Triplanetary

Triplanetary is a science fiction novel and space opera by American writer E. E. Smith. It was first serialized in the magazine Amazing Stories in 1934. After the original four novels of the Lensman series were published, Smith expanded and reworked Triplanetary into the first of two prequels for the series.

Edward Elmer Smith, better known by his pen name E. E. "Doc" Smith, was an American food engineer and science-fiction author, best known for the Lensman and Skylark series. He is sometimes called the father of space opera.