Solar-Powered Plane Flies Over the Pacific in Potentially Record-Breaking Flight

Early Monday morning local time — Sunday in many parts of the world — a solar-powered aircraft that requires no fuel took off from Nagoya, Japan, with the aim of reaching Hawaii in five days.

If Swiss pilot André Borschberg makes it, the trip will be both the longest distance a solar-powered aircraft has ever flown and the longest time a pilot has ever spent in the air on a solo flight.

Five days may seem like a long time to cross the Pacific, but the group of engineers and climate change-minded investors behind the Solar Impulse 2 plane say it will be worth it if the journey can prove that clean energy rather than fossil fuels can power a plane around the planet.

Part of the reason that the trip will take longer than a conventional flight is that unlike a fuel-powered plane, the Solar Impulse 2 only runs its engine for approximately half of each day, when the sun is out. During those hours, the aircraft climbs to an altitude of about 30,000 feet, sunlight powering its 17,000 solar cells, before turning down its engine at night and letting itself drift down to a mere 3,300-foot elevation — just over half a mile above the Earth’s surface — before meeting the sunrise and rising back up again.

Borschberg, the sole occupant of the ultralight plane about the weight of a car, will take only 20-minute naps during the journey. He’ll use yoga and meditation to stay alert the rest of the time.

The flight of more than 5,000 miles will be the longest leg in what the Solar Impulse project’s backers hope will be the first journey around the world in a solar-powered plane. Borschberg began the voyage in Abu Dhabi, United Arab Emirates, in March, and so far has stopped in Oman, India, Myanmar, and China, breaking solar-flight records along the way. Bad weather forced him to cut short his original Pacific flight attempt and land in Japan in May, and to delay his departure again last week. This time, though, the skies are looking clearer.

At 11:29 a.m. U.S. Eastern time, the Solar Impulse website announced: “We passed the point of no return — there is no way back. Now it’s Hawaii or bust!” Bust, here, would mean that too many clouds block Borschberg’s power source and force him to make a water landing — in which case he’d float at sea and live off his several days’ worth of supplies until a team could rescue him.

Solar Impulse is live-streaming the journey from the plane’s cockpit on YouTube:

It’s also tracking the flight on its website and live-tweeting its progress:

Photo credit: Solar Impulse/Twitter.com

Correction, June 29, 2015: The Solar Impulse website announced, “We passed the point of no return” at 11:29 a.m. U.S. Eastern time (3:29 p.m. UTC). An earlier version of this article mistakenly said the announcement occurred at 10:29 a.m. U.S. Eastern time.