- Full name: Penelope Roberta Robinson
- Birth date: September 9, 1985
- Birth place: Santa Fe, New Mexico, USA
- Height (at launch): 4 feet, 9 inches
- Weight (at launch): 75 pounds
- Eyes: Hazel… Hair: Dark brown
- Hobbies/interests: Zoology, classical music, literature
The original pilot describes Penny as aged 11, with an I.Q. of 147, and zoology as a hobby.
With the arrival of second daughter Penny in 1985, Maureen Robinson left her job at the New Mexico Institute for Space Medicine and became a full-time housewife, a position she found fully satisfying.
Like all of John and Maureen's children, Penny Robinson is talented and intelligent. By the time of the Jupiter 2 launch, when she was 11 years old, she had advanced to the 10th grade and had an I.Q. of 147.
Shortly after the Robinsons were chosen as the first family in space, Penny joined the newly formed Space Scouts. This was a nationwide program that Alpha Control had set up to recruit young people for future colonization missions. Penny's leadership abilities were proven when she was soon elected president of the Santa Fe chapter.
Penny has some tomboyish characteristics, probably due to her closeness to her brother Will. She also has a tendency to let her imagination run out of control. Her parents sometimes have difficulty telling whether she is relating fact or fantasy. This got her into some trouble during her year on Priplanus.
An animal lover, Penny adopted a Bloop—a small, ape-like creature—as a pet shortly after the family reached the planet. She named it Debbie.
Another aspect of Penny's character is her outgoing, friendly personality, that made her very popular with Alpha Control instructors and employees. As Alpha Control's psychological tests predicted, Penny adjusted very well to the stresses and pressures of space travel.
Penny is a deeply thoughtful young girl, growing up on the spaceship without companionship of her own age. She likes to be alone and lives quite actively in her imagination. She is brave and cheerful, though sometimes curt or sarcastic with her younger brother Will. She continues her studies on the Jupiter 2, and hopes eventually to become the foremost authority on extra-terrestrial life.