Two Careers in Spaceflight
Franklin Chang Díaz was born in San José, Costa Rica, in 1950, to a Costa Rican mother and a father of Chinese descent. Captivated by the space race as a child, he moved to the United States as a teenager with limited English and very little money, repeated a year of high school to master the language, and went on to earn a doctorate in applied plasma physics from MIT in 1977.
NASA selected him as an astronaut in 1980 — the first immigrant from Latin America chosen for the corps. Between 1986 and 2002 he flew seven space shuttle missions, tying the record for the most spaceflights by any astronaut. His missions deployed satellites, conducted materials and life-science research, and delivered components to the International Space Station.
Throughout his astronaut career he pursued a second line of work: electric propulsion. Conventional chemical rockets burn fuel and expel it at roughly 4.5 kilometers per second. That limits how far a given mass of propellant can take you. Chang Díaz's design, the VASIMR engine, instead heats a gas into plasma using radio waves, then uses magnetic fields to channel and accelerate it — reaching exhaust velocities an order of magnitude higher.
The trade-off is thrust. A plasma engine produces a very gentle push, useless for launching from Earth's surface but valuable in the vacuum of space, where it can run continuously for months and build enormous speed. Chang Díaz founded Ad Astra Rocket Company to develop the technology for cargo and crewed missions beyond Earth orbit.
