Flight performance of the International Space Station active rack isolation system

Abstract

Space flight experiment test results of a Space Station Active Rack Isolation System (ARIS) are presented. The purpose of ARIS is to isolate microgravity sensitive science experiments mounted in Space Station racks from structural vibrations present on the large Space Station orbital structure. The ARIS is shown to solve the very difficult and challenging low frequency isolation problem by providing over an order of magnitude reduction in the acceleration at 0.1 Hz. The Station displacement response to crew motion is discussed along with the control method that ARIS employs to maintain microgravity performance while limiting the motion between the Station and the isolated rack. The dramatic difference between the Station acceleration levels during crew awake and sleep periods are presented. Some microgravity experiments are sensitive to angular acceleration, so both the translational and angular accelerations of the isolated rack are presented. The performance at frequencies up to 300 Hz was measured by exciting the Station structure with a proof-mass shaker and a hammer and these results, and the impacts from payload fans are presented. ARIS has been in operation for two years and three Zeolite Crystal Growth Experiments have been supported.