In 1977 Chang-Díaz finally became an American citizen. Working then as a fusion physicist at the Draper Laboratory at MIT, he saw this achievement as just another step toward the goal that consumed him still: a career as an astronaut. He had applied for the space shuttle program before he got his citizenship and had been rejected; on this second round, he was summoned to Houston for a battery of interviews and tests. The visit was marked by some fanfare because it was the first time a naturalized citizen had ever been considered for the job of astronaut.
And yet months went by without an answer. Then one day in 1980, as he sat in a colleague’s office describing an idea for a superhot, superfast fusion rocket, Chang-Díaz was paged. “Dr. Chang-Díaz,” the caller said, “you have been selected to become a space shuttle astronaut. Do you want the job?”
“What kind of question is that?” Chang-Díaz asks rhetorically, recalling the moment. “I was so excited that I started pacing in circles and wrapped the phone cord around my superior’s neck.”
Six years later, he flew for the first time on a six-day, 96-orbit mission during which he helped deploy a satellite, conduct experiments in astrophysics, and run an onboard materials processing lab. “I had lots of powerful emotions,” he says, recalling that first trip. “When you get to space, as soon as you feel the float, you want to do two things. You want to unstrap because even though you train for zero gravity, you never know exactly what it’s like until you’re in it. The second thing you want to do is look out the window. That’s what blows you away-to see Earth from that point. I’ve flown many times now, and the feeling is always the same.”
Today Chang-Díaz devotes his time to perfecting the rocket engine he first conceived two decades ago. In a lab at Johnson Space Center in Houston, he and his team use hydrogen gas to generate enormous heat. “In space,” Chang-Díaz likes to say, “heat means fast.” Zapped by radio waves, hydrogen atoms lose their electrons and are transformed into a plasma as hot as the sun. This gaseous mass-the fourth state of matter, found in lightning, nebulas, and stars-reaches 1 million degrees Fahrenheit; it can melt any container devised by man. Only magnetic fields tame plasma. With massive electromagnets attached to the exterior of the plasma chamber, his team can lead the hydrogen gas plasma as easily as a pup on a leash, harnessing 1 million degrees of energy to a single unalterable goal: powering a spacecraft to Mars and beyond.
Chang-Díaz hopes that NASA will use his engine to help boost the International Space Station into orbit by 2006. (The station’s low orbit takes it through the upper reaches of Earth’s atmosphere. The drag slows it down, causing its orbit to decay, so it must be lifted and repositioned.) If the system works well, it will be used for later missions to outer planets. “We measure the performance of a rocket in seconds,” he explains. “If the shuttle comes in at 500 seconds, this engine has 30,000 seconds. The space shuttle is unsuitable to go to Mars. It’s an oxcart compared to what we can do.”
You could say that brilliant, unswerving energy is the story of Chang-Díaz’s life. Back in Costa Rica, all schoolchildren know the name Chang-Díaz. His face recently appeared on a stamp, and a pair of biologists named a new species of rain forest beetle in his honor. His mother, Maria Eugenia Díaz de Chang, visits schools to tell how she once lit the flame of fascination that sent a young man to the stars. Chang-Díaz himself works to make sure the young have a chance: He aggressively seeks out graduate students from all over the world to help design the technology his lab uses.
Chang-Díaz may be in his sixties when this planet finally sends a person to Mars, but he still hopes to be tapped for the mission: “Astronauts get better with age.”