Yes, "Rocky Jones: Space Ranger" is in the public domain because its copyright was not renewed, meaning it can be used freely by anyone.
Rocky Jones Space Ranger - 1954 was released on: USA: 27 February 1954
Rocky Jones Space Ranger - 1954 The Trial of Rocky Jones Chapter III 1-39 was released on: USA: 16 November 1954
Rocky Jones Space Ranger - 1954 Rocky's Odyssey Chapter III 1-10 was released on: USA: 30 March 1954
Rocky Jones Space Ranger - 1954 Out of This World Chapter I 1-34 was released on: USA: 20 November 1954
Rocky Jones Space Ranger - 1954 The Pirates of Prah Chapter I 1-11 was released on: USA: 8 May 1954
Rocky Jones Space Ranger - 1954 Crash of the Moons Chapter I 1-21 was released on: USA: 10 July 1954
Rocky Jones Space Ranger - 1954 Inferno in Space Chapter I 1-30 was released on: USA: 30 October 1954
Rocky Jones Space Ranger - 1954 Forbidden Moon Chapter I 1-14 was released on: USA: 19 June 1954
Rocky Jones Space Ranger - 1954 Silver Needle in the Sky Chapter I 1-17 was released on: USA: 29 May 1954
Rocky Jones Space Ranger - 1954 The Cold Sun Chapter III 1-29 was released on: USA: 7 September 1954
Rocky Jones Space Ranger - 1954 Crash of Moons Chapter II 1-22 was released on: USA: 17 July 1954
Rocky Jones Space Ranger - 1954 The Cold Sun Chapter II 1-28 was released on: USA: 31 August 1954