BAIKONUR, Kazakhstan — What is the right stuff for a mother in space?

Karen L. Nyberg, an American astronaut whose son, Jack, is 3 years old, is taking the next six months to find out.

Along with docking space ships and conducting science experiments, Ms. Nyberg, 43, who blasted off in late May, is using her tour at the International Space Station to grapple publicly with the difficulty of separating from a child because of work. She is cooperating with a Scandinavian television documentary on motherhood, has spoken to magazines on parenting and embraced the question her long business trip inevitably poses: how to choose between a dream job that requires long travel and the pull of children at home.

“It’s a challenge because my son is 3. He will do a lot of growing in six months,” Ms. Nyberg told journalists before the launching, speaking from behind a glass wall to prevent last-minute infections.

“But I will see a lot of video of him,” she said. “We will be very well connected. And he will be home with Daddy” — Doug Hurley, who is also an astronaut.