In the 1920s, David Altman and his cousin were the only Jewish boys in the small Poconos town of Hawley, Pennsylvania, where their immigrant fathers ran a silk-weaving factory. With no nearby synagogue and no Hebrew school, they learned to daven from the Yiddish-speaking father of a local clothing shop owner.

“Every Saturday, we went to his house and he opened up the closet in the living room where he kept the Torah,” said Altman, who learned to read Hebrew and recite the prayers, but not necessarily “understand all of it.”

Altman also did his part to ensure that his Orthodox family remained observant. Every Friday afternoon, he walked to the nearby railroad station to meet the train from Scranton delivering his family’s weekly parcel of kosher meat.

Shortly before his 100th birthday on Feb. 13, Altman reflected on his Judaism, his career as an award-winning aerospace scientist and his family.

In his spacious Menlo Park ranch home, where he and his wife raised three children, a grand piano sits in the corner of the living room, overlooking the swimming pool. His wife of 68 years, the former Beverly Adlis, was an accomplished pianist. She passed away suddenly in 2015 at age 89.

Her death was a shock to the entire family, said oldest daughter Jody Altman of San Francisco, who visits her father several times a week. Sometime after her mother’s passing, her father told her, “I’m not ready to leave yet.”

“I’m in reasonable health for my age,” he said later. “The main thing I miss is being able to play tennis … or stand on two feet.” With the help of caregivers, he enjoys daily walks using a walker.

Since his wife’s passing, Altman has attended Saturday services each week at the Conservative Congregation Beth Jacob in Redwood City, which his family joined in the early 1960s. In the 1980s, he helped organize a weekly high-stakes bingo game that enabled Beth Jacob to pay off a half-million-dollar mortgage in just two years.

The one constant throughout his 100-year life, which involved multiple moves before he settled in Silicon Valley, is his connection to Judaism.

“I didn’t have a life that I planned,” said the man who participated in the World War II-era Manhattan Project, worked for NASA’s Jet Propulsion Laboratory and helped launch the Chemical Systems Division of United Technologies. “I went with the flow,” he said.

That included a childhood move from Hawley to Brooklyn, New York, where he celebrated his bar mitzvah. The Depression-era National Youth Administration agency found him an after-school job as a “runner” in a multi-story Brooklyn library, looking up the call numbers of the books and retrieving them from the stacks for patrons.

Graduating high school at the top of his class, Altman attended Cornell with scholarship funding from the university as well as the state of New York. A job washing dishes at a local restaurant covered other expenses, but money was tight.

“My father always wanted me to be a doctor,” but the long training was too expensive, said Altman, who switched from premed to science.

After Cornell, he was accepted into doctoral programs at both Columbia University and UC Berkeley. It would have been more convenient to stay in New York, near his family, but a professor at Columbia said, “Being Jewish, you would find yourself more comfortable there.”

His mother saw his cross-country move as meant to be. Both she and her husband had also taken a chance and left Poland amid the pogroms at the turn of the 20th century, meeting and marrying in America.

“I’m glad I did what I did rather than medicine,” he added, noting that he tells young students, “Find out what you like to do and see how it matches up with job opportunities. … Do what you like to do, not what you’re told to do.”

Meanwhile at Berkeley, where he earned his doctorate in chemistry at age 23, he met Beverly, a first-year student who was playing the piano in the Hillel lounge. They married in 1947 and became parents to three children: Jody, a retired corporate recruiter; Jan, a retired entrepreneur in Palo Alto; and Rick, a presentations consultant who lives in Pleasanton with his wife, Becky. Rick and Becky have two daughters: Erica, 27, who lives in Sacramento and works for a commercial property firm, and Jamie, 24, who lives in San Francisco and works for a tech-oriented public relations firm. Jamie also participated in Write On For Israel, which brought high school students to Israel to write and make documentaries.

Growing older inevitably means doing less. Altman, who played tennis until he was 90, has only one regret — he wishes he’d had knee replacement surgery 20 years ago so he could continue to play. These days, he practices his backhand slice in his dreams.

But he continues to enjoy visits from family, and he always has something to look forward to. Friends, family and work associates from all over the country and from as far away as Turkey are scheduled to honor him Feb. 15 at a birthday celebration at the elegant Garden Court Hotel in Palo Alto. And there is always Shabbat.