Last week we reported that the Solar Impulse 2 could be grounded for up to a year if the experimental solar-powered airplane missed its window to take off across the Pacific Ocean. When the June 23 attempt was canceled due to worsening weather forecasts, co-founder Bertrand Piccard lamented via live web feed about the difficulty of making flight decisions with the whole world watching. It was hardly surprising to hear the news, then, that Solar Impulse successfully took off early this morning from Nagoya, Japan. Pilot André Borschberg has embarked on a solo five-day, five-night flight to Hawaii with nothing but the sun to fuel the journey.

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This long-awaited leg of the round-the-world adventure suffered a series of delays. Beginning in China, poor weather made it impossible to take off and the team was stranded there for three weeks. When the solar-powered plane finally took off, Borschberg was almost immediately turned back by poor weather forecasts, and forced to make an unscheduled stop in Japan. Another three weeks passed before a good weather window opened up on June 23, but that take off was also canceled due to concerns about the plane’s ability to collect enough energy to continue powering the zero-fuel craft through long nights on its way to Hawaii. The experimental plane, which has a wingspan wider than a Boeing 747 but only carries one person, finally took off at 3:03am local Japan time.

Related: Solar Impulse could be grounded in Japan for a whole year

If Solar Impulse reaches Hawaii, it will set a new world record for the longest solar-powered airplane flight. The flight will be the supreme endurance test for both aircraft and pilot. Borschberg will be allowed to rest only 20 minutes at a time, up to 10 times in each 24 hour period, on his five-day journey. He’ll use yoga and meditation techniques during his awake time to keep his mind energized and focused during the dangerous flight.

Despite taking off with little notice, the Solar Impulse mission remains fairly transparent. The team invites the public to tune in to the live feed from the airplane and Mission Control Center in Monaco. In real time, you can listen in on conversations between the pilot and the ground crew, and follow Borschberg’s progress day after day on his way to Hawaii.

+ Solar Impulse

Images via Solar Impulse