The International Space Station is ready for assembly of its next major components -- a football field-sized structural backbone supporting power, cooling and mobile robotics systems -- now that a new generation of computer software is "booted up" and on the job. The product of years of planning, months of testing and the transfer of about 2,500 files to and within the station, the new software is in use aboard the orbiting laboratory today following a carefully coordinated 12-hour process that was finished last Friday.
The software prepares the space station for its new configuration with its main truss, which will support the station's solar arrays, radiators, mobile base system for the robotic arm and other equipment. The first element of the truss, the S0 (or S-zero), is to be launched aboard Atlantis on STS-110 in April. The successful software upgrade had to be completed before Atlantis could be launched.
One of the major new capabilities the new software provides allows activation of equipment on the S0 truss that will use Global Positioning System (GPS) data in the station's attitude control system. The new GPS capability will provide the primary guidance, navigation and control system of the station, transitioning Russian attitude-determination systems to a backup role.
"This software upgrade fits in well with what has been a very productive Expedition," said Sally Davis, lead flight director for this stage of station operations. "We have demonstrated our ability to add major new capabilities to hardware and software, while we keep the International Space Station fully operational."
"The upload involved software for five American and Canadian computer systems and affects their companion Russian systems," said Robert C. Dempsey, one of the International Space Station flight controllers at NASA's Johnson Space Center in Houston, who has been working for months to choreograph the new software installation and activation. Some 150 people in the United States, Russia and Canada participated in the software upload, from planning and testing to Friday's initialization. Just the procedures for the initialization of the computers with the new software were 106 pages long.
The technical name for the software package is the 8A Integrated Flight Load, named for the space station assembly-sequence flight for which it's required.
Friday's process was similar to restarting a personal computer network, including its servers and workstations, after a major operating system upgrade. However, it was vastly more complicated, and had to be carefully coordinated among the computers on board, including those in the station's Russian-built modules. Each of the system computers had to be loaded with the latest software and brought back on line one-by-one so that at least two computers in each system were available to support day-to-day operations while the other was initializing its new software.
The work had to be done while Expedition Four Commander Yury Onunfrienko and Flight Engineers Dan Bursch and Carl Walz were awake, because the station crew had to install new hard drives -- sent up on a previous shuttle flight -- into their laptop computers and follow along as the software was initialized. The software upload also was expected to trigger caution and warning alarms, which would have awakened a sleeping crew. In addition, some of the work had to be done over Russian ground stations, as computers in Mission Control Moscow introduced their computers to the new U.S. software.
The process had to be completed expeditiously because of the possibility of glitches in computers with the new software trying to work with others still using the old software.
"It's been a heck of a lot of work," Dempsey said, of his full-time job for about nine months. "It's probably the most challenging thing I've done in my career." He likened the process to a climber finally reaching the top of a difficult mountain. "I've really enjoyed it."
The next major software upgrade will not take place until April 2003 in preparation for STS-115. That mission will deliver the second truss segment for the port side of the station and the second set of large U.S. solar arrays, doubling the power generating capacity of the station.
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