Marking the passage of kin is among humanity’s most time-honored endeavors. And yet, so often those noted in year-end remembrances are known to us as stars of stage, screen, ballfield, or politics — leaving those who worked behind the scenes to better our world largely unheralded. As we prepare to bid adieu to another calendar year, let us celebrate the outstanding achievements of the following 10 women of science and engineering who left us in 2015. While some may have been underappreciated during their lives, each leaves behind an indelible mark on her field, and a legacy that will ensure improved well-being for our kind, a greater understanding of the animal kingdom, and a more tangible grasp of our place in the cosmos.

Claudia Alexander

NASA Jet Propulsion Lab

The planetary science community lost a shining star when American space scientist Claudia Alexander died of cancer on July 11 at the age of 56. In nearly three decades at NASA’s Jet Propulsion Laboratory, Alexander wore many hats, including researcher, project manager, and science evangelist. Most recently, she had been the U.S. project manager for the European Space Agency’s highly fruitful Rosetta mission to the comet 67P-Churyumov-Gerasimenko. Alexander also served as the final project manager for NASA’s Galileo mission — which successfully explored Jupiter and its moons in the 1990s and early 2000s — and as a contributor to NASA’s Cassini mission presently exploring the Saturn system. In addition to her official duties, Alexander took pride in mentoring and writing science fiction stories as a way to engage young audiences and to inspire children to love science and technology.

Kathryn Barnard

University of Washington School of Nursing

A pivotal figure in the field of nursing whose studies strongly influenced how infants are cared for from their earliest moments, Kathryn Barnard died on June 27 at the age of 77. Barnard is well known for her research on the positive effects of rocking and heartbeat sounds on infants — an insight that led directly to rocking chairs becoming standard items in hospital nurseries and neonatal intensive care units. She established that a mother’s interactions with her newborn can have significant consequences on a child’s social, cognitive, and behavioral development, and she created an influential parent-child interaction scale, which helps to determine whether certain behaviors might impede or support child development. A tireless advocate for improving the care of infants, Barnard had been a professor emeritus at the University of Washington, where she founded the Center on Infant Mental Health and Development in 2001.

Eugenie Clark

University of Maryland Archives

American ichthyologist Eugenie Clark, known as “the Shark Lady” for her seminal work on the biology and behavior of sharks, died on Feb. 25 at the age of 92. As a researcher, Clark was as adventurous as they come, swimming with schools of poisonous fish, communing with giant squid, and getting up-close-and personal with the sharks she studied in great detail. A zoologist by training, Clark began her career in the late 1940s studying the fish of Micronesia. But sharks soon became her muse, and she developed scuba diving techniques for observing the misunderstood — and, she often said, unfairly maligned — creatures. A longtime professor at the University of Maryland and frequent diver in deep-water submersibles, Clark made numerous shark discoveries, such as the fact that some species can be taught to perform tasks. As a testament to her long and illustrious career, Clark’s scientific works, activities, and awards — including the honor of having several fish species named after her — filled up a curriculum vitae some 20 pages long.

Aída Fernández Ríos

Galician Royal Academy of Sciences

A leading Spanish marine biologist and climate scientist, Aída Fernández Ríos was an expert in ocean acidification and anthropogenic sources of carbon dioxide in the world’s oceans, especially the Atlantic. Throughout her career she carried out dozens of oceanographic expeditions; authored over 140 papers; and led the Spanish committee of the International Geosphere-Biosphere Program on global climate change between 2005 and 2011. Fernández Ríos had been a beloved professor at the Spanish National Research Council’s Marine Research Institute in Vigo, where she was also the director from 2006-2011. This past June her life’s work was honored when she was made a full member of the Galician Royal Academy of Sciences. Fernández Ríos died in an automobile incident on Dec. 23. She was 68.

Rose Frisch

Harvard T.H. Chan School of Public Health

Rose Frisch was a pioneering American scientist in fertility and human development who helped discover the hormone leptin, and who established that low body fat can prevent women from getting pregnant. Frisch earned a PhD in 1940 studying the genetics of fruit flies and spent time on the Manhattan Project during World War II calculating figures for physicist Richard Feynman. But her career truly blossomed when she took a research position at the Harvard Center for Population and Development Studies in Cambridge, Massachusetts. She remained there for the rest of her career, studying swimmers, rowers, ballet dancers, and other athletes to learn how body fat affects fertility and the propensity for diseases such as breast cancer. Frisch died on Jan. 30 at age 96.

Frances Kelsey

U.S. Food and Drug Administration

Canadian-born pharmacologist and physician Frances Kelsey, a hero to many after she refused to approve the sedative thalidomide for sale in the United States, died on Aug. 7 at the age of 101. As a young physician/researcher hired to review new drugs for the U.S. Food and Drug Administration in the early 1960s, she stood up to industry pressure, and the fact of thalidomide’s approval for sale in more than 20 countries, due to concerns that the drug’s safety hadn’t been properly tested. Her suspicion was vindicated when studies found that taking thalidomide during pregnancy causes serious birth defects. In addition to personal thanks from then-President John F. Kennedy in the form of the President’s Award for Distinguished Federal Civilian Service, Kelsey’s contribution ultimately led to a new law requiring drug makers to establish “substantial evidence” of a drug’s safety prior to FDA approval. Kelsey continued working at the FDA for nearly half a century, helping to solidify rules and laws to ensure drug safety for the American people. She was inducted into the U.S. National Women’s Hall of Fame in 2000 and this past June was named to the Order of Canada.

Anita Kurmann

Boston University Center for Regenerative Medicine

Anita Kurmann, a Swiss endocrine surgeon who was just beginning a promising career as a research scientist, died suddenly on Aug. 7 when her bicycle collided with a tractor-trailer in Boston. Kurmann, 38, had spent nearly three years as a postdoctoral fellow at the Beth Israel Deaconess Medical Center, where she intended to develop research skills that would help her establish a research lab in Switzerland. During that time, Kurmann began a partnership with researchers at Boston University’s Center for Regenerative Medicine who were aiming to train stem cells to morph into thyroid tissue. The team’s resulting paper, reported as a “major advance” in tissue biology, was published in October and dedicated to her memory. The study essentially describes how to grow functional thyroid follicles from stem cells — a significant step in the ultimate goal of regenerating damaged or malfunctioning organs.

Dottie Thomas

Susie Fitzhugh/Fred Hutchinson Cancer Research Center

Known to many as the “mother of bone marrow transplantation,” Dorothy “Dottie” Thomas played a key role in developing the treatment of once-incurable cancers such as leukemia. Originally a journalist, Thomas trained as a medical technician in the 1940s so she could work alongside her husband, physician E. Donnall Thomas, who would become world-renowned for researching bone marrow transplantation as a novel treatment for blood disorders. The couple formed a working partnership to which Dottie contributed in every aspect, from background research to bench work to writing, editing, and shuttling papers through publication. The Thomas’s efforts eventually led to a Nobel Prize in medicine for Don in 1990, and a new generation of patients who, thanks to their efforts, could survive cancer. Dottie Thomas went on to serve as chief administrator for clinical research at the Fred Hutchinson Cancer Research Center, in Seattle, where the couple worked for over 30 years. She died on Jan. 9 at age 92.

Margaret Tisdale

Welsh clinical virologist Margaret Tisdale, an expert in antiviral resistance, died on April 29 at the age of 64. Over her 30-plus-year career at the Wellcome Research Laboratories (now part of the pharmaceutical giant GalaxoSmithKline), Tisdale was known for her work on HIV drug resistance and the optimal use of HIV medications, as well as for leading the development and approval of the anti-inflenza drug Zanamivir, currently sold under the name Relenza. During her tenure as a scientist at GalaxoSmithKline, Tisdale had risen to head of clinical virology, and had also set up the Neuramindase Inhibitor Susceptibility Network, which monitors resistance to circulating flu strains.

Miranda Yap

Singapore Agency for Science, Technology and Research

One of Singapore’s top researchers, bioengineer Miranda Yap died at the age of 67 on Oct. 14, four years after suffering a coma-inducing aneurysm while playing golf. A professor of chemical and biomolecular engineering at the National University of Singapore, Yap was best known for establishing and directing what is now the Bioprocessing Technology Institute of the Singaporean Agency for Science, Technology and Research. As such, she played a critical role in training Singaporean students as well as more established researchers in biotechnology techniques. In 2006, Yap was named a foreign associate of the U.S. National Academy of Engineering, and in 2009, she became the first woman to receive the President’s Science and Technology Medal, Singapore’s highest honor in science and technology, from Singapore President S. R. Nathan.