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STS-39 Mission: Department of Defense, AFP-675; IBSS; SPAS-II
Space Shuttle: Discovery
Launch Pad: 39A 
Launch Weight: 247,373 pounds
Launched: April 28, 1991, 7:33:14 a.m. EDT
Landing Site: Kennedy Space Center, Florida
Landing: May 6, 1991, 2:55:37 p.m. EDT
Landing Weight: 211,512 pounds
Runway: 15 
Rollout Distance: 9,235 feet
Rollout Time: 56 seconds
Revolution: 134
Mission Duration: 8 days, 7 hours, 22 minutes, 23 seconds
Orbit Altitude: 190 nautical miles
Orbit Inclination: 57 degrees
Miles Traveled: 3.5 million 

Crew Members

                    

Image above: STS-39 Crew photo with Commander Michael L. Coats, Pilot L. Blaine 
Hammond, Mission Specialists Guion S. Bluford Jr., Gregory J. Harbaugh, Richard 
J. Hieb, Donald R. McMonagle and Charles L. Veach. Image Credit: NASA 

Launch Highlights

 The launch was originally scheduled for March 9, but during processing work at 
Pad A, significant cracks were found on all four lug hinges on the two external 
tank umbilical door drive mechanisms. NASA managers opted to roll back the 
vehicle to the VAB on March 7, and then to OPF for repair. Hinges were replaced 
with units taken from orbiter Columbia, and reinforced. Discovery returned to 
the pad on April 1, launch was re-set for April 23. The mission was again 
postponed when, during prelaunch external tank loading, a transducer on the 
high-pressure oxidizer turbopump for main engine number three showed readings 
out of specification. The transducer and its cable harness were replaced and 
tested. Launch was rescheduled for April 28.

Mission Highlights

Dedicated Department of Defense mission. An unclassified payload included Air 
Force Program-675 (AFP675); Infrared Background Signature Survey (IBSS) with 
Critical Ionization Velocity (CIV), Chemical Release Observation (CRO) and 
Shuttle Pallet Satellite-II (SPAS-II) experiments; and Space Test Payload-1 
(STP-1). Classified payload consisted of Multi-Purpose Release Canister (MPEC). 
Also on board was Radiation Monitoring Equipment III (RME III) and Cloud Logic 
to Optimize Use of Defense Systems-IA (CLOUDS-I).

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