Kosmos 53 (Russian: Космос 53 meaning Cosmos 53), also known as DS-A1 No.5 was a technology demonstration satellite which was launched by the Soviet Union in 1965 as part of the Dnepropetrovsk Sputnik programme. Its primary mission was to demonstrate technologies for future Soviet military satellites. It also conducted radiation experiments.
Kosmos 53 was placed into a low Earth orbit with a perigee of 221 kilometres (137 mi), an apogee of 1,172 kilometres (728 mi), 48.7 degrees of inclination, and an orbital period of 98.7 minutes. It decayed on 12 August 1966. Kosmos 53 was the fifth of seven DS-A1 satellites to be launched, and the third to reach orbit after Kosmos 11 and Kosmos 17. The next DS-A1 launch after Kosmos 53 failed, before the last launch of the DS-A1 programme resulted in Kosmos 70 successfully reaching orbit in July 1965. As with earlier DS-A1 satellites, the technological experiments aboard Kosmos 53 were tests of communications and navigation systems which were later used on the GLONASS system.
Payloads are separated by bullets ( · ), launches by pipes ( | ). Manned flights are indicated in bold text. Uncatalogued launch failures are listed in italics. Payloads deployed from other spacecraft are denoted in brackets.