On September 12, 2013, NASA confirmed that Voyager 1 had exited the solar system, becoming the first man-made object to enter interstellar space. It was the culmination of an exceptional journey begun in August 1977, when Voyager 2 lifted off from Cape Canaveral, soon followed by its sister craft, Voyager 1. The Voyagers traveled the solar system, providing humankind with an unprecedented, close-up view of our celestial neighborhood. One of the key figures who made this scientific feat a success was a Slovenian from the region of Bela Krajina.

Anton Mavretič was born in 1934 near the town of Metlika. Despite the beauty of Bela Krajina, with its gentle birch forests, the region has long been poor and offered few opportunities for its people. However, Mavretič’s skills, hard work, and determination took him to Ljubljana, where he studied electrical engineering.

It was during his studies that Mavretič received an invitation from his uncle, who lived in Denver, to continue his studies in the United States. In 1957, Mavretič left for Colorado, where he enrolled at the University of Denver. A hard-driven student, he completed both his undergraduate and Master’s studies in Denver, and later got a Doctor’s degree at Pennsylvania State University.

Mavretič’s exceptional talent for his chosen profession was quickly apparent. One of his first jobs was at Westinghouse, where he worked on that company’s color television system. But Mavretič left his greatest mark on space technology. In 1968, he was hired by the Massachusetts Institute of Technology, where he joined the team of the Center for Space Research.

While at MIT, Mavretič worked on the Interplanetary Magnetic Platform, a series of pioneering satellites that successfully measured the interplanetary magnetic field. His success with the IMP project got Mavretič an invitation to work on the Voyager program, an ambitious mission that would send two probes on a journey to the planets and beyond.

Mavretič developed the Voyagers’ plasma measuring devices. The PLS devices helped the probes to measure plasma levels in interstellar space. While the PLS device aboard Voyager 1 failed in 1980, Voyager 2’s PLS has remained up and running to his day -- far beyond its expected lifespan. Not only has it taught scientists about how solar plasma is distributed in interplanetary space, but since Voyager 2 is now also approaching the edge of the solar system, its PLS is expected to shed new light on the little-known boundary between the solar system and deep space – and help us get a better idea of where one ends and the other begins.

Recently, Mavretič lent one of the PLS devices to the Cultural Center of European Space Technologies, a new space museum in the Slovenian town of Vitanje. The device is one of only three ever made – the other two are aboard the Voyager spacecraft.

Mavretič has also helped to develop devices that measured the Van Allen belts, areas of plasma that surround the Earth. After leaving MIT, Mavretič taught at Harvard and Boston College. He headed a laboratory that focused on interplanetary space and has written a number of key scientific articles on the subject. He has also served as a consultant for several private corporations and holds the rights to several patents.

Despite his success, Mavretič has remained in touch with his hometown in Slovenia. He regularly visits Metlika and has given lectures to high school students in the region. Because of his passion for homeland, he has been named a corresponding member of the Slovenian Academy of the Arts and Sciences, as well as an honorary citizen of Metlika, the town where he was born almost 80 years ago.