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Katherine K. Martin
Media Relations Office

August 24, 2006
RELEASE : 06-046
NASA Glenn Power Management Expertise Plays Role in Upcoming Space Shuttle STS-115 Mission
NASA will resume construction of the International Space Station during the next space shuttle mission, designated STS-115. Shuttle Atlantis is scheduled to lift off the launch pad at NASA's Kennedy Space Center, Fla., at 4:30 p.m. EDT Sunday, August 27. Astronauts will install a girder-like structure, known as the P3/P4 truss segment that will double the station's power capability.

The 35,000-pound segment is comprised mainly of solar cell arrays, batteries and power conditioning equipment. These were developed with expertise provided by NASA's Glenn Research Center, Cleveland.

In partnership with NASA's Johnson Space Center in Houston, Glenn's Electric Power System Management Team continues its responsibility for end to end technical oversight of station's power capability. "The P3/P4 provides station the capability to collect, store, generate, distribute and regulate power," said Thomas Kerslake, electrical power system engineer at Glenn.

In the 1980's, Glenn managed contractor efforts that led to development of technologies to efficiently convert solar energy to electric power. Large numbers of solar cells are assembled into arrays to produce high power levels from the sun. "Glenn-led research and technology enabled the cost-effective, mass production of these large-area, highly efficient solar cells," said Jeff Hojnicki, lead power systems analyst at Glenn.

Since a spacecraft orbiting the Earth is not always in sunlight, energy has to be stored. Rechargeable batteries that could operate in space were also developed under Glenn's guidance. These batteries store power to provide a continuous source of electricity while the spacecraft is in the Earth's shadow. All 12 nickel hydrogen batteries to be flown on STS-115 were replaced, based on recommendations made by a Glenn-led team.

Currently on station, and essential to station's power system, the plasma contactor cathode, or grounding rod for the system, was also developed under Glenn management.

Glenn has also been directly involved in the following crucial portions of the STS-115 mission:
  • Flight certification analysis of the station's power system to determine it ready to support STS-115.
  • Development and implementation of special procedures for boost charging and rebalancing batteries on the launch pad before launch.
  • Sequential shunt units, battery charge-discharge units, circuit isolation devices and radiators, all essential parts of P3/P4.

Additionally, the Materials International Space Station Experiment, MISSE 5, and the Forward Technology Solar Cell Experiment, will be returning to Earth onboard STS-115. These experiments will eventually be returned to Glenn for further analysis. Glenn also designed and built the electronics and wrote the software that will measure the solar cell performance on MISSE 5.

For more information on Glenn's contributions to the International Space Station, visit:

For more information on MISSE, visit:

For more information on STS-115, visit:


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