Mr Nelson has conducted extensive interviews with members of the Apollo space programme and combed through NASA archives, newly declassified CIA documents and oral histories.
For conventional companies, archives are an expensive problem: they need curating, maintenance, storage space, and no-one can ever judge what will be significant in the future.
The tapes appear to have been sent to the US National Archives, before being returned to Nasa, which stored them at its Goddard Space Flight Center in Maryland.