Press Release

Hamilton Sundstrand Power Transfer Unit enables extended shuttle docking time

By SpaceRef Editor
August 9, 2007
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Hamilton Sundstrand Rocketdyne, a subsidiary of United Technologies Corp. (NYSE: UTX), has developed the Power Transfer Unit converter system for NASA’s Station-to- Shuttle Power Transfer System that will be activated during the 11-day STS-118 mission, which launched Wednesday evening, Aug 8.

By using power collected from solar rays, the Station-to-Shuttle Power Transfer System will reduce the load on orbiter fuel cells and enable the shuttle to stay on-orbit for additional days, thereby increasing the crew time available for scientific experiments, extra vehicular activities and remaining International Space Station assembly tasks.

Built by Hamilton Sundstrand Rocketdyne under contract to the Boeing Co., the Power Transfer Unit comprises high-density, high-efficiency converters to provide continuous transfer of electrical power from the International Space Station to a docked shuttle.

Traditionally, the shuttle fleet can transfer power from a 28-volt dc system to a 120-volt dc system. The Power Transfer Unit makes the reverse possible: the station can transfer up to 8 kilowatts of 28-volt dc power back to the shuttle. The converters will be controlled by the shuttle crew via commands from the cockpit, or by ground controllers, when necessary.

“Just as earth-bound travelers need power converters due to differences in voltage levels in various countries, the shuttle and International Space Station need a power converter system because each operates on different volt

“Our Power Transfer Unit replaces the traditional shuttle conversion unit, and adds two 120-to-28 volt 2-kilowatt converter modules, without additional weight or volume and without requiring changes to the shuttle’s cooling system.”

The Power Transfer Unit is designed and built by Hamilton Sundstrand Rocketdyne, based in Canoga Park, Calif. Rocketdyne became part of Hamilton Sundstrand and Pratt & Whitney in 2005, when United Technologies Corp. acquired the company from Boeing.

Among the crew members launched into orbit on Wednesday evening is Rick Mastracchio, the first and only astronaut to have once worked for Hamilton Sundstrand. A Waterbury, Conn., native, Mastracchio worked as an engineer in Hamilton Sundstrand’s system design group from 1982 to 1987. While at Hamilton Sundstrand, he participated in the development of high performance, strapped- down inertial measurement units and flight control computers. During STS-118’s 11-day mission, Mastracchio will wear his former company’s spacesuit as he takes part in each of the mission’s three scheduled spacewalks, which will be his first on-orbit.

Hamilton Sundstrand, a partner in America’s space program since its inception, provides a number of systems for the International Space Station, including those that control electrical power and process water, waste and air. Hamilton Sundstrand has been the prime contractor to NASA for the space suit since the shuttle era began in 1981.

Other United Technologies companies play a major role in America’s space program as well. Pratt & Whitney Rocketdyne supplies the three main engines that power the space shuttle into orbit. The Space Shuttle Main Engines are the world’s only re-usable large rocket engines and also the most efficient ever produced. Each engine can generate a maximum thrust level over 513,000 pounds, or approximately 12 million horsepower. Pratt & Whitney Rocketdyne is one of the pioneers of the American space program.

UTC Power has supplied fuel cells for the U.S. space program since the 1960s, and continues to provide three 12-kilowatt fuel cells that generate all onboard electrical power for each orbiter. Backup batteries are not needed, and the water produced by the electrochemical reaction in the fuel cells is used for crew drinking and spacecraft cooling. Thus far, shuttle fuel cells have accumulated more than 96,000 hours of operation.

With 2006 revenues of $5 billion, Hamilton Sundstrand employs approximately 17,500 people worldwide and is headquartered in Windsor Locks, Conn. In addition to its space business, it is among the world’s largest suppliers of technologically advanced aerospace and industrial products. The company also designs, manufactures and services aerospace systems and provides integrated system solutions for commercial, regional, corporate and military aircraft.

United Technologies Corp., of Hartford, Conn., provides a broad range of high-technology products and support services to the aerospace and building systems industries.

SpaceRef staff editor.