The solar-powered aeroplane Solar Impulse has landed in Silicon Valley, California, after a three-day flight over the Pacific Ocean from Hawaii. High winds delayed the landing at Moffett Airfield, Mountain View, as pilot Bertrand Piccard flew in a holding pattern off the coast.

Piccard and fellow Swiss pilot Andre Borschberg have been taking turns flying the plane on an around-the-world trip since taking off from Abu Dhabi, the capital of the United Arab Emirates, in March 2015. It made stops in Oman, Myanmar, China, Japan and Hawaii. The trans-Pacific leg was the riskiest part of the plane’s global travels because of the lack of emergency landing sites.

The plane’s ideal flight speed is about 28 mph, though that can double during the day when the sun’s rays are strongest. The carbon-fiber aircraft weighs more than 5,000 pounds, or about as much as a midsize truck. The plane’s wings, which stretch wider than those of a Boeing 747, are equipped with 17,000 solar cells that power propellers and charge batteries. The plane runs on stored energy at night.

Solar Impulse 2 will make three more stops in the United States before crossing the Atlantic Ocean to Europe or Northern Africa. The project, which began in 2002 and is estimated to cost more than $100 million, is meant to highlight the importance of renewable energy and the spirit of innovation.