Research

Countermeasures

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.

Closed-Loop Compression Garment

Maintaining adequate blood flow and pressure is essential to ensure that vital organs, particularly the brain, receive sufficient oxygen and nutrients. Under normal conditions, the cardiovascular system can regulate sudden changes in blood pressure and blood flow. However, rapid fluid shifts toward the lower body, known as orthostatic intolerance (OI), can sometimes overwhelm the body’s regulatory mechanisms. This can lead to hypotension and symptoms such as dizziness or fainting, and in severe cases can progress to temporary loss of consciousness. To counteract these effects, compression garments are commonly employed in both medical and operational environments. Examples of this can be seen in pilots through the use of G-suits during high-G maneuvers and astronauts who wear specialized garments to help their cardiovascular systems readjust after returning from space.

Despite their utility, current compression systems have notable drawbacks. They often fail to adapt to individual physiological differences, meaning compression may be applied at the wrong time or at an ineffective level. Many current garments are also bulky and cumbersome, manually operated, and only offer a single static pressure setting, limiting their effectiveness. Recent advances in soft robotics and smart materials, such as shape memory alloys, have improved actuation capabilities, but these systems remain user-controlled and lack full autonomy, which is essential for an individual performing complex tasks such as landing a space vehicle. This research effort focuses on the development of a next generation compression garment that automatically adjusts in real time using biometric feedback, offering a personalized and adaptive countermeasure for OI in demanding environments.

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.

Lower Body Negative Pressure in Parabolic Flight

This experiment aims to better understand how the human body responds to graded Lower Body Negative Pressure (LBNP) under true microgravity conditions, provided by parabolic flight. LBNP is a promising countermeasure for the fluid shifts that occur in space, but most studies to date have been conducted on Earth using analogs such as supine or head-down tilt positions. While these approaches remove vertical hydrostatic gradients, they cannot fully replicate the absence of gravitational forces along the front-to-back human axis, which may influence venous return, tissue pressures, and overall cardiovascular regulation.

To address this limitation, our team will investigate cardiovascular, autonomic, and ocular responses to different levels of LBNP during short-duration microgravity phases in parabolic flight. By generating dose-response curves across multiple physiological systems, we aim to directly compare responses in true microgravity with those obtained under 1g analog conditions. The study will also assess sex-based differences in physiological adaptation, contributing to a more inclusive understanding of individual variability in countermeasure effectiveness and fluid regulation during spaceflight.

This project will deliver the most comprehensive and systematic dataset on LBNP responses ever collected in true microgravity. The results will inform the optimization of LBNP as a spaceflight health countermeasure, with direct applications for reducing risks such as Spaceflight-Associated Neuro-ocular Syndrome (SANS) and venous thromboembolism (VTE). Ultimately, the findings will help define the gravitational thresholds needed to maintain cardiovascular and ocular health duringlong-duration missions to the Moon and Mars.

Multisensory 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 performance. Natural environments provide many psychological, physiologic, and cognitive benefits, and incorporating many sensory modalities could improve realism and enhance benefits of the virtual nature experience. We have developed nature-inspired VR environments with multiple sensory inputs: audio, visual, olfactory (smell), and haptics (wind and thermal stimuli). Uniquely, the scents, wind, and temperature vary based on the user’s location within the virtual environment. For example, the scent of wet ground by a pond or cooler temperatures in the shade. We are using questionnaires along with the NASA Cognition battery to measure the impact of our multisensory VR countermeasure on behavioral health and performance in both a laboratory and operational setting (i.e., Naval ship). This countermeasure could also provide benefits to other populations who do not have free access to nature such as assisted living residents, post-op recovery patients, and individuals with seasonal affective disorder (SAD).