STS-61-B

STS-61-B
	Construction of the ACCESS structure.
Names	Space Transportation System-23
Mission type	Satellites deployment; Technology
Operator	NASA
COSPAR ID	1985-109A
SATCAT no.	16273
Mission duration	6 days, 21 hours, 4 minutes and 49 seconds
Distance travelled	3,970,181 km (2,466,956 mi)
Orbits completed	109
Spacecraft properties
Spacecraft	Space Shuttle Atlantis
Launch mass	118,664 kg (261,609 lb)
Landing mass	93,316 kg (205,727 lb)
Payload mass	21,791 kg (48,041 lb)
Crew
Crew size	7
Members	Brewster H. Shaw Jr.; Bryan D. O'Connor; Jerry L. Ross; Mary L. Cleave; Sherwood C. Spring; Charles D. Walker; Rodolfo Neri Vela;
EVAs	2
EVA duration	12 hours, 13 minutes; 1st EVA: 5 hours, 32 minutes; 2nd EVA: 6 hours, 41 minutes;
Start of mission
Launch date	November 27, 1985, 00:29:00 UTC (7:29 am EST)
Launch site	Kennedy, LC-39A
Contractor	Rockwell International
End of mission
Landing date	December 3, 1985, 21:33:49 UTC (1:33:49 pm PST)
Landing site	Edwards, Runway 22
Orbital parameters
Reference system	Geocentric orbit
Regime	Low Earth orbit
Perigee altitude	361 km (224 mi)
Apogee altitude	370 km (230 mi)
Inclination	28.45°
Period	91.90 minutes
Instruments
	Assembly Concept for Construction of Erectable Space Structures (ACCESS); Continuous Flow Electrophoresis System (CFES); Diffusive Mixing of Organic Solutions (DMOS); Experimental Assembly of Structures in EVA (EASE); Getaway Special (GAS) canister; Morelos Payload Specialist Experiments (MPSE); Orbiter Experiments (OEX);
	; STS-61-B mission patch; ; Back row: Walker, Ross, Cleave, Spring and Neri Vela; Front row: O'Connor and Shaw Space Shuttle program ← STS-61-A (22) STS-61-C (24) →

STS-61-B was the 23rd NASA Space Shuttle mission, and its second using Space Shuttle Atlantis. The shuttle was launched from Kennedy Space Center, Florida, on November 26, 1985. During STS-61-B, the shuttle crew deployed three communications satellites, and tested techniques of constructing structures in orbit. Atlantis landed at Edwards Air Force Base, California, at 16:33:49 EST on December 3, 1985, after 6 days, 21 hours, 4 minutes, and 49 seconds in orbit.

STS-61-B marked the quickest turnaround of a Shuttle orbiter from launch to launch in history – just 54 days elapsed between Atlantis' launch on STS-51-J and launch on STS-61-B. As of August 2022^[update], this is still the record for turn around between two flights of the same orbital space vehicle. The mission was also notable for carrying the first Mexican astronaut, Rodolfo Neri Vela. This was also Atlantis' second and final mission before the Space Shuttle Challenger disaster in 1986. The Challenger disaster would ground the shuttle fleet for two and a half years and Atlantis would not fly again until STS-27, which launched three years later on December 2, 1988.