Franklin Chang Diaz got hooked on space exploration in 1957, when he was 7 and fascinated by the Soviet Union’s launch of Sputnik. Eleven years later, Steve Nadis writes in Discover magazine, Chang Diaz came from his homeland of Costa Rica to live with relatives in the United States; he had $50 in his pocket and knew barely a word of English.

Franklin Chang Diaz spent hundreds of hours in space as a NASA astronaut. (NASA/AP)

Within a decade he had earned a PhD in plasma physics from MIT. He became an astronaut, completing seven space shuttle missions and logging some 1,600 hours in space. He spent 25 years with NASA, then retired to work full time on a goal he’d had ever since graduate school: creating a super-fast rocket engine. His VASIMR VX-200 — the name stands for “variable specific impulse magnetoplasma rocket” — has the potential to get astronauts to Mars in 39 days, he says, more than three times as fast as current engines could. His company, Ad Astra, says it “is engaged in a friendly competition with his former employer, trying to create the rocket of the future.”

Using detailed illustrations, the magazine describes Ad Astra’s engine, which heats a gas such as argon until it turns into plasma — the superheated fourth phase of matter, which responds to electromagnetism. Powerful magnets would blast the plasma out of the engine, thrusting the spacecraft forward at high speed. While hurdles remain, Chang Diaz is filled with optimism, predicting: “The first person that is going to walk on Mars has already been born.”