natural scenes presented using virtual reality. Aerosp Med Hum Perform. 2017; 88(6):520526.

Development of the Polipo Pressure Sensing System for Dynamic Space-Suited Motion

Working inside the space suit causes injury and discomfort, but suit assessment techniques such as measuring joint torques and ranges of motion fail to evaluate injury because they fail to distinguish interactions between the human and the space suit. Contact pressure sensing would allow a quantitative assessment of the nature and location of suit-body contact where injuries occur. However, commercially available systems are not well suited for measurement inside the confined environment of the space suit during movement. We report on the design of a wearable pressure sensing system, the Polipo. The Polipo dynamically measures between 5 and 60 kPa of pressure with ~1 kPa sensitivity, is within 10% root mean square error from a known loading profile during dynamic movement, and is a standalone system able to accommodate a 50th percentile female to a 95th percentile male upper body dimensions with near shirt-sleeve mobility. This paper focuses on the upper body, but the methods may be extended to the full body as future work. It provides a pressure sensing system that could be applied beyond the field of aerospace to assess human-garment interactions, for example recommending armor protection for defense applications or to alleviate fall impacts for medical applications.

Ocular changes over 60 min in supine and prone postures

Some astronauts are returning from long-duration spaceflight with structural ocular and visual changes. We investigated both the transient and sustained effects of changes in the direction of the gravity vector acting on the eye using changes in body posture. Intraocular pressure (IOP; measured by Perkins tonometer), ocular geometry (axial length, corneal thickness, and aqueous depth-noncontact biometer), and the choroid (volume and subfoveal thickness optical coherence tomography) were measured in 10 subjects (5 males and 5 females). Measures were taken over the course of 60 min and analyzed with repeated-measures analysis of covariance to assess the effects of posture and time. In the supine position, choroidal volume increased significantly with time (average value at <5 min = 8.8 ± 2.3 mm3, 60 min = 9.0 ± 2.4 mm3, P = 0.03). In the prone position, IOP and axial length increased with time (IOP at <5 min 15 ± 2.7 mmHg, 60 min = 19.8 ± 4.1 mmHg, P < 0.0001; axial length at <5 min = 24.29 ± 0.77 mm, 60 min = 24.31 ± 0.76 mm, P = 0.002). Each increased exponentially, with time constants of 5.3 and 14 min, respectively. Prone corneal thickness also increased with time (<5 min = 528 ± 35 μm, 60 min = 537 ± 35 μm3, P < 0.001). Aqueous depth was shortened in the prone position (baseline = 3.22 ± 0.31 mm, 60 min = 3.18 ± 0.32 mm, P < 0.0001) but did not change with time. The data show that changes in the gravity vector have pronounced transient and sustained effects on the geometry and physiology of the eye.NEW & NOTEWORTHY We show that gravity has pronounced transient and sustained effects on the eye by making detailed ocular measurements over 60 min in the supine and prone postures. These data inform our understanding of how gravitational forces can affect ocular structures, which is essential for hypothesizing how ocular changes could occur with microgravity exposure.

Statistical evaluation of causal factors associated with astronaut shoulder injury in space suits

INTRODUCTION Shoulder injuries due to working inside the space suit are some of the most serious and debilitating injuries astronauts encounter. Space suit injuries occur primarily in the Neutral Buoyancy Laboratory (NBL) underwater training facility due to accumulated musculoskeletal stress. We quantitatively explored the underlying causal mechanisms of injury. METHODS Logistic regression was used to identify relevant space suit components, training environment variables, and anthropometric dimensions related to an increased propensity for space-suited injury. Two groups of subjects were analyzed: those whose reported shoulder incident is attributable to the NBL or working in the space suit, and those whose shoulder incidence began in active duty, meaning working in the suit could be a contributing factor. RESULTS For both groups, percent of training performed in the space suit planar hard upper torso (HUT) was the most important predictor variable for injury. Frequency of training and recovery between training were also significant metrics. The most relevant anthropometric dimensions were bideltoid breadth, expanded chest depth, and shoulder circumference. Finally, record of previous injury was found to be a relevant predictor for subsequent injury. The first statistical model correctly identifies 39% of injured subjects, while the second model correctly identifies 68% of injured subjects. DISCUSSION A review of the literature suggests this is the first work to quantitatively evaluate the hypothesized causal mechanisms of all space-suited shoulder injuries. Although limited in predictive capability, each of the identified variables can be monitored and modified operationally to reduce future impacts on an astronauts health.

Developing a Spacesuit Injury Countermeasure System for Extravehicular Activity: Modeling and Analysis

Extravehicular activity (EVA) is one of the most critical enabling capabilities for human spaceflight. Performing EVA is both technically challenging and physically demanding, requiring many hours of training and detailed preparation. As a result of working and training in the extravehicular mobility unit (EMU) spacesuit, many astronauts sustain musculoskeletal and minor injuries. Although injuries are typically minor and self-limited, they have the potential to impact mission success. We outline our research methodology to investigate EVA injury ultimately providing solutions that can be implemented both in the EMU and in future spacesuit designs. We review the issues and mechanisms causing injury as documented in the literature. The result of this work will be an injury database with input from many NASA stakeholders. We also highlight our work to model the astronaut performing realistic EVA motions to study the interaction between the person and the suit. Spacesuit models of the EMU and Mark III spacesuits will be used in combination with a human body model driven by the biomechanics of EVA motions. We will investigate joint torque, muscle activation, and contact pressure between the body and suit. This modeling effort informs our spacesuit injury countermeasure designs and recommendations. We present our design process for protection devices that ameliorate current astronaut suitinduced injuries.

Autonomous, Computer-Based Behavioral Health Countermeasure Evaluation at HI-SEAS Mars Analog.

INTRODUCTION Living in an isolated, confined environment (ICE) can induce conflict, stress, and depression. Computer-based behavioral health countermeasures are appealing for training and treatment in ICEs because they provide confidentiality and do not require communication with the outside environment. We evaluated the Virtual Space Station (VSS), a suite of interactive computer-delivered psychological training and treatment programs, at the Hawaii Space Exploration Analog and Simulation (HI-SEAS) III expedition. METHODS Six subjects (3 male, 3 female) spent 8 mo in group-isolation and used the Conflict, Stress, and Depression modules in the VSS. Survey evaluations, data collected within the program, and postdeployment interviews were collected. RESULTS This crew dealt with behavioral health issues common to ICEs. The VSS proved to be a valuable resource and was used both as intended, and in unanticipated ways, to help maintain behavioral health. The Conflict and Stress Modules were rated as highly acceptable (1.8 on a 7-point Likert scale). The crew identified a total of 13 stressors and worked on 9 problems through the VSS. Opinions about the modules were highly individualized. Crewmembers identified exercises in the VSS that were applicable and not applicable to their needs. Additional content to improve the program was identified. DISCUSSION Autonomous, confidential training and treatment for behavioral health issues will need to be a critical component of long duration spaceflight travel. This work provides an evaluation of such a tool in a relevant ICE. Anderson AP, Fellows AM, Binsted KA, Hegel MT, Buckey JC. Autonomous, computer-based behavioral health countermeasure evaluation at HI-SEAS Mars analog. Aerosp Med Hum Perform. 2016; 87(11):912-920.

Framework for Space-Inspired Informal Education Exhibits

Since its inception, the National Aeronautics and Space Administration (NASA) has been dedicated to education. NASA’s challenge is to design a coherent education program that can capitalize on the Agency’s diverse set of projects, skill, and missions. This paper reviews the NASA education framework and recommends how to improve guidance to principal investigators to achieve NASA’s education goals. This study demonstrates how a new proposed framework is being implemented as part of the Montana’s Big Sky Space Education: The NASA ExplorationSpace at ExplorationWorks informal education project. This work contributes to the informal education literature by demonstrating how a portfolio approach can be used to effectively define informal education efforts. It also demonstrates how education projects can maximize effectiveness by defining goals and evaluation techniques early in the design phase.

Modeling and Design of a BioSuit Donning System

Mechanical counterpressure (MCP) spacesuits use form-fitting elastic garments to produce pressure against the skin. MCP suits offer significant mobility, energy expenditure, and safety advantages over stiff, immobile, and bulky gas-pressurized suits currently used for extravehicular activity. However, one of the major challenges associated with MCP suits is the difficulty of putting the suit on and taking it off, or donning and doffing. This research develops a network of gas-pressurized tubes integrated to the outside of an elastic glove to aid in donning. When pressurized, the tubes expand, pulling open the MCP garment. The stretched material and enlarged opening allow the person to don the glove easily. The system was designed using a mathematical model of the expansion properties of the tubes and resistance of the glove material. A prototype consisting of an MCP glove at a fraction of the current spacesuit pressure and the gas-pressurized tubing system was developed to achieve a proof-of-concept design. The use of gas-pressurized tubing to solve the MCP donning problem has been demonstrated at fractional suit pressures and shows promise to be extrapolated to a full pressure MCP glove.

Microgravity-induced ocular changes are related to body weight

On Earth, tissue weight generates compressive forces that press on body structures and act on the walls of vessels throughout the body. In microgravity, tissues no longer have weight, and tissue compressive forces are lost, suggesting that individuals who weigh more may show greater effects from microgravity exposure. One unique effect of long-duration microgravity exposure is spaceflight-associated neuroocular syndrome (SANS), which can present with globe flattening, choroidal folds, optic disk edema, and a hyperopic visual shift. To determine whether weight or other anthropometric measures are related to ocular changes in space, we analyzed data from 45 individual long-duration astronauts (mean age 47, 36 male, 9 female, mean mission duration 165 days) who had pre- and postflight measures of disk edema, choroidal folds, and manifest ocular refraction. The mean preflight weights of astronauts who developed new choroidal folds [78.6 kg with no new folds vs. 88.6 kg with new folds ( F = 6.2, P = 0.02)] and disk edema [79.1 kg with no edema vs. 95 kg with edema ( F = 9.6, P = 0.003)] were significantly greater than those who did not. Chest and waist circumferences were also significantly greater in those who developed folds or edema. The odds of developing disk edema or new choroidal folds were 55% in the highest- and 9% in the lowest-weight quartile. In this cohort, no women developed disk edema or choroidal folds, although women also weighed significantly less than men [62.9 vs. 85.2 kg ( F = 53.2, P < 0.0001)]. Preflight body weight and anthropometric factors may predict microgravity-induced ocular changes.