Joy McNair has a wonderful memory of herself as a toddler running toward her astronaut father as he returns home. But it's not her memory. She borrowed it from someone else.

"My mother has told me often that I was quite the daddy's girl," McNair said on the phone Monday. "I would run to his arms when he arrived from work every day."

But beyond that, her memories are murky.

Joy was just 18 months old in 1986 when the unthinkable happened and the space shuttle Challenger exploded shortly after liftoff. Her father, astronaut Ronald McNair, and his six colleagues lost their lives, prompting President Reagan to call them true American heroes.

Now a 27-year-old Washington-based attorney, Joy experiences Father's Day very much like any other day.

"I've never had Father's Day to celebrate. So in a weird way it's not something that I feel a loss for."

For countless people who lost their dads before they had a chance to know them, Father's Day can force a confrontation with lingering questions and memory gaps. When the loss is part of a public event, when the world remembers your father in some ways better than you do yourself, the search to truly know your father can become a lifelong quest.

History knows Ronald McNair as a top physicist and the second African-American to fly in space. Joy got to know her father through the personal stories shared by family and friends. The storytelling started before she can even remember.

"I just always remember knowing," she said.

Her father was curious. As a first grader, he talked so much about the then-orbiting Soviet Sputnik satellite he gained the nickname "Gizmo."

He was tenacious. As a student at MIT, a mugger robbed McNair, stealing a case containing laser physics data that had taken him two years to gather. He went to work and painstakingly recreated that data within a year.

He was confident. When he announced that he was going to be an astronaut, McNair's brother asked why he was so sure he'd be accepted. "Because I applied," Ronald joked.

NASA proved him right. McNair made history as one of a handful of astronauts selected from thousands of applicants.

A father like that might prove to be a daunting figure for any child, with the potential to assume almost mythical status.

But Joy McNair set out to be her own woman.

"I've made it a point to not live in his shadow and to try to build a legacy of my own and make my own contributions to society. So we have similar characteristics but our delivery might be different."

Recently Joy stumbled upon a published interview with her father. "I was just stunned by some of the things that I read," she said.

The article revealed that her father had developed a study method during high school that was identical to her own. She was astonished to learn that he went through a grad school "adjustment period" before eventually finding his way and excelling, just as Joy did during law school.

Ronald McNair had written and achieved a 10-year life-plan that culminated at age 28 with his Ph.D. in physics. This fascinated Joy because she had been writing five- and 10-year life plans "as long as I can remember."

Just a few weeks ago she finished her 10-year academic plan to earn a bachelor's degree, a law degree and a master's in law. Joy couldn't help but notice she had completed her plan by age 28. Just like her dad.

Despite all the connections and similarities, Joy didn't share her father's desire to make music. The astronaut was also a performing saxophone player - and, according to NASA - the first person to play the instrument in space.

"I'm interested in music, but I don't play a musical instrument," Joy said. Her brother, however, "dabbles" with the saxophone. Reginald still has his dad's sax and plays it sometimes, she said.

Joy said she didn't really know her life was different "until later on in life when people would ask the various questions."

Referring to the tragedy as "the accident," she said she and other children of the Challenger crew have talked often with each other about what they remember about their parents, and what they don't remember.

Related story: New Challenger video surfaces

Psychiatrists say the human body and brain "remember" the stress of being separated from a parent, even at the very young age of 18 months. But the outcome differs for everyone.

"Some people rise to greatness from adversity," said CNN consultant and psychiatrist Dr. Charles Raison. "If the death of a father is eased by the child's environment, and the father is honored and remembered and loved and becomes sort of an icon to the growing child, there's going to be a lot less damage."

That was Joy's experience. She and her brother got support from their mother and grandparents, who nurtured them to be resilient, independent and to follow their hearts.

"My mother was very good at giving us a stable life," she said.

Related story: Challenger widow reflects on final shuttle flight

Together with the rest of the family, Reginald and Joy work to maintain their father's legacy by supporting his educational foundation. Also, hundreds of Ronald McNair scholarship programs nationwide help students who are the first generation of their family to attend college. The program mentors them toward degrees in science, technology, engineering and math.

During her recent master's graduation ceremony at Georgetown Law in Washington, Joy took comfort when Reginald reminded her how proud their father would have been. Joy and her brother are close. They talk about their father "lately more so than ever," she said.

And even now, 26 years later, Joy senses her father's presence.

"I feel a sense of oneness with him - like I really do know him, like he's a part of me and I'm a part of him." When she looks at certain photos of her father, "I even see myself staring back at times.