 Nordtvedt graduated from the Massachusetts Institute of Technology (1960) and Stanford University (Ph.D., 1964) and was a junior fellow in the Harvard Society of Fellows (1963-1965).Soon after witnessing the Sputnik spacecraft cross the Boston sky in fall of 1957, he became a part-time student employee for the Mars Probe project at the MIT Instrumentation Lab, and in early 1960s was staff physicist at the same Laboratory's project to develop the Apollo Mission's navigation and guidance system.In 1968 he calculated how and to what degree the gravitational to inertial mass ratio of gravitationally compact bodies --- bodies with significant gravitational binding energy --- will generally differ from one in gravity theories other than General Relativity, and he then showed how lunar laser ranging data could be used to measure that key ratio to significant precision for the Earth.