Human Perception of Body Longitudinal Axis in Parabolic Flight

Paper number

IAC-05-A1.4.04

Author

Mr. Morten Hannevik Olsen, BI School of Management, Norway

Coauthor

Ms. Tonje Nanette Arnesen, Norwegian Defence Research Establishment, Norway

Coauthor

Mr. Bruno Sylvestre, École de technologie supérieure, Canada

Year

2005

Abstract

Gravity provides vital information to the human sensory and balance system. It helps a person to localize the direction of the person's own longitudinal (Z-) body axis and to maintain balance. Previous studies performed in orbital and parabolic flights showed evidence that the human sensory and balance systems are altered in weightlessness. In weightlessness, the notion of gravitational vertical is meaningless, and when free-floating in darkness only tactile inputs are left for spatial orientation. Consequently, astronauts and cosmonauts commonly experience spatial disorientation when they close their eyes. An experiment was performed by the astronaut Andre Kuipers at the International Space Station in 2004 to test a multi-purpose vibrotactile vest. The main purpose of the vest is to support the astronaut’s orientation awareness. 

A similar experiment was carried out by the authors during the 6th ESA Student Parabolic Flight Campaign in Bordeaux in July 2003 to investigate the short-term changes in the perceived body position and orientation induced by the removal of the perceived gravity. 10 subjects were tested to investigate to what degree free-floating subjects could set a line with respect to their longitudinal body axis. This experiment indicated that the subjective perception of the longitudinal body axis is altered in short-term weightlessness. This alteration could be responsible for the spatial disorientation reported in-flight by astronauts and cosmonauts. However, tactile inputs on the back or on the chest in weightlessness seem to compensate for the absence of graviceptor signals. 

A follow-up experiment will be performed by the authors in the 39th ESA Parabolic Flight Campaign. Each subject will be in total darkness while being tested. The whole experiment will be done on three parabolic flights. During micro gravity, the subjects will be asked to position two lines parallel to their perceived longitudinal body axis, one in the frontal plane and one in the sagittal (forward-backward) plane. The deviations of those lines with respect to the true long body axis will be recorded through the experimental apparatus. The same tests will be preformed on ground in Earth’s gravity pre- and post-flight, and the results will be compared. Human perception and the effects of gravity allow a human to perform the tasks quite accurately while being under the influence of Earth’s gravity. Being in micro-gravity, one must rely on human perception and/or tactile inputs. Each condition will be investigated to see whether tactile input (chest or back) or an inclined head aid the accuracy of the perceived location of the long body vertical. By performing this experiment both in micro gravity and Earth’s gravity, conclusions may be drawn to see if these effects help determining the perceived long body vertical.

While the subject is under investigation, one of the experimenters will take pictures of the subject from the side using a digital camera. This will provide further data, which may be correlated with the data received from the subjects’ perceived location of the long body axis. By studying these pictures it will be easier to calculate the deviation with respect to the position of the subject’s body and head. By comparing the accuracies to which the subject perceives each of the lines, it may be investigated if a subject’s ability to perceive both these vertical lines is coupled. The results from the new experiment will be added to results from the first experiment performed during the student campaign to complete the investigation. This paper will present the results. 

Abstract document

IAC-05-A1.4.04.pdf

Manuscript document

IAC-05-A1.4.04.pdf (🔒 authorized access only).

To get the manuscript, please contact IAF Secretariat.