The University of San Diego’s quest to become big in STEM got a $75 million boost Saturday from philanthropist Darlene Marcos Shiley, whose financial pledge will enrich the school in fields such as space travel and AI. The pledge is the largest in the history of USD, a private, Catholic university that is celebrating its 75th anniversary. The money will be paid at an unspecified time, making it different than a donation, which is immediate. Shiley said STEM — which stands for science, technology, engineering, and mathematics — touches different aspects of people’s lives, and “I believe (the fields) can be a force for good in our society,” she said in a statement. “I was drawn to USD because of its emphasis on a values-based education,” she added. “This gift fulfills my husband’s and my goals and makes me feel like I’ve made an impact.”supp Shiley is the widow of bioengineer Donald P. Shiley, who co-invented an artificial heart valve in the 1960s that became one of the greatest medical advances of its time. The couple’s generosity goes back years as they’ve have spread their wealth across health, education and the arts to support organizations in San Diego County. The money had a particularly deep impact on USD, which received $20 million in 2012 to create a school of engineering. It is the heart of STEM at USD, serving just over 1,200 students majoring in STEM. The STEM number is twice as high as it was just over a decade ago. But the school lives in the shadows of UC San Diego, which brought in $1.7 billion last year for research, and San Diego State University, which got a record $230 million. SDSU has grown so fast it is now eligible to be designated a Research 1 institution, an elite classification awarded through a highly competitive process managed by the American Council on Education. Cal State San Marcos also is surging in STEM and may get state money for a massive science building. The new Shiley pledge will be used to create more lab and teaching space at USD, and to cultivate research among undergraduates. The pledge comes amid a lot of good news for the university. Alumnus Matthew Dominick, a NASA astronaut, recently finished a long stay aboard the International Space Station. The city gave the school permission to double campus housing. And an American Enterprise Institute study says that President James Harris is one of the best college presidents in the country. Harris nodded at Shiley’s generosity, saying in a statement, “She’s always looking out for humanity and the best interests of our society, and she particularly loves our students.”