Bioastronautics and Human Performance

Research

Artificial Gravity as a Countermeasure for Human Spaceflight Deconditioning

There have been proposals over the years for centrifuge modules on the ISS to study artificial gravity. Image credit: Mark Holderman/NASA.

Astronauts experience a strong physiological deconditioning during space missions, primarily due to the weightless conditions. Some of these adverse consequences include bone loss, muscle atrophy, sensory-motor/vestibular deconditioning, visual impairment, and overall cardiovascular adaptation, which may lead to orthostatic intolerance when astronauts are exposed again to a gravitational environment. Physiological deconditioning will be even more challenging in future long-duration space missions, for example to Mars, in which astronauts will be exposed to weightlessness for six to eight months before landing without external help to support egress. In order to mitigate these negative effects, several countermeasures are currently in place, particularly very intensive exercise protocols. However, despite these countermeasures, physiological deconditioning still persist to a certain degree, highlighting the need for new approaches to maintain the astronauts’ physiological state within acceptable limits.

Artificial gravity (generated by centrifugation) has long been suggested as a comprehensive countermeasure that is capable of challenging multiple physiological systems at the same time, therefore maintaining overall health during extended weightlessness. However, human centrifuges hasn’t been tested in space, and there are still many questions about its implementation (including centrifuge configuration, exposure time, gravity level, gravity gradient, and use/intensity of exercise, etc). We want to investigate these research questions using a combination of human experiments on ground-based centrifuges and modeling techniques of physiological systems to complement the experimental results.

Augmenting Exercise Protocols With Interactive Virtual Reality Environments

Adherence to exercise has long been a bane of the modern human experience, despite its litany of extolled virtues. A variety of strategies have developed over the decades to encourage us to stick with our fitness goals, but as technology improves the fidelity of the virtual world to the real one, many once-implausible strategies are becoming plausible.
Team dynamics, an engaging environment, and a personalized program are just a few of the strategies which can be combined and employed using a virtual reality system.  Imagine: instead of looking at the inside of a ship’s hull for six months, you could don a helmet and join any number of other participants (real or virtual) across any distance or time while you work out.

This study will examine the efficacy and viability of such a technology using already-established exercise protocols from the International Space Station and previous NASA studies. This research will be done in collaboration with former astronaut Dr. Gregory Chamitoff’s ASTRO Center and the Human Clinical Research Facility.

 

Bimanual Coordination

Despite humanity’s decades-long relationship with spaceflight, we still do not know the range of gravity levels (or gravity doses) that sustain normal physiological function. This is a concern because astronauts are required to utilize bimanual coordination, a domain of sensorimotor function and physiology, for numerous operational tasks. Critical tasks involving bimanual coordination, such as landing a spacecraft or piloting a rover, may be required during micro/partial gravity or during rapid G-transitions. Previous investigations have provided evidence of decrements in sensorimotor performance in hypo-gravity and hyper-gravity environments. However, these experiments focused primarily on unimanual control, and there is a lack of research on bimanual coordination performance in altered gravity.
We will use various analogs (i.e., head down tilt (HDT)/head up tilt (HUT), short-radius centrifuge, and parabolic flight) to simulate altered gravity. Subjects will be asked to complete two different bimanual coordination tasks at various G-levels (0 to 1.8 G). The first task will require subjects to coordinate forces produced by their left and right triceps while the second task will involve coordinating elbow flexor-extensor movements. We will then compare performance on these tasks between each gravity level that we test. Additionally, we are interested in looking for any evidence of bimanual coordination adaptation after repeated exposure to altered gravity.
Experiments conducted using the centrifuge and parabolic flight also allow us to study bimanual coordination performance during G-transitions. We will use data from these experiments to determine the relationship between gravity dose and bimanual coordination performance and estimate the range of gravity levels that elicits an “Earth-like” performance. During the parabolic flight experiments, we will also investigate the potential impact of an anti motion sickness drug (Promethazine) on bimanual coordination. Work on this project is being done in collaboration with Dr. Bonnie J. Dunbar’s Aerospace Human Systems Laboratory and Dr. Deanna Kennedy’s Neuromuscular Coordination Lab.

Biomechanics and Musculoskeletal Analysis

The musculoskeletal system might experience importent detriments in extreme environments. We use modeling approaches and computational tools to investigate human biomechanics and musculoskeletal performance in challenging environments, such as human-spacesuit interactions and musculoskeletal performance to novel exercise devices.

Human Spacesuit Interaction –  Extravehicular Activity (EVA) is a highly demanding activity during space missions. The current NASA spacesuit, the Extravehicular Mobility Unit (EMU), might be thought of as the ‘world’s smallest spacecraf’ and is quite an engineering achievement. However, the EMU has also led to discomfort and musculoskeletal injuries, mainly due to the lack of mobility in the pressurized suit that makes moving and operating within the suit challenging. We are developing a new musculoskeletal modeling framework in OpenSim to analyze human-spacesuit interaction and musculoskeletal performance during EVA.

Exercise using the HULK Device – Astronauts experience physiological deconditioning in space due to the extended exposure to microgravity including, but not limited to, muscle atrophy, loss of strength, and bone loss. Current countermeasures on the International Space Station include resistance training as well as aerobic exercises, and the use of the Advance Resistive Exercise Device (ARED) has been effective in reducing spaceflight musculoskeletal deconditioning. However, the ARED is a bulky device and compact devices that minimize mass and volume are necessary for use within the new space exploration vehicles. In collaboration with NASA Ames, we are investigating exercise performance on the Hybrid Ultimate Lifting Kit (HULK), a new lighter and more compact exercise device under development.

Enhanced Virtual Reality

Future long duration exploration missions will require astronauts to spend prolonged periods in isolated and confined environments. Combined with sensory deprivation, loss of social connection, and a demanding workload, these factors can adversely affect an astronaut’s mood and stress levels. This places astronauts at an increased risk of developing adverse behavioral health conditions, which can cause performance decrements and jeopardize mission success. Current countermeasures used on the ISS will become increasingly difficult to use as missions venture further from Earth and begin to encounter significant communication delays. Virtual reality (VR) technology is a promising countermeasure, and continual advancements in VR technology have made it more robust and portable.
Our lab is currently investigating the potential of VR technologies to enhance behavioral health and reduce stress. We have constructed a nature-inspired VR environment with digital scents that will be dispersed based on the user’s location in the VR environment. To measure levels of stress, we are using a combination of subjective questionnaires and physiological measurements, such as electrodermal activity. We hope to see that the addition of olfactory stimuli will further immerse the user and more effectively reduce stress. Preliminary experiments have delivered promising results, and future work will incorporate stimuli for additional senses.

VR also has the potential to aid in fulfilling astronauts’ social needs. When synchronous communication is not possible, astronauts could receive virtual care packages in VR from loved ones instead to fortify their connectedness to home. These virtual care packages could also utilize the non-traditional stimuli from the nature-inspired environments. Additionally, we will use physiological and subjective data collected from these experiments to produce machine learning algorithms that could predict individual responses to stress and possibly aid in the selection of astronauts.

Exercise in Altered Gravity Enviroments

Artificial Gravity Combined with Exercise

In order to investigate physiological responses of centrifugation combined with exercise, we conducted a human experiment on 12 subjects using the MIT short-radius centrifuge. The centrifuge was constrained to a radius of 1.4 meters (the upper radial limit for a centrifuge to fit within an International Space Station (ISS) module without extensive structural alterations), and a cycle ergometer was added for exercise during centrifugation. We tested different levels of artificial gravity (0g, 1g, and 1.4g at the feet in the centripetal direction) and exercise intensity (25W warm-up, 50W moderate, and 100W vigorous) while collecting a variety of data including cardiovascular parameters, foot forces, and subjective comfort and motion sickness data.

Subjects successfully completed the exercise protocol and they tolerated the centrifugation well and motion sickness was minimal. Foot forces measurements indicate that there is a significant effect of both artificial gravity (AG) level and workload intensity on peak forces generated during ergometer exercise. The cardiovascular responses were more prominent (measured as larger deviations from their baseline values) at higher levels of artificial gravity and exercise intensity. In particular, cardiac output, stroke volume, and pulse pressure significantly increased with both AG level and workload intensity, suggesting that the combination of artificial gravity and exercise may be beneficial against cardiovascular deconditioning in space. Mathematical models were fit to these variables across the condition tested. These results suggest that centrifugation combined with exercise may be effective in improving musculoskeletal and cardiovascular functions during long-duration spaceflight. This work was partially supported by Fulbright Commission, the NSBRI (PI: Larry Young), and the MIT/Skoltech Seed grant.

Simulated Hypogravity Combined with Exercise

We are conducting studies using tilt platforms combined with cycle ergometer exercise to experimentally determine the impact of simulated hypogravity (including both microgravity and Lunar/Mars conditions) on various physiological parameters.  We measure a number of cardiovascular and pulmonary system parameters using a variety of non-invasive equipment, including intraocular pressure with contact tonometers, whilst subjects carry out varying intensity exercise protocols across a range of conditions.

Modeling Cardiovascular Physiology in Space

The cardiovascular system is one of the body systems affected by spaceflight.  Altered gravity environments cause a change in the hydrostatic pressure distribution on the body leading to a cephalad fluid shift where blood volume in the lower extremities reduces by up to a liter and increases in the trunk and head (sometimes known as puffy face/chicken leg syndrome).  This leads to hypovolemia, changes in hematocrit concentration, aerobic deconditioning, and could be a cause of spaceflight associated neuro-ocular syndrome (SANS).

We use mathematical models of the cardiovascular system to reach beyond the limitations of existing data and study the effects of changing gravity levels and introducing artificial gravity gradients.  These models have been validated over a number of experimental studies and are continuously being extended to include the ability to model new conditions and physiological phenomenon including exercise, pulmonary function, long duration hemodynamic changes, and metabolic cost.

Simultaneously, we are considering the impact of individual physiological variation on cardiovascular performance in space, and beginning to look at the total existing dataset of physiology studies from spaceflight and analogs to determine whether we can generate predictive algorithms for long duration performance deconditioning.

Combined with the experimental work, this research will lead to a greater understanding of the temporal effects of space flight on the cardiovascular system, enabling us to better design and implement countermeasures and protocols for long duration exploration missions.

SmartSuit: Next Generation EVA Suit

The SmartSuit is a hybrid, intelligent, and highly mobile space suit for extravehicular activity (EVA) on a planetary surface. It will be comprised of a full body soft-robotic layer within a gas pressurized suit to maximize mobility by aiding in locomotion and lowering the required gas pressurization due to added mechanical counter pressure. The outside layer will be coated in a stretchable self-healing skin membrane in which transparent sensors have been integrated. The sensors will have the capability to display health and environmental data to assist the astronaut in their EVA.

Compared to current EVA suits, the SmartSuit will improve EVA missions on several fronts. The mobility of the astronaut if vastly improved by the actuation provided by the soft robotics and added mechanical counter pressure. The sensors embedded in the self-healing membrane will lead to an increase in reparability, reusability, and safety of the SmartSuit. There will also be an overall drop in EVA duration due to a reduced pre-breathing times and enhanced dexterity.

Work on this suit is being done in collaboration with Professor Shepherd at Cornell University. The role of the Bioastronautics and Human Performance Lab is focusing on quantifying these improvements in mobility and dexterity. We use a range of techniques from software simulation to prototype testing on human subjects to measure mobility enhancement and the reduction of metabolic cost compared to modern day EVA suits. Operational impacts of these developing technologies are also examined and reviewed.

This research is being funded by the NASA Innovative Advance Concepts (NIAC) program.

 

 

Virtual Assistant for Spacecraft Anomaly Treatment during Long Duration Exploration Missions

During long duration space missions, communication delays and other unknown factors will limit the ground support availability for the crew to mitigate in-flight anomalies. An autonomous virtual assistant capable of detecting such anomalies will be essential to alert the crew and treat the anomalies in a timely manner. This will not only ensure mission success and crew safety, but will also increase overall human performance, decrease the cognitive workload, increase situational awareness and help humans gain trust interacting with autonomous systems.

The Bioastronautics and Human Performance (BHP) lab is working in collaboration with Systems Engineering Architecture

and Knowledge (SEAK) lab to develop a smart virtual assistant Daphne-AT and to measure its effects on human performance, cognitive workload, situational awareness, and trust. Daphne-AT- an autonomous virtual assistant will provide support for various aspects of anomaly treatment. The baseline aspects include detecting and diagnosing the

anomaly, as well as recommending a course of action. Daphne-AT’s advanced skills include the capability to take initiative in the dialogue with the user, and the ability to provide explanations for its recommendations and actions. The BHP lab will design and conduct human-rated experiments to measure the impact of using a virtual assistant. A full-scale model will be deployed in a high-fidelity NASA analog to test the advanced functionality of the virtual assistant and its impact on crew performance.