Physio FreeFall

Kristy Johnson

This project seeks to examine the effects of altered gravity on an individual’s physiology during parabolic flight. Specifically, we will collect flight participants’ heart rate, heart rate variability, breathing rate, skin temperature, and skin conductance measurements using wearable, wireless sensors in order to determine the response of these biosignals to zero/hyper/microgravity and feelings of nausea.

The results of this research will have both significant scientific and civilian value. To our knowledge, this experiment will be the first to investigate the new Multiple Arousal Theory in the context of motion sickness, as well as altered gravity. This theory was developed in the Affective Computing group at the MIT Media Lab and examines asymmetry in skin conductance signals from right and left wrists as differing metrics of emotional arousal and intensity. The parabolic flight configuration provides an inimitable circumstance to systematically analyze the evolution of these signals over the course of the repeated parabolic flight path. For example, we expect to see globally heightened stress and emotional arousal on the first pass, with maximal skin conductance peaks from both wrists just before the first moment of weightlessness. We expect these peaks to monotonically decrease over time with each pass, but to remain more elevated (relative to an individual’s baseline) for participants experiencing more self-reported nausea during flight. For individuals not experiencing extreme nausea, we expect to see a much higher skin conductance signal from their right wrists compared to their left (for right-handed participants) during the first few passes, with this difference decreasing steadily as the participant habituates to the flight pattern and sensations.

Note that NASA and other researchers—including the Boston-local scientists at the Ashton Graybiel Spatial Orientation Lab at Brandeis University—have investigated spatial orientation and motion sickness, but they are just beginning to add the use of physiological sensors to their work. Not only does this demonstrate that the proposed experiment is at the forefront of scientific inquiry, but it also facilitates potential collaboration with world-renowned experts in the Boston area!

In addition to sensor data, we intend to collect pre- and post-flight surveys recording participant reactions to different levels of gravity, including points at which they experienced nausea or discomfort. Pre-flight surveys will include nausea sensitivity metrics, designed to determine how likely a person is to feel nausea (i.e., separating those who feel carsick on a drive through town versus those who approach rollercoasters without hesitation). It will also ask about each participant’s feelings of anxiety, nausea, and excitement in anticipation of flying. Note that while these feelings may be experienced simultaneously, each one has a different effect on one’s physiology.

After the flight, we will ask participants to rank which sections of the flight (e.g., beginning, middle, end) prompted the greatest sensations of anxiety, nausea, and excitement and to what degree. We will also annotate the flight video recordings to denote periods of high anxiety, nausea, or excitement.

Then, we will use the survey, annotation, and sensor information to build a model that predicts when an individual might experience distress in altered gravity environments. This aspect of the study will leverage our research group’s unique expertise building machine learning algorithms for physiological data, but the results could have widespread impact. For example, such a system could be deployed to space travelers to help them monitor their physiology and anticipate or prevent feelings of discomfort during flight. As access to space travel becomes more pervasive, it is critical to understand the physiological effects of altered gravity on a population that does not solely include astronauts or specially trained individuals. Our models, along with the use of low-cost, commercially available sensors, would enable “space hacking” by tourists and other non-technical personnel, allowing them to measure and track their biosignals to achieve optimal wellness during space travel.