PRESS RELEASE 94-09

February 10, 1994
Embargoed until 4 p.m.

Mark Hess
Headquarters, Washington, DC
(Phone: 202/358-1400)

Mary Ann Peto
Lewis Research Center
(Phone: 216/433-2902)

<h3>Lewis to Lead Efforts on Joint U.S./Russia Solar Dynamic test 
Flight</h3> CLEVELAND, OH -- NASA today announced the Lewis Research 
Center, Cleveland, Ohio, has been given responsibility for the 
planning and early technology development work that will lead to the 
first demonstration of a joint U.S.-Russian Solar Dynamic Power 
System aboard the Mir space station in 1997.

Lewis is NASA's Center of Excellence for space power systems. Working 
in partnership with industry, Lewis is performing specific in-line 
and support tasks for development of the photovoltaic power modules 
and electrical power distribution system for the international space 
station. 

In addition to its work on the international space station, Lewis is 
playing a key role in supporting the Agency in the areas of 
developing joint U.S./Russian cooperative efforts.

Lewis' expertise in space power systems is a critical part of the 
integrated product team to provide space station derived solar array 
modules to the Russians for use on the Mir space station and for 
developing the U.S./Russian joint solar arrays on the Russian portion 
of the international space station.

The international space station will receive most of its electrical 
power from photovoltaic arrays. Two 10,000 watt solar dynamic units 
are planned as part of final configuration of the orbiting research 
complex.

The solar dynamics system is much different from the photo-voltaic 
system now used to power spacecraft. Solar dynamic converts the Sun's 
rays into heat for the production of power. Heat is collected in a 
receiver which is located near the focal point of the parabolic 
mirror. Power is then generated the same way as a power station on 
Earth -- by heating a fluid which in turn rotates a turbine and 
generator.

Energy is stored as heat in the solar dynamic receiver so that the 
system can continue generating power when the space station is in the 
dark portion of each orbit. This is more efficient than the use of 
batteries with a photovoltaic system. During the Sun portion of each 
orbit around the Earth, heat is absorbed by melting a salt storage 
media in the receiver. On the dark side of each orbit, the salt 
freezes and gives up its heat to the working fluid of the engine, 
ensuring continuous operations.

Government and industry are working together to develop space power 
systems for today's spacecraft as well as developing new technologies 
that will power future spacecraft. It is expected that industry will 
be able to transfer some of these advanced technologies into power 
systems used here on Earth. 

Today's announcement authorizes Lewis to begin the planning and early 
technology work on a subscale version of the solar dynamic system to 
be jointly developed by NASA and the Russian Space Agency. This test 
unit will fly on the Russian Mir space station in 1997.



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