[1] He played a key role in adapting solid-state scientific research instruments for America's first satellites: Explorer I, II, and III.
[2] Upon completing his doctorate in 1960, from the University of Iowa, Dr. Ludwig joined the Goddard Space Flight Center (GSFC) in Greenbelt, MD as chief of the new fields and particles instrumentation section.
[3] Its first 157 employees were transferred from the United States Navy's Project Vanguard, but continued their work at the Naval Research Laboratory in Washington, D.C., while the center was under construction.
Dr. Ludwig served as Project Scientist for NASA's Orbiting Geophysical Observatory 1, 3 and 5, nicknamed "Street-Car", which carried more than 60 instruments to conduct a wide variety of space science investigations.
He finished the book, Opening Space Research; Dreams, Technology, and Scientific Discovery, published by American Geophysical Union, shortly before his death.