An additional objective of this experiment was to demonstrate alternative hardware for measurement of horizontal head motion on ascent/entry and horizontal and vertical head motion on orbit.
On STS-6 and 8, a variant of the STS-5 technique was used to measure head motion. On orbit/entry during STS-6, a model-airplane gyroscope with battery supply was mounted on the subject's flight helmet and replaced the flexible cable potentiometer. On orbit during STS-8, a miniature 2-axis rate designed for missile use was repackaged and placed on a head harness such that rotational velocities around the Z (vertical) and Y (pitch) axes could be recorded.
STS-5 Launch: Negative horizontal and vertical electrodes were crossed, contaminating horizontal - vertical eye motion records. Flexible potentiometer-to-helmet coupling introduced artifacts. Pre-launch, launch, and post launch EOGs were routinely recorded (for the first time). No anomalies or acute changes were seen and the response to large inertial changes (launch, shutdown) were recorded. Mission constraints required different subjects on launch and entry.
STS-5 Landing: All phases were routinely recorded, but flexible coupling distorted head motion records. No abnormalities or acute changes were seen. Conclusions: (1) Removal or replacement of the weight vector and other aspects of Shuttle launch and entry did not significantly affect extraocular motion or the horizontal VOR reflex. (2) Recording of vertical EOG and VOR was too complex for launch and entry. (3) Flexible coupling of the head potentiometer was unacceptable. (4) Vertical head motion was needed for on-orbit studies of eye motion.
STS-6 and 8: The single-axis gyro was flown successfully on ascent and entry by one subject on STS-6; however, an improved pantograph mounting for the potentiometer proved superior and was used in subsequent flights. The 2-axis rate gyro was used to record horizontal and vertical head motion on EOG studies during entry on one subject. The data were routinely reproduced on analog strip charts and a preliminary analysis done; however, resources were not available to complete the analysis and report the results. The 2-axis rate gyro demonstrated ample capacity for launch, on-orbit and entry studies of horizontal and vertical head motion.