SPACE CABIN LANDING IMPACT VECTOR EFFECTS ON HUMAN PHYSIOLOGY.

Abstract : Fifty-eight human volunteers in 146 experiments endured impact forces simulating space cabin landing impacts following parachute descent. Impact forces were experienced in 16 body positions in combination of pitch and yaw, and seven configurations of onset (1,000, 1,500 and 2,000 G/sec.), magnitude (10, 15, 20 and 25 G) and durations (60 to 130 milliseconds). The volunteer subject sat in a seat mounted in three sets of gimbals providing fixation by 10 degree increments in yaw (0 degrees to 360 degrees), pitch (0 degrees to 180 degrees) and roll (0 degrees to 180 degrees), on a sled suspended by 4 slippers between cylindrical rails of 1.524 meters gauge, 36.6 meters in length. A pneumatic piston propelled the sled through a 13.0 meter stroke to predetermined velocities ranging from 6.1 to 13.7 meters per second, letting the sled coast 23.5 meters to impact on a piston-and-cylinder water inertia brake to penetrations of 43 to 83 centimeters before stopping. A trailing cable from the sled to recorders in a block- house near the track transmitted electrocardiograph, pneu- mograph, haemo-barograph, electroencephalograph, biceps tendon reflex, handgrip dynamometer, and tri-axial accelerometer data before, during and after impact. Stomach X-rays to indicate gastric motility were taken before and after exposure to impact. During impact 2,000 frames per second motion pictures were taken from overhead, and from right and left profile positions to record body displacements. All body positions and impact configurations were within voluntary tolerance limits except the forward facing 45 reclining position at 25.4 G measured on the sled with onset of 1,000 G per second and 60 millisecond duration, in which compression of soft tissues around the 6th, 7th, 8th thoracic vertebrae caused pain and stiffness for 60 days.