|Mission type||Spacecraft test|
|Launch mass||7,000 kilograms (15,000 lb)|
|Start of mission|
|Launch date||12 August 1971, 09:30UTC|
|Launch site||Baikonur 31/6|
|End of mission|
|Decay date||23 August 1981|
|Semi-major axis||12,353.00 kilometres (7,675.80 mi)|
|Perigee altitude||187 kilometres (116 mi)|
|Apogee altitude||11,777 kilometres (7,318 mi)|
|Epoch||11 September 1971|
Kosmos 434 (Russian: Космос 434; meaning Cosmos 434) was the final uncrewed test flight of the Soviet LK Lander. It performed the longest burn of the four uncrewed LK Lander tests, validating the backup rocket engine of the LK's Blok E propulsion system. It finished in a 186 km by 11,804 km orbit. This test qualified the lander as flightworthy.
The LK was the only element of the Soviet human lunar programs that reached this status. In 1980-81 there were fears that it might carry nuclear fuel. When it reentered over Australia on August 22, 1981 the Soviet Foreign Ministry in Australia admitted that Kosmos 434 was an “experiment unit of a lunar cabin,” or lunar lander.