This test was designed to provide data to compare with earlier human performance testing on the Space Vehicle Mockup Center’s Partial Gravity Simulator (POGO) and to provide guidance for the design of other reduced-gravity simulator projects such as the Active Response Gravity Offload System (ARGOS). The test was also designed to conduct new research into the effects of varied center of gravity (CG) and varied mass on suited human performance.
The primary objectives of the experiment were as follows :
Secondary objectives of the experiment were as follows:
To be able to directly or indirectly compare CG results and trends between test environments, four centers of gravity were chosen to test in parabolic flight. The backpack, Crew and Thermal Systems Division (CTSD), and POGO system provided a spread of centers of gravity in the high and aft quadrant, which is expected to be the likely zone for the suit CG given the need to support a suit port entry into the Space Exploration Vehicle (SEV) Rover with a rear-entry suit. The highest and most aft CG chosen for this test coincided with that of the suit/subject/gimbal CG from suited IST testing on POGO. Additionally, the CG of the MKIII with the mass-support rig with no weights was between the CTSD CG and that achieved during POGO testing, and also provided about the same mass of the system during POGO testing. This configuration provided the best achievable comparison of this test to other ISTs.
The tasks chosen for inclusion in this test were walking, kneel and recover, rock pickup, and shoveling. These tasks were chosen to match the tasks performed on previous ISTs on POGO. Because of certain limitations, exact replication of some tasks was not possible. For instance, IST_1 and IST_2 used a treadmill to study ambulation. A treadmill in a ground-based test environment allows exact speed control during walking. However, the C-9 environment has height limitations that make treadmill testing in a suit impossible because the top of the suit could impact the ceiling of the aircraft. Thus, walking was performed on the floor of the aircraft. The kneel-and-recover task was performed the same way as in previous ISTs. The rock pickup and shoveling tasks were modified so that the subject picked up and shoveled bags of lead shot instead of rocks to protect the cleanliness of the aircraft. Also, to replicate limitations of the POGO environment during IST_2, the platform from which rocks were picked up and shoveling was performed was elevated. Although this provided a less realistic task, the intent was to allow more direct comparison with other IST results.
CG locations for the system CG in relation to the subject and the gimbal axes of rotation were modeled before the test to provide the configuration of the CG rig for each condition, but these locations were based on the standard subject model. To determine how much variation occurred because of varied subject anthropometry, further analysis was performed using each individual subject’s height and weight to modify the standard subject model on completion of the test sessions. Subjects were lined up in a consistent orientation to the gimbal support structure before the CG of the system and the relation of the system CG to the gimbal axes of rotation were recalculated. This recalculation proved valuable for another reason: Three of four CGs were well tolerated, but the CTSD CG was consistently the most difficult for all subjects to cope with. When performing tasks in this CG, many subjects described the feeling as similar to a “horse-collar” tackle in football, with subjects feeling as though they were being pulled down and backwards from the base of the neck. Because these subjects did not experience this with any of the other conditions, the investigative team believed there was an error in the initial model calculations.
|Mission||Launch/Start Date||Landing/End Date||Duration|
|EPSP||01/01/2006||09/30/2010||4 years, 9 months|