This book was published by an agency of the U.S. Government and is, by law, considered in the Public Domain. Such works may be republished by others without violation of copyright law as is the case here. This book was originally published by NASA Ames Research Center, Moffet Field Mountain View, CA in June 1995. FWIW, I was the publishing manager who supervised the production of this project by the NASA contractor staff at Ames Research Center. Since the book is about space science and satellites sent to the Planet Venus, it is obviously plain stupid to state that the book was published before 1923... especially since it shows the original publication date as 1995.

Documents the challenges and the social, political, and economic factors involved in the planning and technological achievement of the Mariner 10 mission, and features more than one hundred high-resolution photographs of the surface of Mercury