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¼°áackup 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.