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.
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. Check it out a video of the MIT centrifuge experiment below!
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.
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.
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. This
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.
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.