STS-39

STS-39
	The Critical ionization velocity (CIV) experiment in Discovery's payload bay
Names	Space Transportation System-39
Mission type	DoD research
Operator	NASA
COSPAR ID	1991-031A
SATCAT no.	21242
Mission duration	8 days, 7 hours, 22 minutes, 23 seconds
Distance travelled	5,584,423 km (3,470,000 mi)
Orbits completed	134
Spacecraft properties
Spacecraft	Space Shuttle Discovery
Launch mass	112,207 kg (247,374 lb)
Landing mass	102,755 kg (226,536 lb)
Payload mass	5,663 kg (12,485 lb)
Crew
Crew size	7
Members	Michael L. Coats; L. Blaine Hammond; Gregory J. Harbaugh; Donald R. McMonagle; Guion Bluford; Charles L. Veach; Richard Hieb;
Start of mission
Launch date	April 28, 1991, 11:33:14 UTC (7:33:14 am EDT)
Launch site	Kennedy, LC-39A
Contractor	Rockwell International
End of mission
Landing date	May 6, 1991, 18:55:37 UTC (2:55:37 pm EDT)
Landing site	Kennedy, SLF Runway 15
Orbital parameters
Reference system	Geocentric orbit
Regime	Low Earth orbit
Perigee altitude	248 km (154 mi)
Apogee altitude	263 km (163 mi)
Inclination	57.01°
Period	89.60 minutes
Instruments
	Air Force Program-675 (AFP-675); Chemical Release Observation (CRO); Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS); Cloud Logic to Optimize Use of Defense Systems (CLOUDS-1A); Infrared Background Signature Survey (IBSS); Multi-Purpose Release Canister (MPEC); Shuttle pallet satellite (SPAS-II); Space Test Program (STP-01); Radiation Monitoring Equipment (RME-III);
	; STS-39 mission patch; ; From left: Veach, Coats, Harbaugh, McMonagle, Hammond, Hieb and Bluford Space Shuttle program ← STS-37 (39) STS-40 (41) →

STS-39 was the twelfth mission of the NASA Space Shuttle Discovery, and the 40th orbital shuttle mission overall. The primary purpose of the mission was to conduct a variety of payload experiments for the U.S. Department of Defense (DoD).