This is a Channel 4 Equinox Documentary on the history of development of the NK-33 engines that were originally developed for the Soviet N1 moon rocket.

The Atlas V RD-180 generation of rocket engines is now applying this 'closed cycle' or staged combustion principle in order to achieve much greater efficiency.

The video contains rare footage and interviews with veterans of the early Soviet Space program: including Vasily Mishin and Boris Chertok.