Profiles in Science

Franklin Chang Díaz: Propulsion Pioneer for Future Generations of Astronauts

by David Warmflash, MD

It’s been said that astronaut training means a lot of time and money spent preparing a very small number of people for something they’ll do only a few times in their career. In terms of actual space travel experience, this is generally true. Neil Armstrong, for instance, flew only two space missions. The second of those missions did make him the first human ever to walk on another celestial body, which had enormous implications for all humanity. Still, discovering that astronauts spend 99 percent of their career time practicing on Earth, not actually flying in space, might cause potentially interested children to shake their head in disillusion.

But flying in space was never supposed to be the only important element of an astronaut’s job. From the early days of America’s human space program, astronauts have been selected for their potential to carry out a space mission, but also for what they could achieve on Earth, whether by mentoring and inspiring school children, or contributing to breakthroughs in science or engineering. NASA considers them to be emissaries representing the United States on international space missions as well as providing a face for the space program that the American public can identify with. One excellent example of this is astronaut Franklin Ramón Chang Díaz. He’s been vital from the ground, where he’s developing advanced propulsion systems that could take future astronauts literally where no one has gone before. But he’s also been a workhorse in space, sharing the record with just one other astronaut for the number of space missions. On June 5, 2002, taking a seat in the space shuttle Endeavour, he blasted off on his seventh career space flight as a NASA mission specialist.

Franklin Chang Diaz
Figure 1: Franklin Ramón Chang Díaz from the STS-111 Shuttle Mission (1997). image © NASA

Around the Earth and under the North Pole

When the space program was in its infancy, Chang Díaz was one of thousands of children around the planet who dreamed of spaceflight. As ambitious a goal as this would be today, back in October 1958, when NASA was created, it was practically unthinkable. But Chang Díaz was unusually determined, immensely good at building and fixing things, and imaginative, and through his life these qualities have dovetailed to propel him toward a career in spaceflight and the design of new engines to take spaceflight to new heights.

Born April 5, 1950, in San José, Costa Rica, Chang Díaz was just nine years old when NASA presented its first class of astronauts to the public. Known as the Mercury Seven, these early space travelers were not the kind of “explorers” that Chang Díaz saw himself becoming in his dreams. At the controls of his pretend spaceship – a big cardboard box that took its maiden voyage when he was seven – he and his friends imagined moving swiftly from planet to planet, fighting monsters like the comic book and film character Buck Rogers. But rather than being the Buck Rogers of the 20th century, the Mercury Seven were purely technical – military test pilots, chosen for their experience in new craft in high atmospheric flight. That reality alone rendered the astronaut corps a completely nonviable option for a child in Costa Rica, which, to this day, is famous for having no military. But this did not stop Chang Díaz from dreaming of space. By age fifteen, he was building rockets, making his own gunpowder to launch them into the sky. Much smaller than the cardboard box, he couldn’t play the space traveling comic book hero that he admired, but he did send a mouse 100 meters into the air, fitted with a special helmet (the creature survived).

Growing up in Costa Rica’s capital city, Chang Díaz dared to think seriously about a space career, inspired mostly by two events occurring early during his cardboard spaceship era. One was the launching of humanity’s first artificial satellite, Sputnik, by the USSR in 1957. The other, taking place the following year, was the first voyage directly under the North Pole, from the Pacific to the Atlantic Ocean. Undertaken by the first nuclear submarine, the USS Nautilus, this mission through Earth’s inner space gave eight year-old Chang Díaz an idea that went far beyond Project Mercury. By providing power that could last more than a year instead of just weeks, nuclear technology gave the US Navy’s first atomic vessel the ability to go where no submarine had gone before. Maybe, just maybe, it could do the same for a future spacecraft. Thus, as NASA’s astronauts and their Soviet counterparts, cosmonauts, ascended for hours to days, Chang Díaz knew that it was just an introduction. Like early, hand-cranked submarines of the 19th century, the chemical-propelled space capsules of the mid 20th century were forerunners to something bigger and more ambitious.

Sputnik
Figure 2: Sputnik 1, the first artificial satellite successfully placed in orbit around the Earth (1957). image © NASA

Given his ideas, Chang Díaz’s mother, María, advised her son to study science as a foundation for pursuing his astronaut dream, along with more conventional career options. This was his mindset during his mouse-launching stage, when NASA reached another important milestone: Selection of its first scientist-astronauts. Astronaut Group 4 included medical doctor Joseph Kerwin and geologist Harrison Schmidt, who held a PhD from Harvard University. For missions to the moon and beyond, NASA would continue recruiting top-notch test pilots with 20/20 vision and the rest of the traditional “right stuff,” but clearly the agency now also wanted scientists. At least, this was Chang Díaz’s impression when a visitor from NASA came to San José to talk with students at his high school, Colegio de La Salle.

Encouraged that NASA was tapping the ivory tower, Chang Díaz wrote of his spaceflight interests to Wernher von Braun, who led NASA’s rocket program. In response, an official from the agency’s public relations office wrote back that the agency was encouraged that young people around the world were interested in the space program. It was a form letter, but someone had used a red crayon to underline a sentence noting that jobs at NASA were limited to US citizens. Clearly, the official was hoping to discourage the Costa Rican, politely. But, in the translation to Spanish, that discouragement did not come through, at least not in Chang Díaz’s mind. “The way I interpreted it was, ‘Come on over!’” Chang Díaz explained in a lecture in 2013. It wasn’t the craziest idea, given that immigration was part of the recent family history. His father, Ramon, was the son of a Chinese immigrant, who had fled China during the Boxer Rebellion at the close of the 19th century. And so, Chang Díaz left the “land of the ticos” for the United States – first and foremost to learn fluent English.

Comprehension Checkpoint

NASA's first group of astronauts in space were

El Norte

After graduating from Colegio de La Salle, Chang Díaz went north to live with relatives in Hartford, Connecticut. There, he spent more time in high school until he entered the University of Connecticut in 1969 on a scholarship, just weeks after Neil Armstrong and Buzz Aldrin became the first humans to walk on the moon. In actuality, the scholarship, which served as a springboard for his entire career, was purely the result of good fortune. As a foreigner, he was not supposed to qualify, but someone misclassified him as Puerto Rican and when officials tried to reverse the mistake, Chang Díaz petitioned the Connecticut legislature. Agreeing that it was the scholarship committee’s fault, the legislature allowed Chang Díaz keep the scholarship.

Fascinated with nuclear physics since the Nautilus voyage, Chang Díaz worked as a research assistant in the UConn Physics Department, where he focused on the engineering side of things, helping to design and build instruments for high-energy atomic collision studies. At the same time, he put his interest in physics to immediate practical use. After purchasing a beat up old car, he realized he also needed a used transmission. But the transmission that he bought was too long for the car, so he brought the drive shaft to the physics shop and cut and fused it until it did fit. From cardboard spaceship to mouse-sized rockets to fixing cars, Chang Díaz showed a knack for improvised designs, but there was more of this yet to come.

Plasma physics

Receiving his bachelor’s degree in mechanical engineering in 1973, he went on to the Massachusetts Institute of Technology (MIT), in Cambridge, MA, for graduate school in applied plasma physics. Matter can exist in any of four possible states: Solid, liquid, gas, or plasma. The hottest possible state, plasma, is what a substance becomes when it has absorbed so much energy the electrons are stripped away from the nuclei of the atoms. This is the state of matter of the Sun and all other stars, and the physics of plasma is very different from that of the three other material states. Becoming an expert in this area of physics, Chang Díaz worked on the US research program in controlled fusion while still at graduate school, and for three years at the Charles Draper Laboratory (also in Cambridge) after receiving his PhD (awarded in 1977).

Plasma globe
Figure 3: Filaments of plasma swirling in a globe. Invented by Nikola Tesla, the plasma lamp is a glass sphere containing noble gases with a high-voltage electrode in the center.

Chang Díaz’s time in college and graduate school corresponded to an era when NASA was beginning to benefit from the contributions scientists brought to the astronaut corps. After returning from the moon, for instance, Harrison Schmitt published the findings of his geological investigation of the moon’s Valley of Taurus-Littrow in the prestigious journal Science. Earlier that year, Joseph Kerwin flew as “science-pilot” on NASA’s Skylab 2 mission, where for 28 days he researched the physiologic and medical effects of weightlessness on himself and two other astronauts.

While the Skylab station circled overhead, the agency also pursued a nuclear rocket concept called NERVA. Like the system that powered the Nautilus and all nuclear naval vessels that followed, NASA’s NERVA program was based on nuclear fission, the energy that comes from splitting atoms. This is different from nuclear fusion, the energy that powers the sun and all other stars, the nuclear strategy where Chang Díaz was applying his knowledge of plasma physics. To this day, nuclear power plants all depend on fission, while fusion is still a long-term goal for electrical power generation. But the high efficiency of fusion makes it better both for generating electricity and for propelling any kind of ship – including a spaceship.

Chang Díaz’s plasma physics experience, especially the magnetic confinement approach, would set the stage for the work that he does today: developing new engines for rapid propulsion that might take astronauts from Earth to Mars in a matter of weeks. But while the final two decades of the 20th century would see researchers at a handful of labs passing the milestone of getting more energy from fusion than they needed to supply, Chang Díaz was busy with something else during that period: astronaut training.

Comprehension Checkpoint

NASA based its nuclear rocket concept on

The first Latin American scientist

A year after Chang Díaz joined the Draper lab, NASA presented the public with its next astronaut milestone. With the Space Shuttle program poised to begin, NASA selected a new astronaut class: Astronaut Group 8. As with Group 4, NASA again wanted scientists, but the corps was also diversifying. Consisting of 35 people, the new class included three African Americans, one Asian American, two Jewish Americans, and – most publicized at the time – six women. Not all of this was a first for humanity. The Soviet Union had actually flown both a woman and a Jewish cosmonaut back in 1960s (the latter again in 1976). But clearly NASA’s astronaut corps was no longer limited to white men. It seemed logical that a part-Chinese Latino, even if foreign born, could be next. And that’s exactly what happened. In the spring of 1980, Chang Díaz was selected, and so he packed up for Houston. No more cardboard box for his childhood dream. Now, he was learning to fly in a space shuttle.

Chosen as a mission-specialist astronaut, Chang Díaz’s job would be to conduct and tend to various experiments and special instruments that the space shuttles would carry into orbit. Like the pilot astronauts, he had to learn all of the space shuttle systems, from engines to life support. He had to learn to use the launch and entry suit, the orange pressure suit that all space shuttle crewmembers had to wear during takeoff and landing in case of a sudden loss of cabin pressure. He had to go through survival training to be prepared for an emergency landing or crash in the jungle, desert, sea, or very cold environments. For the latter, he was sent to Montana, whose winters, especially for a Costa Rican, seemed particularly harsh, even compared with MIT’s Massachusetts campus in January.

But while the pilots trained intensively on how to fly the vehicle, Chang Díaz and the other mission specialists were flying for science. For any mission he trained for, he had to learn the specifics of all the experiments. Also, he had to train for spacewalks using the other type of pressure suit, the white suit designed specifically for life support outside of the protective environment of the cabin. Preparing for a spacewalk involved numerous hours in a simulated underwater environment working on models of satellites and other devices. Additionally, prior to each walk, astronauts needed to go through complex procedures to get into the suit, spending more than two hours in the space shuttle airlock “pre-breathing” oxygen to “off-gas”, or flush out, nitrogen. Otherwise, when a person moves from a high-pressure to a low pressure environment – for instance from the space station to a space suit – nitrogen bubbles forming in the blood can produce severe symptoms in the joints, blood vessels, and even the central nervous system (spinal cord and brain). This is known as “decompression illness,” and a great deal of effort goes into preventing it in spacewalking astronauts. For months before any mission with spacewalks, Chang Díaz and his mission specialist colleagues had to practice the needed pre-spacewalk procedures. At the same time, for every mission, there were dozens of experiments to conduct, and they had to be practiced as well. Somehow, while getting ready for all of this, Chang Díaz found the time to marry Dr. Peggy Marguerite Doncaster in 1984. Since then, the couple has raised four children.

Astronaut underwater training
Figure 4: Chang Díaz participates in an underwater simulation of a contingency spacewalk during a training session at the Johnson Space Center. image © NASA

Seven times in space

Logging over 1600 hours in space, Chang Díaz’s seven orbital flights spanned from 1986-2002. On STS-61C, aboard the shuttle Columbia, he helped launch a satellite and conducted experiments in astrophysics and materials science, but the most memorable aspect of this flight is a sad one. Ten days after Chang Díaz’s first mission came to a safe end on January 18, 1986, another group of astronauts ascended into tragedy. This was the Challenger disaster of January 28 of the same year. It brought seven lives to an end and placed the shuttle program on hold for almost three years. The next time that Chang Díaz flew was mission STS-134 in 1989 on the shuttle Atlantis, from which he helped send the unmanned Galileo space probe on its mission to Jupiter.

Flying on Atlantis twice more, Columbia once more, and one time each on the shuttles Discovery and Endeavour, Chang Díaz oversaw a host of experiments in multiple fields. He visited both the Russian Mir space station and finally the International Space Station when it was brand new. As part of missions on both stations, he oversaw physics experiments investigating antimatter with a device called the Alpha Magnetic Spectrometer (AMS). But the science was not the only highlight of this phase of his career. While training for the mission to Mir, Chang Díaz and those who would join him from Russia and other countries were dropped into the forest in Siberia to be prepared for the unlikely event of a crash in that area. To keep warm, he set up a makeshift teepee by trimming a tree with a handsaw and topping it with a parachute. Inside, he lit a fire, which provided a livable environment. So amazed were the Russians that this is now the standard procedure for cold survival on Russian space missions.

Chang Díaz and Alpha Magnetic Spectrometer
Figure 5: Chang Díaz inputs data on a laptop computer associated with the Alpha Magnetic Spectrometer (AMS) hardware, the first large magnet experiment ever placed in Earth orbit. image © NASA

Chang Díaz’s mission to the budding International Space Station, STS-111, blasted off in June, 2002. It was to be his last mission, but also his seventh. To this date, only one other astronaut, Jerry Ross, shares that record with Chang Díaz. Furthermore, the mission, flown in the Endeavour, proved to be a grand finale for Chang Díaz’s shuttle period. During the mission, to help improve the station’s Canadian robot arm Chang Díaz performed three spacewalks.

Back to plasma physics

Although Chang Díaz left nuclear fusion energy research when joining NASA, as early as 1993 plasma physics once again became a key component of his job description. As noted earlier, astronauts often have additional jobs in the space program, especially between space missions. This was the case with Chang Díaz, given the applicability of plasma physics to developing technology of particular interest to NASA. In particular: advanced propulsion. Serving as director of NASA’s Advanced Space Propulsion Laboratory from 1993-2005, Chang Díaz and some colleagues developed an idea called the Variable Specific Impulse Magnetoplasma Rocket (VASIMR).

Extending plasma physics work that Chang Díaz began at MIT, VASIMR is a promising form of electric space propulsion. Standard chemical rocket motors can't move craft through space quickly enough for human interplanetary flight. Not only might astronauts get bored spending years in space, but interplanetary space exposes astronauts to dangerous radiation levels. That means the faster the trip, the safer the trip.

As with magnetic confinement fusion, VASIMR uses magnetism to squeeze plasma. But rather than squeezing the plasma to initiate fusion reactions, the magnetic field is used to direct the plasma to shoot out from engine, providing thrust, just like a rocket. The thrust is not as strong as the best chemical rockets, so VASIMR is not being developed for the sake of launching things from Earth into space. Instead, it is being explored for long-distance travel. Being much more efficient than chemical propulsion, a VASIMR engine could provide thrust for a much longer time than a chemical engine, days to weeks compared with minutes. Thus, a VASIMR-propelled ship would accelerate gradually and reach velocities far beyond those achievable with chemical engines.

Ultimately, a VASIMR ship could carry humans to Mars in approximately 39 days. Compare that with a flight time of 10-12 months that would be normal for a mission using chemical engines, and the capability of Chang Díaz’s idea is particularly striking. And speed is not the only advantage. Because VASIMR propulsion generates a strong magnetic field, the amount of space radiation hitting the crew cabin could be reduced substantially. While radiation in interplanetary space is particularly powerful, here on Earth, and even in spacecraft orbiting Earth at low altitudes, humans are protected from a large segment of the radiation by an enormous magnetic field generated by the Earth itself. Using the magnetic field of the VASIMR engines, a smaller but similarly effective shield could be developed for a craft carrying astronauts to Mars, or more distant points.

Comprehension Checkpoint

NASA saw plasma physics as a promising way to

Vasimr2
Figure 6 The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) designed by Ad Astra Rocket Company. Permission granted by Ad Astra Rocket Company. image © NASA

Post-NASA career

Retiring from NASA in 2005, Chang Díaz founded a company called Ad Astra Rocket, which works almost exclusively on VASIMR. Chang Díaz also passionately engages in outreach to the public on climate change and protection of the environment, which was inspired directly by his experience in watching changes over the surface of the Earth. Looking back at his space flight era, Chang Díaz remembers the various experiments, but what strikes him most are the changes he saw looking down on our planet. Over the course of his seven space flights, not only did he watch urbanization around cities expand on all continents (except Antarctica), he also noticed deforestation, including in the enormous Amazon forest, Earth’s lungs.

Indeed, Chang Díaz views the space program and environmental issues in a similar way, thinking of each topic in terms of sustainability. In addition to pursuing more sustainable propulsion, he welcomes the emerging era in which we’ll be utilizing resources from asteroids, using VASIMR to bring small asteroids closer to Earth. That will support a long-term human space presence, in contrast with early programs like the Space Race between the US and USSR.

“It was not sustainable,” Chang Díaz has said of the Apollo program and the bilateral nature of the Space Race. Instead, he thinks "Space exploration is a task for the whole of humanity.”

Because of the potential impact of the VASMIR project on the space program, in 2012 NASA inducted Franklin Ramón Chang Díaz into the Astronaut Hall of Fame. Not a bad start for a boy who played Buck Rogers in a cardboard box. And it is really just a start. Given where the VASIMR engine could someday take space travelers, it’s quite possible that Chang Díaz may look back at his seven space flights and see them as merely an introduction.

Summary

Franklin Chang Díaz, the first Latin American to travel to space, ties the record for the highest number of space flights. This module traces Chang Diaz’s life and career from his boyhood in Costa Rica where he built his own mini rockets, to his emigration and studies of plasma physics in the US, through his career as an astronaut, and beyond. The module describes Chang Diaz’s work toward a plasma-based rocket engine that could radically change space travel, his ongoing crusade on behalf of the environment, and his induction into NASA’s Astronaut Hall of Fame.

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  • Chang Díaz, F. (2013). "Mars in 39 days?: The VASIMR plasma engine." YouTube video, 1:20:16, posted by "DDPmeetings," August 20, 2013. https://www.youtube.com/watch?v=-nyepvfuHho.
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David Warmflash, MD “Franklin Chang Díaz” Visionlearning Vol. SCIRE-2 (2), 2015.