Kosmos 398 (Russian: Космос 398; meaning Cosmos 398) was the second unmanned test flight of the Soviet LK lander, using the T2K version. It followed the same program as Kosmos 379, launching on February 26, 1971 into a 276 km by 196 km orbit. It main objective was to validate contingency abort-to-lunar orbit manoeuvres.

Kosmos 398

LK Lander
COSPAR ID	1971-016A
SATCAT no.	04966
Spacecraft properties
Spacecraft type	T2K
Launch mass	7,255 kilograms (15,995 lb)
Start of mission
Launch date	26 February 1971, 12:14:00 (1971-02-26UTC12:14Z) UTC
Rocket	Soyuz-L
Launch site	Baikonur 31/6
End of mission
Decay date	10 December 1995
Orbital parameters
Reference system	Geocentric
Regime	Low Earth
Eccentricity	0.006043
Perigee altitude	196 kilometres (122 mi)
Apogee altitude	276 kilometres (171 mi)
Inclination	51.63 degrees
Period	88.9 minutes
Epoch	25 February 1971, 19:00:00 UTC[1]