1950s-70s USA and Russia philatelic covers that are related to the early satellites development, manned and unmanned spaceflights to the moon.
1971-09-29 USSR Luna 19
Luna-19 was a heavy orbiter based on the Luna-17 spacecraft and a lunokhod housing. It entered a low (100 km above surface) orbit on October 3, 1971 and returned 5 panoramas scanned by two cameras as it passed across the Moon. Very few of the Luna-19 images were published, the best being a photo of a lunar crater.