International Space Station environments overview

Abstract

The International Space Station (ISS) will operate for more than 15 years (assembly phase plus operations phase) in the harsh environment of low-Earth orbit. It will permanently house up to six crew members and provide a microgravity environment for a variety of internal payloads. A clean external environment must be maintained to avoid interference with sensitive externally mounted payloads and to avoid degradation of the solar arrays and thermal control surfaces. The hardware design and operational requirements imposed by this unique set of mission requirements necessitates a rigorous definition of the natural environment as well as a set of induced environment constraints. This paper provides an overview of the environment requirements and thenhardware design implications. The organization of the ISS Program Office is briefly described. The changes required by the Russian participation in the ISS and the concomitant orbital inclination change from 28.5 degrees to 51.6 degrees are also discussed. The Risk Mitigation Experiments intended to characterize the high inclination natural environment and the Mir induced environments during the Shuttle/Mir missions are described. Organization and Schedule The transition from the Space Station Freedom Program to the International Space Station Program occurred during the fall of 1994. The Space Station Freedom was modified and reconfigured, Russia was added as an International Partner, and Boeing was chosen as the Prime contractor with responsibility for integrating and delivering the U.S. Segment of ISS and integrating the International Partners' hardware. The ISS Program Office was established and located at the Johnson Space Center where the proximity of Space Shuttle Program and operations personnel has \996 by the American Institute of Aeronautics and Astronautics, Inc. No copyright is asserted in the United States under Title 17, U.S. Code. The U.S. Government has a royalty-free license to exercise all rights under the copyright claimed herein for government AT A A Qfi Ofi?S purposes. All other rights arc reserved by the copyright owner. expedited the shuttle integration and operations planning activities. The Program Office is organized into Integrated Product Teams (IPTs) and Analysis and Integration Teams (AITs) with IPTs responsible for specific hardware products and AITs performing the analyses and coordination necessary to integrate the hardware elements into a system. Each IPT and AIT has a NASA and a Boeing co-lead and the teams are composed of both NASA and Boeing personnel. The team approach and the colocation of NASA and Prime personnel has enabled a novel approach for program control and integration. All design reviews and coordination milestones are conducted inprocess where assessments are performed, designs are reviewed, and issues are addressed hi real-time rather than waiting for a traditional formal review such as a Critical Design Review. The Product Groups (PGs), who are producing the hardware, are also organized into the IPT/AIT structure and are located at the plants of the Boeing Prime's subcontractors. PG-1 is located at the McDonnell Douglas plant in Huntington Beach, CA where the truss structure and related subsystems are being developed. PG-2 is at Rocketdyne's Canoga Park, CA plant where the electrical power system is being developed. PG-3 is at Boeing's Huntsville, AL location where the pressurized modules and related systems are under construction. Boeing also has a contract with Russia's Khrunichev Center to build the Functional Cargo Block (FOB) which will be the first piece of ISS hardware and is scheduled for launch in November 1997. The International Partners are NASDA of Japan which is building a laboratory module and exposed facility, the European Space Agency which is building a laboratory module, the Italian Space Agency which is providing the Mini-Pressurized Logistics Module, the Canadian Space Agency which is providing the Space Station's Remote Manipulator System, and the Russian Space Agency which is