(CNN) — Five days, five nights, one pilot — and no fuel; Solar Impulse, the plane aiming to fly around the world powered only by the sun, has taken off on the toughest leg of its round-the-world voyage.
The 8,000-kilometer (4,971-mile) journey from Nanjing, China, to Hawaii — dubbed the “moment of truth” by alternating pilots Andre Borschberg and Bertrand Piccard –was delayed several times because of poor conditions over the Pacific.
But in the early hours of Sunday (Saturday afternoon, ET), Solar Impulse successfully embarked on the lengthy leg of the journey.
Mission Director Raymond Clerc said the latest route would see Solar Impulse fly over South Korea and northwest of Japan before heading out across the Pacific, and may take slightly longer than planned — potentially landing in Hawaii on the evening of Day 6.
Former fighter pilot Borschberg, who will be at the controls alone for the entire 130-hour flight, had expressed excitement for the flight after weeks of holdups.
Borschberg, who also flew from Abu Dhabi to Oman in March on the first leg of the plane’s 35,000-kilometer, five-month journey, said the latest journey would be “the flight of my life.”
He will spend the entire trip in the 3.8-square-meter cockpit, strapped into a special seat that serves both as bed (it reclines, allowing him to do essential exercises and to rest) and toilet.
At night, if there is no turbulence, Borschberg will be able activate the autopilot and nap, but only for 20 minutes at a time.
He and Piccard have been trained in meditation and self-hypnosis to allow them to concentrate for lengthy periods, and yoga to help them relax in the plane’s confined space.
Solar Impulse will be packed with enough food, water and sports drinks to meet Borschberg’s nutritional needs for a week, in case weather problems mean it has to stay in the air longer than expected.
The aircraft is also equipped with oxygen bottles, a parachute and a life raft in case it gets into trouble and Borschberg has to ditch midflight.
Piccard, who is due to fly the Atlantic leg of the journey later in the year, is open about the challenges they face.
In an interview with CNN last month: “Maybe it will fail. Andre and I are very clear with ourselves, that maybe we’ll bail out.”
Solar Impulse has been stuck in China since March, when a planned overnight pit stop in Chongqing turned into three weeks on the ground there before it was able to fly on to Nanjing, the staging post for the mission’s most challenging flight.
After a stopover in Hawaii, adventurer Piccard — who was part of the first team to circumnavigate the globe nonstop in a balloon in 1999 — will take the controls and fly to the U.S. mainland, landing in Arizona.
Solar Impulse will then cross the United States and the Atlantic, before returning to Abu Dhabi in July.
Solar Impulse’s 72-meter (236-foot) wingspan makes it wider than a Boeing 747, but the plane weighs just 2.5 tons, lighter than a large SUV. Its round-the-world mission is intended to raise awareness about the potential of solar power.