Vostok programme
Since the 1960s critical analysis of the recordings has cast doubt on their provenance. For instance, audio transcripts reveal that none of the cosmonauts, who were supposed to be Soviet air force pilots, followed standard communication protocols, such as identifying themselves when speaking or using correct technical terminology. Likewise all the recordings contain disjointed sentences and grammatical errors (e.g. the meaningless "..аша передача будет сейчас", Nov 1963)←(″аша передача будет сейчас″ Translation: "...[o]ur transmission will now..."). Though some of the transcripts record cosmonauts saying they are leaving Earth's orbit (i.e. heading into interplanetary or "deep" space), the crewed Vostok 3KAs could not reach escape velocity because their designs never contained secondary-burn propulsion units. This was inherent to the Vostok programme, a project to put the first Soviet citizens into low Earth orbit and return them to the surface of the planet safely. OKB-1 only required spacecraft with velocities that could reach Earth orbit () far less than the speed needed to break orbit (). Propulsion units powerful enough to leave Earth's orbit did not begin to appear until the test firing of the RD-270 engine in 1969; and it was not until the N1 moon rocket (with the NK-33 engines) in 1974 that the Soviets built a spacecraft able to reach open space. It is impossible to "accidentally" veer off into deep space without firing a rocket engine powerful enough to accelerate to escape velocity.