In preparation for its flight on the International Space Station, ISU Professors Gilles Clément and Angie Bukley collected data for the Straight-Ahead in Microgravity (SAM) experiment during the 98th CNES parabolic flight campaign in Bordeaux, France, which took place on October 2-4, 2012.
The SAM experiment is a CNES-ESA led activity conducted in collaboration with NASA. It investigates the subjective straight-ahead direction, or egocenter, which is a very basic perceptual reference for spatial orientation and locomotion, and is largely determined by both balance and somatosensory inputs on Earth. These inputs are altered in microgravity, so it is hypothesized that the direction of the subjective straight-ahead changes in astronauts in orbit. Such changes could potentially have negative consequences for the evaluation of the direction of an approaching object or the accuracy of reaching movements or locomotion. Consequently, investigating how microgravity affects the egocenter is important for understanding the problems associated with long-term effects of microgravity on astronauts and how they re-adapt to the return of gravitational forces on Earth, the Moon, and on Mars.
During the three days of flight, six individuals were tested. The test subjects included personnel from CNES, INSERM, and Novespace in addition to Professors Clément and Bukley. The team measured the direction of gaze when free-floating subjects were pointing at targets along their perceived straight-ahead direction, or when making eye saccades along the spatial (aircraft) or body (egocentric) vertical in darkness. The subjects were tested in normal 1g, in 1.8g during the pull-up phase of the parabolic maneuvers, and in 0g. Data analysis is still in process, but preliminary results indicate a clear bias in the subjective straight-ahead when subjects went from 1g to 1.8g, and from 1.8g to 0g.
[Photo credit: Novespace] In the photo on the left, Prof. Clément maneuvers a test subject as part of the Straight Ahead in Microgravity experiment onboard the A300 Zero-G aircraft. In the right hand photo, Prof. Bukley is the test subject.