MOUNTAIN VIEW, Calif. — When Bertrand Piccard was growing up in Switzerland, heady discussions about the boundless potential for human endeavor were standard fare.

His grandfather, a physicist and friend of Albert Einstein and Marie Curie, had invented a special capsule so he and a partner could be first to reach the stratosphere in a balloon. His father, an engineer, helped design the submarine that made him and an American naval officer the first to plunge undersea to the earth’s crust.

“All the most incredible things seemed to be completely normal,” Mr. Piccard, a psychiatrist trained in hypnosis, said last week at Moffett Field at the NASA Ames Research Center here, preparing for his next expedition. “I thought this was the normal way to live and I was very disappointed to see that there are a lot of people who are afraid of the unknown, afraid of the doubts, afraid of the question marks.”

He went on to become part of the team that was first to circumnavigate the globe nonstop in a balloon. But when a propane shortage nearly ended his record-setting ride in 1999, he began dreaming of a way to fly day and night without fuel, an idea that has reached fruition in a featherweight solar airplane set for an initial voyage across the United States starting on Friday, weather permitting. His brainchild, the Solar Impulse, will not be the first sun-powered plane to fly; its chief distinction is its ability to go through the night.