Mark Hess
Headquarters, Washington, D.C.               December 26, 1990
(Phone:  202/453-4164)


RELEASE:  90-165

SPACE STATION INTEGRATED DESIGN REVIEW COMPLETED

     The Integrated System Preliminary Design Review (ISPDR) for 
the Freedom space station, a major milestone leading to the 
construction, launch and assembly of the station, was completed 
on schedule this week marking the end of a year-long assessment 
of Freedom's preliminary design by the NASA centers, their prime 
contractors and the international partners involved in the space 
station project.

     Over the course of the last 13 months, over 80 separate 
design reviews were conducted at NASA centers and contractor 
facilities to ensure Freedom's preliminary design could satisfy 
requirements for safety, physical and functional compatibility 
and for its ability to be built, integrated with other hardware, 
and tested.  During this time, every major component, subsystem 
and system, which together comprise the space station, were 
examined.

     "We did it," said Marc Bensimon, Deputy Manager for 
Freedom's Program and Operations Office, Reston, Va., who headed 
the ISPDR effort.  "We established the schedule for the PDR last 
April and we met every milestone as planned."

     "This was an outstanding effort," said Robert Moorehead, 
Deputy Director for Space Station Freedom Program and 
Operations.  "Not only did we accomplish the PDR on schedule, we 
made the schedule despite having to devote a lot of time and 
attention to other issues, like weight and power and EVA 
(extravehicular activity) resources."

     Preliminary figures for Freedom's weight as of June 1990 
were 143,000 pounds higher than the allocated limit of 512,000 
pounds for the total space station, and housekeeping power 
exceeded the maximum 45 kw available by nearly 15 kw.  An 
intensive summer-long resources scrub reduced weight estimates by 
130,000 pounds and reduced the housekeeping power by 13 kw.  
Users will receive 30 kw of power to conduct their experiments.  

     Despite the added rigors of the ISPDR review progress, 
weight and power levels have remained stable.  "What this means 
is that the design is maturing and converging," said Bensimon.  
"While a PDR is typically conducted with the hardware only 10 
percent designed, I was impressed with the detail of the 
preliminary design and the knowledge our systems managers 
displayed with respect to expected performance of their systems."

     While hardware was a major focus of the ISPDR, space station 
managers also reviewed and baselined ground processing 
procedures, computer software specifications and pre-flight 
verification plans for Freedom.  They also approved design 
modifications such as those suggested by Dr. William F. Fisher 
and Charles R. Price, Co-chairman of the External Maintenance 
Task Team.  In the EVA systems area, program managers approved a 
change that would provide a handle on all external orbital 
replacement units so that those components could be replaced by 
robots as well as humans.  

     Both Moorehead and Bensimon acknowledge the current 
restructure assessment (begun in November as a result of a 1991 
fiscal year budget shortfall of more than $550 million along with 
a Congressional mandate to significantly reduce out-year 
spending) will have an impact on the design but are confident 
that the ISPDR has laid a firm foundation for the restucturing.  

     "Certainly there will be design changes," said Moorehead, 
"but I think that from a systems and subsystems standpoint, the 
ISPDR configuration provides us with an excellent baseline to 
work from for the restructuring.  Afterall, regardless of what 
Freedom will look like from an overall configuration standpoint, 
we will still have to have systems like power, thermal control, 
data management and guidance and control.  I anticipate being 
able to use a significant proportion of those systems in the 
station that comes out of our restructure assessment."

     Bensimon said the next major milestone in the development 
process will take place next spring.  By then, engineers will 
have completed incorporating the design changes that come out 
of the restructuring and can begin a series of stage design 
reviews that carefully examine the configuration at various steps 
along the assembly sequence.  At each stage, engineers must 
make certain the station can function like an independent 
spacecraft, with all the necessary backups, to ensure overall 
mission success.