1968-09-16 USSR Zond 5

On 15 September 1968, the Soviet Union launched Zond 5 on a trajectory that will fly the probe around the moon and back to earth again. It splashed down in the Indian Ocean on 21 September 1968 and recovered by the Russian.
Not much information was released about Zond 5, but many believed it was a precursor to Soviet's manned lunar flight attempt. Zond 5 carried a biological payload (including two russian tortoises, wine flies, meal worms, plants, seeds, bacteria, and other living matter) flew around the moon and returned to Earth six days later. The success of Zond 5 added pressure on the US Apollo program to make its 1969 landing goal. There was speculation within NASA and the press that the Soviet might be preparing to launch cosmonauts on a similar circumlunar mission before the end of 1968.