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Yajaira Sierra-Sastre

Yajaira Sierra-Sastre, currently a research scientist at the U.S. Bureau of Engraving and Printing, has reinvented herself multiple times over the course of her career.

U.S. Department of the Treasury, Bureau of Engraving and Printing

Making money, with an eye to the sky

If you ask Yajaira Sierra-Sastre today what she does for a living, she answers jokingly, “I make a lot of money, but I don’t keep it.” But Sierra-Sastre isn’t kidding. As a research scientist in the U.S. Bureau of Engraving and Printing’s (BEP’s) Office of Technology Development, she works with banknotes to make them more secure and durable.

From the types of fibers to the chemical makeup of the ink to the optical properties of security features, the federal government is putting a lot of new technology into ensuring the resilience and uniqueness of the money it prints. For Sierra-Sastre, whose scientific background includes chemistry, nanotechnology, and materials science, this means a rewarding job where she can contribute to securing the U.S. economy and apply her scientific knowledge to complex down-to-earth problems. “Sometimes it is very difficult for scientists, especially in grad school, who are working on a very tiny aspect of technology to see or realize the impact our technology has in the large scheme of things, but it is very tangible here at the BEP,” she says. “We are interacting with our own product every day.”

But making money is far from Sierra-Sastre’s only ambition. Over her career she has reinvented herself multiple times, pursuing science education, carrying out research, working for a startup, and joining a simulated space mission; she is currently applying to become an astronaut. “I have always been that type of person driven to work, gain new skills, and be ready for the opportunities that arise,” she says. And she is not just out for herself. No matter what she’s doing, she also aims to give back to the community by helping youngsters achieve their own scientific dreams.

An ocean of possibilities

The island of Puerto Rico, where Sierra-Sastre grew up, offers ample access to green mountains, pristine beaches, “and a clear night sky that lured me to learn all things about the universe” as a child, she says. School science fairs did the rest to convince her that blue-sky science, in space or here on Earth, was her path. And as her career has developed, she has discovered how multifaceted that path can be.

One of her first experiences with reinvention came as she became interested in science education while pursuing a bachelor’s degree in chemistry at the University of Puerto Rico (UPR), Mayagüez. “I loved chemistry, but I would get disappointed at the lack of motivation my classmates and I experienced at times for certain topics that seemed to be unrelatable,” she recalls. “It occurred to me that perhaps what I wanted to do in life was to revolutionize the way science was taught.” So she got a teacher’s certification and landed a temporary job as a math and chemistry teacher in Puerto Rico. “I truly enjoyed my teaching job,” she says, adding that she still stays in touch with former students. But education positions were scarce at the time, and as her temporary post ended, she realized that “I had to reinvent myself and find other options,” she says. Fortunately, “the dream of becoming a scientist was still lingering in my head.”

Her transition was propelled in part by her participation in a summer research program for teachers at the Center on Polymer Interfaces and Macromolecular Assemblies at Stanford University. “That was a huge deal for me because I was not very fluent in English, and I never thought that I would ever work at one of the top research institutions in the country,” she says. “The experience empowered me and sparked my interest for materials science and all things nano.” Sierra-Sastre went on to graduate school at UPR Río Piedras, working at the university’s Center for Advanced Nanoscale Materials, and she later transferred to Cornell University, where she obtained a doctorate in materials chemistry with a specialization in materials science and nanotechnology in 2009. She then took a scientist job at a nanotech startup, where she designed nanostructured coatings for military, medical, and textile applications.

There, she also began developing business expertise, writing proposals for federally funded innovation research grants and drafting invention disclosures and provisional patent applications. Her exposure to the startup world eventually inspired her to venture into entrepreneurship within the education sphere. At the end of 2011, she quit her scientist job and started designing and delivering outreach activities and collaborating with nonprofit organizations dedicated to the public understanding of science. This work “allowed me to reconnect to my endless passion for education,” she says.

Sierra-Sastre stands out as an effective and creative communicator, says Yale Ciencia Initiative Director Giovanna Guerrero-Medina, who has partnered with Sierra-Sastre on outreach activities in Puerto Rico. “It’s just not enough for her to mentor somebody; Yajaira thinks of positive ways that kids can experience the emotional side of doing science,” Guerrero-Medina says.

The flexibility of freelancing also allowed Sierra-Sastre “to pursue one of my wildest dreams, yet to be reached,” she says. In 2012, while also doing independent contractor work for a materials company, she made it past the first few rounds of applicants for the NASA Astronaut Candidate Program. She was not selected as a finalist, but she was able “to live my dream here on Earth” when she was chosen to participate in a different program: a 4-month NASA-funded Mars analog mission in Hawaii. As the chief science officer of the Hawaii Space Exploration Analog and Simulation (HI-SEAS), she directed research operations in the simulated Mars habitat, including a study of how the crew interacted with garments and other household textiles that had been treated with antimicrobial agents.

It was as that mission was ending that Sierra-Sastre came across the announcement for the BEP position. Intrigued, she saw it as yet another opportunity to explore new horizons. “I had experienced working in academic and startup environments, but I also wanted to have the experience of working for the federal government and learning about the federal R&D system,” she says. She also felt like her multidisciplinary background made her well equipped “to solve [the] very complex technological challenges” that the BEP tackles.

Now, Sierra-Sastre brainstorms new ideas about materials science and engineering advances that could improve banknote security and durability, which involves keeping up with potentially relevant research from academia, industry, and other government agencies. She also invites researchers to submit research proposals, manages research collaborations, and navigates intellectual property issues. Her work requires a broad view of the complete money printing process, and she regularly collaborates with lab technicians, systems engineers, banknote designers, photoengravers, press operators, legal advisers, and contract specialists. “The BEP is a unique place in the federal government where science, manufacturing, art, and design interconnect with one another,” she says. “As a team leader, I find it exhilarating to employ the skills of creativity we also use in scientific problem solving to find ways to balance the different perspectives that are brought to the table.”

A lifelong mission

Sierra-Sastre “has always thought outside the box with her career, and that has definitely helped her succeed,” Guerrero-Medina says. “[She] can see opportunities that others might not even realize exist, and she goes for them. … [She] doesn’t let anything intimidate her professionally. She did not stand back and say, ‘they won’t take me for the HI-SEAS project,’ or ‘my English is no good so I’m not going to apply for a competitive graduate program in the States.’ She always finds a way to do it.”

Sierra-Sastre is still pursuing her interests in science education and space research. She often volunteers at the National Air and Space Museum in Washington, D.C., and is currently the mission director of a team of students, educators, and scientists designing a small satellite for stratospheric research as part of a national competition. She is also trying her luck at joining the NASA astronaut program for a second time. “It would be great to reach that dream,” she says.

But, ultimately, like all of her other professional experiences, her efforts to make it into space are part of a broader, lifelong mission that Sierra-Sastre has given herself over the years: motivating others, particularly those from Latin America, while looking for her next great adventure, no matter where it takes her. “I see my quest to reach for the stars as a way I can inspire” young people to reach their full potential, she says.

This is the third installment in our "Clandestine Careers" series, highlighting scientists who have taken their careers in particularly unusual directions.