Ed Campion
Headquarters, Washington, DC                    July 28, 1995
(Phone:  202/358-1778)

June Malone
Marshall Space Flight Center, Huntsville, AL
(Phone:  205/544-0034)

RELEASE:  95-130

NASA MANAGERS DEFER NEXT LAUNCH OF SPACE SHUTTLE

     Following a briefing by a special assessment team, NASA 
managers have decided to postpone the August 5th launch of 
Space Shuttle Endeavour on Mission STS-69 in order to finish 
a review of flight hardware associated with O-rings in a 
nozzle joint of the Reusable Solid Rocket Motor (RSRM).  
Launch of Endeavour is now targeted for no earlier than mid-
August.

     The inspection team was formed to address an issue which 
came out of a post-flight assessment of boosters used for the 
last two Shuttle launches.  During their inspections, 
engineers found that a gas path in the RSRM nozzle internal 
joint number 3 had extended from insulation in the motor 
chamber to, but not past, the primary O-ring.  While gas 
paths to the primary O-ring have been observed in previous 
nozzles, the last two flights saw the gas path result in a 
slight heat effect to the primary O-ring seal.

     After reviewing several different aspects of the RSRM 
system, the team has concluded that there are no concerns 
with the design of the nozzle joint.  While there are no 
design issues, the team is looking at a procedure which would 
allow inspection and minor adjustments to the application of 
a thermal barrier, referred to as RTV, or Room Temperature 
Vulcanizing, which may further reduce the possibility of a 
gas path reaching the primary O-ring.

     "This review has been a first-rate effort from the 
entire space flight team" said Brewster Shaw, Director, Space 
Shuttle Operations at Johnson Space Center.  "We've had good 
representation and coordination between the various NASA 
organizations and Thiokol and this issue is being thoroughly 
reviewed.  While the hardware at the launch pad would 
probably operate just as expected during launch, we are going 
to take the time to ensure the Shuttle is in the  absolute 
best condition for flight.  Safety has been, is, and will 
remain our top priority with this program."

     Shuttle managers expect to receive another briefing by 
the RSRM assessment team at the end of next week.  They plan 
to wait until the assessment team has concluded its efforts 
before determining a new launch date for Endeavour.
                    -end-