Franklin Ramón Chang Díaz, Ph.D. is a Costa Rican-American mechanical engineer, physicist and former NASA astronaut. Dr. Chang Díaz became an American citizen in 1977. He is of Chinese (paternal grandfather) and Costa Rican (maternal side) descent. Dr. Chang Díaz is currently President and CEO of Ad Astra Rocket Company. He is a veteran of 7 Space Shuttle missions, making him the record holder as of 2014 for the most spaceflights (a record he shares with Jerry L. Ross). He was the 1st Hispanic and 3rd Latin American to go into space. Díaz is a member of the NASA Astronaut Hall of Fame. He graduated from Colegio de La Salle in San José in November 1967, then moved to the United States to finish his high school education at Hartford Public High School in Connecticut, in 1969. He went on to attend the University of Connecticut, where he earned a Bachelor of Science in mechanical engineering and joined the federal TRIO Student Support Services program in 1973. He then attended the Massachusetts Institute of Technology, where he earned a Doctor of Plasma Physics in applied plasma physics in 1977. For his graduate research at MIT, Chang Díaz worked in the field of fusion technology and plasma-based rocket propulsion. Díaz was selected as an astronaut candidate by NASA in 1980 and 1st flew aboard Space Shuttle mission STS-61-C in 1986. Subsequent missions included STS-34 (1989), STS-46 (1992), STS-60 (1994), STS-75 (1996), STS-91 (1998), and STS-111 (2002). During STS-111, he performed three spacewalks with Philippe Perrin as part of the construction of the International Space Station. He was also director of the Advanced Space Propulsion Laboratory at the Johnson Space Center from 1993 to 2005. Chang Díaz retired from NASA in 2005. After leaving NASA, Díaz set up the Ad Astra Rocket Company, which became dedicated to the development of advanced plasma rocket propulsion technology. Years of research and development have produced the Variable Specific Impulse Magnetoplasma Rocket (VASIMR), an electrical propulsion device for use in space.