(CNN)An experimental plane trying to fly around the world without a single drop of fuel took off from Hawaii on Thursday, resuming a journey that had stalled on the island of Oahu for almost 10 months.

The Solar Impulse 2, piloted by Swiss explorer and psychiatrist Bertrand Piccard, lifted off just before sunrise to cheers and applause.

It will head for the San Francisco Bay area, some 4,000 kilometers (2,500 miles) away. And because the plane travels at about the same speed as a car, the Hawaii-California leg will take about 62 hours to complete.

“It’s a very stable weather window,” Solar Impulse spokeswoman Alexandra Gindroz said.

That forecast will be a relief for Piccard and his business partner, Swiss engineer Andre Borschberg, who take turns flying the plane solo.

Fast forward to this spring, and the Solar Impulse 2 has new batteries, a new cooling system that can be manually operated by the pilot, and $20 million in fresh funding to keep the mission up and running.

The engineers and pilots flew more than eight training and maintenance flights over the past few months, and the plane has been performing remarkably well, Blatt said.

While the team is pumped up and feeling confident, Blatt said he recognizes the challenges ahead, including tricky springtime weather over the U.S. mainland.

After several stops in the United States, the pilots hope to cross the Atlantic Ocean, and then Europe or northern Africa.

They plan to return to the Middle East by late summer, completing a 35,000-kilometer (27,000-mile) trip around the world.

Read more: http://www.cnn.com/2016/04/21/travel/solar-impulse-2-plane/index.html