The late Armstrong’s sons, Mark and Rick, recently spoke with Fortune, discussing their late father, what his pioneering space mission meant to them, and their hopes for the future of space exploration. Mark, now an engineer, was 6 years old when his father became the first man to set foot on the moon. His brother, Rick, a software developer, was 12 years old at the time.

The brothers remember a dining room discussion with their parents, in which they talked about their dad’s upcoming moon trip, and the risks. Then there was the launch, and watching their father on television. Still, to the two young boys, it all seemed very normal.

“We lived in a neighborhood where a lot of people worked at NASA and where that was kind of the norm,” says Mark. “We didn’t understand the risks, the greater historical context.”

What they also didn’t quite understand was the gravity of the moment, 50 years ago, when an estimated 650 million people around the world watched their father set foot on the moon and deliver the now famous phrase: “That’s one small step for man, one giant leap for mankind.”

While the world remembers Neil Armstrong as a space pioneer, Rick shared what it was like growing up with such a celebrated dad, away from the launchpad and the cameras.

“You could get advice from him, talk to him about a lot of things, and he provided information for you to figure out what you want to do,” Rick says of his father, who was 82 years old when he passed away in 2012. “He didn’t push in any direction in particular. He didn’t give us instructions on how to handle a problem. He was just a support network. He was great at that.”

Both Mark and Rick are also excited for the next steps in space exploration, including seeing a woman walk in their father’s footsteps.

NASA has a plan to put the first woman on the moon in 2024. In June, NASA administrator Jim Bridenstine estimated this would cost between $20 billion and $30 billion.

“Going back to the moon is a great plan; it’s the right plan,” Mark says. “We can learn a lot … from the moon. We go back there, set up camp, learn everything that we can, and then we can apply those learnings to Mars and beyond,” he adds.

While the Armstrong brothers are excited that NASA is focusing on a lunar mission, they also have high praise for the billionaire tech titans—including Elon Musk, Jeff Bezos, and Richard Branson—who are racing to send tourists to space.

SpaceX CEO Musk announced last year that his first paying lunar passenger, Japanese entrepreneur Yusaku Maezawa, had put down a “significant deposit” on a lunar trip. Musk did not disclose the cost.

“They aren’t just going to be concerned about getting you there—they’re going to be concerned about the safety of getting there, the safety of getting back, the day-to-day mundane things that you’re going to need to be able to do while you’re in space,” Mark says. “It takes this community of innovators and pioneers to be able to solve the problems of the future.”