Young and healthy, Paul O’Connor drew stares as he rode the bus in Chicago during World War II, when fit men were expected to be serving in the military overseas.

What other passengers didn’t know was that O’Connor was serving his nation in a top-secret mission that would change war forever.

The Manhattan Project at the University of Chicago tapped the brains of America’s most brilliant scientists, including O’Connor, a junior chemist whose work helped create the atomic bomb.

A longtime professor at the University of Minnesota, O’Connor died in Minneapolis this month. He was 92.

He developed mixed views about the Manhattan Project and in 1945 joined 154 other scientists in signing a petition warning President Harry Truman of the destructive power of the bomb and urging him not to use it unless Japan refused to submit to published terms of surrender. The petition never made it to Truman, who authorized the atomic bombing of Hiroshima and Nagasaki.

“Ever since then he’s been fairly opposed to nuclear weapons and nuclear power,” said O’Connor’s son, Mike.

After the war, O’Connor turned his skills to improving education for high school students. As with the Manhattan Project, there was a national sense of urgency.

The Soviets had embarrassed the U.S. in 1957 by launching the space satellite Sputnik, and the breakthrough raised questions about whether American math and science education was good enough.

“There was a real fear that the Russians would outstrip us,” said O’Connor’s daughter, Maggie.

She said her father, then teaching chemistry at the University of Minnesota, was among the scientists who helped develop an easier-to-understand chemistry curriculum for high school students in the 1960s to respond to the challenge.

His work caught the attention of India, which was trying to ramp up its technical skills. With help from the National Science Foundation, O’Connor and his family lived off and on in India over several years and helped upgrade its higher education.

“He felt very lucky to work over there,” Maggie said. “It was considered a hardship post, but it was not hardship for us.”

O’Connor’s teaching career came to an end in the early 1970s after he developed a medical condition that left him with halting, quieter speech. He retired from the U and turned his energies to weaving. The change wasn’t as dramatic as it might seem.

“The math and geometry that goes into weaving was straight out of the chemistry that he used to do,” Mike said.

Veteran weaver Paula Pfaff said O’Connor quickly became a standout in his new field and specialized in double weave, a particularly difficult pattern.

“He had a national reputation,” Pfaff said. “He was creative. ... When Paul explored something, he explored it to the max.”

In addition to his son and daughter, O’Connor is survived by his grandchildren, Elliot, Dan, Robert and Richard. He was preceded in death by his wife, Pat. A memorial service will be held April 20 at Walker Place, 3701 Bryant Av. S., Minneapolis.