The first manned voyage to Mars--a dream that stopped at UConn for fuel--began 45 years ago, in the mind of a little boy up in a mango tree in South America.

Neck craned, he stared at the night sky, hoping for just a glimpse of an object that was roughly the size of a basketball, more than 500 miles away, and traveling at a respectable 300 miles a minute. The thing he was looking for was a 180-pound metal sphere filled with nitrogen. It carried a couple of battery-powered radio transmitters that lasted a scant three weeks. Its name was Sputnik--a Russian satellite launched into orbit on October 4, 1957, that circled our planet every 90 minutes at a speed of 18,000 miles per hour.

In nearly all respects, Sputnik was a simple tool. But for everyone, especially the kid in South America, it changed everything.

In the fading weeks of 1957, short-wave ham radios had little trouble picking up the Russian satellite's signals when it passed overhead. The voice that inaugurated the space race was nothing more than a persistent beeping. But for the anxiety it evoked in the United States, it might as well have been the voice of Soviet Premier Nikita Khruschev, screaming from the darkness of space.

People would stand in their yards and flip their collars against a chill that transcended early winter. They would look up at the sky. And sometimes, at dawn or in the evening, when the sun was close enough to the horizon to illuminate the satellite, some actually saw it--a tiny speck of light, quietly threading the stars, racing toward tomorrow.

Franklin Chang-Diaz '73 (ENG) was living in Venezuela that autumn. His father, Ramon Chang Morales, was a construction foreman who had brought his family from Costa Rica because oil exploration had created a brisk job market.

Young Chang-Diaz was 7 years old the night his mother, Maria Eugenia Diaz, told him the Russians had successfully launched a man-made satellite. He did the only thing a curious little boy could do. He went out into the front yard of the family's home and climbed high into a tree. And for the next few hours -- not with anxiety but with hope -- he stared up at the sky, imagining what it would like to be out there.

If Chang-Diaz's mother had been asked, that October evening, what her son might become when he grew up, she almost certainly could not have imagined the future that lay before him, the extraordinary unfolding of an idea that took root in his mind as he sat up in that tree.

But by 1968, when Chang-Diaz was 18, he had long since decided where his future lay. He was determined to become an astronaut.

And the most unbending determination to achieve his goal was precisely what it would take. To say the odds were against him would be an understatement. He wasn't a U.S. citizen. He didn't even speak English. And there had never been a Hispanic astronaut.

None of those obstacles sidetracked Chang-Diaz. His family had returned to Costa Rica so he could take advantage of that nation's better education system. Chang-Diaz had done well in school and shown a clear aptitude for mathematics and science. He had saved a modest nest egg, and there were cousins in Hartford with whom he could live.

Thus, in the fall of 1968, he came to Connecticut and enrolled in Hartford High School, where, in order to learn English, he repeated his senior year. Recognizing his limited English skills, the school tried to place him in an English orientation program. Chang-Diaz balked. "Everybody in the program spoke Spanish," he recalls. "I knew that if I was going to achieve my goals, I had to learn English quickly. So I asked them to put me in the normal classes."

It was tough going. Through the fall, as he struggled to learn English, he did poorly in all of his classes. But of all the assets Franklin Chang-Diaz brought to his quest, perseverance might have been the most important. By the end of the school year, he had not only mastered English but also graduated near the top of his class.

His progress had been so remarkable, indeed, that he was awarded a scholarship. And in 1969, he enrolled at the University of Connecticut as a mechanical engineering major.

As a freshman at UConn, he wrote a letter to the National Aeronautics and Space Administration, inquiring about career opportunities. The response he got suggested his interest was commendable but told him what he already knew. Careers were limited to U.S. citizens.

Still, Chang-Diaz was undaunted. It was not the polite dismissal from NASA that he took to heart but another letter. As a high school student in Costa Rica, he'd written to Werner von Braun, one of the fathers of space travel. The letter he got from Bart Slatery Jr., then head of public affairs at the Marshall Space Flight Center, became one of the buoys to which he clung whenever obstacles threatened to derail his ambitions.

"I still have that letter," he says. "It has always meant a lot to me."

When the Apollo 11 mission took men to the moon for the first time, Chang-Diaz watched with other UConn students in the Student Union. "I thought, man, that's what I came to this country to do!" he recalls. "And I felt I was closer to my goal. It gave me strength to continue."

Part of what helped keep up his spirits was the encouragement of two UConn professors--Quentin Kessel and Howard Hayden--who became his mentors. While others gave little credence to the young man's goals, Kessel and Hayden listened respectfully and offered constructive suggestions.

Hayden, in fact, was the first professor for whom Chang-Diaz worked. And it was Hayden who introduced him to the world of experimental physics, effectively opening the door that stood between Chang-Diaz and his dream.

The astronaut business, meanwhile, was going quickly downhill. By the time Chang-Diaz completed his junior year at UConn, the last Apollo mission was over and, he recalls, "Thousands of aerospace workers were being laid off. I read about aerospace engineers who were driving taxis and working in gas stations. People advised me there was no future in this field."

Chang-Diaz was undaunted. "I figured it was only temporary," he says.

He also figured something else. Unlike the prototype astronauts who'd flown the first missions, the astronauts of the future would not be military jet pilots. They would be scientists.

"I knew that my future was in physics," he says. "What I really wanted to do was design rockets. I wanted to be like von Braun and rocketry pioneer Robert Goddard."

He was convinced that the rockets of the future--which would carry people to the remote reaches of our solar system and beyond--would be plasma rockets driven by nuclear reactors. Plasma is electrically charged gas with altered atoms. A product of extremely hot, high-pressure environments, it is--quite literally--the stuff of stars.

After graduating from UConn in 1973, Change-Diaz enrolled in the Massachusetts Institute of Technology, from which he earned his Ph.D. in applied plasma physics in 1977. By then he had obtained U.S. citizenship.

There followed a stint with the Charles Stark Draper Laboratory, in Cambridge, Mass., where his work focused on design and integration of control systems for fusion reactors and experimental devices. In May 1980 he was selected by NASA for astronaut training. And in August 1981, nearly a quarter of a century after the night he climbed the mango tree, he finally became an astronaut.

While completing his training, he worked with flight software at the Space Shuttle Avionics Integration Laboratory and on early design studies for the International Space Station.

Late in 1982, he was selected as a member of the support crew for the first Spacelab mission.

In January 1986, just before the Challenger accident, he went into space for the first time. It was a bittersweet victory. Among the astronauts who lost their lives on Challenger was pilot Michael J. Smith, a close friend who had joined NASA at the same time as Chang-Diaz.

Since 1986, he has gone back six times, most recently aboard the shuttle Endeavor last June, delivering a new resident crew to the space station. In the last 19 years, he has logged more than 1,600 hours in space, including nearly 20 hours in three separate space walks.

Since 1993, he has been director of the Advanced Space Propulsion Laboratory at the Johnson Space Center, where he has continued the work on plasma rockets that he began thinking about as an undergraduate at UConn. "The future of space exploration will require spacecraft that are both fast and reliable," he says. "That means revolutionary propulsion systems."

For 20 years, his research team has been developing such a propulsion system. It is called the Variable Specific Impulse Magnetoplasma Rocket (VASIMR), and Chang-Diaz envisions it enabling space travel that is, perhaps, 30 times faster than any system available today. "The objective is to travel to Mars," he says, unambiguously. "A propulsion system like the VASIMR would make it possible to get there in a little more than a month, rather than a year."

Chang-Diaz expects to test the VASIMR in about three years. If the tests are successful, "I assume there would be rapid deployment," he says. His target then would be a human mission to Mars in May 2018, the 38th anniversary of his employment with NASA.

"With a propulsion system like this, we'd have the entire solar system within our reach," he says, envisioning automated mining complexes on large asteroids and missions to Titan, a moon of Saturn, and Callisto and Europa, moons of Jupiter.

So continues the odyssey that began the night Sputnik was launched. Each year, now, Chang-Diaz brings promising students from all over the world to work in his laboratory. They are, in many respects, like him--bright young men and women with a boundless spirit of adventure, who look up at the night sky; at the future.