When Bert Stiller was a teenager in the 1930s, he spent his afternoons after school trooping across the then-partially built Triborough Bridge in New York, selling cold drinks to the construction workers.

If he had any fear of heights, he didn't show it. But this was at the time of the Depression, when one wasn't picky about opportunities to earn money. So, Stiller, son of a Hungarian immigrant, learned to be at ease in high places as he stood on the suspension bridge high above the East River.

Years later, his work as a government scientist would take him much higher: more than 100,000 feet, all the way to the Earth's upper atmosphere.

That's where Stiller's pioneering experiments to study cosmic rays took place, using suspended high-altitude balloons. Specifically, he worked with what was in the 1950s a new experimental technique to measure the high-energy charged particles coming from solar flares and outer space.

The instruments used thick photographic plates to capture tracks left by the cosmic rays, an understanding of which was paramount to protect the health of astronauts as the space race between the United States and the Soviet Union heated up.

He first studied radiation while in the Navy during World War II and was sent to the Bikini Islands to study the effects of atomic bomb tests on decommissioned naval ships.

Stiller, a slim man with dark eyes and an easy smile, joined the Naval Research Laboratory in 1949. He was assigned to the Cosmic Ray Branch of the Nucleonic Division and led expedition teams from his agency to balloon launch sites in Hyderabad, India, and the Galapagos Islands, where the Earth's magnetic field is not as strong.

He also helped establish a processing facility and modified high-power microscopes to analyze the data from the photographic plates, resulting in seminal measurements of the elemental composition of high-energy cosmic rays.

In the late 1950s, while on a research trip to the University of Milan in Italy, he met a young technician, Marie "Mila" E. Puppo, who served as his guide and interpreter. The couple married in 1960. It was Stiller's second marriage.

In Washington, Mila Stiller, as she was known, taught Italian at Georgetown University and the School of Advanced International Studies at Johns Hopkins University.

She also wrote Italian- and Spanish-language textbooks and on occasion found herself as the conciliatory figure in a family of alpha males: her husband and his sons from his first marriage, Richard and David Stiller.

In the meantime, Bert Stiller, a graduate of George Washington University, continued with his meticulous devotion to the study of cosmic radiation. In the 1960s, he was tapped to design cosmic ray experimental packages for the Gemini and Apollo spacecrafts.

His opposition to the Vietnam War led him to retire from the Defense Department in 1970, although later he returned to the Naval Research Laboratory as a part-time employee. He made several trips to the Houston space center to train astronauts in cosmic ray-detector experiments. In the past 10 years, he volunteered with Cuba Solidarity InfoMed USA, refurbishing computers for medical use in Cuba.

"He was always a real go-getter, the guy in charge, a superb organizer and very energetic," his son David said. "That's why it was so unusual to see him at the end like he wanted to give up on life."

The World War II Navy veteran and sports car aficionado had several medical setbacks in recent months: inflammation of blood vessels, an aneurysm and two episodes of cardiac arrest.

He had also seemed worn down from his wife's declining health over the past two years. Wracked by Alzheimer's disease, Mila Stiller didn't appear to recognize those closest to her, David Stiller said.

Before he died Jan. 4 at age 87 at Ruxton Health Care in Alexandria, Bert Stiller composed a note in anticipation of his wife's imminent death.

The note reads: "Bert and Mila have departed, hand in hand, to explore our great universe."

His wife, 79, died four days after him at the condominium they shared at the Watergate at Landmark in Alexandria.