CLEVELAND — When space shuttle Discovery makes the journey to the International Space Station, its crew will deliver and install space station’s final truss segment and set of solar array wings, crowning two decades of NASA’s Glenn Research Center involvement with station’s electrical power system.

Discovery’s STS-119 mission is scheduled to lift off at 9:20 p.m. EDT on March 11, from NASA’s Kennedy Space Center in Florida.

For many employees at Glenn, the fourth and final array delivery to the space station will provide a great sense of satisfaction. Engineers at Glenn were initially responsible for the overall design and architecture of station’s electrical power system — the largest ever constructed for space. They combined state-of-the-art electrical designs with complex computer-aided analysis. After a redesign and re-planning of the station, management of the program was relocated to NASA’s Johnson Space Center in Houston.

In partnership with Johnson, Glenn engineers oversaw the final design and manufacture of the power system. This included close participation in critical design reviews of station hardware, engineering model testing and evaluation, functional and physical configuration audits (ensuring that the equipment performed as designed), qualification of flight electronic boxes and acceptance test procedure development, and test performance monitoring.

The arrays will provide the electricity to fully power science experiments and support the station’s expanded crew of six in May. Altogether, the station’s arrays can generate as much as 120 kilowatts of usable electricity — enough to provide about forty-two 2,800-square-foot homes with power. These arrays of the S6 will nearly double the amount of power for station science — from 15 kilowatts to 30 kilowatts.

“It will be very rewarding to see the final power system operate as planned,” said Gregory V. Schmitz, space station acting project manager at Glenn. “In my mind, this event will be second only to that of when the first arrays were activated and operated perfectly on orbit.”

Glenn will continue to provide the sustaining engineering necessary to evaluate, troubleshoot and repair the hardware in case of problems.

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