With its battered batteries now replaced, the Solar Impulse 2 has been cleared to take to the skies once again after the Pacific leg of its trip around the world caused the sun-powered plan to stumble last year.

The Solar Impulse 2 has been hanging out in a hangar for the past nine months, but it is expected to continue making its way back to Abu Dhabi, its point of origin, at some point this week. Exactly when the plane relaunchces will depend on the weather and the openings it offers.

And when the weather conditions are right, Bertrand Piccard, one of the mission's two pilots, will head off to mainland North America. Piccard, project initiator and chairman, has been splitting time with fellow pilot and explorerer André Borschberg.

The Solar Impulse 2 team is considering Vancouver, Los Angeles, Phoenix and the San Francisco area for the plane's next stop. It will continue on from one of those locations to New York, Europe or North Africa before it tackles the last leg of the trip back to where it began in Abu Dhabi.

Solar Impulse 2

It's a bold attempt to do something that has never been done before. But the Solar Impulse 2 project is more than a historic attempt to fly around the world. It's an effort to contribute to the development of renewable energy, according to Piccard.

"The primary purpose of this adventure is to demonstrate that modern clean technologies can achieve the impossible and encourage everyone to use these same energy efficient solutions on the ground in their daily lives for mobility, construction, lighting, heating, cooling and more," he said.

The plane itself has the wingspan of a 747, about 237 feet. And though it's covered in solar panels, more than 17,000 of them, it only weighs about as much as a typical sedan or about 5,100 pounds.

The single-occupant plane sails along at a speed of about 88 miles per hour, a real test of endurance considering its autopilot mode only affords the pilot about 20 minutes of sleep. It was that low speed and just the vast size of the Pacific Ocean that left the Solar Impulse 2 crawling to Hawaii last July.

What Went Wrong

The flight from Japan to Hawaii last year was a world record. It took five days and five nights, or about 117 hours and 52 minutes, to cross the ocean and land at the Kalaeloa airport.

The grueling trip from Japan to Hawaii uncovered a cooling issue, one that damaged the plane's batteries. The nights were getting longer and the days were getting shorter. There wasn't enough time to replace the batteries and return to the skies while the days were still long enough to adequately charge the plane's 2,077 pounds of batteries.

"As we experienced many times with Solar Impulse, obstacles often turn out to be opportunities for improvement," Borschberg said. "Ultimately, this time was used to recreate the strong mindset within the team to continue our adventure. It takes sometimes more time to build up the right spirit then to develop new technologies."

By late February this year, the Solar Impulse 2 team began to stir again. From then on, the solar-powered plane has gone through 13 test flights and several training flights for the pilots.

With new batteries installed and a new cooling system to go along with them, the team is ready to finish up the trip. This time, the team is targeting landings spots that are even further away to account for possible deviations in the routes.