A broad class of scientific experiments has evolved which utilize extreme low acceleration environments. The Internatinal SPace station will provide such a "microgravity" environment, in conjunction with an unparalleled combination of quiesecent period duration payload volume and power, and manned or telescience interaction. The International Space station is the world's first manned space vehicle with microgravity requirements. These place limits on the acceleration levels within the pressurized laboratories and affect everything from flight altitude and attitude to the mechanical and acoustic energies emitted by an air circulation fan. To achieve such performance within the program's resource constraints, a microgravity control approach has been adopted which balances both suource and receiver disturbance mitigation. The Active Rack Isolation System (ARIS) provides acceleration attenuation at the payload rack level, and dominant sources have been reduced either by isolation or design modifications. Analytical assessments indicate that the vehicle is capable of meeting the challenging microgravity requuirements, although some current marginal non-compliances do exist. Assessment refinements will continue through the verification phase with greater efliance on test and on-0orbit measured data as part of a long term effort to clearly define and understand the constitution of the acceleration enviroment. This proecess will assoure that the design and operation of the International SPace Station will support significant microgravity science esearch.
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