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Kosmos 557 (DOS-3)
	Salyut programme insignia
Station statistics
COSPAR ID	1973-026A
SATCAT no.	6498
Crew	3 (intended)
Launch	11 May 1973, 00:20:00 UTC
Launch pad	LC-81/23, Baikonur Cosmodrome, USSR
Reentry	22 May 1973; 51 years ago
Mass	19,400 kg (42,800 lb)
Periapsis altitude	218 km (135 mi)
Apoapsis altitude	266 km (165 mi)
Orbital inclination	51.6 degrees
Orbital period	89.1 minutes
Days in orbit	11 days (22 May 1973)
Days occupied	0 days (22 May 1973)
No. of orbits	~175 (22 May 1973)
	Statistics as of 11 May 1973; (Unless noted otherwise)
Configuration
	The planned orbital configuration of DOS-3

Kosmos 557 (Russian: Космос 557 meaning Cosmos 557), originally designated DOS-3, was the third space station in the Salyut program. It was originally intended to be launched as Salyut-3, but due to its failure to achieve orbit on May 11, 1973, three days before the launch of Skylab, it was renamed Kosmos-557.

Due to errors in the flight control system while out of the range of ground control, the station fired its attitude thruster until it consumed all of its attitude control fuel and became uncontrollable before raising its orbit to the desired altitude. Since the spacecraft was already in orbit and had been registered by Western radar, the Soviets disguised the launch as "Kosmos 557" and quietly allowed it to reenter Earth's atmosphere and burn up a week later. It was revealed to have been a Salyut station only much later.^[when?]