The Space Eagle- Operation Doomsday was one of a series of books for children of around 10 and up put out by Whitman in the 60s. Other titles included "Bonanza", two "Man From U.N.C.L.E." books, "F Troop",
"The Green Hornet" and more (Watch this blog for future Whitman material)
The two "Space Eagle" books were written by Jack Pearl*, supposedly based on characters created by Raymond J. Meurer. Dedications in both books by Meurer, who was a business partner , in the broadcasting industry, of Lone Ranger co-creator George Trendle. Meurer was also a lawyer involved with the Lone Ranger licensing, so he would have connections with the Whitman/Western Publishing people. It's a shot in the dark, but he probably pitched this idea to them, and they hired Pearl to do the actual writing. Almost all of the other Whitman books in this series are licensed characters.
This book was, like all the others in the series, about 200 pages in length with colorful covers.