The coming year will be the most challenging ever for construction of the International Space Station. Already more than two-thirds of the way through the assembly of its core structure, international crews face a full and busy construction schedule.

2003 will be about power for the Station. Electricity-generating systems will almost triple in capacity during the next 12 months. The Station crew faces a unique challenge, while almost continuously rewiring their orbiting home and laboratory, the electrical work must be done with virtually all-household appliances and computers continuously running without interruption.

"The year ahead will be the most complex so far in the history of the International Space Station and its construction in orbit," NASA Station Program Manager Bill Gerstenmaier said. "The Station literally becomes a new spacecraft with each assembly mission, and that will be true next year with dramatic changes in the operations of its cooling and power systems as well as in its appearance," he said.

During 2003 three new research facilities will be delivered to the U.S. Destiny Laboratory, bringing the total number of research racks on orbit to 10. Approximately 30 experiments are planned on board the Station in 2003. Crewmembers will conduct biology, physics, chemistry, ecology, medicine, and manufacturing experiments and also study long-term effects of space flight on humans. In addition, the continuous detailed measurement of the acceleration environment of the Station will be extended to rigorously characterize background levels that could affect research data.

2003 is planned to be the final full year of assembly of the Station's core structure, with orbital assembly of the complex scheduled to be well into the home stretch as the year draws to a close. Five NASA Space Shuttle flights are scheduled to launch more than 80,000 pounds of components, supplies and experiments to the Station. The Shuttle missions will launch four new sections of the Station's backbone, or truss, to extend its length from the present 134 feet to 310 feet by the end of 2003.

The new truss segments will include two new huge sets of solar array wings for the complex, totaling almost 6,300 square feet of surface area containing more than 65,000 individual solar power cells. The new truss segments include giant rotary joints to allow the tips of the Station "backbone" to continuously move, as the massive panels track the sun. The increased power will allow scientific experiments to expand aboard the complex in the years to come, far surpassing any previous research capability in space.

"Today's station, after four years of orbital assembly, is unprecedented and spectacular," Gerstenmaier said. "But the complex in orbit today pales in comparison to what it is planned to become by early 2004 - a research facility with unmatched capabilities," he said.

Plans call for astronauts to conduct a world record 24 spacewalks next year for Station assembly; 18 of those while the Shuttle is docked to the Station, and six while the Station is flying solo. 2003 will be the third consecutive year to set a single-year record for the number of spacewalks. The installation of the new truss segments and unfurling of the arrays also will require unprecedented robotic operations. Those operations will use both the Shuttle and Station arms. The operations will rely heavily on the capabilities of the Station's space railway to move the Station's robotic arm along the truss to position new components.

Three Expedition crews will live aboard the station during 2003, including the current Expedition Six crew of Commander Ken Bowersox, NASA Station Science Officer Don Pettit and Flight Engineer Nikolai Budarin. They will ring in the New Year in orbit. Another 31 people, representing at least five nationalities, are set to visit the Station during 2003 aboard the Shuttle and aboard Soyuz spacecraft taxi missions. Those visitors include Educator Astronaut Barbara Morgan, whose inspirational mission in late 2003 will carry students to the heights of orbit.

As NASA looks toward an exciting 2003, a tremendously successful year of Station assembly is closing. Four Shuttle missions traveled to the station in 2002, delivering almost 90,000 pounds of new components.

The deliveries included three new segments of the Station's truss backbone. The segments stretch 134 feet across the orbiting outpost and incorporate station "air conditioning," thermal control systems and radiators. The flights also delivered key components of the first "space railroad," a railcar that travels up and down a railway on the truss carrying a Canadian mobile base for the robotic arm. Also installed were two astronaut "handcars" to ease the transport of spacewalkers and their gear up and down the railway. Astronauts conducted a record 22 spacewalks during 2002.

The final segment of the Station's backbone is scheduled for launch in January 2004. It will boost the completed length of the truss to 354 feet. The Station's mass will approach a half-million pounds.

A look at the year ahead for the International Space Station: (Russian Progress flights not listed)

Shuttle Mission STS-114 (Atlantis)
Launch: March 1, 2003
Objectives: ISS ULF 1 -- Deliver new Station crew;deliver research and logistics equipment and install new Control Moment Gyroscope
Spacewalks: Three
Crew: Commander Eileen Collins, Pilot Jim Kelly, Mission Specialists Soichi Noguchi and Steve Robinson; Expedition Seven Crew (Up): Commander Yuri Malenchenko, Flight Engineer Alexander Kaleri and NASA ISS Science Officer Ed Lu; Expedition Six Crew (Down): Commander Ken Bowersox, Flight Engineer Nikolai Budarin and NASA ISS Science Officer Don Pettit

Soyuz 6
Launch: April 26, 2003
Objectives: Deliver fresh Soyuz crew rescue vehicle
Crew: Commander Gennady Padalka, Flight Engineer Pedro Duque, Third crewmember TBD

Shuttle Mission STS-115 (Endeavour)
Launch: May 23, 2003
Objectives: ISS 12A -- Install Port-side truss section consisting of segments 3 and 4 (P3/P4), including solar array wings, batteries and electronics
Spacewalks: Four
Crew: Commander Brent Jett, Pilot Christopher Ferguson, Mission Specialists Dan Burbank, Steve MacLean, Heidemarie Stefanshyn-Piper and Joe Tanner

Shuttle Mission STS-116 (Atlantis)
Launch: July 24, 2003
Objectives: ISS 12A.1 -- Deliver new station crew; deliver Portside truss section number 5 (P5)
Spacewalks: Four
Crew: Commander Terry Wilcutt, Pilot Bill Oefelein, Mission Specialists Bob Curbeam and Christer Fuglesang; Expedition Eight Crew (Up): Commander Mike Foale, Flight Engineer Valery Tokarev and NASA ISS Science Officer Bill McArthur; Expedition Seven Crew (Down): Commander Yuri Malenchenko, Flight Engineer Alexander Kaleri and NASA ISS Science Officer Ed Lu

Shuttle Mission STS-117 (Endeavour)
Launch: Oct. 2, 2003
Objectives: ISS 13A -- Deliver starboard-side truss consisting of segments 3 and 4 (S3/S4), including solar array wings, batteries and electronics
Spacewalks: Four
Crew: Commander Rick Sturckow, Pilot Mark Polansky, Mission Specialists Jim Reilly, Rick Mastracchio, Joan Higginbotham and Pat Forrester

Soyuz 7
Launch: Oct. 18, 2003
Objectives: Deliver fresh Soyuz crew rescue vehicle
Crew: Three-person taxi crew TBD

Shuttle Mission STS-118 (Columbia)
Launch: No earlier than Nov. 13, 2003
Objectives: ISS 13A.1 -- Deliver Starboard-side truss segment 5 (S5); Educator Astronaut flight
Spacewalks: Three
Crew: Commander Scott Kelly, Pilot Charlie Hobaugh, Mission Specialists Scott Parazynski, David Williams and Lisa Nowak, and Educator Astronaut Barbara Morgan