Yajaira Sierra-Sastre

Sierra-Sastre also served as a research scientist and program manager at the U.S. Bureau of Engraving and Printing's (BEP's) Office of Technology Development until April 2020.

A teacher-turned scientist, Yajaira is extremely passionate about STEM education and has collaborated with numerous organizations for the execution of citizen-science initiatives in the Americas. In 2016 she assembled a team of students, educators, scientists, engineers, and makers who designed a CubeSat payload that flew onboard Project Perlan's glider during a high-altitude flight in Calafate, Argentina.. Sierra-Sastre has also collaborated in the development of educational science videos about the contributions of Puerto Rican scientists in the field of space exploration.

One of the biggest food challenges astronauts face is menu fatigue. If the overall food intake declines, astronauts are at risk of nutritional deficiency, loss of bone and muscle mass, and lethargy. In 2013, the NASA Human Research Program funded a project called "HI-SEAS," an acronym for “Hawaii Space Exploration Analog and Simulation,” to determine the best way to keep astronauts well nourished during multiple-year missions to Mars or the moon.

Prior to the four-month mission, which began on March 2013, the crew participated in a two-week training session. Once the mission began the crew was not allowed to have any communication with the outside world, except for limited e-mail, and simulated space suits were required if they stepped outside the module. During the mission they tested new forms of food and food preparation strategies for deep-space travel. Sierra-Sastre also researched pre-market anti-microbial fabrics and how long they lasted, which is important given the limited water availability on a space mission. Members of the crew were given items such as shirts, bedsheets, and socks, and were asked to fill out surveys rating qualitative factors like odor, comfort, and appearance. Samples were also taken from the fabrics after use to measure the microbial growth.. Research teams from Johnson Space Center also provided exercise and sleep clothing for testing during the mission, in preparation for an International Space Station technology demonstration in 2014.

Sierra-Sastre was born in Guayama, Puerto Rico, and raised in the town of Arroyo where she received her secondary education. Throughout her childhood, she dreamed of becoming an astronaut. After graduating from Carmen Bozello de Huyke High School, she attended the Mayagüez Campus of the University of Puerto Rico where she earned a Bachelor of Science degree in Chemistry. After teaching to middle and high school students for a year and a half, Sierra-Sastre participated in a summer research experience program for teachers at Stanford University, where she was first introduced to nanotechnology research. During that time, she was trained in the self-assembly of mono-molecular films. Upon returning to Puerto Rico, she enrolled in graduate Environmental Health courses at the School of Public Health at the University of Puerto Rico Medical Science Campus and graduate Chemistry courses at the University of Puerto Rico at Río Piedras. Sierra-Sastre then attended Cornell University, where she earned a Ph.D. in 2009 in Nanomaterials Chemistry and specialized in the bionanofabrication of semiconductor nanowires. As part of her doctoral studies, Sierra-Sastre researched at Los Alamos National Laboratory.. Among the scientific works which she has co-authored is the 2008 article "Vertical Growth of Ge Nanowires from Biotemplated Au Nanoparticle Catalysts," published in the Journal of the American Chemical Society, volume 130, issue 10488.